Members/tobaru/cbc/CbC_llvm: lib/Transforms/Scalar/TailRecursionElimination.cpp annotate

annotate lib/Transforms/Scalar/TailRecursionElimination.cpp @ 77:54457678186b

LLVM 3.6

author	Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
date	Mon, 08 Sep 2014 22:06:00 +0900
parents	95c75e76d11b
children	67baa08a3894 60c9769439b8

rev	line source
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	1 //===- TailRecursionElimination.cpp - Eliminate Tail Calls ----------------===//
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	2 //
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	3 // The LLVM Compiler Infrastructure
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	4 //
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	5 // This file is distributed under the University of Illinois Open Source
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	6 // License. See LICENSE.TXT for details.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	7 //
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	8 //===----------------------------------------------------------------------===//
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	9 //
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	10 // This file transforms calls of the current function (self recursion) followed
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	11 // by a return instruction with a branch to the entry of the function, creating
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	12 // a loop. This pass also implements the following extensions to the basic
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	13 // algorithm:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	14 //
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	15 // 1. Trivial instructions between the call and return do not prevent the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	16 // transformation from taking place, though currently the analysis cannot
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	17 // support moving any really useful instructions (only dead ones).
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	18 // 2. This pass transforms functions that are prevented from being tail
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	19 // recursive by an associative and commutative expression to use an
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	20 // accumulator variable, thus compiling the typical naive factorial or
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	21 // 'fib' implementation into efficient code.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	22 // 3. TRE is performed if the function returns void, if the return
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	23 // returns the result returned by the call, or if the function returns a
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	24 // run-time constant on all exits from the function. It is possible, though
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	25 // unlikely, that the return returns something else (like constant 0), and
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	26 // can still be TRE'd. It can be TRE'd if ALL OTHER return instructions in
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	27 // the function return the exact same value.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	28 // 4. If it can prove that callees do not access their caller stack frame,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	29 // they are marked as eligible for tail call elimination (by the code
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	30 // generator).
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	31 //
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	32 // There are several improvements that could be made:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	33 //
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	34 // 1. If the function has any alloca instructions, these instructions will be
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	35 // moved out of the entry block of the function, causing them to be
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	36 // evaluated each time through the tail recursion. Safely keeping allocas
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	37 // in the entry block requires analysis to proves that the tail-called
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	38 // function does not read or write the stack object.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	39 // 2. Tail recursion is only performed if the call immediately precedes the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	40 // return instruction. It's possible that there could be a jump between
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	41 // the call and the return.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	42 // 3. There can be intervening operations between the call and the return that
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	43 // prevent the TRE from occurring. For example, there could be GEP's and
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	44 // stores to memory that will not be read or written by the call. This
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	45 // requires some substantial analysis (such as with DSA) to prove safe to
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	46 // move ahead of the call, but doing so could allow many more TREs to be
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	47 // performed, for example in TreeAdd/TreeAlloc from the treeadd benchmark.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	48 // 4. The algorithm we use to detect if callees access their caller stack
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	49 // frames is very primitive.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	50 //
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	51 //===----------------------------------------------------------------------===//
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	52
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	53 #include "llvm/Transforms/Scalar.h"
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	54 #include "llvm/ADT/STLExtras.h"
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	55 #include "llvm/ADT/SmallPtrSet.h"
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	56 #include "llvm/ADT/Statistic.h"
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	57 #include "llvm/Analysis/CaptureTracking.h"
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	58 #include "llvm/Analysis/CFG.h"
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	59 #include "llvm/Analysis/InlineCost.h"
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	60 #include "llvm/Analysis/InstructionSimplify.h"
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	61 #include "llvm/Analysis/Loads.h"
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	62 #include "llvm/Analysis/TargetTransformInfo.h"
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	63 #include "llvm/IR/CFG.h"
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	64 #include "llvm/IR/CallSite.h"
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	65 #include "llvm/IR/Constants.h"
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	66 #include "llvm/IR/DerivedTypes.h"
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	67 #include "llvm/IR/DiagnosticInfo.h"
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	68 #include "llvm/IR/Function.h"
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	69 #include "llvm/IR/Instructions.h"
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	70 #include "llvm/IR/IntrinsicInst.h"
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	71 #include "llvm/IR/Module.h"
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	72 #include "llvm/IR/ValueHandle.h"
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	73 #include "llvm/Pass.h"
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	74 #include "llvm/Support/Debug.h"
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	75 #include "llvm/Support/raw_ostream.h"
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	76 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	77 #include "llvm/Transforms/Utils/Local.h"
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	78 using namespace llvm;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	79
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	80 #define DEBUG_TYPE "tailcallelim"
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	81
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	82 STATISTIC(NumEliminated, "Number of tail calls removed");
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	83 STATISTIC(NumRetDuped, "Number of return duplicated");
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	84 STATISTIC(NumAccumAdded, "Number of accumulators introduced");
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	85
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	86 namespace {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	87 struct TailCallElim : public FunctionPass {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	88 const TargetTransformInfo *TTI;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	89
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	90 static char ID; // Pass identification, replacement for typeid
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	91 TailCallElim() : FunctionPass(ID) {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	92 initializeTailCallElimPass(*PassRegistry::getPassRegistry());
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	93 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	94
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	95 void getAnalysisUsage(AnalysisUsage &AU) const override;
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	96
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	97 bool runOnFunction(Function &F) override;
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	98
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	99 private:
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	100 bool runTRE(Function &F);
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	101 bool markTails(Function &F, bool &AllCallsAreTailCalls);
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	102
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	103 CallInst FindTRECandidate(Instruction I,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	104 bool CannotTailCallElimCallsMarkedTail);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	105 bool EliminateRecursiveTailCall(CallInst CI, ReturnInst Ret,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	106 BasicBlock *&OldEntry,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	107 bool &TailCallsAreMarkedTail,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	108 SmallVectorImpl<PHINode *> &ArgumentPHIs,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	109 bool CannotTailCallElimCallsMarkedTail);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	110 bool FoldReturnAndProcessPred(BasicBlock *BB,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	111 ReturnInst Ret, BasicBlock &OldEntry,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	112 bool &TailCallsAreMarkedTail,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	113 SmallVectorImpl<PHINode *> &ArgumentPHIs,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	114 bool CannotTailCallElimCallsMarkedTail);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	115 bool ProcessReturningBlock(ReturnInst RI, BasicBlock &OldEntry,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	116 bool &TailCallsAreMarkedTail,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	117 SmallVectorImpl<PHINode *> &ArgumentPHIs,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	118 bool CannotTailCallElimCallsMarkedTail);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	119 bool CanMoveAboveCall(Instruction I, CallInst CI);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	120 Value CanTransformAccumulatorRecursion(Instruction I, CallInst *CI);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	121 };
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	122 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	123
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	124 char TailCallElim::ID = 0;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	125 INITIALIZE_PASS_BEGIN(TailCallElim, "tailcallelim",
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	126 "Tail Call Elimination", false, false)
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	127 INITIALIZE_AG_DEPENDENCY(TargetTransformInfo)
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	128 INITIALIZE_PASS_END(TailCallElim, "tailcallelim",
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	129 "Tail Call Elimination", false, false)
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	130
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	131 // Public interface to the TailCallElimination pass
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	132 FunctionPass *llvm::createTailCallEliminationPass() {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	133 return new TailCallElim();
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	134 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	135
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	136 void TailCallElim::getAnalysisUsage(AnalysisUsage &AU) const {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	137 AU.addRequired<TargetTransformInfo>();
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	138 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	139
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	140 /// \brief Scan the specified function for alloca instructions.
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	141 /// If it contains any dynamic allocas, returns false.
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	142 static bool CanTRE(Function &F) {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	143 // Because of PR962, we don't TRE dynamic allocas.
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	144 for (auto &BB : F) {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	145 for (auto &I : BB) {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	146 if (AllocaInst *AI = dyn_cast<AllocaInst>(&I)) {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	147 if (!AI->isStaticAlloca())
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	148 return false;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	149 }
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	150 }
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	151 }
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	152
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	153 return true;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	154 }
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	155
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	156 bool TailCallElim::runOnFunction(Function &F) {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	157 if (skipOptnoneFunction(F))
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	158 return false;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	159
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	160 bool AllCallsAreTailCalls = false;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	161 bool Modified = markTails(F, AllCallsAreTailCalls);
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	162 if (AllCallsAreTailCalls)
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	163 Modified \|= runTRE(F);
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	164 return Modified;
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	165 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	166
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	167 namespace {
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	168 struct AllocaDerivedValueTracker {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	169 // Start at a root value and walk its use-def chain to mark calls that use the
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	170 // value or a derived value in AllocaUsers, and places where it may escape in
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	171 // EscapePoints.
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	172 void walk(Value *Root) {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	173 SmallVector<Use *, 32> Worklist;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	174 SmallPtrSet<Use *, 32> Visited;
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	175
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	176 auto AddUsesToWorklist = [&](Value *V) {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	177 for (auto &U : V->uses()) {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	178 if (!Visited.insert(&U))
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	179 continue;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	180 Worklist.push_back(&U);
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	181 }
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	182 };
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	183
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	184 AddUsesToWorklist(Root);
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	185
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	186 while (!Worklist.empty()) {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	187 Use *U = Worklist.pop_back_val();
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	188 Instruction *I = cast<Instruction>(U->getUser());
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	189
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	190 switch (I->getOpcode()) {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	191 case Instruction::Call:
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	192 case Instruction::Invoke: {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	193 CallSite CS(I);
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	194 bool IsNocapture = !CS.isCallee(U) &&
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	195 CS.doesNotCapture(CS.getArgumentNo(U));
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	196 callUsesLocalStack(CS, IsNocapture);
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	197 if (IsNocapture) {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	198 // If the alloca-derived argument is passed in as nocapture, then it
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	199 // can't propagate to the call's return. That would be capturing.
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	200 continue;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	201 }
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	202 break;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	203 }
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	204 case Instruction::Load: {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	205 // The result of a load is not alloca-derived (unless an alloca has
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	206 // otherwise escaped, but this is a local analysis).
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	207 continue;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	208 }
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	209 case Instruction::Store: {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	210 if (U->getOperandNo() == 0)
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	211 EscapePoints.insert(I);
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	212 continue; // Stores have no users to analyze.
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	213 }
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	214 case Instruction::BitCast:
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	215 case Instruction::GetElementPtr:
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	216 case Instruction::PHI:
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	217 case Instruction::Select:
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	218 case Instruction::AddrSpaceCast:
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	219 break;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	220 default:
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	221 EscapePoints.insert(I);
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	222 break;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	223 }
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	224
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	225 AddUsesToWorklist(I);
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	226 }
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	227 }
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	228
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	229 void callUsesLocalStack(CallSite CS, bool IsNocapture) {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	230 // Add it to the list of alloca users.
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	231 AllocaUsers.insert(CS.getInstruction());
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	232
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	233 // If it's nocapture then it can't capture this alloca.
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	234 if (IsNocapture)
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	235 return;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	236
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	237 // If it can write to memory, it can leak the alloca value.
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	238 if (!CS.onlyReadsMemory())
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	239 EscapePoints.insert(CS.getInstruction());
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	240 }
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	241
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	242 SmallPtrSet<Instruction *, 32> AllocaUsers;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	243 SmallPtrSet<Instruction *, 32> EscapePoints;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	244 };
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	245 }
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	246
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	247 bool TailCallElim::markTails(Function &F, bool &AllCallsAreTailCalls) {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	248 if (F.callsFunctionThatReturnsTwice())
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	249 return false;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	250 AllCallsAreTailCalls = true;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	251
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	252 // The local stack holds all alloca instructions and all byval arguments.
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	253 AllocaDerivedValueTracker Tracker;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	254 for (Argument &Arg : F.args()) {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	255 if (Arg.hasByValAttr())
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	256 Tracker.walk(&Arg);
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	257 }
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	258 for (auto &BB : F) {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	259 for (auto &I : BB)
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	260 if (AllocaInst *AI = dyn_cast<AllocaInst>(&I))
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	261 Tracker.walk(AI);
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	262 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	263
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	264 bool Modified = false;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	265
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	266 // Track whether a block is reachable after an alloca has escaped. Blocks that
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	267 // contain the escaping instruction will be marked as being visited without an
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	268 // escaped alloca, since that is how the block began.
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	269 enum VisitType {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	270 UNVISITED,
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	271 UNESCAPED,
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	272 ESCAPED
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	273 };
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	274 DenseMap<BasicBlock *, VisitType> Visited;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	275
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	276 // We propagate the fact that an alloca has escaped from block to successor.
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	277 // Visit the blocks that are propagating the escapedness first. To do this, we
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	278 // maintain two worklists.
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	279 SmallVector<BasicBlock *, 32> WorklistUnescaped, WorklistEscaped;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	280
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	281 // We may enter a block and visit it thinking that no alloca has escaped yet,
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	282 // then see an escape point and go back around a loop edge and come back to
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	283 // the same block twice. Because of this, we defer setting tail on calls when
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	284 // we first encounter them in a block. Every entry in this list does not
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	285 // statically use an alloca via use-def chain analysis, but may find an alloca
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	286 // through other means if the block turns out to be reachable after an escape
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	287 // point.
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	288 SmallVector<CallInst *, 32> DeferredTails;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	289
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	290 BasicBlock *BB = &F.getEntryBlock();
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	291 VisitType Escaped = UNESCAPED;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	292 do {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	293 for (auto &I : *BB) {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	294 if (Tracker.EscapePoints.count(&I))
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	295 Escaped = ESCAPED;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	296
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	297 CallInst *CI = dyn_cast<CallInst>(&I);
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	298 if (!CI \|\| CI->isTailCall())
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	299 continue;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	300
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	301 if (CI->doesNotAccessMemory()) {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	302 // A call to a readnone function whose arguments are all things computed
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	303 // outside this function can be marked tail. Even if you stored the
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	304 // alloca address into a global, a readnone function can't load the
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	305 // global anyhow.
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	306 //
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	307 // Note that this runs whether we know an alloca has escaped or not. If
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	308 // it has, then we can't trust Tracker.AllocaUsers to be accurate.
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	309 bool SafeToTail = true;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	310 for (auto &Arg : CI->arg_operands()) {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	311 if (isa<Constant>(Arg.getUser()))
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	312 continue;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	313 if (Argument *A = dyn_cast<Argument>(Arg.getUser()))
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	314 if (!A->hasByValAttr())
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	315 continue;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	316 SafeToTail = false;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	317 break;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	318 }
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	319 if (SafeToTail) {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	320 emitOptimizationRemark(
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	321 F.getContext(), "tailcallelim", F, CI->getDebugLoc(),
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	322 "marked this readnone call a tail call candidate");
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	323 CI->setTailCall();
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	324 Modified = true;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	325 continue;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	326 }
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	327 }
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	328
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	329 if (Escaped == UNESCAPED && !Tracker.AllocaUsers.count(CI)) {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	330 DeferredTails.push_back(CI);
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	331 } else {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	332 AllCallsAreTailCalls = false;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	333 }
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	334 }
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	335
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	336 for (auto *SuccBB : make_range(succ_begin(BB), succ_end(BB))) {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	337 auto &State = Visited[SuccBB];
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	338 if (State < Escaped) {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	339 State = Escaped;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	340 if (State == ESCAPED)
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	341 WorklistEscaped.push_back(SuccBB);
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	342 else
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	343 WorklistUnescaped.push_back(SuccBB);
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	344 }
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	345 }
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	346
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	347 if (!WorklistEscaped.empty()) {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	348 BB = WorklistEscaped.pop_back_val();
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	349 Escaped = ESCAPED;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	350 } else {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	351 BB = nullptr;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	352 while (!WorklistUnescaped.empty()) {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	353 auto *NextBB = WorklistUnescaped.pop_back_val();
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	354 if (Visited[NextBB] == UNESCAPED) {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	355 BB = NextBB;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	356 Escaped = UNESCAPED;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	357 break;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	358 }
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	359 }
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	360 }
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	361 } while (BB);
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	362
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	363 for (CallInst *CI : DeferredTails) {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	364 if (Visited[CI->getParent()] != ESCAPED) {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	365 // If the escape point was part way through the block, calls after the
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	366 // escape point wouldn't have been put into DeferredTails.
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	367 emitOptimizationRemark(F.getContext(), "tailcallelim", F,
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	368 CI->getDebugLoc(),
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	369 "marked this call a tail call candidate");
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	370 CI->setTailCall();
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	371 Modified = true;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	372 } else {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	373 AllCallsAreTailCalls = false;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	374 }
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	375 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	376
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	377 return Modified;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	378 }
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	379
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	380 bool TailCallElim::runTRE(Function &F) {
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	381 // If this function is a varargs function, we won't be able to PHI the args
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	382 // right, so don't even try to convert it...
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	383 if (F.getFunctionType()->isVarArg()) return false;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	384
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	385 TTI = &getAnalysis<TargetTransformInfo>();
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	386 BasicBlock *OldEntry = nullptr;
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	387 bool TailCallsAreMarkedTail = false;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	388 SmallVector<PHINode*, 8> ArgumentPHIs;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	389 bool MadeChange = false;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	390
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	391 // CanTRETailMarkedCall - If false, we cannot perform TRE on tail calls
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	392 // marked with the 'tail' attribute, because doing so would cause the stack
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	393 // size to increase (real TRE would deallocate variable sized allocas, TRE
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	394 // doesn't).
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	395 bool CanTRETailMarkedCall = CanTRE(F);
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	396
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	397 // Change any tail recursive calls to loops.
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	398 //
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	399 // FIXME: The code generator produces really bad code when an 'escaping
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	400 // alloca' is changed from being a static alloca to being a dynamic alloca.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	401 // Until this is resolved, disable this transformation if that would ever
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	402 // happen. This bug is PR962.
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	403 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	404 if (ReturnInst *Ret = dyn_cast<ReturnInst>(BB->getTerminator())) {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	405 bool Change = ProcessReturningBlock(Ret, OldEntry, TailCallsAreMarkedTail,
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	406 ArgumentPHIs, !CanTRETailMarkedCall);
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	407 if (!Change && BB->getFirstNonPHIOrDbg() == Ret)
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	408 Change = FoldReturnAndProcessPred(BB, Ret, OldEntry,
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	409 TailCallsAreMarkedTail, ArgumentPHIs,
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	410 !CanTRETailMarkedCall);
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	411 MadeChange \|= Change;
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	412 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	413 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	414
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	415 // If we eliminated any tail recursions, it's possible that we inserted some
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	416 // silly PHI nodes which just merge an initial value (the incoming operand)
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	417 // with themselves. Check to see if we did and clean up our mess if so. This
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	418 // occurs when a function passes an argument straight through to its tail
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	419 // call.
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	420 for (unsigned i = 0, e = ArgumentPHIs.size(); i != e; ++i) {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	421 PHINode *PN = ArgumentPHIs[i];
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	422
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	423 // If the PHI Node is a dynamic constant, replace it with the value it is.
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	424 if (Value *PNV = SimplifyInstruction(PN)) {
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	425 PN->replaceAllUsesWith(PNV);
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	426 PN->eraseFromParent();
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	427 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	428 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	429
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	430 return MadeChange;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	431 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	432
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	433
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	434 /// CanMoveAboveCall - Return true if it is safe to move the specified
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	435 /// instruction from after the call to before the call, assuming that all
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	436 /// instructions between the call and this instruction are movable.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	437 ///
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	438 bool TailCallElim::CanMoveAboveCall(Instruction I, CallInst CI) {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	439 // FIXME: We can move load/store/call/free instructions above the call if the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	440 // call does not mod/ref the memory location being processed.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	441 if (I->mayHaveSideEffects()) // This also handles volatile loads.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	442 return false;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	443
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	444 if (LoadInst *L = dyn_cast<LoadInst>(I)) {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	445 // Loads may always be moved above calls without side effects.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	446 if (CI->mayHaveSideEffects()) {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	447 // Non-volatile loads may be moved above a call with side effects if it
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	448 // does not write to memory and the load provably won't trap.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	449 // FIXME: Writes to memory only matter if they may alias the pointer
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	450 // being loaded from.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	451 if (CI->mayWriteToMemory() \|\|
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	452 !isSafeToLoadUnconditionally(L->getPointerOperand(), L,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	453 L->getAlignment()))
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	454 return false;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	455 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	456 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	457
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	458 // Otherwise, if this is a side-effect free instruction, check to make sure
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	459 // that it does not use the return value of the call. If it doesn't use the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	460 // return value of the call, it must only use things that are defined before
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	461 // the call, or movable instructions between the call and the instruction
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	462 // itself.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	463 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	464 if (I->getOperand(i) == CI)
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	465 return false;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	466 return true;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	467 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	468
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	469 // isDynamicConstant - Return true if the specified value is the same when the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	470 // return would exit as it was when the initial iteration of the recursive
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	471 // function was executed.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	472 //
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	473 // We currently handle static constants and arguments that are not modified as
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	474 // part of the recursion.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	475 //
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	476 static bool isDynamicConstant(Value V, CallInst CI, ReturnInst *RI) {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	477 if (isa<Constant>(V)) return true; // Static constants are always dyn consts
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	478
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	479 // Check to see if this is an immutable argument, if so, the value
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	480 // will be available to initialize the accumulator.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	481 if (Argument *Arg = dyn_cast<Argument>(V)) {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	482 // Figure out which argument number this is...
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	483 unsigned ArgNo = 0;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	484 Function *F = CI->getParent()->getParent();
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	485 for (Function::arg_iterator AI = F->arg_begin(); &*AI != Arg; ++AI)
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	486 ++ArgNo;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	487
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	488 // If we are passing this argument into call as the corresponding
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	489 // argument operand, then the argument is dynamically constant.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	490 // Otherwise, we cannot transform this function safely.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	491 if (CI->getArgOperand(ArgNo) == Arg)
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	492 return true;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	493 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	494
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	495 // Switch cases are always constant integers. If the value is being switched
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	496 // on and the return is only reachable from one of its cases, it's
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	497 // effectively constant.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	498 if (BasicBlock *UniquePred = RI->getParent()->getUniquePredecessor())
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	499 if (SwitchInst *SI = dyn_cast<SwitchInst>(UniquePred->getTerminator()))
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	500 if (SI->getCondition() == V)
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	501 return SI->getDefaultDest() != RI->getParent();
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	502
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	503 // Not a constant or immutable argument, we can't safely transform.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	504 return false;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	505 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	506
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	507 // getCommonReturnValue - Check to see if the function containing the specified
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	508 // tail call consistently returns the same runtime-constant value at all exit
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	509 // points except for IgnoreRI. If so, return the returned value.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	510 //
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	511 static Value getCommonReturnValue(ReturnInst IgnoreRI, CallInst *CI) {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	512 Function *F = CI->getParent()->getParent();
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	513 Value *ReturnedValue = nullptr;
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	514
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	515 for (Function::iterator BBI = F->begin(), E = F->end(); BBI != E; ++BBI) {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	516 ReturnInst *RI = dyn_cast<ReturnInst>(BBI->getTerminator());
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	517 if (RI == nullptr \|\| RI == IgnoreRI) continue;
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	518
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	519 // We can only perform this transformation if the value returned is
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	520 // evaluatable at the start of the initial invocation of the function,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	521 // instead of at the end of the evaluation.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	522 //
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	523 Value *RetOp = RI->getOperand(0);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	524 if (!isDynamicConstant(RetOp, CI, RI))
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	525 return nullptr;
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	526
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	527 if (ReturnedValue && RetOp != ReturnedValue)
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	528 return nullptr; // Cannot transform if differing values are returned.
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	529 ReturnedValue = RetOp;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	530 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	531 return ReturnedValue;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	532 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	533
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	534 /// CanTransformAccumulatorRecursion - If the specified instruction can be
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	535 /// transformed using accumulator recursion elimination, return the constant
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	536 /// which is the start of the accumulator value. Otherwise return null.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	537 ///
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	538 Value TailCallElim::CanTransformAccumulatorRecursion(Instruction I,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	539 CallInst *CI) {
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	540 if (!I->isAssociative() \|\| !I->isCommutative()) return nullptr;
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	541 assert(I->getNumOperands() == 2 &&
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	542 "Associative/commutative operations should have 2 args!");
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	543
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	544 // Exactly one operand should be the result of the call instruction.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	545 if ((I->getOperand(0) == CI && I->getOperand(1) == CI) \|\|
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	546 (I->getOperand(0) != CI && I->getOperand(1) != CI))
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	547 return nullptr;
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	548
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	549 // The only user of this instruction we allow is a single return instruction.
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	550 if (!I->hasOneUse() \|\| !isa<ReturnInst>(I->user_back()))
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	551 return nullptr;
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	552
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	553 // Ok, now we have to check all of the other return instructions in this
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	554 // function. If they return non-constants or differing values, then we cannot
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	555 // transform the function safely.
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	556 return getCommonReturnValue(cast<ReturnInst>(I->user_back()), CI);
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	557 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	558
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	559 static Instruction *FirstNonDbg(BasicBlock::iterator I) {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	560 while (isa<DbgInfoIntrinsic>(I))
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	561 ++I;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	562 return &*I;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	563 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	564
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	565 CallInst*
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	566 TailCallElim::FindTRECandidate(Instruction *TI,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	567 bool CannotTailCallElimCallsMarkedTail) {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	568 BasicBlock *BB = TI->getParent();
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	569 Function *F = BB->getParent();
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	570
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	571 if (&BB->front() == TI) // Make sure there is something before the terminator.
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	572 return nullptr;
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	573
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	574 // Scan backwards from the return, checking to see if there is a tail call in
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	575 // this block. If so, set CI to it.
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	576 CallInst *CI = nullptr;
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	577 BasicBlock::iterator BBI = TI;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	578 while (true) {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	579 CI = dyn_cast<CallInst>(BBI);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	580 if (CI && CI->getCalledFunction() == F)
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	581 break;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	582
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	583 if (BBI == BB->begin())
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	584 return nullptr; // Didn't find a potential tail call.
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	585 --BBI;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	586 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	587
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	588 // If this call is marked as a tail call, and if there are dynamic allocas in
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	589 // the function, we cannot perform this optimization.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	590 if (CI->isTailCall() && CannotTailCallElimCallsMarkedTail)
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	591 return nullptr;
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	592
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	593 // As a special case, detect code like this:
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	594 // double fabs(double f) { return __builtin_fabs(f); } // a 'fabs' call
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	595 // and disable this xform in this case, because the code generator will
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	596 // lower the call to fabs into inline code.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	597 if (BB == &F->getEntryBlock() &&
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	598 FirstNonDbg(BB->front()) == CI &&
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	599 FirstNonDbg(std::next(BB->begin())) == TI &&
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	600 CI->getCalledFunction() &&
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	601 !TTI->isLoweredToCall(CI->getCalledFunction())) {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	602 // A single-block function with just a call and a return. Check that
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	603 // the arguments match.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	604 CallSite::arg_iterator I = CallSite(CI).arg_begin(),
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	605 E = CallSite(CI).arg_end();
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	606 Function::arg_iterator FI = F->arg_begin(),
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	607 FE = F->arg_end();
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	608 for (; I != E && FI != FE; ++I, ++FI)
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	609 if (I != &FI) break;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	610 if (I == E && FI == FE)
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	611 return nullptr;
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	612 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	613
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	614 return CI;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	615 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	616
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	617 bool TailCallElim::EliminateRecursiveTailCall(CallInst CI, ReturnInst Ret,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	618 BasicBlock *&OldEntry,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	619 bool &TailCallsAreMarkedTail,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	620 SmallVectorImpl<PHINode *> &ArgumentPHIs,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	621 bool CannotTailCallElimCallsMarkedTail) {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	622 // If we are introducing accumulator recursion to eliminate operations after
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	623 // the call instruction that are both associative and commutative, the initial
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	624 // value for the accumulator is placed in this variable. If this value is set
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	625 // then we actually perform accumulator recursion elimination instead of
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	626 // simple tail recursion elimination. If the operation is an LLVM instruction
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	627 // (eg: "add") then it is recorded in AccumulatorRecursionInstr. If not, then
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	628 // we are handling the case when the return instruction returns a constant C
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	629 // which is different to the constant returned by other return instructions
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	630 // (which is recorded in AccumulatorRecursionEliminationInitVal). This is a
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	631 // special case of accumulator recursion, the operation being "return C".
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	632 Value *AccumulatorRecursionEliminationInitVal = nullptr;
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	633 Instruction *AccumulatorRecursionInstr = nullptr;
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	634
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	635 // Ok, we found a potential tail call. We can currently only transform the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	636 // tail call if all of the instructions between the call and the return are
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	637 // movable to above the call itself, leaving the call next to the return.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	638 // Check that this is the case now.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	639 BasicBlock::iterator BBI = CI;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	640 for (++BBI; &*BBI != Ret; ++BBI) {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	641 if (CanMoveAboveCall(BBI, CI)) continue;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	642
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	643 // If we can't move the instruction above the call, it might be because it
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	644 // is an associative and commutative operation that could be transformed
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	645 // using accumulator recursion elimination. Check to see if this is the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	646 // case, and if so, remember the initial accumulator value for later.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	647 if ((AccumulatorRecursionEliminationInitVal =
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	648 CanTransformAccumulatorRecursion(BBI, CI))) {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	649 // Yes, this is accumulator recursion. Remember which instruction
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	650 // accumulates.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	651 AccumulatorRecursionInstr = BBI;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	652 } else {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	653 return false; // Otherwise, we cannot eliminate the tail recursion!
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	654 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	655 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	656
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	657 // We can only transform call/return pairs that either ignore the return value
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	658 // of the call and return void, ignore the value of the call and return a
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	659 // constant, return the value returned by the tail call, or that are being
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	660 // accumulator recursion variable eliminated.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	661 if (Ret->getNumOperands() == 1 && Ret->getReturnValue() != CI &&
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	662 !isa<UndefValue>(Ret->getReturnValue()) &&
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	663 AccumulatorRecursionEliminationInitVal == nullptr &&
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	664 !getCommonReturnValue(nullptr, CI)) {
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	665 // One case remains that we are able to handle: the current return
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	666 // instruction returns a constant, and all other return instructions
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	667 // return a different constant.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	668 if (!isDynamicConstant(Ret->getReturnValue(), CI, Ret))
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	669 return false; // Current return instruction does not return a constant.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	670 // Check that all other return instructions return a common constant. If
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	671 // so, record it in AccumulatorRecursionEliminationInitVal.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	672 AccumulatorRecursionEliminationInitVal = getCommonReturnValue(Ret, CI);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	673 if (!AccumulatorRecursionEliminationInitVal)
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	674 return false;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	675 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	676
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	677 BasicBlock *BB = Ret->getParent();
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	678 Function *F = BB->getParent();
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	679
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	680 emitOptimizationRemark(F->getContext(), "tailcallelim", *F, CI->getDebugLoc(),
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	681 "transforming tail recursion to loop");
54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	682
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	683 // OK! We can transform this tail call. If this is the first one found,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	684 // create the new entry block, allowing us to branch back to the old entry.
77 54457678186b LLVM 3.6 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: 0 diff changeset	685 if (!OldEntry) {
0 95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	686 OldEntry = &F->getEntryBlock();
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	687 BasicBlock *NewEntry = BasicBlock::Create(F->getContext(), "", F, OldEntry);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	688 NewEntry->takeName(OldEntry);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	689 OldEntry->setName("tailrecurse");
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	690 BranchInst::Create(OldEntry, NewEntry);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	691
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	692 // If this tail call is marked 'tail' and if there are any allocas in the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	693 // entry block, move them up to the new entry block.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	694 TailCallsAreMarkedTail = CI->isTailCall();
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	695 if (TailCallsAreMarkedTail)
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	696 // Move all fixed sized allocas from OldEntry to NewEntry.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	697 for (BasicBlock::iterator OEBI = OldEntry->begin(), E = OldEntry->end(),
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	698 NEBI = NewEntry->begin(); OEBI != E; )
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	699 if (AllocaInst *AI = dyn_cast<AllocaInst>(OEBI++))
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	700 if (isa<ConstantInt>(AI->getArraySize()))
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	701 AI->moveBefore(NEBI);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	702
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	703 // Now that we have created a new block, which jumps to the entry
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	704 // block, insert a PHI node for each argument of the function.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	705 // For now, we initialize each PHI to only have the real arguments
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	706 // which are passed in.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	707 Instruction *InsertPos = OldEntry->begin();
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	708 for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end();
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	709 I != E; ++I) {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	710 PHINode *PN = PHINode::Create(I->getType(), 2,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	711 I->getName() + ".tr", InsertPos);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	712 I->replaceAllUsesWith(PN); // Everyone use the PHI node now!
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	713 PN->addIncoming(I, NewEntry);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	714 ArgumentPHIs.push_back(PN);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	715 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	716 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	717
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	718 // If this function has self recursive calls in the tail position where some
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	719 // are marked tail and some are not, only transform one flavor or another. We
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	720 // have to choose whether we move allocas in the entry block to the new entry
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	721 // block or not, so we can't make a good choice for both. NOTE: We could do
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	722 // slightly better here in the case that the function has no entry block
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	723 // allocas.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	724 if (TailCallsAreMarkedTail && !CI->isTailCall())
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	725 return false;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	726
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	727 // Ok, now that we know we have a pseudo-entry block WITH all of the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	728 // required PHI nodes, add entries into the PHI node for the actual
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	729 // parameters passed into the tail-recursive call.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	730 for (unsigned i = 0, e = CI->getNumArgOperands(); i != e; ++i)
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	731 ArgumentPHIs[i]->addIncoming(CI->getArgOperand(i), BB);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	732
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	733 // If we are introducing an accumulator variable to eliminate the recursion,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	734 // do so now. Note that we _know_ that no subsequent tail recursion
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	735 // eliminations will happen on this function because of the way the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	736 // accumulator recursion predicate is set up.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	737 //
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	738 if (AccumulatorRecursionEliminationInitVal) {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	739 Instruction *AccRecInstr = AccumulatorRecursionInstr;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	740 // Start by inserting a new PHI node for the accumulator.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	741 pred_iterator PB = pred_begin(OldEntry), PE = pred_end(OldEntry);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	742 PHINode *AccPN =
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	743 PHINode::Create(AccumulatorRecursionEliminationInitVal->getType(),
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	744 std::distance(PB, PE) + 1,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	745 "accumulator.tr", OldEntry->begin());
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	746
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	747 // Loop over all of the predecessors of the tail recursion block. For the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	748 // real entry into the function we seed the PHI with the initial value,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	749 // computed earlier. For any other existing branches to this block (due to
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	750 // other tail recursions eliminated) the accumulator is not modified.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	751 // Because we haven't added the branch in the current block to OldEntry yet,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	752 // it will not show up as a predecessor.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	753 for (pred_iterator PI = PB; PI != PE; ++PI) {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	754 BasicBlock P = PI;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	755 if (P == &F->getEntryBlock())
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	756 AccPN->addIncoming(AccumulatorRecursionEliminationInitVal, P);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	757 else
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	758 AccPN->addIncoming(AccPN, P);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	759 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	760
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	761 if (AccRecInstr) {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	762 // Add an incoming argument for the current block, which is computed by
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	763 // our associative and commutative accumulator instruction.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	764 AccPN->addIncoming(AccRecInstr, BB);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	765
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	766 // Next, rewrite the accumulator recursion instruction so that it does not
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	767 // use the result of the call anymore, instead, use the PHI node we just
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	768 // inserted.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	769 AccRecInstr->setOperand(AccRecInstr->getOperand(0) != CI, AccPN);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	770 } else {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	771 // Add an incoming argument for the current block, which is just the
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	772 // constant returned by the current return instruction.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	773 AccPN->addIncoming(Ret->getReturnValue(), BB);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	774 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	775
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	776 // Finally, rewrite any return instructions in the program to return the PHI
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	777 // node instead of the "initval" that they do currently. This loop will
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	778 // actually rewrite the return value we are destroying, but that's ok.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	779 for (Function::iterator BBI = F->begin(), E = F->end(); BBI != E; ++BBI)
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	780 if (ReturnInst *RI = dyn_cast<ReturnInst>(BBI->getTerminator()))
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	781 RI->setOperand(0, AccPN);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	782 ++NumAccumAdded;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	783 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	784
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	785 // Now that all of the PHI nodes are in place, remove the call and
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	786 // ret instructions, replacing them with an unconditional branch.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	787 BranchInst *NewBI = BranchInst::Create(OldEntry, Ret);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	788 NewBI->setDebugLoc(CI->getDebugLoc());
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	789
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	790 BB->getInstList().erase(Ret); // Remove return.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	791 BB->getInstList().erase(CI); // Remove call.
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	792 ++NumEliminated;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	793 return true;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	794 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	795
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	796 bool TailCallElim::FoldReturnAndProcessPred(BasicBlock *BB,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	797 ReturnInst Ret, BasicBlock &OldEntry,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	798 bool &TailCallsAreMarkedTail,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	799 SmallVectorImpl<PHINode *> &ArgumentPHIs,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	800 bool CannotTailCallElimCallsMarkedTail) {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	801 bool Change = false;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	802
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	803 // If the return block contains nothing but the return and PHI's,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	804 // there might be an opportunity to duplicate the return in its
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	805 // predecessors and perform TRC there. Look for predecessors that end
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	806 // in unconditional branch and recursive call(s).
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	807 SmallVector<BranchInst*, 8> UncondBranchPreds;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	808 for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	809 BasicBlock Pred = PI;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	810 TerminatorInst *PTI = Pred->getTerminator();
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	811 if (BranchInst *BI = dyn_cast<BranchInst>(PTI))
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	812 if (BI->isUnconditional())
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	813 UncondBranchPreds.push_back(BI);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	814 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	815
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	816 while (!UncondBranchPreds.empty()) {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	817 BranchInst *BI = UncondBranchPreds.pop_back_val();
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	818 BasicBlock *Pred = BI->getParent();
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	819 if (CallInst *CI = FindTRECandidate(BI, CannotTailCallElimCallsMarkedTail)){
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	820 DEBUG(dbgs() << "FOLDING: " << *BB
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	821 << "INTO UNCOND BRANCH PRED: " << *Pred);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	822 EliminateRecursiveTailCall(CI, FoldReturnIntoUncondBranch(Ret, BB, Pred),
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	823 OldEntry, TailCallsAreMarkedTail, ArgumentPHIs,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	824 CannotTailCallElimCallsMarkedTail);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	825 ++NumRetDuped;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	826 Change = true;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	827 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	828 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	829
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	830 return Change;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	831 }
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	832
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	833 bool
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	834 TailCallElim::ProcessReturningBlock(ReturnInst Ret, BasicBlock &OldEntry,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	835 bool &TailCallsAreMarkedTail,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	836 SmallVectorImpl<PHINode *> &ArgumentPHIs,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	837 bool CannotTailCallElimCallsMarkedTail) {
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	838 CallInst *CI = FindTRECandidate(Ret, CannotTailCallElimCallsMarkedTail);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	839 if (!CI)
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	840 return false;
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	841
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	842 return EliminateRecursiveTailCall(CI, Ret, OldEntry, TailCallsAreMarkedTail,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	843 ArgumentPHIs,
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	844 CannotTailCallElimCallsMarkedTail);
95c75e76d11b LLVM 3.4 Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp> parents: diff changeset	845 }

Mercurial > hg > Members > tobaru > cbc > CbC_llvm

annotate lib/Transforms/Scalar/TailRecursionElimination.cpp @ 77:54457678186b