CbC/CbC_llvm: lib/Analysis/InlineCost.cpp comparison

comparison lib/Analysis/InlineCost.cpp @ 95:afa8332a0e37 LLVM3.8

LLVM 3.8

author	Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
date	Tue, 13 Oct 2015 17:48:58 +0900
parents
children	7d135dc70f03

comparison

equal deleted inserted replaced

-:f3e34b893a5f
+:afa8332a0e37
+//===- InlineCost.cpp - Cost analysis for inliner -------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements inline cost analysis.
+//
+//===----------------------------------------------------------------------===//
+#include "llvm/Analysis/InlineCost.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SetVector.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/AssumptionCache.h"
+#include "llvm/Analysis/CodeMetrics.h"
+#include "llvm/Analysis/ConstantFolding.h"
+#include "llvm/Analysis/InstructionSimplify.h"
+#include "llvm/Analysis/TargetTransformInfo.h"
+#include "llvm/IR/CallSite.h"
+#include "llvm/IR/CallingConv.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/GetElementPtrTypeIterator.h"
+#include "llvm/IR/GlobalAlias.h"
+#include "llvm/IR/InstVisitor.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/Operator.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+using namespace llvm;
+#define DEBUG_TYPE "inline-cost"
+STATISTIC(NumCallsAnalyzed, "Number of call sites analyzed");
+namespace {
+class CallAnalyzer : public InstVisitor<CallAnalyzer, bool> {
+typedef InstVisitor<CallAnalyzer, bool> Base;
+friend class InstVisitor<CallAnalyzer, bool>;
+/// The TargetTransformInfo available for this compilation.
+const TargetTransformInfo &TTI;
+/// The cache of @llvm.assume intrinsics.
+AssumptionCacheTracker *ACT;
+// The called function.
+Function &F;
+// The candidate callsite being analyzed. Please do not use this to do
+// analysis in the caller function; we want the inline cost query to be
+// easily cacheable. Instead, use the cover function paramHasAttr.
+CallSite CandidateCS;
+int Threshold;
+int Cost;
+bool IsCallerRecursive;
+bool IsRecursiveCall;
+bool ExposesReturnsTwice;
+bool HasDynamicAlloca;
+bool ContainsNoDuplicateCall;
+bool HasReturn;
+bool HasIndirectBr;
+bool HasFrameEscape;
+/// Number of bytes allocated statically by the callee.
+uint64_t AllocatedSize;
+unsigned NumInstructions, NumVectorInstructions;
+int FiftyPercentVectorBonus, TenPercentVectorBonus;
+int VectorBonus;
+// While we walk the potentially-inlined instructions, we build up and
+// maintain a mapping of simplified values specific to this callsite. The
+// idea is to propagate any special information we have about arguments to
+// this call through the inlinable section of the function, and account for
+// likely simplifications post-inlining. The most important aspect we track
+// is CFG altering simplifications -- when we prove a basic block dead, that
+// can cause dramatic shifts in the cost of inlining a function.
+DenseMap<Value *, Constant *> SimplifiedValues;
+// Keep track of the values which map back (through function arguments) to
+// allocas on the caller stack which could be simplified through SROA.
+DenseMap<Value *, Value *> SROAArgValues;
+// The mapping of caller Alloca values to their accumulated cost savings. If
+// we have to disable SROA for one of the allocas, this tells us how much
+// cost must be added.
+DenseMap<Value *, int> SROAArgCosts;
+// Keep track of values which map to a pointer base and constant offset.
+DenseMap<Value *, std::pair<Value *, APInt> > ConstantOffsetPtrs;
+// Custom simplification helper routines.
+bool isAllocaDerivedArg(Value *V);
+bool lookupSROAArgAndCost(Value *V, Value *&Arg,
+DenseMap<Value *, int>::iterator &CostIt);
+void disableSROA(DenseMap<Value *, int>::iterator CostIt);
+void disableSROA(Value *V);
+void accumulateSROACost(DenseMap<Value *, int>::iterator CostIt,
+int InstructionCost);
+bool isGEPOffsetConstant(GetElementPtrInst &GEP);
+bool accumulateGEPOffset(GEPOperator &GEP, APInt &Offset);
+bool simplifyCallSite(Function *F, CallSite CS);
+ConstantInt *stripAndComputeInBoundsConstantOffsets(Value *&V);
+/// Return true if the given argument to the function being considered for
+/// inlining has the given attribute set either at the call site or the
+/// function declaration.  Primarily used to inspect call site specific
+/// attributes since these can be more precise than the ones on the callee
+/// itself.
+bool paramHasAttr(Argument *A, Attribute::AttrKind Attr);
+/// Return true if the given value is known non null within the callee if
+/// inlined through this particular callsite.
+bool isKnownNonNullInCallee(Value *V);
+// Custom analysis routines.
+bool analyzeBlock(BasicBlock *BB, SmallPtrSetImpl<const Value *> &EphValues);
+// Disable several entry points to the visitor so we don't accidentally use
+// them by declaring but not defining them here.
+void visit(Module *);     void visit(Module &);
+void visit(Function *);   void visit(Function &);
+void visit(BasicBlock *); void visit(BasicBlock &);
+// Provide base case for our instruction visit.
+bool visitInstruction(Instruction &I);
+// Our visit overrides.
+bool visitAlloca(AllocaInst &I);
+bool visitPHI(PHINode &I);
+bool visitGetElementPtr(GetElementPtrInst &I);
+bool visitBitCast(BitCastInst &I);
+bool visitPtrToInt(PtrToIntInst &I);
+bool visitIntToPtr(IntToPtrInst &I);
+bool visitCastInst(CastInst &I);
+bool visitUnaryInstruction(UnaryInstruction &I);
+bool visitCmpInst(CmpInst &I);
+bool visitSub(BinaryOperator &I);
+bool visitBinaryOperator(BinaryOperator &I);
+bool visitLoad(LoadInst &I);
+bool visitStore(StoreInst &I);
+bool visitExtractValue(ExtractValueInst &I);
+bool visitInsertValue(InsertValueInst &I);
+bool visitCallSite(CallSite CS);
+bool visitReturnInst(ReturnInst &RI);
+bool visitBranchInst(BranchInst &BI);
+bool visitSwitchInst(SwitchInst &SI);
+bool visitIndirectBrInst(IndirectBrInst &IBI);
+bool visitResumeInst(ResumeInst &RI);
+bool visitCleanupReturnInst(CleanupReturnInst &RI);
+bool visitCatchReturnInst(CatchReturnInst &RI);
+bool visitUnreachableInst(UnreachableInst &I);
+public:
+CallAnalyzer(const TargetTransformInfo &TTI, AssumptionCacheTracker *ACT,
+Function &Callee, int Threshold, CallSite CSArg)
+: TTI(TTI), ACT(ACT), F(Callee), CandidateCS(CSArg), Threshold(Threshold),
+Cost(0), IsCallerRecursive(false), IsRecursiveCall(false),
+ExposesReturnsTwice(false), HasDynamicAlloca(false),
+ContainsNoDuplicateCall(false), HasReturn(false), HasIndirectBr(false),
+HasFrameEscape(false), AllocatedSize(0), NumInstructions(0),
+NumVectorInstructions(0), FiftyPercentVectorBonus(0),
+TenPercentVectorBonus(0), VectorBonus(0), NumConstantArgs(0),
+NumConstantOffsetPtrArgs(0), NumAllocaArgs(0), NumConstantPtrCmps(0),
+NumConstantPtrDiffs(0), NumInstructionsSimplified(0),
+SROACostSavings(0), SROACostSavingsLost(0) {}
+bool analyzeCall(CallSite CS);
+int getThreshold() { return Threshold; }
+int getCost() { return Cost; }
+// Keep a bunch of stats about the cost savings found so we can print them
+// out when debugging.
+unsigned NumConstantArgs;
+unsigned NumConstantOffsetPtrArgs;
+unsigned NumAllocaArgs;
+unsigned NumConstantPtrCmps;
+unsigned NumConstantPtrDiffs;
+unsigned NumInstructionsSimplified;
+unsigned SROACostSavings;
+unsigned SROACostSavingsLost;
+void dump();
+};
+} // namespace
+/// \brief Test whether the given value is an Alloca-derived function argument.
+bool CallAnalyzer::isAllocaDerivedArg(Value *V) {
+return SROAArgValues.count(V);
+}
+/// \brief Lookup the SROA-candidate argument and cost iterator which V maps to.
+/// Returns false if V does not map to a SROA-candidate.
+bool CallAnalyzer::lookupSROAArgAndCost(
+Value *V, Value *&Arg, DenseMap<Value *, int>::iterator &CostIt) {
+if (SROAArgValues.empty() || SROAArgCosts.empty())
+return false;
+DenseMap<Value *, Value *>::iterator ArgIt = SROAArgValues.find(V);
+if (ArgIt == SROAArgValues.end())
+return false;
+Arg = ArgIt->second;
+CostIt = SROAArgCosts.find(Arg);
+return CostIt != SROAArgCosts.end();
+}
+/// \brief Disable SROA for the candidate marked by this cost iterator.
+///
+/// This marks the candidate as no longer viable for SROA, and adds the cost
+/// savings associated with it back into the inline cost measurement.
+void CallAnalyzer::disableSROA(DenseMap<Value *, int>::iterator CostIt) {
+// If we're no longer able to perform SROA we need to undo its cost savings
+// and prevent subsequent analysis.
+Cost += CostIt->second;
+SROACostSavings -= CostIt->second;
+SROACostSavingsLost += CostIt->second;
+SROAArgCosts.erase(CostIt);
+}
+/// \brief If 'V' maps to a SROA candidate, disable SROA for it.
+void CallAnalyzer::disableSROA(Value *V) {
+Value *SROAArg;
+DenseMap<Value *, int>::iterator CostIt;
+if (lookupSROAArgAndCost(V, SROAArg, CostIt))
+disableSROA(CostIt);
+}
+/// \brief Accumulate the given cost for a particular SROA candidate.
+void CallAnalyzer::accumulateSROACost(DenseMap<Value *, int>::iterator CostIt,
+int InstructionCost) {
+CostIt->second += InstructionCost;
+SROACostSavings += InstructionCost;
+}
+/// \brief Check whether a GEP's indices are all constant.
+///
+/// Respects any simplified values known during the analysis of this callsite.
+bool CallAnalyzer::isGEPOffsetConstant(GetElementPtrInst &GEP) {
+for (User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end(); I != E; ++I)
+if (!isa<Constant>(*I) && !SimplifiedValues.lookup(*I))
+return false;
+return true;
+}
+/// \brief Accumulate a constant GEP offset into an APInt if possible.
+///
+/// Returns false if unable to compute the offset for any reason. Respects any
+/// simplified values known during the analysis of this callsite.
+bool CallAnalyzer::accumulateGEPOffset(GEPOperator &GEP, APInt &Offset) {
+const DataLayout &DL = F.getParent()->getDataLayout();
+unsigned IntPtrWidth = DL.getPointerSizeInBits();
+assert(IntPtrWidth == Offset.getBitWidth());
+for (gep_type_iterator GTI = gep_type_begin(GEP), GTE = gep_type_end(GEP);
+GTI != GTE; ++GTI) {
+ConstantInt *OpC = dyn_cast<ConstantInt>(GTI.getOperand());
+if (!OpC)
+if (Constant *SimpleOp = SimplifiedValues.lookup(GTI.getOperand()))
+OpC = dyn_cast<ConstantInt>(SimpleOp);
+if (!OpC)
+return false;
+if (OpC->isZero()) continue;
+// Handle a struct index, which adds its field offset to the pointer.
+if (StructType *STy = dyn_cast<StructType>(*GTI)) {
+unsigned ElementIdx = OpC->getZExtValue();
+const StructLayout *SL = DL.getStructLayout(STy);
+Offset += APInt(IntPtrWidth, SL->getElementOffset(ElementIdx));
+continue;
+}
+APInt TypeSize(IntPtrWidth, DL.getTypeAllocSize(GTI.getIndexedType()));
+Offset += OpC->getValue().sextOrTrunc(IntPtrWidth) * TypeSize;
+}
+return true;
+}
+bool CallAnalyzer::visitAlloca(AllocaInst &I) {
+// Check whether inlining will turn a dynamic alloca into a static
+// alloca, and handle that case.
+if (I.isArrayAllocation()) {
+if (Constant *Size = SimplifiedValues.lookup(I.getArraySize())) {
+ConstantInt *AllocSize = dyn_cast<ConstantInt>(Size);
+assert(AllocSize && "Allocation size not a constant int?");
+Type *Ty = I.getAllocatedType();
+AllocatedSize += Ty->getPrimitiveSizeInBits() * AllocSize->getZExtValue();
+return Base::visitAlloca(I);
+}
+}
+// Accumulate the allocated size.
+if (I.isStaticAlloca()) {
+const DataLayout &DL = F.getParent()->getDataLayout();
+Type *Ty = I.getAllocatedType();
+AllocatedSize += DL.getTypeAllocSize(Ty);
+}
+// We will happily inline static alloca instructions.
+if (I.isStaticAlloca())
+return Base::visitAlloca(I);
+// FIXME: This is overly conservative. Dynamic allocas are inefficient for
+// a variety of reasons, and so we would like to not inline them into
+// functions which don't currently have a dynamic alloca. This simply
+// disables inlining altogether in the presence of a dynamic alloca.
+HasDynamicAlloca = true;
+return false;
+}
+bool CallAnalyzer::visitPHI(PHINode &I) {
+// FIXME: We should potentially be tracking values through phi nodes,
+// especially when they collapse to a single value due to deleted CFG edges
+// during inlining.
+// FIXME: We need to propagate SROA *disabling* through phi nodes, even
+// though we don't want to propagate it's bonuses. The idea is to disable
+// SROA if it *might* be used in an inappropriate manner.
+// Phi nodes are always zero-cost.
+return true;
+}
+bool CallAnalyzer::visitGetElementPtr(GetElementPtrInst &I) {
+Value *SROAArg;
+DenseMap<Value *, int>::iterator CostIt;
+bool SROACandidate = lookupSROAArgAndCost(I.getPointerOperand(),
+SROAArg, CostIt);
+// Try to fold GEPs of constant-offset call site argument pointers. This
+// requires target data and inbounds GEPs.
+if (I.isInBounds()) {
+// Check if we have a base + offset for the pointer.
+Value *Ptr = I.getPointerOperand();
+std::pair<Value *, APInt> BaseAndOffset = ConstantOffsetPtrs.lookup(Ptr);
+if (BaseAndOffset.first) {
+// Check if the offset of this GEP is constant, and if so accumulate it
+// into Offset.
+if (!accumulateGEPOffset(cast<GEPOperator>(I), BaseAndOffset.second)) {
+// Non-constant GEPs aren't folded, and disable SROA.
+if (SROACandidate)
+disableSROA(CostIt);
+return false;
+}
+// Add the result as a new mapping to Base + Offset.
+ConstantOffsetPtrs[&I] = BaseAndOffset;
+// Also handle SROA candidates here, we already know that the GEP is
+// all-constant indexed.
+if (SROACandidate)
+SROAArgValues[&I] = SROAArg;
+return true;
+}
+}
+if (isGEPOffsetConstant(I)) {
+if (SROACandidate)
+SROAArgValues[&I] = SROAArg;
+// Constant GEPs are modeled as free.
+return true;
+}
+// Variable GEPs will require math and will disable SROA.
+if (SROACandidate)
+disableSROA(CostIt);
+return false;
+}
+bool CallAnalyzer::visitBitCast(BitCastInst &I) {
+// Propagate constants through bitcasts.
+Constant *COp = dyn_cast<Constant>(I.getOperand(0));
+if (!COp)
+COp = SimplifiedValues.lookup(I.getOperand(0));
+if (COp)
+if (Constant *C = ConstantExpr::getBitCast(COp, I.getType())) {
+SimplifiedValues[&I] = C;
+return true;
+}
+// Track base/offsets through casts
+std::pair<Value *, APInt> BaseAndOffset
+= ConstantOffsetPtrs.lookup(I.getOperand(0));
+// Casts don't change the offset, just wrap it up.
+if (BaseAndOffset.first)
+ConstantOffsetPtrs[&I] = BaseAndOffset;
+// Also look for SROA candidates here.
+Value *SROAArg;
+DenseMap<Value *, int>::iterator CostIt;
+if (lookupSROAArgAndCost(I.getOperand(0), SROAArg, CostIt))
+SROAArgValues[&I] = SROAArg;
+// Bitcasts are always zero cost.
+return true;
+}
+bool CallAnalyzer::visitPtrToInt(PtrToIntInst &I) {
+// Propagate constants through ptrtoint.
+Constant *COp = dyn_cast<Constant>(I.getOperand(0));
+if (!COp)
+COp = SimplifiedValues.lookup(I.getOperand(0));
+if (COp)
+if (Constant *C = ConstantExpr::getPtrToInt(COp, I.getType())) {
+SimplifiedValues[&I] = C;
+return true;
+}
+// Track base/offset pairs when converted to a plain integer provided the
+// integer is large enough to represent the pointer.
+unsigned IntegerSize = I.getType()->getScalarSizeInBits();
+const DataLayout &DL = F.getParent()->getDataLayout();
+if (IntegerSize >= DL.getPointerSizeInBits()) {
+std::pair<Value *, APInt> BaseAndOffset
+= ConstantOffsetPtrs.lookup(I.getOperand(0));
+if (BaseAndOffset.first)
+ConstantOffsetPtrs[&I] = BaseAndOffset;
+}
+// This is really weird. Technically, ptrtoint will disable SROA. However,
+// unless that ptrtoint is *used* somewhere in the live basic blocks after
+// inlining, it will be nuked, and SROA should proceed. All of the uses which
+// would block SROA would also block SROA if applied directly to a pointer,
+// and so we can just add the integer in here. The only places where SROA is
+// preserved either cannot fire on an integer, or won't in-and-of themselves
+// disable SROA (ext) w/o some later use that we would see and disable.
+Value *SROAArg;
+DenseMap<Value *, int>::iterator CostIt;
+if (lookupSROAArgAndCost(I.getOperand(0), SROAArg, CostIt))
+SROAArgValues[&I] = SROAArg;
+return TargetTransformInfo::TCC_Free == TTI.getUserCost(&I);
+}
+bool CallAnalyzer::visitIntToPtr(IntToPtrInst &I) {
+// Propagate constants through ptrtoint.
+Constant *COp = dyn_cast<Constant>(I.getOperand(0));
+if (!COp)
+COp = SimplifiedValues.lookup(I.getOperand(0));
+if (COp)
+if (Constant *C = ConstantExpr::getIntToPtr(COp, I.getType())) {
+SimplifiedValues[&I] = C;
+return true;
+}
+// Track base/offset pairs when round-tripped through a pointer without
+// modifications provided the integer is not too large.
+Value *Op = I.getOperand(0);
+unsigned IntegerSize = Op->getType()->getScalarSizeInBits();
+const DataLayout &DL = F.getParent()->getDataLayout();
+if (IntegerSize <= DL.getPointerSizeInBits()) {
+std::pair<Value *, APInt> BaseAndOffset = ConstantOffsetPtrs.lookup(Op);
+if (BaseAndOffset.first)
+ConstantOffsetPtrs[&I] = BaseAndOffset;
+}
+// "Propagate" SROA here in the same manner as we do for ptrtoint above.
+Value *SROAArg;
+DenseMap<Value *, int>::iterator CostIt;
+if (lookupSROAArgAndCost(Op, SROAArg, CostIt))
+SROAArgValues[&I] = SROAArg;
+return TargetTransformInfo::TCC_Free == TTI.getUserCost(&I);
+}
+bool CallAnalyzer::visitCastInst(CastInst &I) {
+// Propagate constants through ptrtoint.
+Constant *COp = dyn_cast<Constant>(I.getOperand(0));
+if (!COp)
+COp = SimplifiedValues.lookup(I.getOperand(0));
+if (COp)
+if (Constant *C = ConstantExpr::getCast(I.getOpcode(), COp, I.getType())) {
+SimplifiedValues[&I] = C;
+return true;
+}
+// Disable SROA in the face of arbitrary casts we don't whitelist elsewhere.
+disableSROA(I.getOperand(0));
+return TargetTransformInfo::TCC_Free == TTI.getUserCost(&I);
+}
+bool CallAnalyzer::visitUnaryInstruction(UnaryInstruction &I) {
+Value *Operand = I.getOperand(0);
+Constant *COp = dyn_cast<Constant>(Operand);
+if (!COp)
+COp = SimplifiedValues.lookup(Operand);
+if (COp) {
+const DataLayout &DL = F.getParent()->getDataLayout();
+if (Constant *C = ConstantFoldInstOperands(I.getOpcode(), I.getType(),
+COp, DL)) {
+SimplifiedValues[&I] = C;
+return true;
+}
+}
+// Disable any SROA on the argument to arbitrary unary operators.
+disableSROA(Operand);
+return false;
+}
+bool CallAnalyzer::paramHasAttr(Argument *A, Attribute::AttrKind Attr) {
+unsigned ArgNo = A->getArgNo();
+return CandidateCS.paramHasAttr(ArgNo+1, Attr);
+}
+bool CallAnalyzer::isKnownNonNullInCallee(Value *V) {
+// Does the *call site* have the NonNull attribute set on an argument?  We
+// use the attribute on the call site to memoize any analysis done in the
+// caller. This will also trip if the callee function has a non-null
+// parameter attribute, but that's a less interesting case because hopefully
+// the callee would already have been simplified based on that.
+if (Argument *A = dyn_cast<Argument>(V))
+if (paramHasAttr(A, Attribute::NonNull))
+return true;
+// Is this an alloca in the caller?  This is distinct from the attribute case
+// above because attributes aren't updated within the inliner itself and we
+// always want to catch the alloca derived case.
+if (isAllocaDerivedArg(V))
+// We can actually predict the result of comparisons between an
+// alloca-derived value and null. Note that this fires regardless of
+// SROA firing.
+return true;
+return false;
+}
+bool CallAnalyzer::visitCmpInst(CmpInst &I) {
+Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
+// First try to handle simplified comparisons.
+if (!isa<Constant>(LHS))
+if (Constant *SimpleLHS = SimplifiedValues.lookup(LHS))
+LHS = SimpleLHS;
+if (!isa<Constant>(RHS))
+if (Constant *SimpleRHS = SimplifiedValues.lookup(RHS))
+RHS = SimpleRHS;
+if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
+if (Constant *CRHS = dyn_cast<Constant>(RHS))
+if (Constant *C = ConstantExpr::getCompare(I.getPredicate(), CLHS, CRHS)) {
+SimplifiedValues[&I] = C;
+return true;
+}
+}
+if (I.getOpcode() == Instruction::FCmp)
+return false;
+// Otherwise look for a comparison between constant offset pointers with
+// a common base.
+Value *LHSBase, *RHSBase;
+APInt LHSOffset, RHSOffset;
+std::tie(LHSBase, LHSOffset) = ConstantOffsetPtrs.lookup(LHS);
+if (LHSBase) {
+std::tie(RHSBase, RHSOffset) = ConstantOffsetPtrs.lookup(RHS);
+if (RHSBase && LHSBase == RHSBase) {
+// We have common bases, fold the icmp to a constant based on the
+// offsets.
+Constant *CLHS = ConstantInt::get(LHS->getContext(), LHSOffset);
+Constant *CRHS = ConstantInt::get(RHS->getContext(), RHSOffset);
+if (Constant *C = ConstantExpr::getICmp(I.getPredicate(), CLHS, CRHS)) {
+SimplifiedValues[&I] = C;
+++NumConstantPtrCmps;
+return true;
+}
+}
+}
+// If the comparison is an equality comparison with null, we can simplify it
+// if we know the value (argument) can't be null
+if (I.isEquality() && isa<ConstantPointerNull>(I.getOperand(1)) &&
+isKnownNonNullInCallee(I.getOperand(0))) {
+bool IsNotEqual = I.getPredicate() == CmpInst::ICMP_NE;
+SimplifiedValues[&I] = IsNotEqual ? ConstantInt::getTrue(I.getType())
+: ConstantInt::getFalse(I.getType());
+return true;
+}
+// Finally check for SROA candidates in comparisons.
+Value *SROAArg;
+DenseMap<Value *, int>::iterator CostIt;
+if (lookupSROAArgAndCost(I.getOperand(0), SROAArg, CostIt)) {
+if (isa<ConstantPointerNull>(I.getOperand(1))) {
+accumulateSROACost(CostIt, InlineConstants::InstrCost);
+return true;
+}
+disableSROA(CostIt);
+}
+return false;
+}
+bool CallAnalyzer::visitSub(BinaryOperator &I) {
+// Try to handle a special case: we can fold computing the difference of two
+// constant-related pointers.
+Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
+Value *LHSBase, *RHSBase;
+APInt LHSOffset, RHSOffset;
+std::tie(LHSBase, LHSOffset) = ConstantOffsetPtrs.lookup(LHS);
+if (LHSBase) {
+std::tie(RHSBase, RHSOffset) = ConstantOffsetPtrs.lookup(RHS);
+if (RHSBase && LHSBase == RHSBase) {
+// We have common bases, fold the subtract to a constant based on the
+// offsets.
+Constant *CLHS = ConstantInt::get(LHS->getContext(), LHSOffset);
+Constant *CRHS = ConstantInt::get(RHS->getContext(), RHSOffset);
+if (Constant *C = ConstantExpr::getSub(CLHS, CRHS)) {
+SimplifiedValues[&I] = C;
+++NumConstantPtrDiffs;
+return true;
+}
+}
+}
+// Otherwise, fall back to the generic logic for simplifying and handling
+// instructions.
+return Base::visitSub(I);
+}
+bool CallAnalyzer::visitBinaryOperator(BinaryOperator &I) {
+Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
+const DataLayout &DL = F.getParent()->getDataLayout();
+if (!isa<Constant>(LHS))
+if (Constant *SimpleLHS = SimplifiedValues.lookup(LHS))
+LHS = SimpleLHS;
+if (!isa<Constant>(RHS))
+if (Constant *SimpleRHS = SimplifiedValues.lookup(RHS))
+RHS = SimpleRHS;
+Value *SimpleV = nullptr;
+if (auto FI = dyn_cast<FPMathOperator>(&I))
+SimpleV =
+SimplifyFPBinOp(I.getOpcode(), LHS, RHS, FI->getFastMathFlags(), DL);
+else
+SimpleV = SimplifyBinOp(I.getOpcode(), LHS, RHS, DL);
+if (Constant *C = dyn_cast_or_null<Constant>(SimpleV)) {
+SimplifiedValues[&I] = C;
+return true;
+}
+// Disable any SROA on arguments to arbitrary, unsimplified binary operators.
+disableSROA(LHS);
+disableSROA(RHS);
+return false;
+}
+bool CallAnalyzer::visitLoad(LoadInst &I) {
+Value *SROAArg;
+DenseMap<Value *, int>::iterator CostIt;
+if (lookupSROAArgAndCost(I.getPointerOperand(), SROAArg, CostIt)) {
+if (I.isSimple()) {
+accumulateSROACost(CostIt, InlineConstants::InstrCost);
+return true;
+}
+disableSROA(CostIt);
+}
+return false;
+}
+bool CallAnalyzer::visitStore(StoreInst &I) {
+Value *SROAArg;
+DenseMap<Value *, int>::iterator CostIt;
+if (lookupSROAArgAndCost(I.getPointerOperand(), SROAArg, CostIt)) {
+if (I.isSimple()) {
+accumulateSROACost(CostIt, InlineConstants::InstrCost);
+return true;
+}
+disableSROA(CostIt);
+}
+return false;
+}
+bool CallAnalyzer::visitExtractValue(ExtractValueInst &I) {
+// Constant folding for extract value is trivial.
+Constant *C = dyn_cast<Constant>(I.getAggregateOperand());
+if (!C)
+C = SimplifiedValues.lookup(I.getAggregateOperand());
+if (C) {
+SimplifiedValues[&I] = ConstantExpr::getExtractValue(C, I.getIndices());
+return true;
+}
+// SROA can look through these but give them a cost.
+return false;
+}
+bool CallAnalyzer::visitInsertValue(InsertValueInst &I) {
+// Constant folding for insert value is trivial.
+Constant *AggC = dyn_cast<Constant>(I.getAggregateOperand());
+if (!AggC)
+AggC = SimplifiedValues.lookup(I.getAggregateOperand());
+Constant *InsertedC = dyn_cast<Constant>(I.getInsertedValueOperand());
+if (!InsertedC)
+InsertedC = SimplifiedValues.lookup(I.getInsertedValueOperand());
+if (AggC && InsertedC) {
+SimplifiedValues[&I] = ConstantExpr::getInsertValue(AggC, InsertedC,
+I.getIndices());
+return true;
+}
+// SROA can look through these but give them a cost.
+return false;
+}
+/// \brief Try to simplify a call site.
+///
+/// Takes a concrete function and callsite and tries to actually simplify it by
+/// analyzing the arguments and call itself with instsimplify. Returns true if
+/// it has simplified the callsite to some other entity (a constant), making it
+/// free.
+bool CallAnalyzer::simplifyCallSite(Function *F, CallSite CS) {
+// FIXME: Using the instsimplify logic directly for this is inefficient
+// because we have to continually rebuild the argument list even when no
+// simplifications can be performed. Until that is fixed with remapping
+// inside of instsimplify, directly constant fold calls here.
+if (!canConstantFoldCallTo(F))
+return false;
+// Try to re-map the arguments to constants.
+SmallVector<Constant *, 4> ConstantArgs;
+ConstantArgs.reserve(CS.arg_size());
+for (CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end();
+I != E; ++I) {
+Constant *C = dyn_cast<Constant>(*I);
+if (!C)
+C = dyn_cast_or_null<Constant>(SimplifiedValues.lookup(*I));
+if (!C)
+return false; // This argument doesn't map to a constant.
+ConstantArgs.push_back(C);
+}
+if (Constant *C = ConstantFoldCall(F, ConstantArgs)) {
+SimplifiedValues[CS.getInstruction()] = C;
+return true;
+}
+return false;
+}
+bool CallAnalyzer::visitCallSite(CallSite CS) {
+if (CS.hasFnAttr(Attribute::ReturnsTwice) &&
+!F.hasFnAttribute(Attribute::ReturnsTwice)) {
+// This aborts the entire analysis.
+ExposesReturnsTwice = true;
+return false;
+}
+if (CS.isCall() &&
+cast<CallInst>(CS.getInstruction())->cannotDuplicate())
+ContainsNoDuplicateCall = true;
+if (Function *F = CS.getCalledFunction()) {
+// When we have a concrete function, first try to simplify it directly.
+if (simplifyCallSite(F, CS))
+return true;
+// Next check if it is an intrinsic we know about.
+// FIXME: Lift this into part of the InstVisitor.
+if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(CS.getInstruction())) {
+switch (II->getIntrinsicID()) {
+default:
+return Base::visitCallSite(CS);
+case Intrinsic::memset:
+case Intrinsic::memcpy:
+case Intrinsic::memmove:
+// SROA can usually chew through these intrinsics, but they aren't free.
+return false;
+case Intrinsic::localescape:
+HasFrameEscape = true;
+return false;
+}
+}
+if (F == CS.getInstruction()->getParent()->getParent()) {
+// This flag will fully abort the analysis, so don't bother with anything
+// else.
+IsRecursiveCall = true;
+return false;
+}
+if (TTI.isLoweredToCall(F)) {
+// We account for the average 1 instruction per call argument setup
+// here.
+Cost += CS.arg_size() * InlineConstants::InstrCost;
+// Everything other than inline ASM will also have a significant cost
+// merely from making the call.
+if (!isa<InlineAsm>(CS.getCalledValue()))
+Cost += InlineConstants::CallPenalty;
+}
+return Base::visitCallSite(CS);
+}
+// Otherwise we're in a very special case -- an indirect function call. See
+// if we can be particularly clever about this.
+Value *Callee = CS.getCalledValue();
+// First, pay the price of the argument setup. We account for the average
+// 1 instruction per call argument setup here.
+Cost += CS.arg_size() * InlineConstants::InstrCost;
+// Next, check if this happens to be an indirect function call to a known
+// function in this inline context. If not, we've done all we can.
+Function *F = dyn_cast_or_null<Function>(SimplifiedValues.lookup(Callee));
+if (!F)
+return Base::visitCallSite(CS);
+// If we have a constant that we are calling as a function, we can peer
+// through it and see the function target. This happens not infrequently
+// during devirtualization and so we want to give it a hefty bonus for
+// inlining, but cap that bonus in the event that inlining wouldn't pan
+// out. Pretend to inline the function, with a custom threshold.
+CallAnalyzer CA(TTI, ACT, *F, InlineConstants::IndirectCallThreshold, CS);
+if (CA.analyzeCall(CS)) {
+// We were able to inline the indirect call! Subtract the cost from the
+// bonus we want to apply, but don't go below zero.
+Cost -= std::max(0, InlineConstants::IndirectCallThreshold - CA.getCost());
+}
+return Base::visitCallSite(CS);
+}
+bool CallAnalyzer::visitReturnInst(ReturnInst &RI) {
+// At least one return instruction will be free after inlining.
+bool Free = !HasReturn;
+HasReturn = true;
+return Free;
+}
+bool CallAnalyzer::visitBranchInst(BranchInst &BI) {
+// We model unconditional branches as essentially free -- they really
+// shouldn't exist at all, but handling them makes the behavior of the
+// inliner more regular and predictable. Interestingly, conditional branches
+// which will fold away are also free.
+return BI.isUnconditional() || isa<ConstantInt>(BI.getCondition()) ||
+dyn_cast_or_null<ConstantInt>(
+SimplifiedValues.lookup(BI.getCondition()));
+}
+bool CallAnalyzer::visitSwitchInst(SwitchInst &SI) {
+// We model unconditional switches as free, see the comments on handling
+// branches.
+if (isa<ConstantInt>(SI.getCondition()))
+return true;
+if (Value *V = SimplifiedValues.lookup(SI.getCondition()))
+if (isa<ConstantInt>(V))
+return true;
+// Otherwise, we need to accumulate a cost proportional to the number of
+// distinct successor blocks. This fan-out in the CFG cannot be represented
+// for free even if we can represent the core switch as a jumptable that
+// takes a single instruction.
+//
+// NB: We convert large switches which are just used to initialize large phi
+// nodes to lookup tables instead in simplify-cfg, so this shouldn't prevent
+// inlining those. It will prevent inlining in cases where the optimization
+// does not (yet) fire.
+SmallPtrSet<BasicBlock *, 8> SuccessorBlocks;
+SuccessorBlocks.insert(SI.getDefaultDest());
+for (auto I = SI.case_begin(), E = SI.case_end(); I != E; ++I)
+SuccessorBlocks.insert(I.getCaseSuccessor());
+// Add cost corresponding to the number of distinct destinations. The first
+// we model as free because of fallthrough.
+Cost += (SuccessorBlocks.size() - 1) * InlineConstants::InstrCost;
+return false;
+}
+bool CallAnalyzer::visitIndirectBrInst(IndirectBrInst &IBI) {
+// We never want to inline functions that contain an indirectbr.  This is
+// incorrect because all the blockaddress's (in static global initializers
+// for example) would be referring to the original function, and this
+// indirect jump would jump from the inlined copy of the function into the
+// original function which is extremely undefined behavior.
+// FIXME: This logic isn't really right; we can safely inline functions with
+// indirectbr's as long as no other function or global references the
+// blockaddress of a block within the current function.
+HasIndirectBr = true;
+return false;
+}
+bool CallAnalyzer::visitResumeInst(ResumeInst &RI) {
+// FIXME: It's not clear that a single instruction is an accurate model for
+// the inline cost of a resume instruction.
+return false;
+}
+bool CallAnalyzer::visitCleanupReturnInst(CleanupReturnInst &CRI) {
+// FIXME: It's not clear that a single instruction is an accurate model for
+// the inline cost of a cleanupret instruction.
+return false;
+}
+bool CallAnalyzer::visitCatchReturnInst(CatchReturnInst &CRI) {
+// FIXME: It's not clear that a single instruction is an accurate model for
+// the inline cost of a catchret instruction.
+return false;
+}
+bool CallAnalyzer::visitUnreachableInst(UnreachableInst &I) {
+// FIXME: It might be reasonably to discount the cost of instructions leading
+// to unreachable as they have the lowest possible impact on both runtime and
+// code size.
+return true; // No actual code is needed for unreachable.
+}
+bool CallAnalyzer::visitInstruction(Instruction &I) {
+// Some instructions are free. All of the free intrinsics can also be
+// handled by SROA, etc.
+if (TargetTransformInfo::TCC_Free == TTI.getUserCost(&I))
+return true;
+// We found something we don't understand or can't handle. Mark any SROA-able
+// values in the operand list as no longer viable.
+for (User::op_iterator OI = I.op_begin(), OE = I.op_end(); OI != OE; ++OI)
+disableSROA(*OI);
+return false;
+}
+/// \brief Analyze a basic block for its contribution to the inline cost.
+///
+/// This method walks the analyzer over every instruction in the given basic
+/// block and accounts for their cost during inlining at this callsite. It
+/// aborts early if the threshold has been exceeded or an impossible to inline
+/// construct has been detected. It returns false if inlining is no longer
+/// viable, and true if inlining remains viable.
+bool CallAnalyzer::analyzeBlock(BasicBlock *BB,
+SmallPtrSetImpl<const Value *> &EphValues) {
+for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
+// FIXME: Currently, the number of instructions in a function regardless of
+// our ability to simplify them during inline to constants or dead code,
+// are actually used by the vector bonus heuristic. As long as that's true,
+// we have to special case debug intrinsics here to prevent differences in
+// inlining due to debug symbols. Eventually, the number of unsimplified
+// instructions shouldn't factor into the cost computation, but until then,
+// hack around it here.
+if (isa<DbgInfoIntrinsic>(I))
+continue;
+// Skip ephemeral values.
+if (EphValues.count(&*I))
+continue;
+++NumInstructions;
+if (isa<ExtractElementInst>(I) || I->getType()->isVectorTy())
+++NumVectorInstructions;
+// If the instruction is floating point, and the target says this operation
+// is expensive or the function has the "use-soft-float" attribute, this may
+// eventually become a library call. Treat the cost as such.
+if (I->getType()->isFloatingPointTy()) {
+bool hasSoftFloatAttr = false;
+// If the function has the "use-soft-float" attribute, mark it as
+// expensive.
+if (F.hasFnAttribute("use-soft-float")) {
+Attribute Attr = F.getFnAttribute("use-soft-float");
+StringRef Val = Attr.getValueAsString();
+if (Val == "true")
+hasSoftFloatAttr = true;
+}
+if (TTI.getFPOpCost(I->getType()) == TargetTransformInfo::TCC_Expensive ||
+hasSoftFloatAttr)
+Cost += InlineConstants::CallPenalty;
+}
+// If the instruction simplified to a constant, there is no cost to this
+// instruction. Visit the instructions using our InstVisitor to account for
+// all of the per-instruction logic. The visit tree returns true if we
+// consumed the instruction in any way, and false if the instruction's base
+// cost should count against inlining.
+if (Base::visit(&*I))
+++NumInstructionsSimplified;
+else
+Cost += InlineConstants::InstrCost;
+// If the visit this instruction detected an uninlinable pattern, abort.
+if (IsRecursiveCall || ExposesReturnsTwice || HasDynamicAlloca ||
+HasIndirectBr || HasFrameEscape)
+return false;
+// If the caller is a recursive function then we don't want to inline
+// functions which allocate a lot of stack space because it would increase
+// the caller stack usage dramatically.
+if (IsCallerRecursive &&
+AllocatedSize > InlineConstants::TotalAllocaSizeRecursiveCaller)
+return false;
+// Check if we've past the maximum possible threshold so we don't spin in
+// huge basic blocks that will never inline.
+if (Cost > Threshold)
+return false;
+}
+return true;
+}
+/// \brief Compute the base pointer and cumulative constant offsets for V.
+///
+/// This strips all constant offsets off of V, leaving it the base pointer, and
+/// accumulates the total constant offset applied in the returned constant. It
+/// returns 0 if V is not a pointer, and returns the constant '0' if there are
+/// no constant offsets applied.
+ConstantInt *CallAnalyzer::stripAndComputeInBoundsConstantOffsets(Value *&V) {
+if (!V->getType()->isPointerTy())
+return nullptr;
+const DataLayout &DL = F.getParent()->getDataLayout();
+unsigned IntPtrWidth = DL.getPointerSizeInBits();
+APInt Offset = APInt::getNullValue(IntPtrWidth);
+// Even though we don't look through PHI nodes, we could be called on an
+// instruction in an unreachable block, which may be on a cycle.
+SmallPtrSet<Value *, 4> Visited;
+Visited.insert(V);
+do {
+if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
+if (!GEP->isInBounds() || !accumulateGEPOffset(*GEP, Offset))
+return nullptr;
+V = GEP->getPointerOperand();
+} else if (Operator::getOpcode(V) == Instruction::BitCast) {
+V = cast<Operator>(V)->getOperand(0);
+} else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
+if (GA->mayBeOverridden())
+break;
+V = GA->getAliasee();
+} else {
+break;
+}
+assert(V->getType()->isPointerTy() && "Unexpected operand type!");
+} while (Visited.insert(V).second);
+Type *IntPtrTy = DL.getIntPtrType(V->getContext());
+return cast<ConstantInt>(ConstantInt::get(IntPtrTy, Offset));
+}
+/// \brief Analyze a call site for potential inlining.
+///
+/// Returns true if inlining this call is viable, and false if it is not
+/// viable. It computes the cost and adjusts the threshold based on numerous
+/// factors and heuristics. If this method returns false but the computed cost
+/// is below the computed threshold, then inlining was forcibly disabled by
+/// some artifact of the routine.
+bool CallAnalyzer::analyzeCall(CallSite CS) {
+++NumCallsAnalyzed;
+// Perform some tweaks to the cost and threshold based on the direct
+// callsite information.
+// We want to more aggressively inline vector-dense kernels, so up the
+// threshold, and we'll lower it if the % of vector instructions gets too
+// low. Note that these bonuses are some what arbitrary and evolved over time
+// by accident as much as because they are principled bonuses.
+//
+// FIXME: It would be nice to remove all such bonuses. At least it would be
+// nice to base the bonus values on something more scientific.
+assert(NumInstructions == 0);
+assert(NumVectorInstructions == 0);
+FiftyPercentVectorBonus = 3 * Threshold / 2;
+TenPercentVectorBonus = 3 * Threshold / 4;
+const DataLayout &DL = F.getParent()->getDataLayout();
+// Track whether the post-inlining function would have more than one basic
+// block. A single basic block is often intended for inlining. Balloon the
+// threshold by 50% until we pass the single-BB phase.
+bool SingleBB = true;
+int SingleBBBonus = Threshold / 2;
+// Speculatively apply all possible bonuses to Threshold. If cost exceeds
+// this Threshold any time, and cost cannot decrease, we can stop processing
+// the rest of the function body.
+Threshold += (SingleBBBonus + FiftyPercentVectorBonus);
+// Give out bonuses per argument, as the instructions setting them up will
+// be gone after inlining.
+for (unsigned I = 0, E = CS.arg_size(); I != E; ++I) {
+if (CS.isByValArgument(I)) {
+// We approximate the number of loads and stores needed by dividing the
+// size of the byval type by the target's pointer size.
+PointerType *PTy = cast<PointerType>(CS.getArgument(I)->getType());
+unsigned TypeSize = DL.getTypeSizeInBits(PTy->getElementType());
+unsigned PointerSize = DL.getPointerSizeInBits();
+// Ceiling division.
+unsigned NumStores = (TypeSize + PointerSize - 1) / PointerSize;
+// If it generates more than 8 stores it is likely to be expanded as an
+// inline memcpy so we take that as an upper bound. Otherwise we assume
+// one load and one store per word copied.
+// FIXME: The maxStoresPerMemcpy setting from the target should be used
+// here instead of a magic number of 8, but it's not available via
+// DataLayout.
+NumStores = std::min(NumStores, 8U);
+Cost -= 2 * NumStores * InlineConstants::InstrCost;
+} else {
+// For non-byval arguments subtract off one instruction per call
+// argument.
+Cost -= InlineConstants::InstrCost;
+}
+}
+// If there is only one call of the function, and it has internal linkage,
+// the cost of inlining it drops dramatically.
+bool OnlyOneCallAndLocalLinkage = F.hasLocalLinkage() && F.hasOneUse() &&
+&F == CS.getCalledFunction();
+if (OnlyOneCallAndLocalLinkage)
+Cost += InlineConstants::LastCallToStaticBonus;
+// If the instruction after the call, or if the normal destination of the
+// invoke is an unreachable instruction, the function is noreturn. As such,
+// there is little point in inlining this unless there is literally zero
+// cost.
+Instruction *Instr = CS.getInstruction();
+if (InvokeInst *II = dyn_cast<InvokeInst>(Instr)) {
+if (isa<UnreachableInst>(II->getNormalDest()->begin()))
+Threshold = 0;
+} else if (isa<UnreachableInst>(++BasicBlock::iterator(Instr)))
+Threshold = 0;
+// If this function uses the coldcc calling convention, prefer not to inline
+// it.
+if (F.getCallingConv() == CallingConv::Cold)
+Cost += InlineConstants::ColdccPenalty;
+// Check if we're done. This can happen due to bonuses and penalties.
+if (Cost > Threshold)
+return false;
+if (F.empty())
+return true;
+Function *Caller = CS.getInstruction()->getParent()->getParent();
+// Check if the caller function is recursive itself.
+for (User *U : Caller->users()) {
+CallSite Site(U);
+if (!Site)
+continue;
+Instruction *I = Site.getInstruction();
+if (I->getParent()->getParent() == Caller) {
+IsCallerRecursive = true;
+break;
+}
+}
+// Populate our simplified values by mapping from function arguments to call
+// arguments with known important simplifications.
+CallSite::arg_iterator CAI = CS.arg_begin();
+for (Function::arg_iterator FAI = F.arg_begin(), FAE = F.arg_end();
+FAI != FAE; ++FAI, ++CAI) {
+assert(CAI != CS.arg_end());
+if (Constant *C = dyn_cast<Constant>(CAI))
+SimplifiedValues[&*FAI] = C;
+Value *PtrArg = *CAI;
+if (ConstantInt *C = stripAndComputeInBoundsConstantOffsets(PtrArg)) {
+ConstantOffsetPtrs[&*FAI] = std::make_pair(PtrArg, C->getValue());
+// We can SROA any pointer arguments derived from alloca instructions.
+if (isa<AllocaInst>(PtrArg)) {
+SROAArgValues[&*FAI] = PtrArg;
+SROAArgCosts[PtrArg] = 0;
+}
+}
+}
+NumConstantArgs = SimplifiedValues.size();
+NumConstantOffsetPtrArgs = ConstantOffsetPtrs.size();
+NumAllocaArgs = SROAArgValues.size();
+// FIXME: If a caller has multiple calls to a callee, we end up recomputing
+// the ephemeral values multiple times (and they're completely determined by
+// the callee, so this is purely duplicate work).
+SmallPtrSet<const Value *, 32> EphValues;
+CodeMetrics::collectEphemeralValues(&F, &ACT->getAssumptionCache(F), EphValues);
+// The worklist of live basic blocks in the callee *after* inlining. We avoid
+// adding basic blocks of the callee which can be proven to be dead for this
+// particular call site in order to get more accurate cost estimates. This
+// requires a somewhat heavyweight iteration pattern: we need to walk the
+// basic blocks in a breadth-first order as we insert live successors. To
+// accomplish this, prioritizing for small iterations because we exit after
+// crossing our threshold, we use a small-size optimized SetVector.
+typedef SetVector<BasicBlock *, SmallVector<BasicBlock *, 16>,
+SmallPtrSet<BasicBlock *, 16> > BBSetVector;
+BBSetVector BBWorklist;
+BBWorklist.insert(&F.getEntryBlock());
+// Note that we *must not* cache the size, this loop grows the worklist.
+for (unsigned Idx = 0; Idx != BBWorklist.size(); ++Idx) {
+// Bail out the moment we cross the threshold. This means we'll under-count
+// the cost, but only when undercounting doesn't matter.
+if (Cost > Threshold)
+break;
+BasicBlock *BB = BBWorklist[Idx];
+if (BB->empty())
+continue;
+// Disallow inlining a blockaddress. A blockaddress only has defined
+// behavior for an indirect branch in the same function, and we do not
+// currently support inlining indirect branches. But, the inliner may not
+// see an indirect branch that ends up being dead code at a particular call
+// site. If the blockaddress escapes the function, e.g., via a global
+// variable, inlining may lead to an invalid cross-function reference.
+if (BB->hasAddressTaken())
+return false;
+// Analyze the cost of this block. If we blow through the threshold, this
+// returns false, and we can bail on out.
+if (!analyzeBlock(BB, EphValues)) {
+if (IsRecursiveCall || ExposesReturnsTwice || HasDynamicAlloca ||
+HasIndirectBr || HasFrameEscape)
+return false;
+// If the caller is a recursive function then we don't want to inline
+// functions which allocate a lot of stack space because it would increase
+// the caller stack usage dramatically.
+if (IsCallerRecursive &&
+AllocatedSize > InlineConstants::TotalAllocaSizeRecursiveCaller)
+return false;
+break;
+}
+TerminatorInst *TI = BB->getTerminator();
+// Add in the live successors by first checking whether we have terminator
+// that may be simplified based on the values simplified by this call.
+if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
+if (BI->isConditional()) {
+Value *Cond = BI->getCondition();
+if (ConstantInt *SimpleCond
+= dyn_cast_or_null<ConstantInt>(SimplifiedValues.lookup(Cond))) {
+BBWorklist.insert(BI->getSuccessor(SimpleCond->isZero() ? 1 : 0));
+continue;
+}
+}
+} else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
+Value *Cond = SI->getCondition();
+if (ConstantInt *SimpleCond
+= dyn_cast_or_null<ConstantInt>(SimplifiedValues.lookup(Cond))) {
+BBWorklist.insert(SI->findCaseValue(SimpleCond).getCaseSuccessor());
+continue;
+}
+}
+// If we're unable to select a particular successor, just count all of
+// them.
+for (unsigned TIdx = 0, TSize = TI->getNumSuccessors(); TIdx != TSize;
+++TIdx)
+BBWorklist.insert(TI->getSuccessor(TIdx));
+// If we had any successors at this point, than post-inlining is likely to
+// have them as well. Note that we assume any basic blocks which existed
+// due to branches or switches which folded above will also fold after
+// inlining.
+if (SingleBB && TI->getNumSuccessors() > 1) {
+// Take off the bonus we applied to the threshold.
+Threshold -= SingleBBBonus;
+SingleBB = false;
+}
+}
+// If this is a noduplicate call, we can still inline as long as
+// inlining this would cause the removal of the caller (so the instruction
+// is not actually duplicated, just moved).
+if (!OnlyOneCallAndLocalLinkage && ContainsNoDuplicateCall)
+return false;
+// We applied the maximum possible vector bonus at the beginning. Now,
+// subtract the excess bonus, if any, from the Threshold before
+// comparing against Cost.
+if (NumVectorInstructions <= NumInstructions / 10)
+Threshold -= FiftyPercentVectorBonus;
+else if (NumVectorInstructions <= NumInstructions / 2)
+Threshold -= (FiftyPercentVectorBonus - TenPercentVectorBonus);
+return Cost < Threshold;
+}
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+/// \brief Dump stats about this call's analysis.
+void CallAnalyzer::dump() {
+#define DEBUG_PRINT_STAT(x) dbgs() << "      " #x ": " << x << "\n"
+DEBUG_PRINT_STAT(NumConstantArgs);
+DEBUG_PRINT_STAT(NumConstantOffsetPtrArgs);
+DEBUG_PRINT_STAT(NumAllocaArgs);
+DEBUG_PRINT_STAT(NumConstantPtrCmps);
+DEBUG_PRINT_STAT(NumConstantPtrDiffs);
+DEBUG_PRINT_STAT(NumInstructionsSimplified);
+DEBUG_PRINT_STAT(NumInstructions);
+DEBUG_PRINT_STAT(SROACostSavings);
+DEBUG_PRINT_STAT(SROACostSavingsLost);
+DEBUG_PRINT_STAT(ContainsNoDuplicateCall);
+DEBUG_PRINT_STAT(Cost);
+DEBUG_PRINT_STAT(Threshold);
+#undef DEBUG_PRINT_STAT
+}
+#endif
+INITIALIZE_PASS_BEGIN(InlineCostAnalysis, "inline-cost", "Inline Cost Analysis",
+true, true)
+INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
+INITIALIZE_PASS_END(InlineCostAnalysis, "inline-cost", "Inline Cost Analysis",
+true, true)
+char InlineCostAnalysis::ID = 0;
+InlineCostAnalysis::InlineCostAnalysis() : CallGraphSCCPass(ID) {}
+InlineCostAnalysis::~InlineCostAnalysis() {}
+void InlineCostAnalysis::getAnalysisUsage(AnalysisUsage &AU) const {
+AU.setPreservesAll();
+AU.addRequired<AssumptionCacheTracker>();
+AU.addRequired<TargetTransformInfoWrapperPass>();
+CallGraphSCCPass::getAnalysisUsage(AU);
+}
+bool InlineCostAnalysis::runOnSCC(CallGraphSCC &SCC) {
+TTIWP = &getAnalysis<TargetTransformInfoWrapperPass>();
+ACT = &getAnalysis<AssumptionCacheTracker>();
+return false;
+}
+InlineCost InlineCostAnalysis::getInlineCost(CallSite CS, int Threshold) {
+return getInlineCost(CS, CS.getCalledFunction(), Threshold);
+}
+/// \brief Test that two functions either have or have not the given attribute
+///        at the same time.
+template<typename AttrKind>
+static bool attributeMatches(Function *F1, Function *F2, AttrKind Attr) {
+return F1->getFnAttribute(Attr) == F2->getFnAttribute(Attr);
+}
+/// \brief Test that there are no attribute conflicts between Caller and Callee
+///        that prevent inlining.
+static bool functionsHaveCompatibleAttributes(Function *Caller,
+Function *Callee,
+TargetTransformInfo &TTI) {
+return TTI.areInlineCompatible(Caller, Callee) &&
+attributeMatches(Caller, Callee, Attribute::SanitizeAddress) &&
+attributeMatches(Caller, Callee, Attribute::SanitizeMemory) &&
+attributeMatches(Caller, Callee, Attribute::SanitizeThread);
+}
+InlineCost InlineCostAnalysis::getInlineCost(CallSite CS, Function *Callee,
+int Threshold) {
+// Cannot inline indirect calls.
+if (!Callee)
+return llvm::InlineCost::getNever();
+// Calls to functions with always-inline attributes should be inlined
+// whenever possible.
+if (CS.hasFnAttr(Attribute::AlwaysInline)) {
+if (isInlineViable(*Callee))
+return llvm::InlineCost::getAlways();
+return llvm::InlineCost::getNever();
+}
+// Never inline functions with conflicting attributes (unless callee has
+// always-inline attribute).
+if (!functionsHaveCompatibleAttributes(CS.getCaller(), Callee,
+TTIWP->getTTI(*Callee)))
+return llvm::InlineCost::getNever();
+// Don't inline this call if the caller has the optnone attribute.
+if (CS.getCaller()->hasFnAttribute(Attribute::OptimizeNone))
+return llvm::InlineCost::getNever();
+// Don't inline functions which can be redefined at link-time to mean
+// something else.  Don't inline functions marked noinline or call sites
+// marked noinline.
+if (Callee->mayBeOverridden() ||
+Callee->hasFnAttribute(Attribute::NoInline) || CS.isNoInline())
+return llvm::InlineCost::getNever();
+DEBUG(llvm::dbgs() << "      Analyzing call of " << Callee->getName()
+<< "...\n");
+CallAnalyzer CA(TTIWP->getTTI(*Callee), ACT, *Callee, Threshold, CS);
+bool ShouldInline = CA.analyzeCall(CS);
+DEBUG(CA.dump());
+// Check if there was a reason to force inlining or no inlining.
+if (!ShouldInline && CA.getCost() < CA.getThreshold())
+return InlineCost::getNever();
+if (ShouldInline && CA.getCost() >= CA.getThreshold())
+return InlineCost::getAlways();
+return llvm::InlineCost::get(CA.getCost(), CA.getThreshold());
+}
+bool InlineCostAnalysis::isInlineViable(Function &F) {
+bool ReturnsTwice = F.hasFnAttribute(Attribute::ReturnsTwice);
+for (Function::iterator BI = F.begin(), BE = F.end(); BI != BE; ++BI) {
+// Disallow inlining of functions which contain indirect branches or
+// blockaddresses.
+if (isa<IndirectBrInst>(BI->getTerminator()) || BI->hasAddressTaken())
+return false;
+for (auto &II : *BI) {
+CallSite CS(&II);
+if (!CS)
+continue;
+// Disallow recursive calls.
+if (&F == CS.getCalledFunction())
+return false;
+// Disallow calls which expose returns-twice to a function not previously
+// attributed as such.
+if (!ReturnsTwice && CS.isCall() &&
+cast<CallInst>(CS.getInstruction())->canReturnTwice())
+return false;
+// Disallow inlining functions that call @llvm.localescape. Doing this
+// correctly would require major changes to the inliner.
+if (CS.getCalledFunction() &&
+CS.getCalledFunction()->getIntrinsicID() ==
+llvm::Intrinsic::localescape)
+return false;
+}
+}
+return true;
+}

Mercurial > hg > CbC > CbC_llvm

comparison lib/Analysis/InlineCost.cpp @ 95:afa8332a0e37 LLVM3.8