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comparison lib/CodeGen/PatchableFunction.cpp @ 120:1172e4bd9c6f

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update 4.0.0
author mir3636
date Fri, 25 Nov 2016 19:14:25 +0900
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children 803732b1fca8
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101:34baf5011add 120:1172e4bd9c6f
1 //===-- PatchableFunction.cpp - Patchable prologues for LLVM -------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements edits function bodies in place to support the
11 // "patchable-function" attribute.
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "llvm/CodeGen/Passes.h"
16 #include "llvm/CodeGen/MachineFunction.h"
17 #include "llvm/CodeGen/MachineFunctionPass.h"
18 #include "llvm/CodeGen/MachineInstrBuilder.h"
19 #include "llvm/Target/TargetFrameLowering.h"
20 #include "llvm/Target/TargetInstrInfo.h"
21 #include "llvm/Target/TargetSubtargetInfo.h"
22
23 using namespace llvm;
24
25 namespace {
26 struct PatchableFunction : public MachineFunctionPass {
27 static char ID; // Pass identification, replacement for typeid
28 PatchableFunction() : MachineFunctionPass(ID) {
29 initializePatchableFunctionPass(*PassRegistry::getPassRegistry());
30 }
31
32 bool runOnMachineFunction(MachineFunction &F) override;
33 MachineFunctionProperties getRequiredProperties() const override {
34 return MachineFunctionProperties().set(
35 MachineFunctionProperties::Property::NoVRegs);
36 }
37 };
38 }
39
40 /// Returns true if instruction \p MI will not result in actual machine code
41 /// instructions.
42 static bool doesNotGeneratecode(const MachineInstr &MI) {
43 // TODO: Introduce an MCInstrDesc flag for this
44 switch (MI.getOpcode()) {
45 default: return false;
46 case TargetOpcode::IMPLICIT_DEF:
47 case TargetOpcode::KILL:
48 case TargetOpcode::CFI_INSTRUCTION:
49 case TargetOpcode::EH_LABEL:
50 case TargetOpcode::GC_LABEL:
51 case TargetOpcode::DBG_VALUE:
52 return true;
53 }
54 }
55
56 bool PatchableFunction::runOnMachineFunction(MachineFunction &MF) {
57 if (!MF.getFunction()->hasFnAttribute("patchable-function"))
58 return false;
59
60 #ifndef NDEBUG
61 Attribute PatchAttr = MF.getFunction()->getFnAttribute("patchable-function");
62 StringRef PatchType = PatchAttr.getValueAsString();
63 assert(PatchType == "prologue-short-redirect" && "Only possibility today!");
64 #endif
65
66 auto &FirstMBB = *MF.begin();
67 MachineBasicBlock::iterator FirstActualI = FirstMBB.begin();
68 for (; doesNotGeneratecode(*FirstActualI); ++FirstActualI)
69 assert(FirstActualI != FirstMBB.end());
70
71 auto *TII = MF.getSubtarget().getInstrInfo();
72 auto MIB = BuildMI(FirstMBB, FirstActualI, FirstActualI->getDebugLoc(),
73 TII->get(TargetOpcode::PATCHABLE_OP))
74 .addImm(2)
75 .addImm(FirstActualI->getOpcode());
76
77 for (auto &MO : FirstActualI->operands())
78 MIB.addOperand(MO);
79
80 FirstActualI->eraseFromParent();
81 MF.ensureAlignment(4);
82 return true;
83 }
84
85 char PatchableFunction::ID = 0;
86 char &llvm::PatchableFunctionID = PatchableFunction::ID;
87 INITIALIZE_PASS(PatchableFunction, "patchable-function",
88 "Implement the 'patchable-function' attribute", false, false)