85 lines · cpp
1//===-- PatchableFunction.cpp - Patchable prologues for LLVM -------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8//9// This file implements edits function bodies in place to support the10// "patchable-function" attribute.11//12//===----------------------------------------------------------------------===//13 14#include "llvm/CodeGen/PatchableFunction.h"15#include "llvm/CodeGen/MachineFunction.h"16#include "llvm/CodeGen/MachineFunctionPass.h"17#include "llvm/CodeGen/MachineInstrBuilder.h"18#include "llvm/CodeGen/TargetInstrInfo.h"19#include "llvm/CodeGen/TargetSubtargetInfo.h"20#include "llvm/InitializePasses.h"21#include "llvm/Pass.h"22#include "llvm/PassRegistry.h"23 24using namespace llvm;25 26namespace {27struct PatchableFunction {28 bool run(MachineFunction &F);29};30 31struct PatchableFunctionLegacy : public MachineFunctionPass {32 static char ID;33 PatchableFunctionLegacy() : MachineFunctionPass(ID) {34 initializePatchableFunctionLegacyPass(*PassRegistry::getPassRegistry());35 }36 bool runOnMachineFunction(MachineFunction &F) override {37 return PatchableFunction().run(F);38 }39 40 MachineFunctionProperties getRequiredProperties() const override {41 return MachineFunctionProperties().setNoVRegs();42 }43};44 45} // namespace46 47PreservedAnalyses48PatchableFunctionPass::run(MachineFunction &MF,49 MachineFunctionAnalysisManager &MFAM) {50 MFPropsModifier _(*this, MF);51 if (!PatchableFunction().run(MF))52 return PreservedAnalyses::all();53 return getMachineFunctionPassPreservedAnalyses();54}55 56bool PatchableFunction::run(MachineFunction &MF) {57 MachineBasicBlock &FirstMBB = *MF.begin();58 59 if (MF.getFunction().hasFnAttribute("patchable-function-entry")) {60 const TargetInstrInfo *TII = MF.getSubtarget().getInstrInfo();61 // The initial .loc covers PATCHABLE_FUNCTION_ENTER.62 BuildMI(FirstMBB, FirstMBB.begin(), DebugLoc(),63 TII->get(TargetOpcode::PATCHABLE_FUNCTION_ENTER));64 return true;65 } else if (MF.getFunction().hasFnAttribute("patchable-function")) {66#ifndef NDEBUG67 Attribute PatchAttr = MF.getFunction().getFnAttribute("patchable-function");68 StringRef PatchType = PatchAttr.getValueAsString();69 assert(PatchType == "prologue-short-redirect" && "Only possibility today!");70#endif71 auto *TII = MF.getSubtarget().getInstrInfo();72 BuildMI(FirstMBB, FirstMBB.begin(), DebugLoc(),73 TII->get(TargetOpcode::PATCHABLE_OP))74 .addImm(2);75 MF.ensureAlignment(Align(16));76 return true;77 }78 return false;79}80 81char PatchableFunctionLegacy::ID = 0;82char &llvm::PatchableFunctionID = PatchableFunctionLegacy::ID;83INITIALIZE_PASS(PatchableFunctionLegacy, "patchable-function",84 "Implement the 'patchable-function' attribute", false, false)85