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//===-- PatchableFunction.cpp - Patchable prologues for LLVM -------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements edits function bodies in place to support the
// "patchable-function" attribute.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/PatchableFunction.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/TargetInstrInfo.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
#include "llvm/PassRegistry.h"
using namespace llvm;
namespace {
struct PatchableFunction {
bool run(MachineFunction &F);
};
struct PatchableFunctionLegacy : public MachineFunctionPass {
static char ID;
PatchableFunctionLegacy() : MachineFunctionPass(ID) {
initializePatchableFunctionLegacyPass(*PassRegistry::getPassRegistry());
}
bool runOnMachineFunction(MachineFunction &F) override {
return PatchableFunction().run(F);
}
MachineFunctionProperties getRequiredProperties() const override {
return MachineFunctionProperties().setNoVRegs();
}
};
} // namespace
PreservedAnalyses
PatchableFunctionPass::run(MachineFunction &MF,
MachineFunctionAnalysisManager &MFAM) {
MFPropsModifier _(*this, MF);
if (!PatchableFunction().run(MF))
return PreservedAnalyses::all();
return getMachineFunctionPassPreservedAnalyses();
}
bool PatchableFunction::run(MachineFunction &MF) {
MachineBasicBlock &FirstMBB = *MF.begin();
if (MF.getFunction().hasFnAttribute("patchable-function-entry")) {
const TargetInstrInfo *TII = MF.getSubtarget().getInstrInfo();
// The initial .loc covers PATCHABLE_FUNCTION_ENTER.
BuildMI(FirstMBB, FirstMBB.begin(), DebugLoc(),
TII->get(TargetOpcode::PATCHABLE_FUNCTION_ENTER));
return true;
} else if (MF.getFunction().hasFnAttribute("patchable-function")) {
#ifndef NDEBUG
Attribute PatchAttr = MF.getFunction().getFnAttribute("patchable-function");
StringRef PatchType = PatchAttr.getValueAsString();
assert(PatchType == "prologue-short-redirect" && "Only possibility today!");
#endif
auto *TII = MF.getSubtarget().getInstrInfo();
BuildMI(FirstMBB, FirstMBB.begin(), DebugLoc(),
TII->get(TargetOpcode::PATCHABLE_OP))
.addImm(2);
MF.ensureAlignment(Align(16));
return true;
}
return false;
}
char PatchableFunctionLegacy::ID = 0;
char &llvm::PatchableFunctionID = PatchableFunctionLegacy::ID;
INITIALIZE_PASS(PatchableFunctionLegacy, "patchable-function",
"Implement the 'patchable-function' attribute", false, false)
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