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//===- RISCVExegesisPreprocessing.cpp -------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
// \file
//
//===----------------------------------------------------------------------===//
#include "RISCV.h"
#include "RISCVExegesisPasses.h"
#include "RISCVRegisterInfo.h"
#include "RISCVSubtarget.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
using namespace llvm;
#define DEBUG_TYPE "riscv-exegesis-preprocessing"
namespace {
struct RISCVExegesisPreprocessing : public MachineFunctionPass {
static char ID;
RISCVExegesisPreprocessing() : MachineFunctionPass(ID) {}
bool runOnMachineFunction(MachineFunction &MF) override;
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesCFG();
MachineFunctionPass::getAnalysisUsage(AU);
}
};
} // anonymous namespace
char RISCVExegesisPreprocessing::ID = 0;
static bool processAVLOperand(MachineInstr &MI, MachineRegisterInfo &MRI,
const TargetInstrInfo &TII) {
const MCInstrDesc &Desc = TII.get(MI.getOpcode());
uint64_t TSFlags = Desc.TSFlags;
if (!RISCVII::hasVLOp(TSFlags))
return false;
const MachineOperand &VLOp = MI.getOperand(RISCVII::getVLOpNum(Desc));
if (VLOp.isReg()) {
Register VLReg = VLOp.getReg();
if (VLReg.isVirtual())
return false;
assert(RISCV::GPRRegClass.contains(VLReg));
// Replace all uses of the original physical register with a new virtual
// register. The only reason we can do such replacement here is because it's
// almost certain that VLReg only has a single definition.
Register NewVLReg = MRI.createVirtualRegister(&RISCV::GPRRegClass);
MRI.replaceRegWith(VLReg, NewVLReg);
return true;
}
return false;
}
bool RISCVExegesisPreprocessing::runOnMachineFunction(MachineFunction &MF) {
MachineRegisterInfo &MRI = MF.getRegInfo();
const auto &STI = MF.getSubtarget<RISCVSubtarget>();
if (!STI.hasVInstructions())
return false;
const TargetInstrInfo &TII = *STI.getInstrInfo();
LLVM_DEBUG(MF.print(dbgs() << "===Before RISCVExegesisPoreprocessing===\n");
dbgs() << "\n");
bool Changed = false;
for (auto &MBB : MF)
for (auto &MI : MBB) {
Changed |= processAVLOperand(MI, MRI, TII);
}
return Changed;
}
FunctionPass *llvm::exegesis::createRISCVPreprocessingPass() {
return new RISCVExegesisPreprocessing();
}
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