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//===-- RISCVExpandPseudoInsts.cpp - Expand pseudo instructions -----------===//
//
// 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 contains a pass that expands pseudo instructions into target
// instructions. This pass should be run after register allocation but before
// the post-regalloc scheduling pass.
//
//===----------------------------------------------------------------------===//
#include "RISCV.h"
#include "RISCVInstrInfo.h"
#include "RISCVTargetMachine.h"
#include "llvm/CodeGen/LivePhysRegs.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
using namespace llvm;
#define RISCV_EXPAND_PSEUDO_NAME "RISCV pseudo instruction expansion pass"
namespace {
class RISCVExpandPseudo : public MachineFunctionPass {
public:
const RISCVInstrInfo *TII;
static char ID;
RISCVExpandPseudo() : MachineFunctionPass(ID) {
initializeRISCVExpandPseudoPass(*PassRegistry::getPassRegistry());
}
bool runOnMachineFunction(MachineFunction &MF) override;
StringRef getPassName() const override { return RISCV_EXPAND_PSEUDO_NAME; }
private:
bool expandMBB(MachineBasicBlock &MBB);
bool expandMI(MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI,
MachineBasicBlock::iterator &NextMBBI);
bool expandAuipcInstPair(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI,
MachineBasicBlock::iterator &NextMBBI,
unsigned FlagsHi, unsigned SecondOpcode);
bool expandLoadLocalAddress(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI,
MachineBasicBlock::iterator &NextMBBI);
bool expandLoadAddress(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI,
MachineBasicBlock::iterator &NextMBBI);
bool expandLoadTLSIEAddress(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI,
MachineBasicBlock::iterator &NextMBBI);
bool expandLoadTLSGDAddress(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI,
MachineBasicBlock::iterator &NextMBBI);
};
char RISCVExpandPseudo::ID = 0;
bool RISCVExpandPseudo::runOnMachineFunction(MachineFunction &MF) {
TII = static_cast<const RISCVInstrInfo *>(MF.getSubtarget().getInstrInfo());
bool Modified = false;
for (auto &MBB : MF)
Modified |= expandMBB(MBB);
return Modified;
}
bool RISCVExpandPseudo::expandMBB(MachineBasicBlock &MBB) {
bool Modified = false;
MachineBasicBlock::iterator MBBI = MBB.begin(), E = MBB.end();
while (MBBI != E) {
MachineBasicBlock::iterator NMBBI = std::next(MBBI);
Modified |= expandMI(MBB, MBBI, NMBBI);
MBBI = NMBBI;
}
return Modified;
}
bool RISCVExpandPseudo::expandMI(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI,
MachineBasicBlock::iterator &NextMBBI) {
// RISCVInstrInfo::getInstSizeInBytes hard-codes the number of expanded
// instructions for each pseudo, and must be updated when adding new pseudos
// or changing existing ones.
switch (MBBI->getOpcode()) {
case RISCV::PseudoLLA:
return expandLoadLocalAddress(MBB, MBBI, NextMBBI);
case RISCV::PseudoLA:
return expandLoadAddress(MBB, MBBI, NextMBBI);
case RISCV::PseudoLA_TLS_IE:
return expandLoadTLSIEAddress(MBB, MBBI, NextMBBI);
case RISCV::PseudoLA_TLS_GD:
return expandLoadTLSGDAddress(MBB, MBBI, NextMBBI);
}
return false;
}
bool RISCVExpandPseudo::expandAuipcInstPair(
MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI,
MachineBasicBlock::iterator &NextMBBI, unsigned FlagsHi,
unsigned SecondOpcode) {
MachineFunction *MF = MBB.getParent();
MachineInstr &MI = *MBBI;
DebugLoc DL = MI.getDebugLoc();
Register DestReg = MI.getOperand(0).getReg();
const MachineOperand &Symbol = MI.getOperand(1);
MachineBasicBlock *NewMBB = MF->CreateMachineBasicBlock(MBB.getBasicBlock());
// Tell AsmPrinter that we unconditionally want the symbol of this label to be
// emitted.
NewMBB->setLabelMustBeEmitted();
MF->insert(++MBB.getIterator(), NewMBB);
BuildMI(NewMBB, DL, TII->get(RISCV::AUIPC), DestReg)
.addDisp(Symbol, 0, FlagsHi);
BuildMI(NewMBB, DL, TII->get(SecondOpcode), DestReg)
.addReg(DestReg)
.addMBB(NewMBB, RISCVII::MO_PCREL_LO);
// Move all the rest of the instructions to NewMBB.
NewMBB->splice(NewMBB->end(), &MBB, std::next(MBBI), MBB.end());
// Update machine-CFG edges.
NewMBB->transferSuccessorsAndUpdatePHIs(&MBB);
// Make the original basic block fall-through to the new.
MBB.addSuccessor(NewMBB);
// Make sure live-ins are correctly attached to this new basic block.
LivePhysRegs LiveRegs;
computeAndAddLiveIns(LiveRegs, *NewMBB);
NextMBBI = MBB.end();
MI.eraseFromParent();
return true;
}
bool RISCVExpandPseudo::expandLoadLocalAddress(
MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI,
MachineBasicBlock::iterator &NextMBBI) {
return expandAuipcInstPair(MBB, MBBI, NextMBBI, RISCVII::MO_PCREL_HI,
RISCV::ADDI);
}
bool RISCVExpandPseudo::expandLoadAddress(
MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI,
MachineBasicBlock::iterator &NextMBBI) {
MachineFunction *MF = MBB.getParent();
unsigned SecondOpcode;
unsigned FlagsHi;
if (MF->getTarget().isPositionIndependent()) {
const auto &STI = MF->getSubtarget<RISCVSubtarget>();
SecondOpcode = STI.is64Bit() ? RISCV::LD : RISCV::LW;
FlagsHi = RISCVII::MO_GOT_HI;
} else {
SecondOpcode = RISCV::ADDI;
FlagsHi = RISCVII::MO_PCREL_HI;
}
return expandAuipcInstPair(MBB, MBBI, NextMBBI, FlagsHi, SecondOpcode);
}
bool RISCVExpandPseudo::expandLoadTLSIEAddress(
MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI,
MachineBasicBlock::iterator &NextMBBI) {
MachineFunction *MF = MBB.getParent();
const auto &STI = MF->getSubtarget<RISCVSubtarget>();
unsigned SecondOpcode = STI.is64Bit() ? RISCV::LD : RISCV::LW;
return expandAuipcInstPair(MBB, MBBI, NextMBBI, RISCVII::MO_TLS_GOT_HI,
SecondOpcode);
}
bool RISCVExpandPseudo::expandLoadTLSGDAddress(
MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI,
MachineBasicBlock::iterator &NextMBBI) {
return expandAuipcInstPair(MBB, MBBI, NextMBBI, RISCVII::MO_TLS_GD_HI,
RISCV::ADDI);
}
} // end of anonymous namespace
INITIALIZE_PASS(RISCVExpandPseudo, "riscv-expand-pseudo",
RISCV_EXPAND_PSEUDO_NAME, false, false)
namespace llvm {
FunctionPass *createRISCVExpandPseudoPass() { return new RISCVExpandPseudo(); }
} // end of namespace llvm
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