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-rw-r--r--lib/CodeGen/LowerSubregs.cpp223
1 files changed, 0 insertions, 223 deletions
diff --git a/lib/CodeGen/LowerSubregs.cpp b/lib/CodeGen/LowerSubregs.cpp
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--- a/lib/CodeGen/LowerSubregs.cpp
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-//===-- LowerSubregs.cpp - Subregister Lowering instruction pass ----------===//
-//
-// The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// This file defines a MachineFunction pass which runs after register
-// allocation that turns subreg insert/extract instructions into register
-// copies, as needed. This ensures correct codegen even if the coalescer
-// isn't able to remove all subreg instructions.
-//
-//===----------------------------------------------------------------------===//
-
-#define DEBUG_TYPE "lowersubregs"
-#include "llvm/CodeGen/Passes.h"
-#include "llvm/Function.h"
-#include "llvm/CodeGen/MachineFunctionPass.h"
-#include "llvm/CodeGen/MachineInstr.h"
-#include "llvm/CodeGen/MachineInstrBuilder.h"
-#include "llvm/CodeGen/MachineRegisterInfo.h"
-#include "llvm/Target/TargetRegisterInfo.h"
-#include "llvm/Target/TargetInstrInfo.h"
-#include "llvm/Target/TargetMachine.h"
-#include "llvm/Support/Debug.h"
-#include "llvm/Support/raw_ostream.h"
-using namespace llvm;
-
-namespace {
- struct LowerSubregsInstructionPass : public MachineFunctionPass {
- private:
- const TargetRegisterInfo *TRI;
- const TargetInstrInfo *TII;
-
- public:
- static char ID; // Pass identification, replacement for typeid
- LowerSubregsInstructionPass() : MachineFunctionPass(ID) {}
-
- const char *getPassName() const {
- return "Subregister lowering instruction pass";
- }
-
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
- AU.setPreservesCFG();
- AU.addPreservedID(MachineLoopInfoID);
- AU.addPreservedID(MachineDominatorsID);
- MachineFunctionPass::getAnalysisUsage(AU);
- }
-
- /// runOnMachineFunction - pass entry point
- bool runOnMachineFunction(MachineFunction&);
-
- private:
- bool LowerSubregToReg(MachineInstr *MI);
- bool LowerCopy(MachineInstr *MI);
-
- void TransferDeadFlag(MachineInstr *MI, unsigned DstReg,
- const TargetRegisterInfo *TRI);
- void TransferImplicitDefs(MachineInstr *MI);
- };
-
- char LowerSubregsInstructionPass::ID = 0;
-}
-
-FunctionPass *llvm::createLowerSubregsPass() {
- return new LowerSubregsInstructionPass();
-}
-
-/// TransferDeadFlag - MI is a pseudo-instruction with DstReg dead,
-/// and the lowered replacement instructions immediately precede it.
-/// Mark the replacement instructions with the dead flag.
-void
-LowerSubregsInstructionPass::TransferDeadFlag(MachineInstr *MI,
- unsigned DstReg,
- const TargetRegisterInfo *TRI) {
- for (MachineBasicBlock::iterator MII =
- prior(MachineBasicBlock::iterator(MI)); ; --MII) {
- if (MII->addRegisterDead(DstReg, TRI))
- break;
- assert(MII != MI->getParent()->begin() &&
- "copyPhysReg output doesn't reference destination register!");
- }
-}
-
-/// TransferImplicitDefs - MI is a pseudo-instruction, and the lowered
-/// replacement instructions immediately precede it. Copy any implicit-def
-/// operands from MI to the replacement instruction.
-void
-LowerSubregsInstructionPass::TransferImplicitDefs(MachineInstr *MI) {
- MachineBasicBlock::iterator CopyMI = MI;
- --CopyMI;
-
- for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
- MachineOperand &MO = MI->getOperand(i);
- if (!MO.isReg() || !MO.isImplicit() || MO.isUse())
- continue;
- CopyMI->addOperand(MachineOperand::CreateReg(MO.getReg(), true, true));
- }
-}
-
-bool LowerSubregsInstructionPass::LowerSubregToReg(MachineInstr *MI) {
- MachineBasicBlock *MBB = MI->getParent();
- assert((MI->getOperand(0).isReg() && MI->getOperand(0).isDef()) &&
- MI->getOperand(1).isImm() &&
- (MI->getOperand(2).isReg() && MI->getOperand(2).isUse()) &&
- MI->getOperand(3).isImm() && "Invalid subreg_to_reg");
-
- unsigned DstReg = MI->getOperand(0).getReg();
- unsigned InsReg = MI->getOperand(2).getReg();
- assert(!MI->getOperand(2).getSubReg() && "SubIdx on physreg?");
- unsigned SubIdx = MI->getOperand(3).getImm();
-
- assert(SubIdx != 0 && "Invalid index for insert_subreg");
- unsigned DstSubReg = TRI->getSubReg(DstReg, SubIdx);
-
- assert(TargetRegisterInfo::isPhysicalRegister(DstReg) &&
- "Insert destination must be in a physical register");
- assert(TargetRegisterInfo::isPhysicalRegister(InsReg) &&
- "Inserted value must be in a physical register");
-
- DEBUG(dbgs() << "subreg: CONVERTING: " << *MI);
-
- if (DstSubReg == InsReg) {
- // No need to insert an identify copy instruction.
- // Watch out for case like this:
- // %RAX<def> = SUBREG_TO_REG 0, %EAX<kill>, 3
- // We must leave %RAX live.
- if (DstReg != InsReg) {
- MI->setDesc(TII->get(TargetOpcode::KILL));
- MI->RemoveOperand(3); // SubIdx
- MI->RemoveOperand(1); // Imm
- DEBUG(dbgs() << "subreg: replace by: " << *MI);
- return true;
- }
- DEBUG(dbgs() << "subreg: eliminated!");
- } else {
- TII->copyPhysReg(*MBB, MI, MI->getDebugLoc(), DstSubReg, InsReg,
- MI->getOperand(2).isKill());
- // Transfer the kill/dead flags, if needed.
- if (MI->getOperand(0).isDead())
- TransferDeadFlag(MI, DstSubReg, TRI);
- DEBUG({
- MachineBasicBlock::iterator dMI = MI;
- dbgs() << "subreg: " << *(--dMI);
- });
- }
-
- DEBUG(dbgs() << '\n');
- MBB->erase(MI);
- return true;
-}
-
-bool LowerSubregsInstructionPass::LowerCopy(MachineInstr *MI) {
- MachineOperand &DstMO = MI->getOperand(0);
- MachineOperand &SrcMO = MI->getOperand(1);
-
- if (SrcMO.getReg() == DstMO.getReg()) {
- DEBUG(dbgs() << "identity copy: " << *MI);
- // No need to insert an identity copy instruction, but replace with a KILL
- // if liveness is changed.
- if (DstMO.isDead() || SrcMO.isUndef() || MI->getNumOperands() > 2) {
- // We must make sure the super-register gets killed. Replace the
- // instruction with KILL.
- MI->setDesc(TII->get(TargetOpcode::KILL));
- DEBUG(dbgs() << "replaced by: " << *MI);
- return true;
- }
- // Vanilla identity copy.
- MI->eraseFromParent();
- return true;
- }
-
- DEBUG(dbgs() << "real copy: " << *MI);
- TII->copyPhysReg(*MI->getParent(), MI, MI->getDebugLoc(),
- DstMO.getReg(), SrcMO.getReg(), SrcMO.isKill());
-
- if (DstMO.isDead())
- TransferDeadFlag(MI, DstMO.getReg(), TRI);
- if (MI->getNumOperands() > 2)
- TransferImplicitDefs(MI);
- DEBUG({
- MachineBasicBlock::iterator dMI = MI;
- dbgs() << "replaced by: " << *(--dMI);
- });
- MI->eraseFromParent();
- return true;
-}
-
-/// runOnMachineFunction - Reduce subregister inserts and extracts to register
-/// copies.
-///
-bool LowerSubregsInstructionPass::runOnMachineFunction(MachineFunction &MF) {
- DEBUG(dbgs() << "Machine Function\n"
- << "********** LOWERING SUBREG INSTRS **********\n"
- << "********** Function: "
- << MF.getFunction()->getName() << '\n');
- TRI = MF.getTarget().getRegisterInfo();
- TII = MF.getTarget().getInstrInfo();
-
- bool MadeChange = false;
-
- for (MachineFunction::iterator mbbi = MF.begin(), mbbe = MF.end();
- mbbi != mbbe; ++mbbi) {
- for (MachineBasicBlock::iterator mi = mbbi->begin(), me = mbbi->end();
- mi != me;) {
- MachineBasicBlock::iterator nmi = llvm::next(mi);
- MachineInstr *MI = mi;
- assert(!MI->isInsertSubreg() && "INSERT_SUBREG should no longer appear");
- assert(MI->getOpcode() != TargetOpcode::EXTRACT_SUBREG &&
- "EXTRACT_SUBREG should no longer appear");
- if (MI->isSubregToReg()) {
- MadeChange |= LowerSubregToReg(MI);
- } else if (MI->isCopy()) {
- MadeChange |= LowerCopy(MI);
- }
- mi = nmi;
- }
- }
-
- return MadeChange;
-}
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