// 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/Compiler.h"
+#include "llvm/Support/raw_ostream.h"
using namespace llvm;
namespace {
struct VISIBILITY_HIDDEN LowerSubregsInstructionPass
: public MachineFunctionPass {
static char ID; // Pass identification, replacement for typeid
- LowerSubregsInstructionPass() : MachineFunctionPass((intptr_t)&ID) {}
+ 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&);
bool LowerExtract(MachineInstr *MI);
bool LowerInsert(MachineInstr *MI);
+ bool LowerSubregToReg(MachineInstr *MI);
+
+ void TransferDeadFlag(MachineInstr *MI, unsigned DstReg,
+ const TargetRegisterInfo &TRI);
+ void TransferKillFlag(MachineInstr *MI, unsigned SrcReg,
+ const TargetRegisterInfo &TRI,
+ bool AddIfNotFound = false);
};
char LowerSubregsInstructionPass::ID = 0;
return new LowerSubregsInstructionPass();
}
-// Returns the Register Class of a physical register.
-static const TargetRegisterClass *getPhysicalRegisterRegClass(
- const TargetRegisterInfo &TRI,
- unsigned reg) {
- assert(TargetRegisterInfo::isPhysicalRegister(reg) &&
- "reg must be a physical register");
- // Pick the register class of the right type that contains this physreg.
- for (TargetRegisterInfo::regclass_iterator I = TRI.regclass_begin(),
- E = TRI.regclass_end(); I != E; ++I)
- if ((*I)->contains(reg))
- return *I;
- assert(false && "Couldn't find the register class");
- return 0;
+/// 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() &&
+ "copyRegToReg output doesn't reference destination register!");
+ }
}
-bool LowerSubregsInstructionPass::LowerExtract(MachineInstr *MI) {
- MachineBasicBlock *MBB = MI->getParent();
- MachineFunction &MF = *MBB->getParent();
- const TargetRegisterInfo &TRI = *MF.getTarget().getRegisterInfo();
- const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();
-
- assert(MI->getOperand(0).isRegister() && MI->getOperand(0).isDef() &&
- MI->getOperand(1).isRegister() && MI->getOperand(1).isUse() &&
- MI->getOperand(2).isImmediate() && "Malformed extract_subreg");
-
- unsigned SuperReg = MI->getOperand(1).getReg();
- unsigned SubIdx = MI->getOperand(2).getImm();
-
- assert(TargetRegisterInfo::isPhysicalRegister(SuperReg) &&
- "Extract supperg source must be a physical register");
- unsigned SrcReg = TRI.getSubReg(SuperReg, SubIdx);
- unsigned DstReg = MI->getOperand(0).getReg();
-
- DOUT << "subreg: CONVERTING: " << *MI;
-
- if (SrcReg != DstReg) {
- const TargetRegisterClass *TRC = 0;
- if (TargetRegisterInfo::isPhysicalRegister(DstReg)) {
- TRC = getPhysicalRegisterRegClass(TRI, DstReg);
- } else {
- TRC = MF.getRegInfo().getRegClass(DstReg);
- }
- assert(TRC == getPhysicalRegisterRegClass(TRI, SrcReg) &&
- "Extract subreg and Dst must be of same register class");
-
- TII.copyRegToReg(*MBB, MI, DstReg, SrcReg, TRC, TRC);
- MachineBasicBlock::iterator dMI = MI;
- DOUT << "subreg: " << *(--dMI);
- }
-
- DOUT << "\n";
- MBB->remove(MI);
- return true;
+/// TransferKillFlag - MI is a pseudo-instruction with SrcReg killed,
+/// and the lowered replacement instructions immediately precede it.
+/// Mark the replacement instructions with the kill flag.
+void
+LowerSubregsInstructionPass::TransferKillFlag(MachineInstr *MI,
+ unsigned SrcReg,
+ const TargetRegisterInfo &TRI,
+ bool AddIfNotFound) {
+ for (MachineBasicBlock::iterator MII =
+ prior(MachineBasicBlock::iterator(MI)); ; --MII) {
+ if (MII->addRegisterKilled(SrcReg, &TRI, AddIfNotFound))
+ break;
+ assert(MII != MI->getParent()->begin() &&
+ "copyRegToReg output doesn't reference source register!");
+ }
}
-
-bool LowerSubregsInstructionPass::LowerInsert(MachineInstr *MI) {
+bool LowerSubregsInstructionPass::LowerExtract(MachineInstr *MI) {
MachineBasicBlock *MBB = MI->getParent();
MachineFunction &MF = *MBB->getParent();
- const TargetRegisterInfo &TRI = *MF.getTarget().getRegisterInfo();
+ const TargetRegisterInfo &TRI = *MF.getTarget().getRegisterInfo();
const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();
- unsigned DstReg = 0;
- unsigned SrcReg = 0;
- unsigned InsReg = 0;
- unsigned SubIdx = 0;
-
- // If only have 3 operands, then the source superreg is undef
- // and we can supress the copy from the undef value
- if (MI->getNumOperands() == 3) {
- assert((MI->getOperand(0).isRegister() && MI->getOperand(0).isDef()) &&
- (MI->getOperand(1).isRegister() && MI->getOperand(1).isUse()) &&
- MI->getOperand(2).isImmediate() && "Invalid extract_subreg");
- DstReg = MI->getOperand(0).getReg();
- SrcReg = DstReg;
- InsReg = MI->getOperand(1).getReg();
- SubIdx = MI->getOperand(2).getImm();
- } else if (MI->getNumOperands() == 4) {
- assert((MI->getOperand(0).isRegister() && MI->getOperand(0).isDef()) &&
- (MI->getOperand(1).isRegister() && MI->getOperand(1).isUse()) &&
- (MI->getOperand(2).isRegister() && MI->getOperand(2).isUse()) &&
- MI->getOperand(3).isImmediate() && "Invalid extract_subreg");
- DstReg = MI->getOperand(0).getReg();
- SrcReg = MI->getOperand(1).getReg();
- InsReg = MI->getOperand(2).getReg();
- SubIdx = MI->getOperand(3).getImm();
- } else
- assert(0 && "Malformed extract_subreg");
-
- assert(SubIdx != 0 && "Invalid index for extract_subreg");
- unsigned DstSubReg = TRI.getSubReg(DstReg, SubIdx);
- assert(TargetRegisterInfo::isPhysicalRegister(SrcReg) &&
- "Insert superreg source must be in a physical register");
+ assert(MI->getOperand(0).isReg() && MI->getOperand(0).isDef() &&
+ MI->getOperand(1).isReg() && MI->getOperand(1).isUse() &&
+ MI->getOperand(2).isImm() && "Malformed extract_subreg");
+
+ unsigned DstReg = MI->getOperand(0).getReg();
+ unsigned SuperReg = MI->getOperand(1).getReg();
+ unsigned SubIdx = MI->getOperand(2).getImm();
+ unsigned SrcReg = TRI.getSubReg(SuperReg, SubIdx);
+
+ assert(TargetRegisterInfo::isPhysicalRegister(SuperReg) &&
+ "Extract supperg source must be a physical register");
assert(TargetRegisterInfo::isPhysicalRegister(DstReg) &&
- "Insert destination must be in a physical register");
- assert(TargetRegisterInfo::isPhysicalRegister(InsReg) &&
- "Inserted value must be in a physical register");
+ "Extract destination must be in a physical register");
+ assert(SrcReg && "invalid subregister index for register");
DOUT << "subreg: CONVERTING: " << *MI;
-
- // If the inserted register is already allocated into a subregister
- // of the destination, we copy the subreg into the source
- // However, this is only safe if the insert instruction is the kill
- // of the source register
- bool revCopyOrder = TRI.isSubRegister(DstReg, InsReg);
- if (revCopyOrder && InsReg != DstSubReg) {
+
+ if (SrcReg == DstReg) {
+ // No need to insert an identity copy instruction.
if (MI->getOperand(1).isKill()) {
- DstSubReg = TRI.getSubReg(SrcReg, SubIdx);
- // Insert sub-register copy
- const TargetRegisterClass *TRC1 = 0;
- if (TargetRegisterInfo::isPhysicalRegister(InsReg)) {
- TRC1 = getPhysicalRegisterRegClass(TRI, InsReg);
- } else {
- TRC1 = MF.getRegInfo().getRegClass(InsReg);
- }
- TII.copyRegToReg(*MBB, MI, DstSubReg, InsReg, TRC1, TRC1);
+ // We must make sure the super-register gets killed.Replace the
+ // instruction with IMPLICIT_DEF.
+ MI->setDesc(TII.get(TargetInstrInfo::IMPLICIT_DEF));
+ MI->RemoveOperand(2); // SubIdx
+ DOUT << "subreg: replace by: " << *MI;
+ return true;
+ }
+ DOUT << "subreg: eliminated!";
+ } else {
+ // Insert copy
+ const TargetRegisterClass *TRCS = TRI.getPhysicalRegisterRegClass(DstReg);
+ const TargetRegisterClass *TRCD = TRI.getPhysicalRegisterRegClass(SrcReg);
+ bool Emitted = TII.copyRegToReg(*MBB, MI, DstReg, SrcReg, TRCD, TRCS);
+ (void)Emitted;
+ assert(Emitted && "Subreg and Dst must be of compatible register class");
+ // Transfer the kill/dead flags, if needed.
+ if (MI->getOperand(0).isDead())
+ TransferDeadFlag(MI, DstReg, TRI);
+ if (MI->getOperand(1).isKill())
+ TransferKillFlag(MI, SuperReg, TRI, true);
#ifndef NDEBUG
- MachineBasicBlock::iterator dMI = MI;
- DOUT << "subreg: " << *(--dMI);
+ MachineBasicBlock::iterator dMI = MI;
+ DOUT << "subreg: " << *(--dMI);
#endif
- } else {
- assert(0 && "Don't know how to convert this insert");
- }
- }
-#ifndef NDEBUG
- if (InsReg == DstSubReg) {
- DOUT << "subreg: Eliminated subreg copy\n";
}
-#endif
- if (SrcReg != DstReg) {
- // Insert super-register copy
- const TargetRegisterClass *TRC0 = 0;
- if (TargetRegisterInfo::isPhysicalRegister(DstReg)) {
- TRC0 = getPhysicalRegisterRegClass(TRI, DstReg);
- } else {
- TRC0 = MF.getRegInfo().getRegClass(DstReg);
- }
- assert(TRC0 == getPhysicalRegisterRegClass(TRI, SrcReg) &&
- "Insert superreg and Dst must be of same register class");
+ DOUT << "\n";
+ MBB->erase(MI);
+ return true;
+}
+
+bool LowerSubregsInstructionPass::LowerSubregToReg(MachineInstr *MI) {
+ MachineBasicBlock *MBB = MI->getParent();
+ MachineFunction &MF = *MBB->getParent();
+ const TargetRegisterInfo &TRI = *MF.getTarget().getRegisterInfo();
+ const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();
+ 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();
+ unsigned InsSIdx = MI->getOperand(2).getSubReg();
+ unsigned SubIdx = MI->getOperand(3).getImm();
- TII.copyRegToReg(*MBB, MI, DstReg, SrcReg, TRC0, TRC0);
+ 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");
+
+ DOUT << "subreg: CONVERTING: " << *MI;
+
+ if (DstSubReg == InsReg && InsSIdx == 0) {
+ // No need to insert an identify copy instruction.
+ // Watch out for case like this:
+ // %RAX<def> = ...
+ // %RAX<def> = SUBREG_TO_REG 0, %EAX:3<kill>, 3
+ // The first def is defining RAX, not EAX so the top bits were not
+ // zero extended.
+ DOUT << "subreg: eliminated!";
+ } else {
+ // Insert sub-register copy
+ const TargetRegisterClass *TRC0= TRI.getPhysicalRegisterRegClass(DstSubReg);
+ const TargetRegisterClass *TRC1= TRI.getPhysicalRegisterRegClass(InsReg);
+ TII.copyRegToReg(*MBB, MI, DstSubReg, InsReg, TRC0, TRC1);
+ // Transfer the kill/dead flags, if needed.
+ if (MI->getOperand(0).isDead())
+ TransferDeadFlag(MI, DstSubReg, TRI);
+ if (MI->getOperand(2).isKill())
+ TransferKillFlag(MI, InsReg, TRI);
#ifndef NDEBUG
MachineBasicBlock::iterator dMI = MI;
DOUT << "subreg: " << *(--dMI);
#endif
}
-
+
+ DOUT << "\n";
+ MBB->erase(MI);
+ return true;
+}
+
+bool LowerSubregsInstructionPass::LowerInsert(MachineInstr *MI) {
+ MachineBasicBlock *MBB = MI->getParent();
+ MachineFunction &MF = *MBB->getParent();
+ const TargetRegisterInfo &TRI = *MF.getTarget().getRegisterInfo();
+ const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();
+ assert((MI->getOperand(0).isReg() && MI->getOperand(0).isDef()) &&
+ (MI->getOperand(1).isReg() && MI->getOperand(1).isUse()) &&
+ (MI->getOperand(2).isReg() && MI->getOperand(2).isUse()) &&
+ MI->getOperand(3).isImm() && "Invalid insert_subreg");
+
+ unsigned DstReg = MI->getOperand(0).getReg();
#ifndef NDEBUG
- if (SrcReg == DstReg) {
- DOUT << "subreg: Eliminated superreg copy\n";
- }
+ unsigned SrcReg = MI->getOperand(1).getReg();
#endif
+ unsigned InsReg = MI->getOperand(2).getReg();
+ unsigned SubIdx = MI->getOperand(3).getImm();
+
+ assert(DstReg == SrcReg && "insert_subreg not a two-address instruction?");
+ assert(SubIdx != 0 && "Invalid index for insert_subreg");
+ unsigned DstSubReg = TRI.getSubReg(DstReg, SubIdx);
+ assert(DstSubReg && "invalid subregister index for register");
+ assert(TargetRegisterInfo::isPhysicalRegister(SrcReg) &&
+ "Insert superreg source must be in a physical register");
+ assert(TargetRegisterInfo::isPhysicalRegister(InsReg) &&
+ "Inserted value must be in a physical register");
+
+ DOUT << "subreg: CONVERTING: " << *MI;
- if (!revCopyOrder && InsReg != DstSubReg) {
+ if (DstSubReg == InsReg) {
+ // No need to insert an identity copy instruction. If the SrcReg was
+ // <undef>, we need to make sure it is alive by inserting an IMPLICIT_DEF
+ if (MI->getOperand(1).isUndef() && !MI->getOperand(0).isDead()) {
+ MachineInstrBuilder MIB = BuildMI(*MBB, MI, MI->getDebugLoc(),
+ TII.get(TargetInstrInfo::IMPLICIT_DEF), DstReg);
+ if (MI->getOperand(2).isUndef())
+ MIB.addReg(InsReg, RegState::Implicit | RegState::Undef);
+ else
+ MIB.addReg(InsReg, RegState::ImplicitKill);
+ } else {
+ DOUT << "subreg: eliminated!\n";
+ MBB->erase(MI);
+ return true;
+ }
+ } else {
// Insert sub-register copy
- const TargetRegisterClass *TRC1 = 0;
- if (TargetRegisterInfo::isPhysicalRegister(InsReg)) {
- TRC1 = getPhysicalRegisterRegClass(TRI, InsReg);
+ const TargetRegisterClass *TRC0= TRI.getPhysicalRegisterRegClass(DstSubReg);
+ const TargetRegisterClass *TRC1= TRI.getPhysicalRegisterRegClass(InsReg);
+ if (MI->getOperand(2).isUndef())
+ // If the source register being inserted is undef, then this becomes an
+ // implicit_def.
+ BuildMI(*MBB, MI, MI->getDebugLoc(),
+ TII.get(TargetInstrInfo::IMPLICIT_DEF), DstSubReg);
+ else
+ TII.copyRegToReg(*MBB, MI, DstSubReg, InsReg, TRC0, TRC1);
+ MachineBasicBlock::iterator CopyMI = MI;
+ --CopyMI;
+
+ // INSERT_SUBREG is a two-address instruction so it implicitly kills SrcReg.
+ if (!MI->getOperand(1).isUndef())
+ CopyMI->addOperand(MachineOperand::CreateReg(DstReg, false, true, true));
+
+ // Transfer the kill/dead flags, if needed.
+ if (MI->getOperand(0).isDead()) {
+ TransferDeadFlag(MI, DstSubReg, TRI);
} else {
- TRC1 = MF.getRegInfo().getRegClass(InsReg);
+ // Make sure the full DstReg is live after this replacement.
+ CopyMI->addOperand(MachineOperand::CreateReg(DstReg, true, true));
}
- TII.copyRegToReg(*MBB, MI, DstSubReg, InsReg, TRC1, TRC1);
+
+ // Make sure the inserted register gets killed
+ if (MI->getOperand(2).isKill() && !MI->getOperand(2).isUndef())
+ TransferKillFlag(MI, InsReg, TRI);
+ }
#ifndef NDEBUG
- MachineBasicBlock::iterator dMI = MI;
- DOUT << "subreg: " << *(--dMI);
+ MachineBasicBlock::iterator dMI = MI;
+ DOUT << "subreg: " << *(--dMI);
#endif
- }
DOUT << "\n";
- MBB->remove(MI);
- return true;
+ MBB->erase(MI);
+ return true;
}
/// runOnMachineFunction - Reduce subregister inserts and extracts to register
bool MadeChange = false;
DOUT << "********** LOWERING SUBREG INSTRS **********\n";
- DOUT << "********** Function: " << MF.getFunction()->getName() << '\n';
+ DEBUG(errs() << "********** Function: "
+ << MF.getFunction()->getName() << '\n');
for (MachineFunction::iterator mbbi = MF.begin(), mbbe = MF.end();
mbbi != mbbe; ++mbbi) {
MadeChange |= LowerExtract(MI);
} else if (MI->getOpcode() == TargetInstrInfo::INSERT_SUBREG) {
MadeChange |= LowerInsert(MI);
+ } else if (MI->getOpcode() == TargetInstrInfo::SUBREG_TO_REG) {
+ MadeChange |= LowerSubregToReg(MI);
}
}
}
projects / oota-llvm.git / blobdiff