--- /dev/null
+//===-- LowerSubregs.cpp - Subregister Lowering instruction pass ----------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by Christopher Lamb and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#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/SSARegMap.h"
+#include "llvm/Target/MRegisterInfo.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/Compiler.h"
+using namespace llvm;
+
+namespace {
+ struct VISIBILITY_HIDDEN LowerSubregsInstructionPass
+ : public MachineFunctionPass {
+ static char ID; // Pass identification, replacement for typeid
+ LowerSubregsInstructionPass() : MachineFunctionPass((intptr_t)&ID) {}
+
+ const char *getPassName() const {
+ return "Subregister lowering instruction pass";
+ }
+
+ /// runOnMachineFunction - pass entry point
+ bool runOnMachineFunction(MachineFunction&);
+ };
+
+ char LowerSubregsInstructionPass::ID = 0;
+}
+
+FunctionPass *llvm::createLowerSubregsPass() {
+ return new LowerSubregsInstructionPass();
+}
+
+// Returns the Register Class of a physical register
+static const TargetRegisterClass *getPhysicalRegisterRegClass(
+ const MRegisterInfo &MRI,
+ unsigned reg) {
+ assert(MRegisterInfo::isPhysicalRegister(reg) &&
+ "reg must be a physical register");
+ // Pick the register class of the right type that contains this physreg.
+ for (MRegisterInfo::regclass_iterator I = MRI.regclass_begin(),
+ E = MRI.regclass_end(); I != E; ++I)
+ if ((*I)->contains(reg))
+ return *I;
+ assert(false && "Couldn't find the register class");
+ return 0;
+}
+
+static bool isSubRegOf(const MRegisterInfo &MRI,
+ unsigned SubReg,
+ unsigned SupReg) {
+ const TargetRegisterDesc &RD = MRI[SubReg];
+ for (const unsigned *reg = RD.SuperRegs; *reg != 0; ++reg)
+ if (*reg == SupReg)
+ return true;
+
+ return false;
+}
+
+
+/// runOnMachineFunction - Reduce subregister inserts and extracts to register
+/// copies.
+///
+bool LowerSubregsInstructionPass::runOnMachineFunction(MachineFunction &MF) {
+ DOUT << "Machine Function\n";
+ const TargetMachine &TM = MF.getTarget();
+ const MRegisterInfo &MRI = *TM.getRegisterInfo();
+
+ bool MadeChange = false;
+
+ DOUT << "********** LOWERING SUBREG INSTRS **********\n";
+ DOUT << "********** Function: " << MF.getFunction()->getName() << '\n';
+
+ for (MachineFunction::iterator mbbi = MF.begin(), mbbe = MF.end();
+ mbbi != mbbe; ++mbbi) {
+ for (MachineBasicBlock::iterator mi = mbbi->begin(), me = mbbi->end();
+ mi != me; ++mi) {
+
+ if (mi->getOpcode() == TargetInstrInfo::EXTRACT_SUBREG) {
+ assert(mi->getOperand(0).isRegister() && mi->getOperand(0).isDef() &&
+ mi->getOperand(1).isRegister() && mi->getOperand(1).isUse() &&
+ mi->getOperand(2).isImm() && "Malformed extract_subreg");
+
+ unsigned SuperReg = mi->getOperand(1).getReg();
+ unsigned SubIdx = mi->getOperand(2).getImm();
+
+ assert(MRegisterInfo::isPhysicalRegister(SuperReg) &&
+ "Extract supperg source must be a physical register");
+ unsigned SrcReg = MRI.getSubReg(SuperReg, SubIdx);
+ unsigned DstReg = mi->getOperand(0).getReg();
+
+ DOUT << "subreg: CONVERTING: " << *mi;
+
+ if (SrcReg != DstReg) {
+ const TargetRegisterClass *TRC = 0;
+ if (MRegisterInfo::isPhysicalRegister(DstReg)) {
+ TRC = getPhysicalRegisterRegClass(MRI, DstReg);
+ } else {
+ TRC = MF.getSSARegMap()->getRegClass(DstReg);
+ }
+ assert(TRC == getPhysicalRegisterRegClass(MRI, SrcReg) &&
+ "Extract subreg and Dst must be of same register class");
+
+ MRI.copyRegToReg(*mbbi, mi, DstReg, SrcReg, TRC);
+ MachineBasicBlock::iterator dmi = mi;
+ DOUT << "subreg: " << *(--dmi);
+ }
+
+ DOUT << "\n";
+ mbbi->erase(mi);
+ MadeChange = true;
+
+ } else if (mi->getOpcode() == TargetInstrInfo::INSERT_SUBREG) {
+
+ 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).isImm() && "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).isImm() && "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 = MRI.getSubReg(DstReg, SubIdx);
+
+ assert(MRegisterInfo::isPhysicalRegister(SrcReg) &&
+ "Insert superreg source must be in a physical register");
+ assert(MRegisterInfo::isPhysicalRegister(DstReg) &&
+ "Insert destination must be in a physical register");
+ assert(MRegisterInfo::isPhysicalRegister(InsReg) &&
+ "Inserted value must be in a physical 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 = isSubRegOf(MRI, InsReg, DstReg);
+ if (revCopyOrder) {
+ if (mi->getOperand(1).isKill()) {
+ DstSubReg = MRI.getSubReg(SrcReg, SubIdx);
+ // Insert sub-register copy
+ const TargetRegisterClass *TRC1 = 0;
+ if (MRegisterInfo::isPhysicalRegister(InsReg)) {
+ TRC1 = getPhysicalRegisterRegClass(MRI, InsReg);
+ } else {
+ TRC1 = MF.getSSARegMap()->getRegClass(InsReg);
+ }
+
+ MRI.copyRegToReg(*mbbi, mi, DstSubReg, InsReg, TRC1);
+ MachineBasicBlock::iterator dmi = mi;
+ DOUT << "subreg: " << *(--dmi);
+ } else {
+ assert(0 && "Don't know how to convert this insert");
+ }
+ }
+
+ if (SrcReg != DstReg) {
+ // Insert super-register copy
+ const TargetRegisterClass *TRC0 = 0;
+ if (MRegisterInfo::isPhysicalRegister(DstReg)) {
+ TRC0 = getPhysicalRegisterRegClass(MRI, DstReg);
+ } else {
+ TRC0 = MF.getSSARegMap()->getRegClass(DstReg);
+ }
+ assert(TRC0 == getPhysicalRegisterRegClass(MRI, SrcReg) &&
+ "Insert superreg and Dst must be of same register class");
+
+ MRI.copyRegToReg(*mbbi, mi, DstReg, SrcReg, TRC0);
+ MachineBasicBlock::iterator dmi = mi;
+ DOUT << "subreg: " << *(--dmi);
+ }
+
+ if (!revCopyOrder && InsReg != DstSubReg) {
+ // Insert sub-register copy
+ const TargetRegisterClass *TRC1 = 0;
+ if (MRegisterInfo::isPhysicalRegister(InsReg)) {
+ TRC1 = getPhysicalRegisterRegClass(MRI, InsReg);
+ } else {
+ TRC1 = MF.getSSARegMap()->getRegClass(InsReg);
+ }
+
+ MRI.copyRegToReg(*mbbi, mi, DstSubReg, InsReg, TRC1);
+ MachineBasicBlock::iterator dmi = mi;
+ DOUT << "subreg: " << *(--dmi);
+ }
+
+ DOUT << "\n";
+ mbbi->erase(mi);
+ MadeChange = true;
+ }
+ }
+ }
+
+ return MadeChange;
+}
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