+++ /dev/null
-//===-- OptimizeCmps.cpp - Optimize comparison instrs ---------------------===//
-//
-// The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// This pass performs optimization of comparison instructions. For instance, in
-// this code:
-//
-// sub r1, 1
-// cmp r1, 0
-// bz L1
-//
-// If the "sub" instruction all ready sets (or could be modified to set) the
-// same flag that the "cmp" instruction sets and that "bz" uses, then we can
-// eliminate the "cmp" instruction.
-//
-//===----------------------------------------------------------------------===//
-
-#define DEBUG_TYPE "opt-compares"
-#include "llvm/CodeGen/Passes.h"
-#include "llvm/CodeGen/MachineFunctionPass.h"
-#include "llvm/CodeGen/MachineInstrBuilder.h"
-#include "llvm/CodeGen/MachineRegisterInfo.h"
-#include "llvm/Target/TargetInstrInfo.h"
-#include "llvm/Target/TargetRegisterInfo.h"
-#include "llvm/Support/CommandLine.h"
-#include "llvm/ADT/Statistic.h"
-using namespace llvm;
-
-STATISTIC(NumEliminated, "Number of compares eliminated");
-
-static cl::opt<bool>
-EnableOptCmps("enable-optimize-cmps", cl::init(false), cl::Hidden);
-
-namespace {
- class OptimizeCmps : public MachineFunctionPass {
- const TargetMachine *TM;
- const TargetInstrInfo *TII;
- MachineRegisterInfo *MRI;
-
- bool OptimizeCmpInstr(MachineInstr *MI, MachineBasicBlock *MBB);
-
- public:
- static char ID; // Pass identification
- OptimizeCmps() : MachineFunctionPass(ID) {}
-
- virtual bool runOnMachineFunction(MachineFunction &MF);
-
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
- AU.setPreservesCFG();
- MachineFunctionPass::getAnalysisUsage(AU);
- }
- };
-}
-
-char OptimizeCmps::ID = 0;
-INITIALIZE_PASS(OptimizeCmps, "opt-cmps",
- "Optimize comparison instrs", false, false);
-
-FunctionPass *llvm::createOptimizeCmpsPass() { return new OptimizeCmps(); }
-
-/// OptimizeCmpInstr - If the instruction is a compare and the previous
-/// instruction it's comparing against all ready sets (or could be modified to
-/// set) the same flag as the compare, then we can remove the comparison and use
-/// the flag from the previous instruction.
-bool OptimizeCmps::OptimizeCmpInstr(MachineInstr *MI, MachineBasicBlock *MBB) {
- // If this instruction is a comparison against zero and isn't comparing a
- // physical register, we can try to optimize it.
- unsigned SrcReg;
- int CmpValue;
- if (!TII->AnalyzeCompare(MI, SrcReg, CmpValue) ||
- TargetRegisterInfo::isPhysicalRegister(SrcReg) || CmpValue != 0)
- return false;
-
- MachineRegisterInfo::def_iterator DI = MRI->def_begin(SrcReg);
- if (llvm::next(DI) != MRI->def_end())
- // Only support one definition.
- return false;
-
- // Attempt to convert the defining instruction to set the "zero" flag.
- if (TII->ConvertToSetZeroFlag(&*DI, MI)) {
- ++NumEliminated;
- return true;
- }
-
- return false;
-}
-
-bool OptimizeCmps::runOnMachineFunction(MachineFunction &MF) {
- TM = &MF.getTarget();
- TII = TM->getInstrInfo();
- MRI = &MF.getRegInfo();
-
- if (!EnableOptCmps) return false;
-
- bool Changed = false;
- for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
- MachineBasicBlock *MBB = &*I;
- for (MachineBasicBlock::iterator
- MII = MBB->begin(), ME = MBB->end(); MII != ME; ) {
- MachineInstr *MI = &*MII++;
- if (MI->getDesc().isCompare())
- Changed |= OptimizeCmpInstr(MI, MBB);
- }
- }
-
- return Changed;
-}
-//===-- OptimizeExts.cpp - Optimize sign / zero extension instrs -----===//
+//===-- PeepholeOptimizer.cpp - Peephole Optimizations --------------------===//
//
// The LLVM Compiler Infrastructure
//
//
//===----------------------------------------------------------------------===//
//
-// This pass performs optimization of sign / zero extension instructions. It
-// may be extended to handle other instructions of similar property.
+// Perform peephole optimizations on the machine code:
//
-// On some targets, some instructions, e.g. X86 sign / zero extension, may
-// leave the source value in the lower part of the result. This pass will
-// replace (some) uses of the pre-extension value with uses of the sub-register
-// of the results.
+// - Optimize Extensions
//
+// Optimization of sign / zero extension instructions. It may be extended to
+// handle other instructions with similar properties.
+//
+// On some targets, some instructions, e.g. X86 sign / zero extension, may
+// leave the source value in the lower part of the result. This optimization
+// will replace some uses of the pre-extension value with uses of the
+// sub-register of the results.
+//
+// - Optimize Comparisons
+//
+// Optimization of comparison instructions. For instance, in this code:
+//
+// sub r1, 1
+// cmp r1, 0
+// bz L1
+//
+// If the "sub" instruction all ready sets (or could be modified to set) the
+// same flag that the "cmp" instruction sets and that "bz" uses, then we can
+// eliminate the "cmp" instruction.
+//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "ext-opt"
+#define DEBUG_TYPE "peephole-opt"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/ADT/Statistic.h"
using namespace llvm;
-static cl::opt<bool> Aggressive("aggressive-ext-opt", cl::Hidden,
- cl::desc("Aggressive extension optimization"));
+// Optimize Extensions
+static cl::opt<bool>
+Aggressive("aggressive-ext-opt", cl::Hidden,
+ cl::desc("Aggressive extension optimization"));
STATISTIC(NumReuse, "Number of extension results reused");
+// Optimize Comparisons
+static cl::opt<bool>
+EnableOptCmps("enable-optimize-cmps", cl::init(false), cl::Hidden);
+
+STATISTIC(NumEliminated, "Number of compares eliminated");
+
namespace {
- class OptimizeExts : public MachineFunctionPass {
+ class PeepholeOptimizer : public MachineFunctionPass {
const TargetMachine *TM;
const TargetInstrInfo *TII;
- MachineRegisterInfo *MRI;
- MachineDominatorTree *DT; // Machine dominator tree
+ MachineRegisterInfo *MRI;
+ MachineDominatorTree *DT; // Machine dominator tree
public:
static char ID; // Pass identification
- OptimizeExts() : MachineFunctionPass(ID) {}
+ PeepholeOptimizer() : MachineFunctionPass(ID) {}
virtual bool runOnMachineFunction(MachineFunction &MF);
}
private:
- bool OptimizeInstr(MachineInstr *MI, MachineBasicBlock *MBB,
- SmallPtrSet<MachineInstr*, 8> &LocalMIs);
+ bool OptimizeCmpInstr(MachineInstr *MI, MachineBasicBlock *MBB);
+ bool OptimizeExtInstr(MachineInstr *MI, MachineBasicBlock *MBB,
+ SmallPtrSet<MachineInstr*, 8> &LocalMIs);
};
}
-char OptimizeExts::ID = 0;
-INITIALIZE_PASS(OptimizeExts, "opt-exts",
- "Optimize sign / zero extensions", false, false);
-
-FunctionPass *llvm::createOptimizeExtsPass() { return new OptimizeExts(); }
-
-/// OptimizeInstr - If instruction is a copy-like instruction, i.e. it reads
-/// a single register and writes a single register and it does not modify
-/// the source, and if the source value is preserved as a sub-register of
-/// the result, then replace all reachable uses of the source with the subreg
-/// of the result.
-/// Do not generate an EXTRACT that is used only in a debug use, as this
-/// changes the code. Since this code does not currently share EXTRACTs, just
-/// ignore all debug uses.
-bool OptimizeExts::OptimizeInstr(MachineInstr *MI, MachineBasicBlock *MBB,
- SmallPtrSet<MachineInstr*, 8> &LocalMIs) {
+char PeepholeOptimizer::ID = 0;
+INITIALIZE_PASS(PeepholeOptimizer, "peephole-opts",
+ "Peephole Optimizations", false, false);
+
+FunctionPass *llvm::createPeepholeOptimizerPass() {
+ return new PeepholeOptimizer();
+}
+
+/// OptimizeExtInstr - If instruction is a copy-like instruction, i.e. it reads
+/// a single register and writes a single register and it does not modify the
+/// source, and if the source value is preserved as a sub-register of the
+/// result, then replace all reachable uses of the source with the subreg of the
+/// result.
+///
+/// Do not generate an EXTRACT that is used only in a debug use, as this changes
+/// the code. Since this code does not currently share EXTRACTs, just ignore all
+/// debug uses.
+bool PeepholeOptimizer::
+OptimizeExtInstr(MachineInstr *MI, MachineBasicBlock *MBB,
+ SmallPtrSet<MachineInstr*, 8> &LocalMIs) {
LocalMIs.insert(MI);
unsigned SrcReg, DstReg, SubIdx;
// No other uses.
return false;
- // Ok, the source has other uses. See if we can replace the other uses
- // with use of the result of the extension.
+ // The source has other uses. See if we can replace the other uses with use of
+ // the result of the extension.
SmallPtrSet<MachineBasicBlock*, 4> ReachedBBs;
UI = MRI->use_nodbg_begin(DstReg);
for (MachineRegisterInfo::use_nodbg_iterator UE = MRI->use_nodbg_end();
UI != UE; ++UI)
ReachedBBs.insert(UI->getParent());
- bool ExtendLife = true;
// Uses that are in the same BB of uses of the result of the instruction.
SmallVector<MachineOperand*, 8> Uses;
+
// Uses that the result of the instruction can reach.
SmallVector<MachineOperand*, 8> ExtendedUses;
+ bool ExtendLife = true;
UI = MRI->use_nodbg_begin(SrcReg);
for (MachineRegisterInfo::use_nodbg_iterator UE = MRI->use_nodbg_end();
UI != UE; ++UI) {
MachineInstr *UseMI = &*UI;
if (UseMI == MI)
continue;
+
if (UseMI->isPHI()) {
ExtendLife = false;
continue;
// Local uses that come after the extension.
if (!LocalMIs.count(UseMI))
Uses.push_back(&UseMO);
- } else if (ReachedBBs.count(UseMBB))
- // Non-local uses where the result of extension is used. Always replace
- // these unless it's a PHI.
+ } else if (ReachedBBs.count(UseMBB)) {
+ // Non-local uses where the result of the extension is used. Always
+ // replace these unless it's a PHI.
Uses.push_back(&UseMO);
- else if (Aggressive && DT->dominates(MBB, UseMBB))
- // We may want to extend live range of the extension result in order to
- // replace these uses.
+ } else if (Aggressive && DT->dominates(MBB, UseMBB)) {
+ // We may want to extend the live range of the extension result in order
+ // to replace these uses.
ExtendedUses.push_back(&UseMO);
- else {
+ } else {
// Both will be live out of the def MBB anyway. Don't extend live range of
// the extension result.
ExtendLife = false;
}
if (ExtendLife && !ExtendedUses.empty())
- // Ok, we'll extend the liveness of the extension result.
+ // Extend the liveness of the extension result.
std::copy(ExtendedUses.begin(), ExtendedUses.end(),
std::back_inserter(Uses));
bool Changed = false;
if (!Uses.empty()) {
SmallPtrSet<MachineBasicBlock*, 4> PHIBBs;
+
// Look for PHI uses of the extended result, we don't want to extend the
// liveness of a PHI input. It breaks all kinds of assumptions down
// stream. A PHI use is expected to be the kill of its source values.
UI = MRI->use_nodbg_begin(DstReg);
- for (MachineRegisterInfo::use_nodbg_iterator UE = MRI->use_nodbg_end();
- UI != UE; ++UI)
+ for (MachineRegisterInfo::use_nodbg_iterator
+ UE = MRI->use_nodbg_end(); UI != UE; ++UI)
if (UI->isPHI())
PHIBBs.insert(UI->getParent());
MachineBasicBlock *UseMBB = UseMI->getParent();
if (PHIBBs.count(UseMBB))
continue;
+
unsigned NewVR = MRI->createVirtualRegister(RC);
BuildMI(*UseMBB, UseMI, UseMI->getDebugLoc(),
TII->get(TargetOpcode::COPY), NewVR)
.addReg(DstReg, 0, SubIdx);
+
UseMO->setReg(NewVR);
++NumReuse;
Changed = true;
return Changed;
}
-bool OptimizeExts::runOnMachineFunction(MachineFunction &MF) {
- TM = &MF.getTarget();
+/// OptimizeCmpInstr - If the instruction is a compare and the previous
+/// instruction it's comparing against all ready sets (or could be modified to
+/// set) the same flag as the compare, then we can remove the comparison and use
+/// the flag from the previous instruction.
+bool PeepholeOptimizer::OptimizeCmpInstr(MachineInstr *MI,
+ MachineBasicBlock *MBB) {
+ if (!EnableOptCmps) return false;
+
+ // If this instruction is a comparison against zero and isn't comparing a
+ // physical register, we can try to optimize it.
+ unsigned SrcReg;
+ int CmpValue;
+ if (!TII->AnalyzeCompare(MI, SrcReg, CmpValue) ||
+ TargetRegisterInfo::isPhysicalRegister(SrcReg) || CmpValue != 0)
+ return false;
+
+ MachineRegisterInfo::def_iterator DI = MRI->def_begin(SrcReg);
+ if (llvm::next(DI) != MRI->def_end())
+ // Only support one definition.
+ return false;
+
+ // Attempt to convert the defining instruction to set the "zero" flag.
+ if (TII->ConvertToSetZeroFlag(&*DI, MI)) {
+ ++NumEliminated;
+ return true;
+ }
+
+ return false;
+}
+
+bool PeepholeOptimizer::runOnMachineFunction(MachineFunction &MF) {
+ TM = &MF.getTarget();
TII = TM->getInstrInfo();
MRI = &MF.getRegInfo();
- DT = Aggressive ? &getAnalysis<MachineDominatorTree>() : 0;
+ DT = Aggressive ? &getAnalysis<MachineDominatorTree>() : 0;
bool Changed = false;
for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
MachineBasicBlock *MBB = &*I;
LocalMIs.clear();
- for (MachineBasicBlock::iterator MII = I->begin(), ME = I->end(); MII != ME;
- ++MII) {
+
+ for (MachineBasicBlock::iterator
+ MII = I->begin(), ME = I->end(); MII != ME; ) {
MachineInstr *MI = &*MII;
- Changed |= OptimizeInstr(MI, MBB, LocalMIs);
+
+ if (MI->getDesc().isCompare()) {
+ ++MII; // The iterator may become invalid if the compare is deleted.
+ Changed |= OptimizeCmpInstr(MI, MBB);
+ } else {
+ Changed |= OptimizeExtInstr(MI, MBB, LocalMIs);
+ ++MII;
+ }
}
}
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