#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Support/CommandLine.h"
+#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/Statistic.h"
using namespace llvm;
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);
+DisablePeephole("disable-peephole", cl::Hidden, cl::init(false),
+ cl::desc("Disable the peephole optimizer"));
+STATISTIC(NumReuse, "Number of extension results reused");
STATISTIC(NumEliminated, "Number of compares eliminated");
+STATISTIC(NumImmFold, "Number of move immediate foled");
namespace {
class PeepholeOptimizer : public MachineFunctionPass {
public:
static char ID; // Pass identification
- PeepholeOptimizer() : MachineFunctionPass(ID) {}
+ PeepholeOptimizer() : MachineFunctionPass(ID) {
+ initializePeepholeOptimizerPass(*PassRegistry::getPassRegistry());
+ }
virtual bool runOnMachineFunction(MachineFunction &MF);
bool OptimizeCmpInstr(MachineInstr *MI, MachineBasicBlock *MBB);
bool OptimizeExtInstr(MachineInstr *MI, MachineBasicBlock *MBB,
SmallPtrSet<MachineInstr*, 8> &LocalMIs);
+ bool isMoveImmediate(MachineInstr *MI,
+ SmallSet<unsigned, 4> &ImmDefRegs,
+ DenseMap<unsigned, MachineInstr*> &ImmDefMIs);
+ bool FoldImmediate(MachineInstr *MI, MachineBasicBlock *MBB,
+ SmallSet<unsigned, 4> &ImmDefRegs,
+ DenseMap<unsigned, MachineInstr*> &ImmDefMIs);
};
}
char PeepholeOptimizer::ID = 0;
-INITIALIZE_PASS(PeepholeOptimizer, "peephole-opts",
- "Peephole Optimizations", false, false);
+INITIALIZE_PASS_BEGIN(PeepholeOptimizer, "peephole-opts",
+ "Peephole Optimizations", false, false)
+INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
+INITIALIZE_PASS_END(PeepholeOptimizer, "peephole-opts",
+ "Peephole Optimizations", false, false)
FunctionPass *llvm::createPeepholeOptimizerPass() {
return new PeepholeOptimizer();
bool PeepholeOptimizer::
OptimizeExtInstr(MachineInstr *MI, MachineBasicBlock *MBB,
SmallPtrSet<MachineInstr*, 8> &LocalMIs) {
- LocalMIs.insert(MI);
-
unsigned SrcReg, DstReg, SubIdx;
if (!TII->isCoalescableExtInstr(*MI, SrcReg, DstReg, SubIdx))
return false;
-
+
if (TargetRegisterInfo::isPhysicalRegister(DstReg) ||
TargetRegisterInfo::isPhysicalRegister(SrcReg))
return false;
/// 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;
-
+ 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.
+ int CmpMask, CmpValue;
+ if (!TII->AnalyzeCompare(MI, SrcReg, CmpMask, CmpValue) ||
+ TargetRegisterInfo::isPhysicalRegister(SrcReg))
return false;
- // Attempt to convert the defining instruction to set the "zero" flag.
- if (TII->ConvertToSetZeroFlag(&*DI, MI)) {
+ // Attempt to optimize the comparison instruction.
+ if (TII->OptimizeCompareInstr(MI, SrcReg, CmpMask, CmpValue, MRI)) {
++NumEliminated;
return true;
}
return false;
}
+bool PeepholeOptimizer::isMoveImmediate(MachineInstr *MI,
+ SmallSet<unsigned, 4> &ImmDefRegs,
+ DenseMap<unsigned, MachineInstr*> &ImmDefMIs) {
+ const TargetInstrDesc &TID = MI->getDesc();
+ if (!TID.isMoveImmediate())
+ return false;
+ if (TID.getNumDefs() != 1)
+ return false;
+ unsigned Reg = MI->getOperand(0).getReg();
+ if (TargetRegisterInfo::isVirtualRegister(Reg)) {
+ ImmDefMIs.insert(std::make_pair(Reg, MI));
+ ImmDefRegs.insert(Reg);
+ return true;
+ }
+
+ return false;
+}
+
+/// FoldImmediate - Try folding register operands that are defined by move
+/// immediate instructions, i.e. a trivial constant folding optimization, if
+/// and only if the def and use are in the same BB.
+bool PeepholeOptimizer::FoldImmediate(MachineInstr *MI, MachineBasicBlock *MBB,
+ SmallSet<unsigned, 4> &ImmDefRegs,
+ DenseMap<unsigned, MachineInstr*> &ImmDefMIs) {
+ for (unsigned i = 0, e = MI->getDesc().getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = MI->getOperand(i);
+ if (!MO.isReg() || MO.isDef())
+ continue;
+ unsigned Reg = MO.getReg();
+ if (!Reg || TargetRegisterInfo::isPhysicalRegister(Reg))
+ continue;
+ if (ImmDefRegs.count(Reg) == 0)
+ continue;
+ DenseMap<unsigned, MachineInstr*>::iterator II = ImmDefMIs.find(Reg);
+ assert(II != ImmDefMIs.end());
+ if (TII->FoldImmediate(MI, II->second, Reg, MRI)) {
+ ++NumImmFold;
+ return true;
+ }
+ }
+ return false;
+}
+
bool PeepholeOptimizer::runOnMachineFunction(MachineFunction &MF) {
+ if (DisablePeephole)
+ return false;
+
TM = &MF.getTarget();
TII = TM->getInstrInfo();
MRI = &MF.getRegInfo();
bool Changed = false;
SmallPtrSet<MachineInstr*, 8> LocalMIs;
+ SmallSet<unsigned, 4> ImmDefRegs;
+ DenseMap<unsigned, MachineInstr*> ImmDefMIs;
for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
MachineBasicBlock *MBB = &*I;
+
+ bool SeenMoveImm = false;
LocalMIs.clear();
+ ImmDefRegs.clear();
+ ImmDefMIs.clear();
for (MachineBasicBlock::iterator
- MII = I->begin(), ME = I->end(); MII != ME; ) {
- MachineInstr *MI = &*MII;
+ MII = I->begin(), MIE = I->end(); MII != MIE; ) {
+ MachineInstr *MI = &*MII++;
+ LocalMIs.insert(MI);
+
+ if (MI->isLabel() || MI->isPHI() || MI->isImplicitDef() ||
+ MI->isKill() || MI->isInlineAsm() || MI->isDebugValue() ||
+ MI->hasUnmodeledSideEffects())
+ continue;
if (MI->getDesc().isCompare()) {
- ++MII; // The iterator may become invalid if the compare is deleted.
Changed |= OptimizeCmpInstr(MI, MBB);
+ } else if (isMoveImmediate(MI, ImmDefRegs, ImmDefMIs)) {
+ SeenMoveImm = true;
} else {
Changed |= OptimizeExtInstr(MI, MBB, LocalMIs);
- ++MII;
+ if (SeenMoveImm)
+ Changed |= FoldImmediate(MI, MBB, ImmDefRegs, ImmDefMIs);
}
}
}
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