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[X86][FixupLEA] Avoid checking target features for every single processed instruction. NFCI 

llvm-svn: 346309
This commit is contained in:
Andrea Di Biagio 2018-11-07 12:26:00 +00:00
parent f84a7d8d4f
commit 4ae974e745
1 changed files with 24 additions and 18 deletions
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32
llvm/lib/Target/X86/X86FixupLEAs.cpp
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@ -39,8 +39,8 @@ class FixupLEAPass : public MachineFunctionPass {
/// Loop over all of the instructions in the basic block
/// replacing applicable instructions with LEA instructions,
/// where appropriate.
bool processBasicBlock(MachineFunction &MF, MachineFunction::iterator MFI);
bool processBasicBlock(MachineFunction &MF, MachineFunction::iterator MFI,
bool IsSlowLEA, bool IsSlow3OpsLEA);
/// Given a machine register, look for the instruction
/// which writes it in the current basic block. If found,
@ -192,8 +192,11 @@ bool FixupLEAPass::runOnMachineFunction(MachineFunction &Func) {
MF = &Func;
const X86Subtarget &ST = Func.getSubtarget<X86Subtarget>();
bool IsSlowLEA = ST.slowLEA();
bool IsSlow3OpsLEA = ST.slow3OpsLEA();
OptIncDec = !ST.slowIncDec() || Func.getFunction().optForMinSize();
OptLEA = ST.LEAusesAG() || ST.slowLEA() || ST.slow3OpsLEA();
OptLEA = ST.LEAusesAG() || IsSlowLEA || IsSlow3OpsLEA;
if (!OptLEA && !OptIncDec)
return false;
@ -204,7 +207,7 @@ bool FixupLEAPass::runOnMachineFunction(MachineFunction &Func) {
LLVM_DEBUG(dbgs() << "Start X86FixupLEAs\n";);
// Process all basic blocks.
for (MachineFunction::iterator I = Func.begin(), E = Func.end(); I != E; ++I)
processBasicBlock(Func, I);
processBasicBlock(Func, I, IsSlowLEA, IsSlow3OpsLEA);
LLVM_DEBUG(dbgs() << "End X86FixupLEAs\n";);
return true;
@ -280,8 +283,9 @@ static inline bool isInefficientLEAReg(unsigned int Reg) {
static inline bool isRegOperand(const MachineOperand &Op) {
return Op.isReg() && Op.getReg() != X86::NoRegister;
}
/// hasIneffecientLEARegs - LEA that uses base and index registers
/// where the base is EBP, RBP, or R13
/// Returns true if this LEA uses base an index registers, and the base register
/// is known to be inefficient for the subtarget.
// TODO: use a variant scheduling class to model the latency profile
// of LEA instructions, and implement this logic as a scheduling predicate.
static inline bool hasInefficientLEABaseReg(const MachineOperand &Base,
@ -566,26 +570,28 @@ FixupLEAPass::processInstrForSlow3OpLEA(MachineInstr &MI,
}
bool FixupLEAPass::processBasicBlock(MachineFunction &MF,
MachineFunction::iterator MFI) {
MachineFunction::iterator MFI,
bool IsSlowLEA, bool IsSlow3OpsLEA) {
for (MachineBasicBlock::iterator I = MFI->begin(); I != MFI->end(); ++I) {
if (OptIncDec)
if (fixupIncDec(I, MFI))
continue;
if (OptLEA) {
if (MF.getSubtarget<X86Subtarget>().slowLEA())
if (IsSlowLEA) {
processInstructionForSlowLEA(I, MFI);
continue;
}
else {
if (MF.getSubtarget<X86Subtarget>().slow3OpsLEA()) {
if (IsSlow3OpsLEA) {
if (auto *NewMI = processInstrForSlow3OpLEA(*I, MFI)) {
MFI->erase(I);
I = NewMI;
}
} else
processInstruction(I, MFI);
continue;
}
processInstruction(I, MFI);
}
}
return false;