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Provide an option to restore old-style if-conversion heuristics for Thumb2.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@115339 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Owen Anderson 2010-10-01 20:28:06 +00:00
parent 7267e14327
commit aa9f0a57d0
2 changed files with 35 additions and 0 deletions
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29
lib/Target/ARM/Thumb2InstrInfo.cpp
View File

@ -28,6 +28,11 @@
using namespace llvm;
static cl::opt<bool>
OldT2IfCvt("old-thumb2-ifcvt", cl::Hidden,
cl::desc("Use old-style Thumb2 if-conversion heuristics"),
cl::init(false));
Thumb2InstrInfo::Thumb2InstrInfo(const ARMSubtarget &STI)
: ARMBaseInstrInfo(STI), RI(*this, STI) {
}
@ -37,6 +42,30 @@ unsigned Thumb2InstrInfo::getUnindexedOpcode(unsigned Opc) const {
return 0;
}
bool Thumb2InstrInfo::isProfitableToIfCvt(MachineBasicBlock &MBB,
unsigned NumInstrs,
float Prediction) const {
if (!OldT2IfCvt)
return ARMBaseInstrInfo::isProfitableToIfCvt(MBB, NumInstrs, Prediction);
return NumInstrs && NumInstrs <= 3;
}
bool Thumb2InstrInfo::
isProfitableToIfCvt(MachineBasicBlock &TMBB, unsigned NumT,
MachineBasicBlock &FMBB, unsigned NumF,
float Prediction) const {
if (!OldT2IfCvt)
return ARMBaseInstrInfo::isProfitableToIfCvt(TMBB, NumT,
FMBB, NumF, Prediction);
// FIXME: Catch optimization such as:
// r0 = movne
// r0 = moveq
return NumT && NumF &&
NumT <= 3 && NumF <= 3;
}
void
Thumb2InstrInfo::ReplaceTailWithBranchTo(MachineBasicBlock::iterator Tail,
MachineBasicBlock *NewDest) const {

6
lib/Target/ARM/Thumb2InstrInfo.h
View File

@ -38,6 +38,12 @@ public:
bool isLegalToSplitMBBAt(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI) const;
bool isProfitableToIfCvt(MachineBasicBlock &MBB, unsigned NumInstrs,
float Prediction) const;
bool isProfitableToIfCvt(MachineBasicBlock &TMBB, unsigned NumTInstrs,
MachineBasicBlock &FMBB, unsigned NumFInstrs,
float Prediction) const;
void copyPhysReg(MachineBasicBlock &MBB,
MachineBasicBlock::iterator I, DebugLoc DL,
unsigned DestReg, unsigned SrcReg,