[PowerPC] enable optimizeCompareInstr for branch with static branch hint
In optimizeCompareInstr, a compare instruction is eliminated by using a record form instruction if possible.
If the branch instruction that uses the result of the compare has a static branch hint, the optimization does not happen.
This patch makes this optimization happen regardless of the branch hint by splitting branch hint and branch condition before checking the predicate to identify the possible optimizations.
Differential Revision: https://reviews.llvm.org/D35801
llvm-svn: 309255
diff --git a/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp b/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
index e74ba38..d65d17b 100644
--- a/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
+++ b/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
@@ -1640,8 +1640,10 @@
I != IE; ++I) {
MachineInstr *UseMI = &*I;
if (UseMI->getOpcode() == PPC::BCC) {
- unsigned Pred = UseMI->getOperand(0).getImm();
- if (Pred != PPC::PRED_EQ && Pred != PPC::PRED_NE)
+ PPC::Predicate Pred = (PPC::Predicate)UseMI->getOperand(0).getImm();
+ unsigned PredCond = PPC::getPredicateCondition(Pred);
+ // We ignore hint bits when checking for non-equality comparisons.
+ if (PredCond != PPC::PRED_EQ && PredCond != PPC::PRED_NE)
return false;
} else if (UseMI->getOpcode() == PPC::ISEL ||
UseMI->getOpcode() == PPC::ISEL8) {
@@ -1695,19 +1697,23 @@
MachineInstr *UseMI = &*MRI->use_instr_begin(CRReg);
if (UseMI->getOpcode() == PPC::BCC) {
PPC::Predicate Pred = (PPC::Predicate)UseMI->getOperand(0).getImm();
+ unsigned PredCond = PPC::getPredicateCondition(Pred);
+ unsigned PredHint = PPC::getPredicateHint(Pred);
int16_t Immed = (int16_t)Value;
- if (Immed == -1 && Pred == PPC::PRED_GT) {
+ // When modyfing the condition in the predicate, we propagate hint bits
+ // from the original predicate to the new one.
+ if (Immed == -1 && PredCond == PPC::PRED_GT) {
// We convert "greater than -1" into "greater than or equal to 0",
// since we are assuming signed comparison by !equalityOnly
PredsToUpdate.push_back(std::make_pair(&(UseMI->getOperand(0)),
- PPC::PRED_GE));
+ PPC::getPredicate(PPC::PRED_GE, PredHint)));
Success = true;
}
- else if (Immed == 1 && Pred == PPC::PRED_LT) {
+ else if (Immed == 1 && PredCond == PPC::PRED_LT) {
// We convert "less than 1" into "less than or equal to 0".
PredsToUpdate.push_back(std::make_pair(&(UseMI->getOperand(0)),
- PPC::PRED_LE));
+ PPC::getPredicate(PPC::PRED_LE, PredHint)));
Success = true;
}
}
@@ -1804,9 +1810,11 @@
MachineInstr *UseMI = &*I;
if (UseMI->getOpcode() == PPC::BCC) {
PPC::Predicate Pred = (PPC::Predicate) UseMI->getOperand(0).getImm();
+ unsigned PredCond = PPC::getPredicateCondition(Pred);
assert((!equalityOnly ||
- Pred == PPC::PRED_EQ || Pred == PPC::PRED_NE) &&
+ PredCond == PPC::PRED_EQ || PredCond == PPC::PRED_NE) &&
"Invalid predicate for equality-only optimization");
+ (void)PredCond; // To suppress warning in release build.
PredsToUpdate.push_back(std::make_pair(&(UseMI->getOperand(0)),
PPC::getSwappedPredicate(Pred)));
} else if (UseMI->getOpcode() == PPC::ISEL ||