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If a unconditional branch is added to branch to the false path during ifcvt, the predicated block cannot be iteratively ifcvted.

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llvm-svn: 37456
This commit is contained in:
Evan Cheng 2007-06-06 02:08:52 +00:00
parent 501e5873d4
commit 4c42a30bad
1 changed files with 33 additions and 6 deletions
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39
lib/CodeGen/IfConversion.cpp
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@ -165,8 +165,8 @@ bool IfConverter::runOnMachineFunction(MachineFunction &MF) {
RetVal = IfConvertSimple(BBI);
DOUT << (RetVal ? "succeeded!" : "failed!") << "\n";
if (RetVal)
if (isRev) NumSimple++;
else NumSimpleRev++;
if (isRev) NumSimpleRev++;
else NumSimple++;
break;
}
case ICTriangle:
@ -515,12 +515,25 @@ bool IfConverter::IfConvertSimple(BBInfo &BBI) {
// to the 'false' branch.
BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
MergeBlocks(BBI, *CvtBBI);
if (!isNextBlock(BBI.BB, NextBBI->BB))
bool IterIfcvt = true;
if (!isNextBlock(BBI.BB, NextBBI->BB)) {
// Now ifcvt'd block will look like this:
// BB:
// ...
// t, f = cmp
// if t op
// b BBf
//
// We cannot further ifcvt this block because the unconditional branch will
// have to be predicated on the new condition, that will not be available
// if cmp executes.
InsertUncondBranch(BBI.BB, NextBBI->BB, TII);
}
std::copy(Cond.begin(), Cond.end(), std::back_inserter(BBI.Predicate));
// Update block info. BB can be iteratively if-converted.
BBI.Kind = ICReAnalyze;
if (IterIfcvt)
BBI.Kind = ICReAnalyze;
ReTryPreds(BBI.BB);
CvtBBI->Kind = ICDead;
@ -552,11 +565,24 @@ bool IfConverter::IfConvertTriangle(BBInfo &BBI) {
// predecessors. Otherwise, add a unconditional branch from 'true' to 'false'.
BBInfo &FalseBBI = BBAnalysis[BBI.FalseBB->getNumber()];
bool FalseBBDead = false;
bool IterIfcvt = true;
if (!HasEarlyExit && FalseBBI.BB->pred_size() == 2) {
MergeBlocks(TrueBBI, FalseBBI);
FalseBBDead = true;
} else if (!isNextBlock(TrueBBI.BB, FalseBBI.BB))
} else if (!isNextBlock(TrueBBI.BB, FalseBBI.BB)) {
InsertUncondBranch(TrueBBI.BB, FalseBBI.BB, TII);
// Now ifcvt'd block will look like this:
// BB:
// ...
// t, f = cmp
// if t op
// b BBf
//
// We cannot further ifcvt this block because the unconditional branch will
// have to be predicated on the new condition, that will not be available
// if cmp executes.
IterIfcvt = false;
}
// Now merge the entry of the triangle with the true block.
BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
@ -565,7 +591,8 @@ bool IfConverter::IfConvertTriangle(BBInfo &BBI) {
std::back_inserter(BBI.Predicate));
// Update block info. BB can be iteratively if-converted.
BBI.Kind = ICReAnalyze;
if (IterIfcvt)
BBI.Kind = ICReAnalyze;
ReTryPreds(BBI.BB);
TrueBBI.Kind = ICDead;
if (FalseBBDead)