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ifcvt a triangle: don't merge ifcvt block with rejoin block if it can fall through to it. If merged, the resulting block is not a candidate for iterative ifcvting since it contains both predicated and non-predicated code.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@37487 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2007-06-07 08:13:00 +00:00
parent 5cbf316686
commit f476961ae6
1 changed files with 29 additions and 17 deletions
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14
lib/CodeGen/IfConversion.cpp
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@ -615,10 +615,18 @@ bool IfConverter::IfConvertTriangle(BBInfo &BBI) {
BBInfo &FalseBBI = BBAnalysis[BBI.FalseBB->getNumber()]; BBInfo &FalseBBI = BBAnalysis[BBI.FalseBB->getNumber()];
bool FalseBBDead = false; bool FalseBBDead = false;
bool IterIfcvt = true; bool IterIfcvt = true;
bool isFallThrough = isNextBlock(TrueBBI.BB, FalseBBI.BB);
if (!isFallThrough) {
// Only merge them if the true block does not fallthrough to the false
// block. By not merging them, we make it possible to iteratively
// ifcvt the blocks.
if (!HasEarlyExit && FalseBBI.BB->pred_size() == 2) { if (!HasEarlyExit && FalseBBI.BB->pred_size() == 2) {
MergeBlocks(TrueBBI, FalseBBI); MergeBlocks(TrueBBI, FalseBBI);
FalseBBDead = true; FalseBBDead = true;
} else if (!isNextBlock(TrueBBI.BB, FalseBBI.BB)) { // Mixed predicated and unpredicated code. This cannot be iteratively
// predicated.
IterIfcvt = false;
} else {
InsertUncondBranch(TrueBBI.BB, FalseBBI.BB, TII); InsertUncondBranch(TrueBBI.BB, FalseBBI.BB, TII);
TrueBBI.hasFallThrough = false; TrueBBI.hasFallThrough = false;
if (BBI.ModifyPredicate || TrueBBI.ModifyPredicate) if (BBI.ModifyPredicate || TrueBBI.ModifyPredicate)
@ -634,10 +642,14 @@ bool IfConverter::IfConvertTriangle(BBInfo &BBI) {
// if cmp executes. // if cmp executes.
IterIfcvt = false; IterIfcvt = false;
} }
}
// Now merge the entry of the triangle with the true block. // Now merge the entry of the triangle with the true block.
BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB); BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
MergeBlocks(BBI, TrueBBI); MergeBlocks(BBI, TrueBBI);
// Remove entry to false edge.
if (BBI.BB->isSuccessor(FalseBBI.BB))
BBI.BB->removeSuccessor(FalseBBI.BB);
std::copy(BBI.BrCond.begin(), BBI.BrCond.end(), std::copy(BBI.BrCond.begin(), BBI.BrCond.end(),
std::back_inserter(BBI.Predicate)); std::back_inserter(BBI.Predicate));