If a unconditional branch is added to branch to the false path during ifcvt, the predicated block cannot be iteratively ifcvted.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@37456 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/IfConversion.cpp b/lib/CodeGen/IfConversion.cpp
index a81508f..4572f4c 100644
--- a/lib/CodeGen/IfConversion.cpp
+++ b/lib/CodeGen/IfConversion.cpp
@@ -165,8 +165,8 @@
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 @@
// 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 @@
// 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 @@
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)