Disable PRE for landing pads.
PRE needs the landing pads to have their critical edges split. Doing this for a
landing pad is non-trivial. Abandon the attempt to perform PRE when we come
across a landing pad. (Reviewed by Owen!)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@137876 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/GVN.cpp b/lib/Transforms/Scalar/GVN.cpp
index 8124169..9785b31 100644
--- a/lib/Transforms/Scalar/GVN.cpp
+++ b/lib/Transforms/Scalar/GVN.cpp
@@ -1446,8 +1446,8 @@
for (unsigned i = 0, e = UnavailableBlocks.size(); i != e; ++i)
Blockers.insert(UnavailableBlocks[i]);
- // Lets find first basic block with more than one predecessor. Walk backwards
- // through predecessors if needed.
+ // Let's find the first basic block with more than one predecessor. Walk
+ // backwards through predecessors if needed.
BasicBlock *LoadBB = LI->getParent();
BasicBlock *TmpBB = LoadBB;
@@ -1519,10 +1519,19 @@
<< Pred->getName() << "': " << *LI << '\n');
return false;
}
+
+ if (LoadBB->isLandingPad()) {
+ DEBUG(dbgs()
+ << "COULD NOT PRE LOAD BECAUSE OF LANDING PAD CRITICAL EDGE '"
+ << Pred->getName() << "': " << *LI << '\n');
+ return false;
+ }
+
unsigned SuccNum = GetSuccessorNumber(Pred, LoadBB);
NeedToSplit.push_back(std::make_pair(Pred->getTerminator(), SuccNum));
}
}
+
if (!NeedToSplit.empty()) {
toSplit.append(NeedToSplit.begin(), NeedToSplit.end());
return false;
@@ -2071,6 +2080,9 @@
// Nothing to PRE in the entry block.
if (CurrentBlock == &F.getEntryBlock()) continue;
+ // Don't perform PRE on a landing pad.
+ if (CurrentBlock->isLandingPad()) continue;
+
for (BasicBlock::iterator BI = CurrentBlock->begin(),
BE = CurrentBlock->end(); BI != BE; ) {
Instruction *CurInst = BI++;