Fix my previous patch to handle a degenerate case that the llvm-gcc
bootstrap buildbot tripped over.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121674 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp
index 7f9ef7c..68f6905 100644
--- a/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -1820,6 +1820,22 @@
return SimplifyCFG(BB) | true;
}
+ // Ok, the block is reachable from the default dest. If the constant we're
+ // comparing exists in one of the other edges, then we can constant fold ICI
+ // and zap it.
+ if (SI->findCaseValue(Cst) != 0) {
+ Value *V;
+ if (ICI->getPredicate() == ICmpInst::ICMP_EQ)
+ V = ConstantInt::getFalse(BB->getContext());
+ else
+ V = ConstantInt::getTrue(BB->getContext());
+
+ ICI->replaceAllUsesWith(V);
+ ICI->eraseFromParent();
+ // BB is now empty, so it is likely to simplify away.
+ return SimplifyCFG(BB) | true;
+ }
+
// The use of the icmp has to be in the 'end' block, by the only PHI node in
// the block.
BasicBlock *SuccBlock = BB->getTerminator()->getSuccessor(0);