From 1fea77c6fc6ab0d5557078656be6c54eba769b42 Mon Sep 17 00:00:00 2001 From: David Majnemer Date: Sat, 25 Jun 2016 07:37:27 +0000 Subject: [SimplifyCFG] Replace calls to null/undef with unreachable Calling null is undefined behavior, a call to undef can be trivially treated as a call to null. llvm-svn: 273776 --- llvm/lib/Transforms/Utils/SimplifyCFG.cpp | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'llvm/lib/Transforms/Utils/SimplifyCFG.cpp') diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp index d22f5c63dee..7924c33038a 100644 --- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp +++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp @@ -5388,7 +5388,7 @@ static bool passingValueIsAlwaysUndefined(Value *V, Instruction *I) { if (I->use_empty()) return false; - if (C->isNullValue()) { + if (C->isNullValue() || isa(C)) { // Only look at the first use, avoid hurting compile time with long uselists User *Use = *I->user_begin(); @@ -5417,6 +5417,10 @@ static bool passingValueIsAlwaysUndefined(Value *V, Instruction *I) { if (!SI->isVolatile()) return SI->getPointerAddressSpace() == 0 && SI->getPointerOperand() == I; + + // A call to null is undefined. + if (auto CS = CallSite(Use)) + return CS.getCalledValue() == I; } return false; } -- cgit v1.2.3