[InstCombine] Fix SimplifyLibCalls erasing an instruction while IC still had references to it.

InstCombine keeps a worklist and assumes that optimizations don't
eraseFromParent() the instruction, which SimplifyLibCalls violates. This change
adds a new callback to SimplifyLibCalls to let clients specify their own hander
for erasing actions.

Differential Revision: https://reviews.llvm.org/D52729

llvm-svn: 344251

1 files changed, 5 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 4e404933a22..714c6176884 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -3960,7 +3960,11 @@ Instruction *InstCombiner::tryOptimizeCall(CallInst *CI) {
   auto InstCombineRAUW = [this](Instruction *From, Value *With) {
     replaceInstUsesWith(*From, With);
   };
-  LibCallSimplifier Simplifier(DL, &TLI, ORE, InstCombineRAUW);
+  auto InstCombineErase = [this](Instruction *I) {
+    eraseInstFromFunction(*I);
+  };
+  LibCallSimplifier Simplifier(DL, &TLI, ORE, InstCombineRAUW,
+                               InstCombineErase);
   if (Value *With = Simplifier.optimizeCall(CI)) {
     ++NumSimplified;
     return CI->use_empty() ? CI : replaceInstUsesWith(*CI, With);