[BypassSlowDivision][CodeGenPrepare] avoid crashing on unused code (PR43514)
https://bugs.llvm.org/show_bug.cgi?id=43514
llvm-svn: 373394
diff --git a/llvm/lib/Transforms/Utils/BypassSlowDivision.cpp b/llvm/lib/Transforms/Utils/BypassSlowDivision.cpp
index df299f6..9a67610 100644
--- a/llvm/lib/Transforms/Utils/BypassSlowDivision.cpp
+++ b/llvm/lib/Transforms/Utils/BypassSlowDivision.cpp
@@ -448,13 +448,17 @@
DivCacheTy PerBBDivCache;
bool MadeChange = false;
- Instruction* Next = &*BB->begin();
+ Instruction *Next = &*BB->begin();
while (Next != nullptr) {
// We may add instructions immediately after I, but we want to skip over
// them.
- Instruction* I = Next;
+ Instruction *I = Next;
Next = Next->getNextNode();
+ // Ignore dead code to save time and avoid bugs.
+ if (I->hasNUses(0))
+ continue;
+
FastDivInsertionTask Task(I, BypassWidths);
if (Value *Replacement = Task.getReplacement(PerBBDivCache)) {
I->replaceAllUsesWith(Replacement);