1 files changed, 10 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index d5e301b..d95c053 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -491,6 +491,16 @@ bool llvm::wouldInstructionBeTriviallyDead(Instruction *I,
     if (isMathLibCallNoop(Call, TLI))
       return true;
 
+  // To express possible interaction with floating point environment constrained
+  // intrinsics are described as if they access memory. So they look like having
+  // side effect but actually do not have it unless they raise floating point
+  // exception. If FP exceptions are ignored, the intrinsic may be deleted.
+  if (auto *CI = dyn_cast<ConstrainedFPIntrinsic>(I)) {
+    Optional<fp::ExceptionBehavior> EB = CI->getExceptionBehavior();
+    if (!EB || *EB == fp::ExceptionBehavior::ebIgnore)
+      return true;
+  }
+
   return false;
 }