calls in nothrow functions can be marked nothrow even if the callee
is not known to be nothrow. This allows readnone/readonly functions
to be deleted even if we don't know whether the callee can throw.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@71676 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index c76403e..527ed43 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -9578,6 +9578,16 @@
/// the heavy lifting.
///
Instruction *InstCombiner::visitCallInst(CallInst &CI) {
+ // If the caller function is nounwind, mark the call as nounwind, even if the
+ // callee isn't.
+ if (CI.getParent()->getParent()->doesNotThrow() &&
+ !CI.doesNotThrow()) {
+ CI.setDoesNotThrow();
+ return &CI;
+ }
+
+
+
IntrinsicInst *II = dyn_cast<IntrinsicInst>(&CI);
if (!II) return visitCallSite(&CI);