Reapply 239795 - [InstCombine] Propagate non-null facts to call parameters
The original change broke clang side tests. I will be submitting those momentarily. This change includes post commit feedback on the original change from from Pete Cooper.
Original Submission comments:
If a parameter to a function is known non-null, use the existing parameter attributes to record that fact at the call site. This has no optimization benefit by itself - that I know of - but is an enabling change for http://reviews.llvm.org/D9129.
Differential Revision: http://reviews.llvm.org/D9132
llvm-svn: 239849
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index e83b9dd..6de380b 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -1391,11 +1391,29 @@
// visitCallSite - Improvements for call and invoke instructions.
//
Instruction *InstCombiner::visitCallSite(CallSite CS) {
+
if (isAllocLikeFn(CS.getInstruction(), TLI))
return visitAllocSite(*CS.getInstruction());
bool Changed = false;
+ // Mark any parameters that are known to be non-null with the nonnull
+ // attribute. This is helpful for inlining calls to functions with null
+ // checks on their arguments.
+ unsigned ArgNo = 0;
+ for (Value *V : CS.args()) {
+ if (!CS.paramHasAttr(ArgNo+1, Attribute::NonNull) &&
+ isKnownNonNull(V)) {
+ AttributeSet AS = CS.getAttributes();
+ AS = AS.addAttribute(CS.getInstruction()->getContext(), ArgNo+1,
+ Attribute::NonNull);
+ CS.setAttributes(AS);
+ Changed = true;
+ }
+ ArgNo++;
+ }
+ assert(ArgNo == CS.arg_size() && "sanity check");
+
// If the callee is a pointer to a function, attempt to move any casts to the
// arguments of the call/invoke.
Value *Callee = CS.getCalledValue();