[Inline] Fix incorrect noalias metadata application (PR48209)

The VMap also contains a mapping from Argument => Instruction,
where the instruction is part of the original function, not the
inlined one. The code was assuming that all the instructions in
the VMap were inlined.

This was a pre-existing problem for the loop access metadata, but
was extended to the more common noalias metadata by
27f647d117087ca11959e232e6443f4aee31e966, thus causing miscompiles.

There is a similar assumption inside CloneAliasScopeMetadata(), so
that one likely needs to be fixed as well.

1 files changed, 3 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/Utils/InlineFunction.cpp b/llvm/lib/Transforms/Utils/InlineFunction.cpp
index 05e6929..c16433c 100644
--- a/llvm/lib/Transforms/Utils/InlineFunction.cpp
+++ b/llvm/lib/Transforms/Utils/InlineFunction.cpp
@@ -785,7 +785,9 @@ static void PropagateCallSiteMetadata(CallBase &CB, ValueToValueMapTy &VMap) {
 
   for (ValueToValueMapTy::iterator VMI = VMap.begin(), VMIE = VMap.end();
        VMI != VMIE; ++VMI) {
-    if (!VMI->second)
+    // Check that key is an instruction, to skip the Argument mapping, which
+    // points to an instruction in the original function, not the inlined one.
+    if (!VMI->second || !isa<Instruction>(VMI->first))
       continue;
 
     Instruction *NI = dyn_cast<Instruction>(VMI->second);