[BasicAA] Add support for memmove intrinsic

Currently, basic AA has special support for llvm.memcpy.* intrinsics. This change extends this support for any memory trancsfer opration and in particular llvm.memmove.* intrinsic.

Reviewed By: reames, nikic

Differential Revision: https://reviews.llvm.org/D117095

1 files changed, 7 insertions, 4 deletions

diff --git a/llvm/lib/Analysis/BasicAliasAnalysis.cpp b/llvm/lib/Analysis/BasicAliasAnalysis.cpp
index b4c9859..0a0b537 100644
--- a/llvm/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/llvm/lib/Analysis/BasicAliasAnalysis.cpp
@@ -1010,10 +1010,13 @@ ModRefInfo BasicAAResult::getModRefInfo(const CallBase *Call,
       return ModRefInfo::NoModRef;
   }
 
-  // The semantics of memcpy intrinsics either exactly overlap or do not
-  // overlap, i.e., source and destination of any given memcpy are either
-  // no-alias or must-alias.
-  if (auto *Inst = dyn_cast<AnyMemCpyInst>(Call)) {
+  // Ideally, there should be no need to special case for memcpy/memove
+  // intrinsics here since general machinery (based on memory attributes) should
+  // already handle it just fine. Unfortunately, it doesn't due to deficiency in
+  // operand bundles support. At the moment it's not clear if complexity behind
+  // enhancing general mechanism worths it.
+  // TODO: Consider improving operand bundles support in general mechanism.
+  if (auto *Inst = dyn_cast<AnyMemTransferInst>(Call)) {
     AliasResult SrcAA =
         getBestAAResults().alias(MemoryLocation::getForSource(Inst), Loc, AAQI);
     AliasResult DestAA =