[llvm] r275065 - AliasAnalysis: unify getModRefInfo(I, CS) semantics with other overloads

[Nicolai Haehnle via llvm-commits]

Author: nha
Date: Mon Jul 11 09:11:45 2016
New Revision: 275065

URL: http://llvm.org/viewvc/llvm-project?rev=275065&view=rev
Log:
AliasAnalysis: unify getModRefInfo(I, CS) semantics with other overloads

This subtle change to getModRefInfo(Instruction, ImmutableCallSite) is to
ensure that the semantics are equal to that of getModRefInfo(CS1, CS2) when
the Instruction is a call-site.

This is now more in line with getModRefInfo generally: it returns Mod when
I modifies a memory location that is accessed (read or written) by CS and
Ref when I reads a memory location that is written by CS.

>From a grep of the code, the only uses of this particular getModRefInfo
overload are in MemorySSA and MemCpyOptimizer, and they only care about
where the result is MR_NoModRef or not. Therefore, this change should have
no visible effect.

Separated out from D17279 upon request.

Modified:
    llvm/trunk/lib/Analysis/AliasAnalysis.cpp

Modified: llvm/trunk/lib/Analysis/AliasAnalysis.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/AliasAnalysis.cpp?rev=275065&r1=275064&r2=275065&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/AliasAnalysis.cpp (original)
+++ llvm/trunk/lib/Analysis/AliasAnalysis.cpp Mon Jul 11 09:11:45 2016
@@ -110,7 +110,7 @@ ModRefInfo AAResults::getModRefInfo(Inst
   // We may have two calls
   if (auto CS = ImmutableCallSite(I)) {
     // Check if the two calls modify the same memory
-    return getModRefInfo(Call, CS);
+    return getModRefInfo(CS, Call);
   } else {
     // Otherwise, check if the call modifies or references the
     // location this memory access defines.  The best we can say