Handle invariant.group.barrier in BasicAA

Summary:
llvm.invariant.group.barrier returns pointer that mustalias
pointer it takes. It can't be marked with `returned` attribute,
because it would be remove easily. The other reason is that
only Alias Analysis can know about this, because if any other
pass would know it, then the result would be replaced with it's
argument, which would be invalid.

We can think about returned pointer as something that mustalias, but
it doesn't have to be bitwise the same as the argument.

Reviewers: dberlin, chandlerc, hfinkel, sanjoy

Subscribers: reames, nlewycky, rsmith, anna, amharc

Differential Revision: https://reviews.llvm.org/D31585

llvm-svn: 301227

1 files changed, 6 insertions, 6 deletions

diff --git a/llvm/lib/Analysis/BasicAliasAnalysis.cpp b/llvm/lib/Analysis/BasicAliasAnalysis.cpp
index 3db041cc0fa..53782302030 100644
--- a/llvm/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/llvm/lib/Analysis/BasicAliasAnalysis.cpp
@@ -924,8 +924,8 @@ static AliasResult aliasSameBasePointerGEPs(const GEPOperator *GEP1,
                                             uint64_t V2Size,
                                             const DataLayout &DL) {
 
-  assert(GEP1->getPointerOperand()->stripPointerCasts() ==
-             GEP2->getPointerOperand()->stripPointerCasts() &&
+  assert(GEP1->getPointerOperand()->stripPointerCastsAndBarriers() ==
+             GEP2->getPointerOperand()->stripPointerCastsAndBarriers() &&
          GEP1->getPointerOperandType() == GEP2->getPointerOperandType() &&
          "Expected GEPs with the same pointer operand");
 
@@ -1184,8 +1184,8 @@ AliasResult BasicAAResult::aliasGEP(const GEPOperator *GEP1, uint64_t V1Size,
     // If we know the two GEPs are based off of the exact same pointer (and not
     // just the same underlying object), see if that tells us anything about
     // the resulting pointers.
-    if (GEP1->getPointerOperand()->stripPointerCasts() ==
-            GEP2->getPointerOperand()->stripPointerCasts() &&
+    if (GEP1->getPointerOperand()->stripPointerCastsAndBarriers() ==
+            GEP2->getPointerOperand()->stripPointerCastsAndBarriers() &&
         GEP1->getPointerOperandType() == GEP2->getPointerOperandType()) {
       AliasResult R = aliasSameBasePointerGEPs(GEP1, V1Size, GEP2, V2Size, DL);
       // If we couldn't find anything interesting, don't abandon just yet.
@@ -1500,8 +1500,8 @@ AliasResult BasicAAResult::aliasCheck(const Value *V1, uint64_t V1Size,
     return NoAlias;
 
   // Strip off any casts if they exist.
-  V1 = V1->stripPointerCasts();
-  V2 = V2->stripPointerCasts();
+  V1 = V1->stripPointerCastsAndBarriers();
+  V2 = V2->stripPointerCastsAndBarriers();
 
   // If V1 or V2 is undef, the result is NoAlias because we can always pick a
   // value for undef that aliases nothing in the program.