[Attributor] Use Alias Analysis in noalias callsite argument deduction

Summary: This patch adds a check of alias analysis in `noalias` callsite argument deduction.

Reviewers: jdoerfert, sstefan1

Reviewed By: jdoerfert

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D67604

llvm-svn: 372075

1 files changed, 12 insertions, 5 deletions

diff --git a/llvm/lib/Transforms/IPO/Attributor.cpp b/llvm/lib/Transforms/IPO/Attributor.cpp
index 90b0772a869..a6f8472e85d 100644
--- a/llvm/lib/Transforms/IPO/Attributor.cpp
+++ b/llvm/lib/Transforms/IPO/Attributor.cpp
@@ -1762,11 +1762,18 @@ struct AANoAliasCallSiteArgument final : AANoAliasImpl {
       if (!ArgOp->getType()->isPointerTy())
         continue;
 
-      // TODO: Use AliasAnalysis
-      //       AAResults& AAR = ..;
-      //       if(AAR.isNoAlias(&getAssociatedValue(), ArgOp))
-      //          return indicatePessimitisicFixpoint();
-
+      if (const Function *F = getAnchorScope()) {
+        if (AAResults *AAR = A.getInfoCache().getAAResultsForFunction(*F)) {
+          LLVM_DEBUG(dbgs()
+                     << "[Attributor][NoAliasCSArg] Check alias between "
+                        "callsite arguments "
+                     << AAR->isNoAlias(&getAssociatedValue(), ArgOp) << " "
+                     << getAssociatedValue() << " " << *ArgOp << "\n");
+
+          if (AAR->isNoAlias(&getAssociatedValue(), ArgOp))
+            continue;
+        }
+      }
       return indicatePessimisticFixpoint();
     }