[llvm] 6f5ef64 - [BasicAA] Avoid unnecessary cache update (NFC)

[Nikita Popov via llvm-commits]

Author: Nikita Popov
Date: 2020-11-22T20:10:45+01:00
New Revision: 6f5ef648a57aed3274118dcbd6467e8ac4f6ed1f

URL: https://github.com/llvm/llvm-project/commit/6f5ef648a57aed3274118dcbd6467e8ac4f6ed1f
DIFF: https://github.com/llvm/llvm-project/commit/6f5ef648a57aed3274118dcbd6467e8ac4f6ed1f.diff

LOG: [BasicAA] Avoid unnecessary cache update (NFC)

If the final recursive query returns MayAlias as well, there is
no need to update the cache (which already stores MayAlias).

Added: 
    

Modified: 
    llvm/lib/Analysis/BasicAliasAnalysis.cpp

Removed: 
    


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diff  --git a/llvm/lib/Analysis/BasicAliasAnalysis.cpp b/llvm/lib/Analysis/BasicAliasAnalysis.cpp
index cfc1c59c15d9..16043da339c3 100644
--- a/llvm/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/llvm/lib/Analysis/BasicAliasAnalysis.cpp
@@ -1785,7 +1785,11 @@ AliasResult BasicAAResult::aliasCheck(const Value *V1, LocationSize V1Size,
   // memory locations. We have already ensured that BasicAA has a MayAlias
   // cache result for these, so any recursion back into BasicAA won't loop.
   AliasResult Result = getBestAAResults().alias(Locs.first, Locs.second, AAQI);
-  return AAQI.updateResult(Locs, Result);
+  if (Result != MayAlias)
+    return AAQI.updateResult(Locs, Result);
+
+  // MayAlias is already in the cache.
+  return MayAlias;
 }
 
 /// Check whether two Values can be considered equivalent.