[PATCH] D93602: [AA] byval argument is identified function local

[Nikita Popov via Phabricator via llvm-commits]

nikic created this revision.
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I believe that as far as alias analysis is concerned, byval arguments should get the same (or stronger) treatment as noalias arguments, which was not the case for the isIdentifiedFunctionLocal() function. Marking byval arguments as identified function local means that they cannot alias with any other arguments, which I believe is correct.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D93602

Files:
  llvm/include/llvm/Analysis/AliasAnalysis.h
  llvm/lib/Analysis/AliasAnalysis.cpp
  llvm/test/Analysis/BasicAA/noalias-param.ll


Index: llvm/test/Analysis/BasicAA/noalias-param.ll
===================================================================
--- llvm/test/Analysis/BasicAA/noalias-param.ll
+++ llvm/test/Analysis/BasicAA/noalias-param.ll
@@ -22,9 +22,9 @@
   ret void
 }
 
-; TODO: Result should be the same for byval instead of noalias.
+; Result should be the same for byval instead of noalias.
 ; CHECK-LABEL: byval
-; CHECK: MayAlias: i32* %a, i32* %b
+; CHECK: NoAlias: i32* %a, i32* %b
 define void @byval(i32* byval(i32) %a, i32* %b) nounwind {
 entry:
   store i32 1, i32* %a
Index: llvm/lib/Analysis/AliasAnalysis.cpp
===================================================================
--- llvm/lib/Analysis/AliasAnalysis.cpp
+++ llvm/lib/Analysis/AliasAnalysis.cpp
@@ -943,9 +943,9 @@
   return false;
 }
 
-bool llvm::isNoAliasArgument(const Value *V) {
+static bool isNoAliasOrByValArgument(const Value *V) {
   if (const Argument *A = dyn_cast<Argument>(V))
-    return A->hasNoAliasAttr();
+    return A->hasNoAliasAttr() || A->hasByValAttr();
   return false;
 }
 
@@ -956,13 +956,13 @@
     return true;
   if (isNoAliasCall(V))
     return true;
-  if (const Argument *A = dyn_cast<Argument>(V))
-    return A->hasNoAliasAttr() || A->hasByValAttr();
+  if (isNoAliasOrByValArgument(V))
+    return true;
   return false;
 }
 
 bool llvm::isIdentifiedFunctionLocal(const Value *V) {
-  return isa<AllocaInst>(V) || isNoAliasCall(V) || isNoAliasArgument(V);
+  return isa<AllocaInst>(V) || isNoAliasCall(V) || isNoAliasOrByValArgument(V);
 }
 
 void llvm::getAAResultsAnalysisUsage(AnalysisUsage &AU) {
Index: llvm/include/llvm/Analysis/AliasAnalysis.h
===================================================================
--- llvm/include/llvm/Analysis/AliasAnalysis.h
+++ llvm/include/llvm/Analysis/AliasAnalysis.h
@@ -1097,9 +1097,6 @@
 /// Return true if this pointer is returned by a noalias function.
 bool isNoAliasCall(const Value *V);
 
-/// Return true if this is an argument with the noalias attribute.
-bool isNoAliasArgument(const Value *V);
-
 /// Return true if this pointer refers to a distinct and identifiable object.
 /// This returns true for:
 ///    Global Variables and Functions (but not Global Aliases)


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