Merging r228525:

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r228525 | bsteinbr | 2015-02-08 09:07:14 -0800 (Sun, 08 Feb 2015) | 14 lines

Correctly combine alias.scope metadata by a union instead of intersecting

Summary:
The alias.scope metadata represents sets of things an instruction might
alias with. When generically combining the metadata from two
instructions the result must be the union of the original sets, because
the new instruction might alias with anything any of the original
instructions aliased with.

Reviewers: hfinkel

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D7490
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_36@228561 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/IR/Metadata.h b/include/llvm/IR/Metadata.h
index 3bf6d38d311d6f0d99522f78f4c3c5c64a7fd72f..27a5d6f800410e734d0064ea85afdb1a784ea164 100644 (file)
--- a/include/llvm/IR/Metadata.h
+++ b/include/llvm/IR/Metadata.h
@@ -693,6 +693,7 @@ public:
   static AAMDNodes getMostGenericAA(const AAMDNodes &A, const AAMDNodes &B);
   static MDNode *getMostGenericFPMath(MDNode *A, MDNode *B);
   static MDNode *getMostGenericRange(MDNode *A, MDNode *B);
+  static MDNode *getMostGenericAliasScope(MDNode *A, MDNode *B);
 };
 
 /// \brief Uniquable metadata node.

diff --git a/lib/Analysis/TypeBasedAliasAnalysis.cpp b/lib/Analysis/TypeBasedAliasAnalysis.cpp
index 085ce920139b44048a3ed2ecbfe1c8f8dd1798c2..ff8955870cb554e9fc477d82d1032053c874f083 100644 (file)
--- a/lib/Analysis/TypeBasedAliasAnalysis.cpp
+++ b/lib/Analysis/TypeBasedAliasAnalysis.cpp
@@ -623,8 +623,8 @@ void Instruction::getAAMetadata(AAMDNodes &N, bool Merge) const {
     N.TBAA = getMetadata(LLVMContext::MD_tbaa);
 
   if (Merge)
-    N.Scope =
-        MDNode::intersect(N.Scope, getMetadata(LLVMContext::MD_alias_scope));
+    N.Scope = MDNode::getMostGenericAliasScope(
+        N.Scope, getMetadata(LLVMContext::MD_alias_scope));
   else
     N.Scope = getMetadata(LLVMContext::MD_alias_scope);
 

diff --git a/lib/IR/Metadata.cpp b/lib/IR/Metadata.cpp
index 2c6b332dc8ee902f951565f5e2eec8f29f784445..63e5730f954eafd2260fe165161fda47f9a5265e 100644 (file)
--- a/lib/IR/Metadata.cpp
+++ b/lib/IR/Metadata.cpp
@@ -826,6 +826,28 @@ MDNode *MDNode::intersect(MDNode *A, MDNode *B) {
   return getOrSelfReference(A->getContext(), MDs);
 }
 
+MDNode *MDNode::getMostGenericAliasScope(MDNode *A, MDNode *B) {
+  if (!A || !B)
+    return nullptr;
+
+  SmallVector<Metadata *, 4> MDs(B->op_begin(), B->op_end());
+  for (unsigned i = 0, ie = A->getNumOperands(); i != ie; ++i) {
+    Metadata *MD = A->getOperand(i);
+    bool insert = true;
+    for (unsigned j = 0, je = B->getNumOperands(); j != je; ++j)
+      if (MD == B->getOperand(j)) {
+        insert = false;
+        break;
+      }
+    if (insert)
+        MDs.push_back(MD);
+  }
+
+  // FIXME: This preserves long-standing behaviour, but is it really the right
+  // behaviour?  Or was that an unintended side-effect of node uniquing?
+  return getOrSelfReference(A->getContext(), MDs);
+}
+
 MDNode *MDNode::getMostGenericFPMath(MDNode *A, MDNode *B) {
   if (!A || !B)
     return nullptr;

diff --git a/lib/Transforms/Utils/Local.cpp b/lib/Transforms/Utils/Local.cpp
index 08a4b3f3b73744b1adf06e093345794568e70ea1..2a84d7e0c484d5529c286ce0c2863419bcbadddf 100644 (file)
--- a/lib/Transforms/Utils/Local.cpp
+++ b/lib/Transforms/Utils/Local.cpp
@@ -1328,6 +1328,8 @@ void llvm::combineMetadata(Instruction *K, const Instruction *J, ArrayRef<unsign
         K->setMetadata(Kind, MDNode::getMostGenericTBAA(JMD, KMD));
         break;
       case LLVMContext::MD_alias_scope:
+        K->setMetadata(Kind, MDNode::getMostGenericAliasScope(JMD, KMD));
+        break;
       case LLVMContext::MD_noalias:
         K->setMetadata(Kind, MDNode::intersect(JMD, KMD));
         break;

diff --git a/lib/Transforms/Vectorize/SLPVectorizer.cpp b/lib/Transforms/Vectorize/SLPVectorizer.cpp
index 4834782ecc14316fe67886f29f32df97319187f2..2213031ecdb99b327bd915deaf2424f37e5c271e 100644 (file)
--- a/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ b/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -208,6 +208,8 @@ static Instruction *propagateMetadata(Instruction *I, ArrayRef<Value *> VL) {
         MD = MDNode::getMostGenericTBAA(MD, IMD);
         break;
       case LLVMContext::MD_alias_scope:
+        MD = MDNode::getMostGenericAliasScope(MD, IMD);
+        break;
       case LLVMContext::MD_noalias:
         MD = MDNode::intersect(MD, IMD);
         break;

diff --git a/test/Transforms/Util/combine-alias-scope-metadata.ll b/test/Transforms/Util/combine-alias-scope-metadata.ll
new file mode 100644 (file)
index 0000000..fd0a3d5
--- /dev/null
+++ b/test/Transforms/Util/combine-alias-scope-metadata.ll
@@ -0,0 +1,24 @@
+; RUN: opt < %s -S -basicaa -memcpyopt | FileCheck %s
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+
+define void @test(i8* noalias dereferenceable(1) %in, i8* noalias dereferenceable(1) %out) {
+  %tmp = alloca i8
+  %tmp2 = alloca i8
+; CHECK: call void @llvm.memcpy.p0i8.p0i8.i64(i8* %out, i8* %in, i64 1, i32 8, i1 false)
+  call void @llvm.memcpy.p0i8.p0i8.i64(i8* %tmp, i8* %in, i64 1, i32 8, i1 false), !alias.scope !4
+  call void @llvm.memcpy.p0i8.p0i8.i64(i8* %tmp2, i8* %tmp, i64 1, i32 8, i1 false), !alias.scope !5
+
+  call void @llvm.memcpy.p0i8.p0i8.i64(i8* %out, i8* %tmp2, i64 1, i32 8, i1 false), !noalias !6
+
+  ret void
+}
+
+declare void @llvm.memcpy.p0i8.p0i8.i64(i8*, i8*, i64, i32, i1)
+
+!0 = !{!0}
+!1 = distinct !{!1, !0, !"in"}
+!2 = distinct !{!2, !0, !"tmp"}
+!3 = distinct !{!3, !0, !"tmp2"}
+!4 = distinct !{!1, !2}
+!5 = distinct !{!2, !3}
+!6 = distinct !{!1, !2}