From 975d83c291821de340eef3c3498104172b375f79 Mon Sep 17 00:00:00 2001
From: Manman Ren <mren@apple.com>
Date: Sat, 27 Apr 2013 00:39:37 +0000
Subject: [PATCH] Struct-path aware TBAA: fix handling of may_alias attribute.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@180656 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/CGExpr.cpp   |  4 ++--
 test/CodeGen/may-alias.c | 15 +++++++++++++--
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/lib/CodeGen/CGExpr.cpp b/lib/CodeGen/CGExpr.cpp
index ea13de17ab..f426a52bcd 100644
--- a/lib/CodeGen/CGExpr.cpp
+++ b/lib/CodeGen/CGExpr.cpp
@@ -2588,8 +2588,8 @@ LValue CodeGenFunction::EmitLValueForField(LValue base,
         getContext().getASTRecordLayout(field->getParent());
     // Set the base type to be the base type of the base LValue and
     // update offset to be relative to the base type.
-    LV.setTBAABaseType(base.getTBAABaseType());
-    LV.setTBAAOffset(base.getTBAAOffset() +
+    LV.setTBAABaseType(mayAlias ? getContext().CharTy : base.getTBAABaseType());
+    LV.setTBAAOffset(mayAlias ? 0 : base.getTBAAOffset() +
                      Layout.getFieldOffset(field->getFieldIndex()) /
                                            getContext().getCharWidth());
   }
diff --git a/test/CodeGen/may-alias.c b/test/CodeGen/may-alias.c
index b73ee15f87..c76724444b 100644
--- a/test/CodeGen/may-alias.c
+++ b/test/CodeGen/may-alias.c
@@ -1,5 +1,5 @@
-// RUN: %clang_cc1 -Werror -triple i386-unknown-unknown -emit-llvm -O1 -disable-llvm-optzns -o %t %s
-// RUN: FileCheck < %t %s
+// RUN: %clang_cc1 -Werror -triple i386-unknown-unknown -emit-llvm -O1 -disable-llvm-optzns -o - %s | FileCheck %s
+// RUN: %clang_cc1 -Werror -triple i386-unknown-unknown -emit-llvm -O1 -struct-path-tbaa -disable-llvm-optzns -o - %s | FileCheck %s -check-prefix=PATH
 
 // Types with the may_alias attribute should be considered equivalent
 // to char for aliasing.
@@ -9,8 +9,10 @@ typedef int __attribute__((may_alias)) aliasing_int;
 void test0(aliasing_int *ai, int *i)
 {
 // CHECK: store i32 0, i32* %{{.*}}, !tbaa !1
+// PATH: store i32 0, i32* %{{.*}}, !tbaa [[TAG_CHAR:!.*]]
   *ai = 0;
 // CHECK: store i32 1, i32* %{{.*}}, !tbaa !3
+// PATH: store i32 1, i32* %{{.*}}, !tbaa [[TAG_INT:!.*]]
   *i = 1;
 }
 
@@ -19,8 +21,10 @@ struct Test1 { int x; };
 struct Test1MA { int x; } __attribute__((may_alias));
 void test1(struct Test1MA *p1, struct Test1 *p2) {
   // CHECK: store i32 2, i32* {{%.*}}, !tbaa !1
+  // PATH: store i32 2, i32* {{%.*}}, !tbaa [[TAG_CHAR]]
   p1->x = 2;
   // CHECK: store i32 3, i32* {{%.*}}, !tbaa !3
+  // PATH: store i32 3, i32* {{%.*}}, !tbaa [[TAG_test1_x:!.*]]
   p2->x = 3;
 }
 
@@ -28,3 +32,10 @@ void test1(struct Test1MA *p1, struct Test1 *p2) {
 // CHECK: !1 = metadata !{metadata !"omnipotent char", metadata !2}
 // CHECK: !2 = metadata !{metadata !"Simple C/C++ TBAA"}
 // CHECK: !3 = metadata !{metadata !"int", metadata !1}
+
+// PATH: [[TYPE_CHAR:!.*]] = metadata !{metadata !"omnipotent char", metadata !{{.*}}
+// PATH: [[TAG_CHAR]] = metadata !{metadata [[TYPE_CHAR]], metadata [[TYPE_CHAR]], i64 0}
+// PATH: [[TAG_INT]] = metadata !{metadata [[TYPE_INT:!.*]], metadata [[TYPE_INT]], i64 0}
+// PATH: [[TYPE_INT]] = metadata !{metadata !"int", metadata [[TYPE_CHAR]]
+// PATH: [[TAG_test1_x]] = metadata !{metadata [[TYPE_test1:!.*]], metadata [[TYPE_INT]], i64 0}
+// PATH: [[TYPE_test1]] = metadata !{metadata !"_ZTS5Test1", metadata [[TYPE_INT]], i64 0}
-- 
2.40.0