[PR26550] Use a different TBAA root for C++ vs C.

This commit changes the root from "Simple C/C++ TBAA" to "Simple C++ TBAA" for
C++.

The problem is that the type name in the TBAA nodes is generated differently
for C vs C++. If we link an IR file for C with an IR file for C++, since they
have the same root and the type names are different, accesses to the two type
nodes will be considered no-alias, even though the two type nodes are from
the same type in a header file.

The fix is to use different roots for C and C++. Types from C will be treated
conservatively in respect to types from C++.

Follow-up commits will change the C root to "Simple C TBAA" plus some mangling
change for C types to make it a little more aggresive.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@260567 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/CodeGenTBAA.cpp b/lib/CodeGen/CodeGenTBAA.cpp
index c3c925cde2fd1f825563d0dca632a15d393c40ef..04224e726797abb0e55bfe8a911b57bc982433a4 100644 (file)
--- a/lib/CodeGen/CodeGenTBAA.cpp
+++ b/lib/CodeGen/CodeGenTBAA.cpp
@@ -44,8 +44,12 @@ llvm::MDNode *CodeGenTBAA::getRoot() {
   // if our LLVM IR is linked with LLVM IR from a different front-end
   // (or a different version of this front-end), their TBAA trees will
   // remain distinct, and the optimizer will treat them conservatively.
-  if (!Root)
-    Root = MDHelper.createTBAARoot("Simple C/C++ TBAA");
+  if (!Root) {
+    if (Features.CPlusPlus)
+      Root = MDHelper.createTBAARoot("Simple C++ TBAA");
+    else
+      Root = MDHelper.createTBAARoot("Simple C/C++ TBAA");
+  }
 
   return Root;
 }

diff --git a/test/CodeGen/tbaa-class.cpp b/test/CodeGen/tbaa-class.cpp
index f611ae5abb885aa8bd4a3e718a766d586e2a8c40..7172e05d9e34c9e09f2e8d18133a3e3d391d34f7 100644 (file)
--- a/test/CodeGen/tbaa-class.cpp
+++ b/test/CodeGen/tbaa-class.cpp
@@ -199,7 +199,7 @@ uint32_t g12(StructC *C, StructD *D, uint64_t count) {
 }
 
 // CHECK: [[TYPE_char:!.*]] = !{!"omnipotent char", [[TAG_cxx_tbaa:!.*]],
-// CHECK: [[TAG_cxx_tbaa]] = !{!"Simple C/C++ TBAA"}
+// CHECK: [[TAG_cxx_tbaa]] = !{!"Simple C++ TBAA"}
 // CHECK: [[TAG_i32]] = !{[[TYPE_i32:!.*]], [[TYPE_i32]], i64 0}
 // CHECK: [[TYPE_i32]] = !{!"int", [[TYPE_char]],
 // CHECK: [[TAG_i16]] = !{[[TYPE_i16:!.*]], [[TYPE_i16]], i64 0}

diff --git a/test/CodeGen/tbaa-for-vptr.cpp b/test/CodeGen/tbaa-for-vptr.cpp
index 35e95a54dab2157a37db0c1fd3c2589ad001c8d7..7b8ae2099e470b6395c4551b7fef203060b169d9 100644 (file)
--- a/test/CodeGen/tbaa-for-vptr.cpp
+++ b/test/CodeGen/tbaa-for-vptr.cpp
@@ -32,4 +32,4 @@ void CallFoo(A *a, int (A::*fp)() const) {
 //
 // CHECK: [[NUM]] = !{[[TYPE:!.*]], [[TYPE]], i64 0}
 // CHECK: [[TYPE]] = !{!"vtable pointer", !{{.*}}
-// NOTBAA-NOT: = !{!"Simple C/C++ TBAA"}
+// NOTBAA-NOT: = !{!"Simple C++ TBAA"}

diff --git a/test/CodeGen/tbaa.cpp b/test/CodeGen/tbaa.cpp
index c43ca58bc3f62b524444481fc5bfc36493050fb0..f98c46f1497b975bd8522182a2ad846cafdfd45b 100644 (file)
--- a/test/CodeGen/tbaa.cpp
+++ b/test/CodeGen/tbaa.cpp
@@ -237,7 +237,7 @@ uint32_t g15(StructS *S, StructS3 *S3, uint64_t count) {
 }
 
 // CHECK: [[TYPE_char:!.*]] = !{!"omnipotent char", [[TAG_cxx_tbaa:!.*]],
-// CHECK: [[TAG_cxx_tbaa]] = !{!"Simple C/C++ TBAA"}
+// CHECK: [[TAG_cxx_tbaa]] = !{!"Simple C++ TBAA"}
 // CHECK: [[TAG_i32]] = !{[[TYPE_i32:!.*]], [[TYPE_i32]], i64 0}
 // CHECK: [[TYPE_i32]] = !{!"int", [[TYPE_char]],
 // CHECK: [[TAG_i16]] = !{[[TYPE_i16:!.*]], [[TYPE_i16]], i64 0}