From: David Majnemer <david.majnemer@gmail.com>
Date: Thu, 18 Jun 2015 20:20:10 +0000 (+0000)
Subject: [MS ABI] Initialize "most general" member pointers which don't point at a vbase
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=a57b5b2fa4ccf0d136454271173bbfa91ac610ce;p=clang

[MS ABI] Initialize "most general" member pointers which don't point at a vbase

The most general model has fields for the vbptr offset and the vbindex.
Don't initialize the vbptr offset if the vbindex is 0: we aren't
referencing an entity from a vbase.

Getting this wrong can make member pointer equality fail.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@240043 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/MicrosoftCXXABI.cpp b/lib/CodeGen/MicrosoftCXXABI.cpp
index e19ad690fb..36d6953020 100644
--- a/lib/CodeGen/MicrosoftCXXABI.cpp
+++ b/lib/CodeGen/MicrosoftCXXABI.cpp
@@ -2351,7 +2351,7 @@ MicrosoftCXXABI::EmitFullMemberPointer(llvm::Constant *FirstField,
 
   if (MSInheritanceAttr::hasVBPtrOffsetField(Inheritance)) {
     CharUnits Offs = CharUnits::Zero();
-    if (RD->getNumVBases())
+    if (VBTableIndex && RD->getNumVBases())
       Offs = getContext().getASTRecordLayout(RD).getVBPtrOffset();
     fields.push_back(llvm::ConstantInt::get(CGM.IntTy, Offs.getQuantity()));
   }
diff --git a/test/CodeGenCXX/microsoft-abi-member-pointers.cpp b/test/CodeGenCXX/microsoft-abi-member-pointers.cpp
index cf9da81ea2..9525ffd67b 100644
--- a/test/CodeGenCXX/microsoft-abi-member-pointers.cpp
+++ b/test/CodeGenCXX/microsoft-abi-member-pointers.cpp
@@ -119,7 +119,7 @@ void (UnspecSingle::*us_f_mp)() = &UnspecSingle::foo;
 // CHECK: @"\01?v_f_mp@Const@@3P8Virtual@@AEXXZQ2@" =
 // CHECK:   global { i8*, i32, i32 } { i8* bitcast ({{.*}} @"\01?foo@Virtual@@QAEXXZ" to i8*), i32 0, i32 0 }, align 4
 // CHECK: @"\01?u_f_mp@Const@@3P8Unspecified@@AEXXZQ2@" =
-// CHECK:   global { i8*, i32, i32, i32 } { i8* bitcast ({{.*}} @"\01?foo@Unspecified@@QAEXXZ" to i8*), i32 0, i32 12, i32 0 }, align 4
+// CHECK:   global { i8*, i32, i32, i32 } { i8* bitcast ({{.*}} @"\01?foo@Unspecified@@QAEXXZ" to i8*), i32 0, i32 0, i32 0 }, align 4
 // CHECK: @"\01?us_f_mp@Const@@3P8UnspecSingle@@AEXXZQ2@" =
 // CHECK:   global { i8*, i32, i32, i32 } { i8* bitcast ({{.*}} @"\01?foo@UnspecSingle@@QAEXXZ" to i8*), i32 0, i32 0, i32 0 }, align 4
 }