[PATCH] D25779: MS ABI: Don't assert when generating virtual function call with virtual bases and -flto (PR30731)

[Hans Wennborg via cfe-commits]

hans created this revision.
hans added a reviewer: pcc.
hans added a subscriber: cfe-commits.
Herald added a subscriber: mehdi_amini.

getClassAtVTableLocation() was calling ASTRecordLayout::getBaseClassOffset() on a virtual base, causing an assert.


https://reviews.llvm.org/D25779

Files:
  lib/CodeGen/MicrosoftCXXABI.cpp
  test/CodeGenCXX/pr30731.cpp


Index: test/CodeGenCXX/pr30731.cpp
===================================================================
--- /dev/null
+++ test/CodeGenCXX/pr30731.cpp
@@ -0,0 +1,21 @@
+// RUN: %clang_cc1 -triple i386-pc-win32 -emit-llvm -flto -std=c++11 -o - %s | FileCheck %s
+
+struct A {
+  virtual ~A();
+};
+
+struct B {};
+
+struct C {
+  virtual void f();
+};
+
+struct S : A, virtual B, C {
+  void f() override;
+};
+
+void f(S* s) { s->f(); }
+
+// CHECK-LABEL: define void @"\01?f@@YAXPAUS@@@Z"
+// CHECK: call
+// CHECK: ret void
Index: lib/CodeGen/MicrosoftCXXABI.cpp
===================================================================
--- lib/CodeGen/MicrosoftCXXABI.cpp
+++ lib/CodeGen/MicrosoftCXXABI.cpp
@@ -1773,15 +1773,8 @@
   CharUnits MaxBaseOffset;
   for (auto &&B : RD->bases()) {
     const CXXRecordDecl *Base = B.getType()->getAsCXXRecordDecl();
-    CharUnits BaseOffset = Layout.getBaseClassOffset(Base);
-    if (BaseOffset <= Offset && BaseOffset >= MaxBaseOffset) {
-      MaxBase = Base;
-      MaxBaseOffset = BaseOffset;
-    }
-  }
-  for (auto &&B : RD->vbases()) {
-    const CXXRecordDecl *Base = B.getType()->getAsCXXRecordDecl();
-    CharUnits BaseOffset = Layout.getVBaseClassOffset(Base);
+    CharUnits BaseOffset = B.isVirtual() ? Layout.getVBaseClassOffset(Base)
+                                         : Layout.getBaseClassOffset(Base);
     if (BaseOffset <= Offset && BaseOffset >= MaxBaseOffset) {
       MaxBase = Base;
       MaxBaseOffset = BaseOffset;


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