[MS-ABI] Fixed alias-avoidance padding in the presence of vtordisps

If a vtordisp exists between two bases, then there is no need for
additional alias avoidance padding.  Test case included.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@206087 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/AST/RecordLayoutBuilder.cpp b/lib/AST/RecordLayoutBuilder.cpp
index 73267f70a6a5ea1c61d25172f852da9e9bed50b9..fda374e9a0837e180c29311e5925ae0a15833d3d 100644 (file)
--- a/lib/AST/RecordLayoutBuilder.cpp
+++ b/lib/AST/RecordLayoutBuilder.cpp
@@ -2620,10 +2620,7 @@ void MicrosoftRecordLayoutBuilder::layoutVirtualBases(const CXXRecordDecl *RD) {
     // bytes (in both 32 and 64 bits modes) and always involves rounding up to
     // the required alignment, we don't know why.
     if (PreviousBaseLayout && PreviousBaseLayout->hasZeroSizedSubObject() &&
-        BaseLayout.leadsWithZeroSizedBase())
-      Size = Size.RoundUpToAlignment(VtorDispAlignment) + VtorDispSize;
-    // Insert the vtordisp.
-    if (HasVtordisp)
+        BaseLayout.leadsWithZeroSizedBase() || HasVtordisp)
       Size = Size.RoundUpToAlignment(VtorDispAlignment) + VtorDispSize;
     // Insert the virtual base.
     ElementInfo Info = getAdjustedElementInfo(BaseLayout);

diff --git a/test/Layout/ms-x86-alias-avoidance-padding.cpp b/test/Layout/ms-x86-alias-avoidance-padding.cpp
index 7a78f8732ca3dcc78ff3fbb1883bd5a322e6d55f..e51bab387115198455f2e6ec57fa3a8bcd51ff73 100644 (file)
--- a/test/Layout/ms-x86-alias-avoidance-padding.cpp
+++ b/test/Layout/ms-x86-alias-avoidance-padding.cpp
@@ -547,7 +547,37 @@ struct RZ8 : RX8, RY {};
 // CHECK-X64-NEXT:      | [sizeof=16, align=8
 // CHECK-X64-NEXT:      |  nvsize=8, nvalign=8]
 
+struct JA {};
+struct JB {};
+struct JC : JA { virtual void f() {} };
+struct JD : virtual JB, virtual JC { virtual void f() {} JD() {} };
 
+// CHECK: *** Dumping AST Record Layout
+// CHECK: *** Dumping AST Record Layout
+// CHECK: *** Dumping AST Record Layout
+// CHECK: *** Dumping AST Record Layout
+// CHECK-NEXT:    0 | struct JD
+// CHECK-NEXT:    0 |   (JD vbtable pointer)
+// CHECK-NEXT:    4 |   struct JB (virtual base) (empty)
+// CHECK-NEXT:    4 |   (vtordisp for vbase JC)
+// CHECK-NEXT:    8 |   struct JC (virtual base)
+// CHECK-NEXT:    8 |     (JC vftable pointer)
+// CHECK-NEXT:   12 |     struct JA (base) (empty)
+// CHECK-NEXT:      | [sizeof=12, align=4
+// CHECK-NEXT:      |  nvsize=4, nvalign=4]
+// CHECK-X64: *** Dumping AST Record Layout
+// CHECK-X64: *** Dumping AST Record Layout
+// CHECK-X64: *** Dumping AST Record Layout
+// CHECK-X64: *** Dumping AST Record Layout
+// CHECK-X64-NEXT:    0 | struct JD
+// CHECK-X64-NEXT:    0 |   (JD vbtable pointer)
+// CHECK-X64-NEXT:    8 |   struct JB (virtual base) (empty)
+// CHECK-X64-NEXT:   12 |   (vtordisp for vbase JC)
+// CHECK-X64-NEXT:   16 |   struct JC (virtual base)
+// CHECK-X64-NEXT:   16 |     (JC vftable pointer)
+// CHECK-X64-NEXT:   24 |     struct JA (base) (empty)
+// CHECK-X64-NEXT:      | [sizeof=24, align=8
+// CHECK-X64-NEXT:      |  nvsize=8, nvalign=8]
 
 int a[
 sizeof(AT3) +
@@ -565,4 +595,5 @@ sizeof(RZ5) +
 sizeof(RZ6) +
 sizeof(RZ7) +
 sizeof(RZ8) +
+sizeof(JD) +
 0];