Commit fcab280f authored by Bill Wendling's avatar Bill Wendling
Browse files

Merging r195158: 

------------------------------------------------------------------------
r195158 | whunt | 2013-11-19 14:11:09 -0800 (Tue, 19 Nov 2013) | 9 lines

Microsoft Record Layout: zero sized base after base with vbtbl fix

Microsoft adds an extra byte of padding before laying out zero sized 
non-virtual bases if the non-virtual base before it contains a vbptr.  
This patch adds the same behavior to clang.

Differential Revision: http://llvm-reviews.chandlerc.com/D2106


------------------------------------------------------------------------

llvm-svn: 195167
parent a6a08e04

clang/lib/AST/RecordLayoutBuilder.cpp

+11 −0
Original line number Diff line number Diff line
@@ -2017,6 +2017,8 @@ static bool isMsLayout(const RecordDecl* D) { 
// * If the last field is a non-zero length bitfield and we have any virtual

//   bases then some extra padding is added before the virtual bases for no

//   obvious reason.

// * When laying out empty non-virtual bases, an extra byte of padding is added

//   if the non-virtual base before the empty non-virtual base has a vbptr.





namespace {
@@ -2141,6 +2143,8 @@ public: 
  bool LastBaseWasEmpty;

  /// \brief Lets us know if we're in 64-bit mode

  bool Is64BitMode;

  /// \brief True if the last non-virtual base has a vbptr.

  bool LastNonVirtualBaseHasVBPtr;

};

} // namespace
@@ -2304,6 +2308,7 @@ void 
MicrosoftRecordLayoutBuilder::layoutNonVirtualBases(const CXXRecordDecl *RD) {

  LazyEmptyBase = 0;

  LastBaseWasEmpty = false;

  LastNonVirtualBaseHasVBPtr = false;



  // Lay out the primary base first.

  if (PrimaryBase)
@@ -2331,6 +2336,10 @@ MicrosoftRecordLayoutBuilder::layoutNonVirtualBase(const CXXRecordDecl *RD) { 
    const ASTRecordLayout &LazyLayout =

        Context.getASTRecordLayout(LazyEmptyBase);

    Size = Size.RoundUpToAlignment(LazyLayout.getAlignment());

    // If the last non-virtual base has a vbptr we add a byte of padding for no

    // obvious reason.

    if (LastNonVirtualBaseHasVBPtr)

      Size++;

    Bases.insert(std::make_pair(LazyEmptyBase, Size));

    // Empty bases only consume space when followed by another empty base.

    if (RD && Layout->getNonVirtualSize().isZero()) {
@@ -2338,6 +2347,7 @@ MicrosoftRecordLayoutBuilder::layoutNonVirtualBase(const CXXRecordDecl *RD) { 
      Size++;

    }

    LazyEmptyBase = 0;

    LastNonVirtualBaseHasVBPtr = false;

  }



  // RD is null when flushing the final lazy base.
@@ -2356,6 +2366,7 @@ MicrosoftRecordLayoutBuilder::layoutNonVirtualBase(const CXXRecordDecl *RD) { 
  // Note: we don't update alignment here because it was accounted

  // for during initalization.

  LastBaseWasEmpty = false;

  LastNonVirtualBaseHasVBPtr = Layout->hasVBPtr();

}



void MicrosoftRecordLayoutBuilder::layoutVBPtr(const CXXRecordDecl *RD) {

clang/test/Layout/ms-x86-empty-base-after-base-with-vbptr.cpp

0 → 100644
+216 −0
Original line number Diff line number Diff line 
// RUN: %clang_cc1 -fno-rtti -emit-llvm-only -triple i686-pc-win32 -fdump-record-layouts -cxx-abi microsoft %s 2>/dev/null \

// RUN:            | FileCheck %s

// RUN: %clang_cc1 -fno-rtti -emit-llvm-only -triple x86_64-pc-win32 -fdump-record-layouts -cxx-abi microsoft %s 2>/dev/null \

// RUN:            | FileCheck %s -check-prefix CHECK-X64





struct U { char a; };

struct V { };

struct W { };

struct X : virtual V { char a; };

struct Y : virtual V { char a; };

struct Z : Y { };



struct A : X, W  { char a; };



// CHECK: *** Dumping AST Record Layout

// CHECK:    0 | struct A

// CHECK:    0 |   struct X (base)

// CHECK:    0 |     (X vbtable pointer)

// CHECK:    4 |     char a

// CHECK:    9 |   struct W (base) (empty)

// CHECK:    9 |   char a

// CHECK:   12 |   struct V (virtual base) (empty)

// CHECK:      | [sizeof=12, align=4

// CHECK:      |  nvsize=12, nvalign=4]

// CHECK-X64: *** Dumping AST Record Layout

// CHECK-X64:    0 | struct A

// CHECK-X64:    0 |   struct X (base)

// CHECK-X64:    0 |     (X vbtable pointer)

// CHECK-X64:    8 |     char a

// CHECK-X64:   17 |   struct W (base) (empty)

// CHECK-X64:   17 |   char a

// CHECK-X64:   24 |   struct V (virtual base) (empty)

// CHECK-X64:      | [sizeof=24, align=8

// CHECK-X64:      |  nvsize=24, nvalign=8]



struct B : X, U, W  { char a; };



// CHECK: *** Dumping AST Record Layout

// CHECK:    0 | struct B

// CHECK:    0 |   struct X (base)

// CHECK:    0 |     (X vbtable pointer)

// CHECK:    4 |     char a

// CHECK:    8 |   struct U (base)

// CHECK:    8 |     char a

// CHECK:    9 |   struct W (base) (empty)

// CHECK:    9 |   char a

// CHECK:   12 |   struct V (virtual base) (empty)

// CHECK:      | [sizeof=12, align=4

// CHECK:      |  nvsize=12, nvalign=4]

// CHECK-X64: *** Dumping AST Record Layout

// CHECK-X64:    0 | struct B

// CHECK-X64:    0 |   struct X (base)

// CHECK-X64:    0 |     (X vbtable pointer)

// CHECK-X64:    8 |     char a

// CHECK-X64:   16 |   struct U (base)

// CHECK-X64:   16 |     char a

// CHECK-X64:   17 |   struct W (base) (empty)

// CHECK-X64:   17 |   char a

// CHECK-X64:   24 |   struct V (virtual base) (empty)

// CHECK-X64:      | [sizeof=24, align=8

// CHECK-X64:      |  nvsize=24, nvalign=8]



struct C : X, V, W  { char a; };



// CHECK: *** Dumping AST Record Layout

// CHECK:    0 | struct C

// CHECK:    0 |   struct X (base)

// CHECK:    0 |     (X vbtable pointer)

// CHECK:    4 |     char a

// CHECK:    9 |   struct V (base) (empty)

// CHECK:   10 |   struct W (base) (empty)

// CHECK:   10 |   char a

// CHECK:   12 |   struct V (virtual base) (empty)

// CHECK:      | [sizeof=12, align=4

// CHECK:      |  nvsize=12, nvalign=4]

// CHECK-X64: *** Dumping AST Record Layout

// CHECK-X64:    0 | struct C

// CHECK-X64:    0 |   struct X (base)

// CHECK-X64:    0 |     (X vbtable pointer)

// CHECK-X64:    8 |     char a

// CHECK-X64:   17 |   struct V (base) (empty)

// CHECK-X64:   18 |   struct W (base) (empty)

// CHECK-X64:   18 |   char a

// CHECK-X64:   24 |   struct V (virtual base) (empty)

// CHECK-X64:      | [sizeof=24, align=8

// CHECK-X64:      |  nvsize=24, nvalign=8]



struct D : X, U, V, W  { char a; };



// CHECK: *** Dumping AST Record Layout

// CHECK:    0 | struct D

// CHECK:    0 |   struct X (base)

// CHECK:    0 |     (X vbtable pointer)

// CHECK:    4 |     char a

// CHECK:    8 |   struct U (base)

// CHECK:    8 |     char a

// CHECK:    9 |   struct V (base) (empty)

// CHECK:   10 |   struct W (base) (empty)

// CHECK:   10 |   char a

// CHECK:   12 |   struct V (virtual base) (empty)

// CHECK:      | [sizeof=12, align=4

// CHECK:      |  nvsize=12, nvalign=4]

// CHECK-X64: *** Dumping AST Record Layout

// CHECK-X64:    0 | struct D

// CHECK-X64:    0 |   struct X (base)

// CHECK-X64:    0 |     (X vbtable pointer)

// CHECK-X64:    8 |     char a

// CHECK-X64:   16 |   struct U (base)

// CHECK-X64:   16 |     char a

// CHECK-X64:   17 |   struct V (base) (empty)

// CHECK-X64:   18 |   struct W (base) (empty)

// CHECK-X64:   18 |   char a

// CHECK-X64:   24 |   struct V (virtual base) (empty)

// CHECK-X64:      | [sizeof=24, align=8

// CHECK-X64:      |  nvsize=24, nvalign=8]



struct E : X, U, Y, V, W  { char a; };



// CHECK: *** Dumping AST Record Layout

// CHECK:    0 | struct E

// CHECK:    0 |   struct X (base)

// CHECK:    0 |     (X vbtable pointer)

// CHECK:    4 |     char a

// CHECK:    8 |   struct U (base)

// CHECK:    8 |     char a

// CHECK:   12 |   struct Y (base)

// CHECK:   12 |     (Y vbtable pointer)

// CHECK:   16 |     char a

// CHECK:   21 |   struct V (base) (empty)

// CHECK:   22 |   struct W (base) (empty)

// CHECK:   22 |   char a

// CHECK:   24 |   struct V (virtual base) (empty)

// CHECK:      | [sizeof=24, align=4

// CHECK:      |  nvsize=24, nvalign=4]

// CHECK-X64: *** Dumping AST Record Layout

// CHECK-X64:    0 | struct E

// CHECK-X64:    0 |   struct X (base)

// CHECK-X64:    0 |     (X vbtable pointer)

// CHECK-X64:    8 |     char a

// CHECK-X64:   16 |   struct U (base)

// CHECK-X64:   16 |     char a

// CHECK-X64:   24 |   struct Y (base)

// CHECK-X64:   24 |     (Y vbtable pointer)

// CHECK-X64:   32 |     char a

// CHECK-X64:   41 |   struct V (base) (empty)

// CHECK-X64:   42 |   struct W (base) (empty)

// CHECK-X64:   42 |   char a

// CHECK-X64:   48 |   struct V (virtual base) (empty)

// CHECK-X64:      | [sizeof=48, align=8

// CHECK-X64:      |  nvsize=48, nvalign=8]



struct F : Z, W  { char a; };



// CHECK: *** Dumping AST Record Layout

// CHECK:    0 | struct F

// CHECK:    0 |   struct Z (base)

// CHECK:    0 |     struct Y (base)

// CHECK:    0 |       (Y vbtable pointer)

// CHECK:    4 |       char a

// CHECK:    9 |   struct W (base) (empty)

// CHECK:    9 |   char a

// CHECK:   12 |   struct V (virtual base) (empty)

// CHECK:      | [sizeof=12, align=4

// CHECK:      |  nvsize=12, nvalign=4]

// CHECK-X64: *** Dumping AST Record Layout

// CHECK-X64:    0 | struct F

// CHECK-X64:    0 |   struct Z (base)

// CHECK-X64:    0 |     struct Y (base)

// CHECK-X64:    0 |       (Y vbtable pointer)

// CHECK-X64:    8 |       char a

// CHECK-X64:   17 |   struct W (base) (empty)

// CHECK-X64:   17 |   char a

// CHECK-X64:   24 |   struct V (virtual base) (empty)

// CHECK-X64:      | [sizeof=24, align=8

// CHECK-X64:      |  nvsize=24, nvalign=8]



struct G : X, W, Y, V  { char a; };



// CHECK: *** Dumping AST Record Layout

// CHECK:    0 | struct G

// CHECK:    0 |   struct X (base)

// CHECK:    0 |     (X vbtable pointer)

// CHECK:    4 |     char a

// CHECK:    9 |   struct W (base) (empty)

// CHECK:   12 |   struct Y (base)

// CHECK:   12 |     (Y vbtable pointer)

// CHECK:   16 |     char a

// CHECK:   21 |   struct V (base) (empty)

// CHECK:   21 |   char a

// CHECK:   24 |   struct V (virtual base) (empty)

// CHECK:      | [sizeof=24, align=4

// CHECK:      |  nvsize=24, nvalign=4]

// CHECK-X64: *** Dumping AST Record Layout

// CHECK-X64:    0 | struct G

// CHECK-X64:    0 |   struct X (base)

// CHECK-X64:    0 |     (X vbtable pointer)

// CHECK-X64:    8 |     char a

// CHECK-X64:   17 |   struct W (base) (empty)

// CHECK-X64:   24 |   struct Y (base)

// CHECK-X64:   24 |     (Y vbtable pointer)

// CHECK-X64:   32 |     char a

// CHECK-X64:   41 |   struct V (base) (empty)

// CHECK-X64:   41 |   char a

// CHECK-X64:   48 |   struct V (virtual base) (empty)

// CHECK-X64:      | [sizeof=48, align=8

// CHECK-X64:      |  nvsize=48, nvalign=8]



int a[

sizeof(A)+

sizeof(B)+

sizeof(C)+

sizeof(D)+

sizeof(E)+

sizeof(F)+

sizeof(G)];