From ec8d5a825d8f511199d110be14ce57f652461aae Mon Sep 17 00:00:00 2001 From: Warren Hunt Date: Fri, 6 Dec 2013 20:16:49 +0000 Subject: [PATCH] [MS-ABI] adds padding before all vbases after a bitfield MS-ABI adds padding before *every* vbase if the last field in a record is a bit-field. This changes clangs behavior to match. I also fix some windows-style line endings in the test file. Differential Revision: http://llvm-reviews.chandlerc.com/D2277 git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@196605 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/AST/RecordLayoutBuilder.cpp | 15 ++- test/Layout/ms-x86-bitfields-vbases.cpp | 152 ++++++++++++++---------- 2 files changed, 99 insertions(+), 68 deletions(-) diff --git a/lib/AST/RecordLayoutBuilder.cpp b/lib/AST/RecordLayoutBuilder.cpp index ec79156489..b692025aa0 100644 --- a/lib/AST/RecordLayoutBuilder.cpp +++ b/lib/AST/RecordLayoutBuilder.cpp @@ -2014,9 +2014,9 @@ static bool isMsLayout(const RecordDecl* D) { // one. // * The last zero size virtual base may be placed at the end of the struct. // and can potentially alias a zero sized type in the next struct. -// * 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. +// * If the last field is a non-zero length bitfield, all virtual bases will +// have extra padding added before them for no obvious reason. The padding +// has the same number of bits as the type of the bitfield. // * 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. // * The ABI attempts to avoid aliasing of zero sized bases by adding padding @@ -2558,17 +2558,16 @@ void MicrosoftRecordLayoutBuilder::layoutVirtualBases(const CXXRecordDecl *RD) { llvm::SmallPtrSet HasVtordisp = computeVtorDispSet(RD); - // If the last field we laid out was a non-zero length bitfield then add some - // extra padding for no obvious reason. - if (LastFieldIsNonZeroWidthBitfield) - Size += CurrentBitfieldSize; - // Iterate through the virtual bases and lay them out. for (CXXRecordDecl::base_class_const_iterator i = RD->vbases_begin(), e = RD->vbases_end(); i != e; ++i) { const CXXRecordDecl *BaseDecl = cast(i->getType()->castAs()->getDecl()); + // If the last field we laid out was a non-zero length bitfield then add + // some extra padding for no obvious reason. + if (LastFieldIsNonZeroWidthBitfield) + Size += CurrentBitfieldSize; layoutVirtualBase(BaseDecl, HasVtordisp.count(BaseDecl)); } } diff --git a/test/Layout/ms-x86-bitfields-vbases.cpp b/test/Layout/ms-x86-bitfields-vbases.cpp index e11ef67a63..f973edd6a3 100644 --- a/test/Layout/ms-x86-bitfields-vbases.cpp +++ b/test/Layout/ms-x86-bitfields-vbases.cpp @@ -3,82 +3,114 @@ // RUN: %clang_cc1 -fno-rtti -emit-llvm-only -triple x86_64-pc-win32 -fdump-record-layouts -fsyntax-only -cxx-abi microsoft %s 2>/dev/null \ // RUN: | FileCheck %s -check-prefix CHECK-X64 -struct B0 { }; - -struct A : virtual B0 { char a : 1; }; +struct B0 { int a; }; +struct B1 { int a; }; -// CHECK: *** Dumping AST Record Layout -// CHECK: 0 | struct A -// CHECK: 0 | (A vbtable pointer) -// CHECK: 4 | char a -// CHECK: 9 | struct B0 (virtual base) (empty) -// CHECK: | [sizeof=9, align=4 -// CHECK: | nvsize=8, nvalign=4] +struct A : virtual B0 { char a : 1; }; + +// CHECK: *** Dumping AST Record Layout +// CHECK: 0 | struct A +// CHECK: 0 | (A vbtable pointer) +// CHECK: 4 | char a +// CHECK: 12 | struct B0 (virtual base) +// CHECK: 12 | int a +// CHECK: | [sizeof=16, align=4 +// CHECK: | nvsize=8, nvalign=4] // CHECK-X64: *** Dumping AST Record Layout -// CHECK-X64: 0 | struct A -// CHECK-X64: 0 | (A vbtable pointer) -// CHECK-X64: 8 | char a -// CHECK-X64: 17 | struct B0 (virtual base) (empty) -// CHECK-X64: | [sizeof=24, align=8 -// CHECK-X64: | nvsize=16, nvalign=8] +// CHECK-X64: 0 | struct A +// CHECK-X64: 0 | (A vbtable pointer) +// CHECK-X64: 8 | char a +// CHECK-X64: 20 | struct B0 (virtual base) +// CHECK-X64: 20 | int a +// CHECK-X64: | [sizeof=24, align=8 +// CHECK-X64: | nvsize=16, nvalign=8] -struct B : virtual B0 { short a : 1; }; +struct B : virtual B0 { short a : 1; }; // CHECK: *** Dumping AST Record Layout -// CHECK: 0 | struct B -// CHECK: 0 | (B vbtable pointer) -// CHECK: 4 | short a -// CHECK: 10 | struct B0 (virtual base) (empty) -// CHECK: | [sizeof=10, align=4 -// CHECK: | nvsize=8, nvalign=4] +// CHECK: 0 | struct B +// CHECK: 0 | (B vbtable pointer) +// CHECK: 4 | short a +// CHECK: 12 | struct B0 (virtual base) +// CHECK: 12 | int a +// CHECK: | [sizeof=16, align=4 +// CHECK: | nvsize=8, nvalign=4] // CHECK-X64: *** Dumping AST Record Layout -// CHECK-X64: 0 | struct B -// CHECK-X64: 0 | (B vbtable pointer) -// CHECK-X64: 8 | short a -// CHECK-X64: 18 | struct B0 (virtual base) (empty) -// CHECK-X64: | [sizeof=24, align=8 -// CHECK-X64: | nvsize=16, nvalign=8] +// CHECK-X64: 0 | struct B +// CHECK-X64: 0 | (B vbtable pointer) +// CHECK-X64: 8 | short a +// CHECK-X64: 20 | struct B0 (virtual base) +// CHECK-X64: 20 | int a +// CHECK-X64: | [sizeof=24, align=8 +// CHECK-X64: | nvsize=16, nvalign=8] -struct C : virtual B0 { char a : 1; char : 0; }; +struct C : virtual B0 { char a : 1; char : 0; }; // CHECK: *** Dumping AST Record Layout -// CHECK: 0 | struct C -// CHECK: 0 | (C vbtable pointer) -// CHECK: 4 | char a -// CHECK: 5 | char -// CHECK: 8 | struct B0 (virtual base) (empty) -// CHECK: | [sizeof=8, align=4 -// CHECK: | nvsize=8, nvalign=4] +// CHECK: 0 | struct C +// CHECK: 0 | (C vbtable pointer) +// CHECK: 4 | char a +// CHECK: 5 | char +// CHECK: 8 | struct B0 (virtual base) +// CHECK: 8 | int a +// CHECK: | [sizeof=12, align=4 +// CHECK: | nvsize=8, nvalign=4] // CHECK-X64: *** Dumping AST Record Layout -// CHECK-X64: 0 | struct C -// CHECK-X64: 0 | (C vbtable pointer) -// CHECK-X64: 8 | char a -// CHECK-X64: 9 | char -// CHECK-X64: 16 | struct B0 (virtual base) (empty) -// CHECK-X64: | [sizeof=16, align=8 -// CHECK-X64: | nvsize=16, nvalign=8] +// CHECK-X64: 0 | struct C +// CHECK-X64: 0 | (C vbtable pointer) +// CHECK-X64: 8 | char a +// CHECK-X64: 9 | char +// CHECK-X64: 16 | struct B0 (virtual base) +// CHECK-X64: 16 | int a +// CHECK-X64: | [sizeof=24, align=8 +// CHECK-X64: | nvsize=16, nvalign=8] + +struct D : virtual B0 { char a : 1; char b; }; -struct D : virtual B0 { char a : 1; char b; }; +// CHECK: *** Dumping AST Record Layout +// CHECK: 0 | struct D +// CHECK: 0 | (D vbtable pointer) +// CHECK: 4 | char a +// CHECK: 5 | char b +// CHECK: 8 | struct B0 (virtual base) +// CHECK: 8 | int a +// CHECK: | [sizeof=12, align=4 +// CHECK: | nvsize=8, nvalign=4] +// CHECK-X64: *** Dumping AST Record Layout +// CHECK-X64: 0 | struct D +// CHECK-X64: 0 | (D vbtable pointer) +// CHECK-X64: 8 | char a +// CHECK-X64: 9 | char b +// CHECK-X64: 16 | struct B0 (virtual base) +// CHECK-X64: 16 | int a +// CHECK-X64: | [sizeof=24, align=8 +// CHECK-X64: | nvsize=16, nvalign=8] +struct E : virtual B0, virtual B1 { long long : 1; }; // CHECK: *** Dumping AST Record Layout -// CHECK: 0 | struct D -// CHECK: 0 | (D vbtable pointer) -// CHECK: 4 | char a -// CHECK: 5 | char b -// CHECK: 8 | struct B0 (virtual base) (empty) -// CHECK: | [sizeof=8, align=4 -// CHECK: | nvsize=8, nvalign=4] +// CHECK: 0 | struct E +// CHECK: 0 | (E vbtable pointer) +// CHECK: 8 | long long +// CHECK: 24 | struct B0 (virtual base) +// CHECK: 24 | int a +// CHECK: 36 | struct B1 (virtual base) +// CHECK: 36 | int a +// CHECK: | [sizeof=40, align=8 +// CHECK: | nvsize=16, nvalign=8] // CHECK-X64: *** Dumping AST Record Layout -// CHECK-X64: 0 | struct D -// CHECK-X64: 0 | (D vbtable pointer) -// CHECK-X64: 8 | char a -// CHECK-X64: 9 | char b -// CHECK-X64: 16 | struct B0 (virtual base) (empty) -// CHECK-X64: | [sizeof=16, align=8 -// CHECK-X64: | nvsize=16, nvalign=8] +// CHECK-X64: 0 | struct E +// CHECK-X64: 0 | (E vbtable pointer) +// CHECK-X64: 8 | long long +// CHECK-X64: 24 | struct B0 (virtual base) +// CHECK-X64: 24 | int a +// CHECK-X64: 36 | struct B1 (virtual base) +// CHECK-X64: 36 | int a +// CHECK-X64: | [sizeof=40, align=8 +// CHECK-X64: | nvsize=16, nvalign=8] int a[ sizeof(A)+ sizeof(B)+ sizeof(C)+ -sizeof(D)]; +sizeof(D)+ +sizeof(E)]; -- 2.40.0