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Improves compatibility with cl.exe when laying out array fields 

Differential Revision: http://llvm-reviews.chandlerc.com/D2090

Clang was "improperly" over-aligning arrays with sizes are not a multiple of 
their alignment. 
This behavior was removed in microsoft 32 bit mode.

In addition, after examination of ASTContext::getTypeInfoImpl, a redundant code block in 
MicrosoftRecordLayoutBuilder::getAdjustedFieldInfo was deleted.

llvm-svn: 193898
This commit is contained in:
Warren Hunt 2013-11-01 23:59:41 +00:00
parent 365bd0c88c
commit 5ae586ad45
3 changed files with 32 additions and 21 deletions
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8
clang/lib/AST/ASTContext.cpp
View File

@ -1387,7 +1387,9 @@ static getConstantArrayInfoInChars(const ASTContext &Context,
"Overflow in array type char size evaluation");
uint64_t Width = EltInfo.first.getQuantity() * Size;
unsigned Align = EltInfo.second.getQuantity();
Width = llvm::RoundUpToAlignment(Width, Align);
if (!Context.getTargetInfo().getCXXABI().isMicrosoft() ||
Context.getTargetInfo().getPointerWidth(0) == 64)
Width = llvm::RoundUpToAlignment(Width, Align);
return std::make_pair(CharUnits::fromQuantity(Width),
CharUnits::fromQuantity(Align));
}
@ -1460,7 +1462,9 @@ ASTContext::getTypeInfoImpl(const Type *T) const {
"Overflow in array type bit size evaluation");
Width = EltInfo.first*Size;
Align = EltInfo.second;
Width = llvm::RoundUpToAlignment(Width, Align);
if (!getTargetInfo().getCXXABI().isMicrosoft() ||
getTargetInfo().getPointerWidth(0) == 64)
Width = llvm::RoundUpToAlignment(Width, Align);
break;
}
case Type::ExtVector:

22
clang/lib/AST/RecordLayoutBuilder.cpp
View File

@ -2140,23 +2140,8 @@ public:
std::pair<CharUnits, CharUnits>
MicrosoftRecordLayoutBuilder::getAdjustedFieldInfo(const FieldDecl *FD) {
std::pair<CharUnits, CharUnits> FieldInfo;
if (FD->getType()->isIncompleteArrayType()) {
// This is a flexible array member; we can't directly
// query getTypeInfo about these, so we figure it out here.
// Flexible array members don't have any size, but they
// have to be aligned appropriately for their element type.
FieldInfo.first = CharUnits::Zero();
const ArrayType *ATy = Context.getAsArrayType(FD->getType());
FieldInfo.second = Context.getTypeAlignInChars(ATy->getElementType());
} else if (const ReferenceType *RT = FD->getType()->getAs<ReferenceType>()) {
unsigned AS = RT->getPointeeType().getAddressSpace();
FieldInfo.first = Context
.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(AS));
FieldInfo.second = Context
.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(AS));
} else
FieldInfo = Context.getTypeInfoInChars(FD->getType());
std::pair<CharUnits, CharUnits> FieldInfo =
Context.getTypeInfoInChars(FD->getType());
// If we're not on win32 and using ms_struct the field alignment will be wrong
// for 64 bit types, so we fix that here.
@ -2187,8 +2172,7 @@ MicrosoftRecordLayoutBuilder::getAdjustedFieldInfo(const FieldDecl *FD) {
void MicrosoftRecordLayoutBuilder::initializeLayout(const RecordDecl *RD) {
IsUnion = RD->isUnion();
Is64BitMode = RD->getASTContext().getTargetInfo().getTriple().getArch() ==
llvm::Triple::x86_64;
Is64BitMode = Context.getTargetInfo().getPointerWidth(0) == 64;
Size = CharUnits::Zero();
Alignment = CharUnits::One();

23
clang/test/Layout/ms-x86-misalignedarray.cpp Normal file
View File

@ -0,0 +1,23 @@
// RUN: %clang_cc1 -fno-rtti -emit-llvm-only -triple i686-pc-win32 -fdump-record-layouts -fsyntax-only -cxx-abi microsoft %s 2>&1 \
// RUN: | FileCheck %s
// 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 T0 { char c; };
struct T2 : virtual T0 { };
struct T3 { T2 a[1]; char c; };
// CHECK: *** Dumping AST Record Layout
// CHECK: 0 | struct T3
// CHECK: 0 | struct T2 [1] a
// CHECK: 5 | char c
// CHECK: | [sizeof=8, align=4
// CHECK: | nvsize=8, nvalign=4]
// CHECK-X64: *** Dumping AST Record Layout
// CHECK-X64: 0 | struct T3
// CHECK-X64: 0 | struct T2 [1] a
// CHECK-X64: 16 | char c
// CHECK-X64: | [sizeof=24, align=8
// CHECK-X64: | nvsize=24, nvalign=8]
int a[sizeof(T3)];