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Teach __alignof__ to look through arrays before performing the 

preferred-alignment transformations. Corrects alignof(T[]) to return
alignof(T) in all cases, as required by relevant standards.

llvm-svn: 210609
This commit is contained in:
Richard Smith 2014-06-10 23:43:44 +00:00
parent f6d7030f0f
commit d7e1fe40e1
2 changed files with 5 additions and 9 deletions
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10
clang/lib/AST/ASTContext.cpp
View File

@ -1328,15 +1328,6 @@ CharUnits ASTContext::getDeclAlign(const Decl *D, bool ForAlignof) const {
MinWidth <= getTypeSize(cast<ConstantArrayType>(arrayType)))
Align = std::max(Align, Target->getLargeArrayAlign());
}
// Keep track of extra alignment requirements on the array itself, then
// work with the element type.
//
// FIXME: Computing the preferred type alignment for the array element
// type should not be necessary, but getPreferredTypeAlign returns the
// wrong thing in some cases (such as 'long long[]' on x86_64).
Align = std::max(Align, getPreferredTypeAlign(T.getTypePtr()));
T = BaseT;
}
Align = std::max(Align, getPreferredTypeAlign(T.getTypePtr()));
if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
@ -1788,6 +1779,7 @@ unsigned ASTContext::getPreferredTypeAlign(const Type *T) const {
const TypedefType *TT = T->getAs<TypedefType>();
// Double and long long should be naturally aligned if possible.
T = T->getBaseElementTypeUnsafe();
if (const ComplexType *CT = T->getAs<ComplexType>())
T = CT->getElementType().getTypePtr();
if (T->isSpecificBuiltinType(BuiltinType::Double) ||

4
clang/test/Sema/align-x86.c
View File

@ -23,6 +23,10 @@ struct __attribute__((packed)) {unsigned int a;} g4;
short chk1[__alignof__(g4) == 1 ? 1 : -1];
short chk2[__alignof__(g4.a) == 1 ? 1 : -1];
double g6[3];
short chk1[__alignof__(g6) == 8 ? 1 : -1];
short chk2[__alignof__(double[3]) == 8 ? 1 : -1];
// PR5637