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Fix PR9253, allowing attribute(aligned) to reduce the alignment of 

a typedef.

llvm-svn: 126059
This commit is contained in:
Chris Lattner 2011-02-19 22:55:41 +00:00
parent ef200db4fd
commit 29eb47bd68
2 changed files with 22 additions and 1 deletions
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8
clang/lib/AST/ASTContext.cpp
View File

@ -882,7 +882,13 @@ ASTContext::getTypeInfo(const Type *T) const {
const TypedefDecl *Typedef = cast<TypedefType>(T)->getDecl();
std::pair<uint64_t, unsigned> Info
= getTypeInfo(Typedef->getUnderlyingType().getTypePtr());
Align = std::max(Typedef->getMaxAlignment(), Info.second);
// If the typedef has an aligned attribute on it, it overrides any computed
// alignment we have. This violates the GCC documentation (which says that
// attribute(aligned) can only round up) but matches its implementation.
if (unsigned AttrAlign = Typedef->getMaxAlignment())
Align = AttrAlign;
else
Align = Info.second;
Width = Info.first;
break;
}

15
clang/test/Sema/struct-packed-align.c
View File

@ -117,3 +117,18 @@ struct packed_fas2 {
extern int m1[sizeof(struct packed_fas2) == 1 ? 1 : -1];
extern int m2[__alignof(struct packed_fas2) == 1 ? 1 : -1];
// Attribute aligned can round down typedefs. PR9253
typedef long long __attribute__((aligned(1))) nt;
struct nS {
char buf_nr;
nt start_lba;
};
extern int n1[sizeof(struct nS) == 9 ? 1 : -1];
extern int n2[__alignof(struct nS) == 1 ? 1 : -1];