[cfe-commits] r133450 - in /cfe/trunk: lib/CodeGen/CodeGenModule.cpp lib/Sema/SemaDecl.cpp test/CodeGen/attr-weak-import.c
jahanian
fjahanian at apple.com
Tue Jun 21 15:35:09 PDT 2011
On Jun 21, 2011, at 3:22 PM, Eli Friedman wrote:
> On Mon, Jun 20, 2011 at 10:50 AM, Fariborz Jahanian <fjahanian at apple.com> wrote:
>> Author: fjahanian
>> Date: Mon Jun 20 12:50:03 2011
>> New Revision: 133450
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=133450&view=rev
>> Log:
>> llvm-gcc treats a tentative definition with a previous
>> (or follow up) extern declaration with weak_import as
>> an actual definition. make clang follows this behavior.
>> // rdar://9538608
>> llvm-gcc treats an extern declaration with weak_import
>>
>> Added:
>> cfe/trunk/test/CodeGen/attr-weak-import.c
>> Modified:
>> cfe/trunk/lib/CodeGen/CodeGenModule.cpp
>> cfe/trunk/lib/Sema/SemaDecl.cpp
>>
>> Modified: cfe/trunk/lib/CodeGen/CodeGenModule.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenModule.cpp?rev=133450&r1=133449&r2=133450&view=diff
>> ==============================================================================
>> --- cfe/trunk/lib/CodeGen/CodeGenModule.cpp (original)
>> +++ cfe/trunk/lib/CodeGen/CodeGenModule.cpp Mon Jun 20 12:50:03 2011
>> @@ -1351,7 +1351,8 @@
>> ((!CodeGenOpts.NoCommon && !D->getAttr<NoCommonAttr>()) ||
>> D->getAttr<CommonAttr>()) &&
>> !D->hasExternalStorage() && !D->getInit() &&
>> - !D->getAttr<SectionAttr>() && !D->isThreadSpecified()) {
>> + !D->getAttr<SectionAttr>() && !D->isThreadSpecified() &&
>> + !D->getAttr<WeakImportAttr>()) {
>> // Thread local vars aren't considered common linkage.
>> return llvm::GlobalVariable::CommonLinkage;
>> }
>>
>> Modified: cfe/trunk/lib/Sema/SemaDecl.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDecl.cpp?rev=133450&r1=133449&r2=133450&view=diff
>> ==============================================================================
>> --- cfe/trunk/lib/Sema/SemaDecl.cpp (original)
>> +++ cfe/trunk/lib/Sema/SemaDecl.cpp Mon Jun 20 12:50:03 2011
>> @@ -2039,6 +2039,12 @@
>> }
>>
>> mergeDeclAttributes(New, Old, Context);
>> + // weak_import on current declaration is applied to previous
>> + // tentative definiton.
>> + if (New->getAttr<WeakImportAttr>() &&
>> + Old->getStorageClass() == SC_None &&
>> + !Old->getAttr<WeakImportAttr>())
>> + Old->addAttr(::new (Context) WeakImportAttr(SourceLocation(), Context));
>
> Applying attributes backwards is generally not how we do things... we
> can't in general apply attributes backwards (even if it might happen
> to work here to some extent). Is this really necessary?
Unfortunately yes. Need to make this test compatible with llvm-gcc:
int C;
extern int C __attribute__((weak_import));
% llvm-gcc -c t.c
% nm -nm t.o
0000000000000000 (__DATA,__common) external _C
% $CLANG -c t.c
% nm -nm t.o
0000000000000000 (__DATA,__common) external _C
- Fariborz
>
> -Eli
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