[cfe-commits] r157483 - in /cfe/trunk: lib/CodeGen/CGCall.cpp test/CodeGen/alloc_size.c

[Nuno Lopes]

There has been some discussion on both the bounds checking and the  
alloc_size proposals on the various mailing lists (dev & commits) for  
the past month.
Yes, the design is not finished. But I've been making changes to the  
implementation to accommodate the feedback.

Nuno


Citando Chandler Carruth <chandlerc at google.com>:

> Nuno, this patch didn't get reviewed before commit. The LLVM review is
> ongoing, and seems to indicate the solution is not yet ready. Folks have
> also raised serious concerns about the implementation strategy here.
>
> While supporting the alloc_size attribute at least enough to parse it and
> reject invalid formulations seems good for GCC compatibility, adding code
> generation and LLVM support to it is adding a significant amount of
> maintenance for this feature, and there has been no discussion or general
> consensus that this functionality's design is the right long-term solution
> for Clang/LLVM. In fact, there was no discussion at all until Kostya
> started his email thread, which I don't think you've responded to yet.
>
> I would like to suggest you not continue committing (especially without
> review) patches toward a system that hasn't been designed and supported by
> the larger community. I think you really need to take time to engage the
> rest of the open source group in your efforts, and figure out what the
> correct design and implementation strategy is here.
>
> I've CC'ed Chris and Doug as they may feel differently. =] I would be very
> interested in their feedback at least about what is the best process.
> -Chandler
>
> On Fri, May 25, 2012 at 10:04 AM, Nuno Lopes <nunoplopes at sapo.pt> wrote:
>
>> Author: nlopes
>> Date: Fri May 25 12:04:42 2012
>> New Revision: 157483
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=157483&view=rev
>> Log:
>> add CodeGen support for the alloc_size attribute
>>
>> Added:
>>    cfe/trunk/test/CodeGen/alloc_size.c
>> Modified:
>>    cfe/trunk/lib/CodeGen/CGCall.cpp
>>
>> Modified: cfe/trunk/lib/CodeGen/CGCall.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGCall.cpp?rev=157483&r1=157482&r2=157483&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/lib/CodeGen/CGCall.cpp (original)
>> +++ cfe/trunk/lib/CodeGen/CGCall.cpp Fri May 25 12:04:42 2012
>> @@ -2087,6 +2087,23 @@
>>   CS.setAttributes(Attrs);
>>   CS.setCallingConv(static_cast<llvm::CallingConv::ID>(CallingConv));
>>
>> +  // add metadata for __attribute__((alloc_size(foo)))
>> +  if (TargetDecl) {
>> +    if (const AllocSizeAttr* Attr = TargetDecl->getAttr<AllocSizeAttr>())
>> {
>> +      std::vector<llvm::Value*> Args;
>> +      llvm::IntegerType *Ty =
>> llvm::IntegerType::getInt32Ty(getLLVMContext());
>> +      bool isMethod = isa<CXXMethodDecl>(TargetDecl);
>> +
>> +      for (AllocSizeAttr::args_iterator I = Attr->args_begin(),
>> +           E = Attr->args_end(); I != E; ++I) {
>> +        Args.push_back(llvm::ConstantInt::get(Ty, *I + isMethod));
>> +      }
>> +
>> +      llvm::MDNode *MD = llvm::MDNode::get(getLLVMContext(), Args);
>> +      CS.getInstruction()->setMetadata("alloc_size", MD);
>> +    }
>> +  }
>> +
>>   // In ObjC ARC mode with no ObjC ARC exception safety, tell the ARC
>>   // optimizer it can aggressively ignore unwind edges.
>>   if (CGM.getLangOpts().ObjCAutoRefCount)
>>
>> Added: cfe/trunk/test/CodeGen/alloc_size.c
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/alloc_size.c?rev=157483&view=auto
>>
>> ==============================================================================
>> --- cfe/trunk/test/CodeGen/alloc_size.c (added)
>> +++ cfe/trunk/test/CodeGen/alloc_size.c Fri May 25 12:04:42 2012
>> @@ -0,0 +1,11 @@
>> +// RUN: %clang_cc1 %s -emit-llvm -o - | FileCheck %s
>> +
>> +void *my_recalloc(void *, unsigned, unsigned)
>> __attribute__((alloc_size(2,3)));
>> +
>> +// CHECK: @f
>> +void* f() {
>> +  // CHECK: call i8* @my_recalloc{{.*}}, !alloc_size !0
>> +  return my_recalloc(0, 11, 27);
>> +}
>> +
>> +// CHECK: !0 = metadata !{i32 1, i32 2}
>>