[llvm-commits] [llvm] r58673 - in /llvm/trunk: include/llvm/CodeGen/Passes.h lib/CodeGen/LLVMTargetMachine.cpp lib/CodeGen/StackProtector.cpp

[Bill Wendling]

On Thu, Nov 6, 2008 at 10:24 AM, Chris Lattner <clattner at apple.com> wrote:
> On Nov 4, 2008, at 11:44 AM, Bill Wendling wrote:
>> On Tue, Nov 4, 2008 at 10:13 AM, Dan Gohman <gohman at apple.com> wrote:
>>> On Nov 4, 2008, at 10:06 AM, Evan Cheng wrote:
>>>> On Nov 4, 2008, at 5:28 AM, Chris Lattner wrote:
>>>>>
>>>>>
>>>>>> +  StackProtFrameSlot = new
>>>>>> AllocaInst(PointerType::getUnqual(Type::Int8Ty),
>>>>>> +                                      "StackProt_Frame",
>>>>>> &InsertPt);
>>>>>
>>>>> What ensures that this alloca ends up in the right place in the
>>>>> stack
>>>>> frame at codegen time?
>>>>
>>>> This is unclear.Can we give it a special name that starts with "__"
>>>> and sdisel will mark the corresponding stack object. PEI will have
>>>> to
>>>> make sure it's in the right location. I don't particularly like it
>>>> but
>>>> I can't think of anything better. Any ideas?
>>>
>>> Names aren't always preserved. How about replacing the Alloca with
>>> an intrinsic that does the allocation?
>>>
>> I'm not sure that that's necessary. It should be possible to keep
>> track of the alloca instruction from this pass through code gen. Once
>> it's lowered, then I'll know what FI it's at, etc. Then PEI can
>> perform its magic.
>
> Good idea, how about something like this:
>
> %tmp = alloca ...
> call llvm.makestackcanary(%tmp)
>
> ?  A better name is prefered :)
>
Did. :-)

-bw