[cfe-commits] Please review: enable TBAA at "-O0 -fthread-sanitizer"

[Kostya Serebryany]

ping?


On Thu, Apr 5, 2012 at 5:17 PM, Kostya Serebryany <kcc at google.com> wrote:

>
>
> On Thu, Apr 5, 2012 at 1:56 PM, Chris Lattner <clattner at apple.com> wrote:
>
>>
>> On Apr 5, 2012, at 10:50 AM, Kostya Serebryany wrote:
>>
>>
>>
>> On Thu, Apr 5, 2012 at 10:37 AM, Chris Lattner <clattner at apple.com>wrote:
>>
>>>
>>> On Apr 5, 2012, at 9:43 AM, Kostya Serebryany wrote:
>>>
>>> > Hello,
>>> >
>>> > Please review the following patch:
>>> > ThreadSanitizer instrumentation relies on TBAA for correctness, so we
>>> need to generate TBAA at "-O0 -fthread-sanitizer".
>>>
>>> This is close, but not the right solution.  TBAA can cause a semantic
>>> change when enabled (though I admit it is unlikely given that nearly all of
>>> the optimizers are disabled at -O0).
>>>
>>> The right fix is for TSAN to generate *vtable* TBAA info, but not other
>>> TBAA info.
>>>
>>
>> Ok...
>> Do you mean that we need to check "CodeGenOpts.OptimizationLevel > 0"
>> inside CodeGenTBAA methods?
>> Or pass a flag to CodeGenTBAA::CodeGenTBAA saying that we need
>> only vtable TBAA?
>>
>>
>> The former is probably the right way.
>>
>
> New patch attached, please take a look.
>
> Alternatively we may create a CodeGenTBAA object unconditionally and check
> all the flags
> (CodeGenOpts.RelaxedAliasing, CodeGenOpts.OptimizationLevel,
> LangOpts.ThreadSanitizer)
> inside CodeGenTBAA methods.
>
> --kcc
>
>
>>
>> -Chris
>>
>>
>
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