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Re: [RFC] Using function clones for Pointer Bounds Checker
- From: Ilya Enkovich <enkovich dot gnu at gmail dot com>
- To: "H.J. Lu" <hjl dot tools at gmail dot com>
- Cc: Jeff Law <law at redhat dot com>, gcc-patches <gcc-patches at gcc dot gnu dot org>, Richard Biener <richard dot guenther at gmail dot com>, "Zamyatin, Igor" <igor dot zamyatin at intel dot com>
- Date: Thu, 15 May 2014 13:03:22 +0400
- Subject: Re: [RFC] Using function clones for Pointer Bounds Checker
- Authentication-results: sourceware.org; auth=none
- References: <CAMbmDYaxC0tZim+AysTLrqak=nX6RmEZQr1QDPU+NG6BYfoE-g at mail dot gmail dot com> <53713B09 dot 9080501 at redhat dot com> <CAMbmDYYjBaafnjym9pQ6y5aErN+TWxvKqBH66LbV6QUFOc8w+A at mail dot gmail dot com> <537270B6 dot 1080103 at redhat dot com> <CAMbmDYZr+q90-rWJriRzm8+Rjygp8H=biudWZthaYkUciRmH=Q at mail dot gmail dot com> <CAMe9rOp-wefKDeM_=o_=9X9g+sqpO85jkRKT8PgmKLG=WmaD8g at mail dot gmail dot com>
2014-05-14 19:09 GMT+04:00 H.J. Lu <hjl.tools@gmail.com>:
> On Wed, May 14, 2014 at 1:18 AM, Ilya Enkovich <enkovich.gnu@gmail.com> wrote:
>> 2014-05-13 23:21 GMT+04:00 Jeff Law <law@redhat.com>:
>>> On 05/13/14 02:38, Ilya Enkovich wrote:
>>>>>>
>>>>>> propagate constant bounds value and remove checks in called function).
>>>>>
>>>>>
>>>>> So from a linking standpoint, presumably you have to mangle the
>>>>> instrumented
>>>>> caller/callee in some manner. Right? Or are you dynamically dispatching
>>>>> somehow?
>>>>
>>>>
>>>> Originally the idea was o have instrumented clone to have the same
>>>> assembler name as the original function. Since instrumented code is
>>>> fully compatible with not instrumented code, we always emit only one
>>>> version. Usage of the same assembler name allows instrumented and not
>>>> instrumented calls to look similar in assembler. It worked fine until
>>>> I tried it with LTO where assembler name is used as a unique
>>>> identifier. With linker resolutions files it became even more harder
>>>> to use such approach. To resolve these issues I started to use new
>>>> assembler name with postfix, but linked with the original name using
>>>> IDENTIFIER_TRANSPARENT_ALIAS. It gives different assembler names for
>>>> clones and originals during compilation, but both clone and original
>>>> functions have similar name in output assembler.
>>>
>>> OK. So if I read that correctly, it implies that the existence of bounds
>>> information does not change the signature of the callee. This is obviously
>>> important for C++.
>>>
>>> Sounds like I need to sit down with the branch and see how this works in the
>>> new scheme.
>>
>> Both mpx branch and Wiki
>> (http://gcc.gnu.org/wiki/Intel%20MPX%20support%20in%20the%20GCC%20compiler)
>> page are up-to-date now and may be tried out either in NOP mode or
>> with simulator. Let me know if you have any troubles with using it.
>>
>
> I built it. But "-fcheck-pointer-bounds -mmpx" doesn't generate
> MPX enabled executable which runs on both MPX-enabled and
> non MPX-enabled hardwares. I didn't see any MPX run-time library.
MPX run-time library is not a part of GCC now. It goes with Intel SDE.
See https://software.intel.com/en-us/articles/using-intel-mpx-with-the-intel-software-development-emulator
for usage instructions.
Ilya
>
> --
> H.J.