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Re: [PATCH, i386, MPX 1/X] Support of Intel MPX ISA
- From: Ilya Enkovich <enkovich dot gnu at gmail dot com>
- To: "Joseph S. Myers" <joseph at codesourcery dot com>
- Cc: gcc-patches <gcc-patches at gcc dot gnu dot org>, Uros Bizjak <ubizjak at gmail dot com>, Jakub Jelinek <jakub at redhat dot com>, Areg Melik-Adamyan <areg dot melikadamyan at gmail dot com>
- Date: Thu, 8 Aug 2013 15:57:38 +0400
- Subject: Re: [PATCH, i386, MPX 1/X] Support of Intel MPX ISA
- References: <CAMbmDYZdrR8t66VtNPFxbz33mMX0M-tMj_Bv=uvrejui_YnVWg at mail dot gmail dot com> <Pine dot LNX dot 4 dot 64 dot 1307242237420 dot 5307 at digraph dot polyomino dot org dot uk> <CAMbmDYbNvPh8MiJkgx29Hc+d_czzLeFuxeG4uDz_AozqX3j1cg at mail dot gmail dot com> <Pine dot LNX dot 4 dot 64 dot 1307251415290 dot 18813 at digraph dot polyomino dot org dot uk> <CAMbmDYamg+jwEY6FiZ_+_DT8nqug58Gi5Nf2PSDZ26Bi17K5=A at mail dot gmail dot com> <CAMbmDYYM5Qfayx2yoFyZ4oKUhOi8aD=jWCNMyzEMadSYYC2fqA at mail dot gmail dot com> <Pine dot LNX dot 4 dot 64 dot 1308072202290 dot 26185 at digraph dot polyomino dot org dot uk>
2013/8/8 Joseph S. Myers <joseph@codesourcery.com>:
> On Fri, 2 Aug 2013, Ilya Enkovich wrote:
>
>> Hi All,
>>
>> I've updated MPX Wiki page
>> (http://gcc.gnu.org/wiki/Intel%20MPX%20support%20in%20the%20GCC%20compiler).
>> I added instrumentation description, programming model description,
>> differences with other checkers, implementation details.
>
> Thanks. As noted, there should be a clean separation between what's
> generic and what's architecture-specific - the generic command-line
> options, hooks etc. shouldn't mention "MPX" in their names.
That is not a big issue to rename generic names. But I'm just still
trying to choose proper names. I looked into -fbounds-check but its
description already mention C/C++ and its semantics differs from what
new instrumentation does. I consider using -fcheck=pointer (currently
valid for Fortran) and 'chkp' instead of 'mpx' for generic things.
Does it look OK?
>
> I'm unclear on the references to *_nobnd and *_nochk functions - are there
> corresponding library (glibc etc.) changes to add additional function
> variants? Are all built-in functions that use pointers modified so that
> GCC will insert the required checks when expanding inline?
The idea was to add new versions of some functions into glibc and
replace normal versions call with special versions call when possible
(e.g. when we know memcpy call does not copy pointers). Currently in
MPX mode expanding is allowed for _nochk_nobnd variant which is equal
to regular call. I cannot be sure new version will be added into
glibc. If not, we would probably create additional library in GCC.
>
> I'm also unclear on how much --enable-mpx does - in general, it's
> desirable for a single compiler to be able to generate binaries both with
> and without the checks, and so quite possibly to build libgcc, libstdc++
> etc. as multilibs both with and without MPX, rather than needing to make a
> static decision when GCC is built (so, any configure option should
> preferably be about building *extra* library variants, for example, rather
> than changing the options with which existing variants are built).
Currently (in public mpx branch) --enable-mpx just adds compilation
options to some libraries.
I made an attempt to use multilibs instead. I tried to add mpx variant
to target libraries build but got fail for libgfortran build. Does
multilib support partial library rebuild? Actually I do not need
libgfortran library (an many other libraries) to be in mpx version. Is
it possible to get some libs from one place and some libs from another
place?
Thanks,
Ilya
>
> --
> Joseph S. Myers
> joseph@codesourcery.com