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Re: [PATHCH] Disable inline asm for in-tree mpfr (PR69134)

From: Marc Glisse <marc dot glisse at inria dot fr>
To: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>
Cc: bernd dot edlinger at hotmail dot de
Date: Sat, 19 Mar 2016 21:29:43 +0100 (CET)
Subject: Re: [PATHCH] Disable inline asm for in-tree mpfr (PR69134)
Authentication-results: sourceware.org; auth=none
References: <HE1PR07MB0905C105ACF251FCE1780826E4F30 at HE1PR07MB0905 dot eurprd07 dot prod dot outlook dot com> <568BBDF7 dot 8040300 at redhat dot com> <HE1PR07MB090587484749F80CBD81F67CE4F30 at HE1PR07MB0905 dot eurprd07 dot prod dot outlook dot com> <9FFD837C-4FE2-405D-B1C6-94770F8BCA9C at suse dot de>
Reply-to: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>

On Tue, 5 Jan 2016, Richard Biener wrote:

On January 5, 2016 2:20:42 PM GMT+01:00, Bernd Edlinger <bernd.edlinger@hotmail.de> wrote:

On 05.01.2016 13:58, Bernd Schmidt wrote:

On 01/05/2016 09:44 AM, Bernd Edlinger wrote:

Using asm code is generally not desirable for in-tree mpfr builds.


Why not?


for the same reason why we disable the asm code for in-tree gmp.
If we think mpfr is fine to use assembler, why don't we let gmp use the
assember code too?


IIRC the logic at some point at least used host CPU detection to select asm.

Note that GMP only does host CPU detection if you let it (config.guess).As soon as you pass an explicit --host= option to configure (easy forgcc), that mechanism is disabled (at least that's what I think happens).

So I looked for a way to disable the asm code, and found it can bedone, but differently than for in-tree gmp. See the attached patch.

As noted in PR 67728, it seems that gcc's intrusive way of overridingCFLAGS also breaks GMP itself, not just MPFR, by hiding the macro NO_ASMthat GMP tries to define through its own CFLAGS. So maybe Bernd's patchshould be duplicated to also apply to GMP?


--
Marc Glisse

Follow-Ups:
- Re: [PATHCH] Disable inline asm for in-tree mpfr (PR69134)
  - From: Bernd Edlinger

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