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Re: GCC 4.8 and -ftree-loop-distribute-patterns.
- From: Andreas Jaeger <aj at suse dot com>
- To: libc-alpha at sourceware dot org
- Date: Mon, 08 Apr 2013 16:16:28 +0200
- Subject: Re: GCC 4.8 and -ftree-loop-distribute-patterns.
- References: <511D4F82 dot 3080604 at redhat dot com> <5162C589 dot 7090009 at redhat dot com> <5162CE2B dot 9020006 at linux dot vnet dot ibm dot com>
On Monday, April 08, 2013 11:03:23 Adhemerval Zanella wrote:
> 2013-04-08 Adhemerval Zanella <azanella@linux.vnet.ibm.com>
>
> * config.h.in: Add HAVE_CC_PREDEF_DISTRIBUTE_PATTERNS define.
> * configure.in (libc_cv_predef_loop_distribute_patttern):
> Check if compiler with defined optimization may generate
> memset/memmove library calls for some loop constructions.
> * configure: Regenerate.
> * stdlib/divrem.c: Include <string.h> if
> HAVE_CC_PREDEF_DISTRIBUTE_PATTERNS is defined.
> * stdlib/mul.c: Likewise.
> * stdlib/mul_n.c: Likewise.
> * wcsmbs/wcpncpy.c: Likewise.
> * wcsmbs/wcsncpy.c: Likewise.
Sorry for jumping in late. I thought we had two issues:
1) Compiling without -ftree-loop-distribute patterns on files so that
memcpy does not get replaced with a compiler call to it - Roland
suggested to use __attribute__ ((optimize ("no-tree-loop-distribute-
patterns"))) in this case and using a configure check. It seems that this
is not needed at all.
2) The issue were just the redefinition helps so that a call to internal
functions is issued.
For this case I do not see the need for a configure check, IMO it would
be enough to add the include together with a comment on why it's
included so that the include does not get accidentially removed. This is
far less maintenance burden than adding a configure test.
Adhemerval, thanks for the patch - but I do not agree with Carlos that
this is the best solution,
Andreas
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