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Re: [patch] set -mabi=altivec with -ftree-vectorize
- From: "Andrew Pinski" <pinskia at gmail dot com>
- To: "David Edelsohn" <dje at watson dot ibm dot com>, "Zdenek Dvorak" <rakdver at kam dot mff dot cuni dot cz>, gcc-patches at gcc dot gnu dot org
- Date: Tue, 7 Aug 2007 11:58:11 -0400
- Subject: Re: [patch] set -mabi=altivec with -ftree-vectorize
- References: <20070731071457.GB32641@kam.mff.cuni.cz> <20070731110821.GA7127@caradoc.them.org> <200707311202.l6VC2C6U029180@makai.watson.ibm.com> <20070731132042.GA10523@caradoc.them.org> <20070807153553.GA3577@caradoc.them.org>
On 8/7/07, Daniel Jacobowitz <drow@false.org> wrote:
> I have been working on patches which add a .gnu_attribute entry
> describing the vector ABI. This is primarily for GDB's benefit, since
> a number of tests in its testsuite fail on -mabi=no-altivec if AltiVec
> hardware is detected. But at the same time, I added support to the
> linker to warn if you mix -mabi=no-altivec and -mabi=altivec code.
> That caused a bunch of testcases in the GCC testsuite to fail.
The ABI is only difference if you actually use altivec registers or
VMX sized vectors (except for vector long long which does not exist).
So I think the warning is wrong and will get people confused even
more. In most cases you only want to compile some parts of the
program with -maltivec -mabi=altivec and then only call those parts
when VMX exists. This is very very common in generic programs that
people compile for PowerPC and allow to run on mutliple pieces of
hardware. Remember not all users of GCC can provide full different
versions of their program in an effient manor.
Thanks,
Andrew Pinski