Re: Disable SPE instructions for MPC85xx (e500)

[Dan Kegel <dank at kegel dot com>]

Sébastien Douheret wrote:
> I have generate a crosscompiler to target a PowerQuicc3 (MPC85xx with a core
> e500) with these flags :
>
> export TARGET=powerpc-eabispe
> export TARGET_CFLAGS="-O -msoft-float -mno-string -Wa,-me500"
> export NEWLIB_DIR=newlib-1.12.0
> export NEWLIB_URL=ftp://sources.redhat.com/pub/newlib
> export NEWLIB_EXTRA_CONFIG="--without-fp"
>
> export GCC_LANGUAGES="c,c++"
>
> export BINUTILS_DIR=binutils-2.14
> export BINUTILS_URL=ftp://gcc.gnu.org/pub/binutils/releases/
>
> export GCC_DIR=gcc-3.3.2
> export GCC_EXTRA_CONFIG=""

Ah, are you using the newlib-patched crosstool?

> Motorola advise against using SPE instructions for MPC85xx (see extract
> below).
> My compiler produce instruction in entry C function like "vmhraddshs
> v31,v1,v4,v12" that require SPE functionnalities !
>
> How can i disable it ?
> With CFLAGS modification of makefile that generate crosscompiler or with
> CFLAGS modification of makefile of my project ?
> I have try -mno-altivec or -mabi=no-spe option without successful ;-(
>
> ... 
> Extract of MPC8560TS/D(Rev. 1.0, 8/2003) :
> NOTE
> The e500 definition includes additional signal processing engine (SPE)
> computational instructions that use the 64-bit GPRs. These are not
> supported on the MPC8540 or the MPC8560 and should not be used.

I dunno... you've read
http://gcc.gnu.org/onlinedocs/gcc-3.4.0/gcc/RS-6000-and-PowerPC-Options.html
more carefully than I have, I suspect!

How about putting together a minimal test case showing the -S output?
- Dan

--
My technical stuff: http://kegel.com
My politics: see http://www.misleader.org for examples of why I'm for regime change

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