[PATCH], PR 68404 patch #2 (disable power8/power9 fusion on PowerPC)

[Jakub Jelinek]

On Wed, Feb 10, 2016 at 05:42:17PM -0500, Michael Meissner wrote:
> This patch disables -mcpu=power8/-mtune=power8 from setting -mpower8-fusion and
> -mcpu=power9/-mtune=power9 from setting -mpower9-fusion.  I will look at the
> earlyclobber that Bernd Schmidt mentioned, but for now it may be safest to just
> disable it for GCC 6.0.
> 
> I built it on a little endian power8 system, and there were no regressions.  Is
> it ok to install?

Doesn't this mean the bug is still there, just not enabled unless
-mpower[89]-fusion (ok, perhaps mitigated by the previous workaround patch)?
Wouldn't it be better to just forcefully clear the options (and thus ignore
-them) for the time being if they are known to be broken?

> [gcc]
> 2016-02-10  Michael Meissner  <meissner@linux.vnet.ibm.com>
> 
> 	PR target/68404
> 	* config/rs6000/predicates.md (fusion_gpr_addis): Revert
> 	2016-02-09 change.
> 
> 	* config/rs6000/rs6000-cpus.def (ISA_2_7_MASKS_SERVER): Do not set
> 	power8/power9 fusion by default.
> 	(ISA_3_0_MASKS_SERVER): Likewise.
> 
> 	* config/rs6000/rs6000.c (rs6000_option_override_internal): Remove
> 	code setting -mpower8-fusion if -mtune=power8 and -mpower9-fusion
> 	if -mtune=power9.
> 
> 	* doc/invoke.texi (RS/6000 and PowerPC Options): Document that
> 	-mpower8-fusion and -mpower9-fusion are not set by default.
> 
> [gcc/testsuites]
> 2016-02-10  Michael Meissner  <meissner@linux.vnet.ibm.com>
> 
> 	PR target/68404
> 	* gcc.target/powerpc/fusion.c: Do not assume that -mtune=power8
> 	sets -mpower8-fusion or -mtune=power9 sets -mpower9-fusion.
> 	* gcc.target/powerpc/fusion2.c: Likewise.
> 	* gcc.target/powerpc/fusion3.c: Likewise.
> 
> -- 
> Michael Meissner, IBM
> IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
> email: meissner@linux.vnet.ibm.com, phone: +1 (978) 899-4797

	Jakub