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Re: [PATCH] rs6000: Use xori for HTM builtins and vector compares
- From: Peter Bergner <bergner at vnet dot ibm dot com>
- To: David Edelsohn <dje dot gcc at gmail dot com>
- Cc: Segher Boessenkool <segher at kernel dot crashing dot org>, GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Wed, 10 Sep 2014 13:38:13 -0500
- Subject: Re: [PATCH] rs6000: Use xori for HTM builtins and vector compares
- Authentication-results: sourceware.org; auth=none
- References: <3970eebb20386837608385f3e276f7c33080e8c0 dot 1410289982 dot git dot segher at kernel dot crashing dot org> <CAGWvnyn=0=FPOwd5Dj=9_tYr1r3fPk5dVE7zo9GOwaRLZoagYA at mail dot gmail dot com>
On Tue, 2014-09-09 at 19:28 -0400, David Edelsohn wrote:
> On Tue, Sep 9, 2014 at 3:29 PM, Segher Boessenkool
> > 2014-09-09 Segher Boessenkool <segher@kernel.crashing.org>
> >
> > * config/rs6000/htm.md (tabort, tabortdc, tabortdci, tabortwc,
> > tabortwci, tbegin, tcheck, tend, trechkpt, treclaim, tsr): Use xor
> > instead of minus.
> > * config/rs6000/vector.md (cr6_test_for_zero_reverse,
> > cr6_test_for_lt_reverse): Ditto.
>
> This is okay with me, but let me give Peter a chance to comment if
> there was a specific reason to use subfic instead of xori. This may
> have been a carry-over from Z, which does not have the same CA clobber
> issue.
Actually, I just copied the usage in cr6_test_for_zero_reverse and
cr6_test_for_lt_reverse, so I'm not against using xori...as long as
compiling a "if __builtin_tbegin (0) {...}" still ends up with a
.tbegin followed immediately by a branch (ie, no interleaving copy
from CR and compare instruction).
Peter