Re: [PATCH][ARM][2/4] Fix operand costing logic for SMUL[TB][TB]

[Kyrill Tkachov <kyrylo dot tkachov at foss dot arm dot com>]

On 04/02/16 09:00, Ramana Radhakrishnan wrote:
> On Fri, Jan 22, 2016 at 9:52 AM, Kyrill Tkachov
> <kyrylo.tkachov@foss.arm.com> wrote:
> > Hi all,
> >
> > As part of investigating the codegen effects of a fix for PR 65932 I found
> > we assign
> > too high a cost for the sign-extending multiply instruction SMULBB.
> > This is because we add the cost of a multiply-extend but then also recurse
> > into the
> > SIGN_EXTEND sub-expressions rather than the registers (or subregs) being
> > sign-extended.
> >
> > This patch is a simple fix. The fix is right by itself, but in combination
> > with patch 3
> > fix the gcc.target/arm/wmul-2.c testcase.
> >
> > Bootstrapped and tested on arm-none-linux-gnueabihf.
> >
> > Ok for trunk?
> OK.

Is it ok to backport this to the GCC 5 branch?
It fixes a testcase with cortex-a5 tuning and was tested by Christophe:
https://gcc.gnu.org/ml/gcc-patches/2016-02/msg01238.html

Thanks,
Kyrill

> Thanks,
> Ramana
> > Thanks,
> > Kyrill
> >
> > 2016-01-22  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
> >
> >      * config/arm/arm.c (arm_new_rtx_costs, MULT case): Properly extract
> >      the operands of the SIGN_EXTENDs from a SMUL[TB][TB] rtx.