This is the mail archive of the gcc-patches@gcc.gnu.org mailing list for the GCC project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: [PATCH][ARM] minmax_arithsi for non-canonical operand order with MINUS operator


On 02/04/13 17:06, Kyrylo Tkachov wrote:
From: Ramana Radhakrishnan [mailto:ramana.gcc@googlemail.com]
Sent: 02 April 2013 11:10
To: Kyrylo Tkachov
Cc: gcc-patches@gcc.gnu.org; Richard Earnshaw; Ramana Radhakrishnan
Subject: Re: [PATCH][ARM] minmax_arithsi for non-canonical operand
order with MINUS operator

On Thu, Mar 21, 2013 at 6:09 PM, Kyrylo Tkachov
<kyrylo.tkachov@arm.com> wrote:
Hi all,

This patch adds a splitter variant of the minmax_arithsi pattern for
when
the operator
is non-commutative (MINUS) and the ordering of the operands is not
canonical.

That is, it will trigger for:
#define MAX(a, b) (a > b ? a : b)
int
foo (int a, int b, int c)
{
   return c - MAX (a,b);
}

and will generate:
          cmp     r1, r0
          rsbge   r0, r1, r2
          rsblt   r0, r0, r2

instead of the current:
         cmp     r0, r1
         movlt   r0, r1
         rsb     r0, r0, r2

No regressions on arm-none-eabi.

Ok for trunk?


Split after reload please into cond-exec or use if_then_else instead
if you are splitting before reload - I originally thought it to be
safe when you asked me, but then have gone back and corrected myself.

Read this thread . http://patches.linaro.org/6469/ .

Hi Ramana, thanks for the review.
How about this? We split after reload now.
Using if_then_else got me a lot of unrecognisable instruction ICEs and
delaying the split till after reload seemed like a cleaner approach.

Tested arm-none-eabi on qemu.


gcc/
2013-04-02  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>

         * config/arm/arm.md (minmax_arithsi_non_canon): New pattern.

gcc/testsuite
2013-04-02  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>

         * gcc.target/arm/minmax_minus.c: New test.



OK.

R.




Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]