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, microblaze]: Adjustments to pcmp instruction generation

From: Michael Eager <eager at eagerm dot com>
To: David Holsgrove <david dot holsgrove at xilinx dot com>
Cc: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>, "Michael Eager (eager at eagercon dot com)" <eager at eagercon dot com>, John Williams <jwilliams at xilinx dot com>, "Edgar E. Iglesias (edgar dot iglesias at gmail dot com)" <edgar dot iglesias at gmail dot com>, Vinod Kathail <vinodk at xilinx dot com>, Vidhumouli Hunsigida <vidhum at xilinx dot com>, Nagaraju Mekala <nmekala at xilinx dot com>, Tom Shui <tshui at xilinx dot com>
Date: Wed, 27 Feb 2013 09:22:00 -0800
Subject: Re: [Patch, microblaze]: Adjustments to pcmp instruction generation
References: <9eea6a6b-166e-4935-a564-3ce47195e93b@CO1EHSMHS024.ehs.local>

On 02/10/2013 10:40 PM, David Holsgrove wrote:

Adjustments to pcmp instruction generation

avoid pcmpe insns when not valuable

For pure in and equality comparisions, xor is better,
Xor is a one cycle insn as pcmp.

Pattern insns will still be used when you need to
conditionally set something to one or zero, e.g

if (a)
   return 1;
else
   return 0;

Define contraint for first operand in insn matching
fcmp as general register

Add a constraint to the cstoresf pattern forcing the use of
general regs for the operands. This avoids an ICE where the
compiler would crash on late usage of pseudo registers.

Changelog

2013-02-11 Edgar E. Iglesias <edgar.iglesias@gmail.com>

   * config/microblaze/microblaze.c (microblaze_emit_compare):
      Use xor for EQ/NE comparisions
   * config/microblaze/microblaze.md (cstoresf4): Add constraints
      (cbranchsf4): Adjust operator to comparison_operator

Committed revision 196315.


--
Michael Eager	 eager@eagercon.com
1960 Park Blvd., Palo Alto, CA 94306  650-325-8077

References:
- [Patch, microblaze]: Adjustments to pcmp instruction generation
  - From: David Holsgrove

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