RE: [MIPS] MADD issue

["Fu, Chao-Ying" <fu at mips dot com>]

Hi,

  How about a patch like this to support signed and unsigned
multiplication and addition?  We can extend to MSUB/MSUBU as well.
Thanks!

2007-04-20  Chao-ying Fu  <fu@mips.com>

	* optabs.c (init_optabs): Initialize smadd_widen_optab and umadd_widen_optab.
	* optabs.h (optab_index): Add OTI_smadd_widen and OTI_umadd_widen.
	(smadd_widen_optab, umadd_widen_optab): Define.
	* genopinit.c (optabs): Add smadd_widen_optab and usmadd_widen_optab.
	* expr.c (expand_expr_real_1): Add rtx of op2.
	Process PLUS_EXPR to generate multiplication and add instructions.
	* config/mips/mips-dspr2.md (maddsidi4, umaddsidi4): New patterns.

Ex: (bug72.c)
long long t1 (int a, int b, long long c)
{
  return (long long)a * b + c;
}

unsigned long long t2 (unsigned int a, unsigned int b, unsigned long long c)
{
  return (unsigned long long)a * b + c;
}

# <812> ~/dev/gcc4x/install32/bin/mipsisa32r2-elf-gcc -S -mdspr2 bug72.c -O

t1:
        mtlo    $7
        mthi    $6
        madd    $ac0,$5,$4
        mflo    $7
        mfhi    $6
        move    $2,$6
        j       $31
        move    $3,$7

t2:
        mtlo    $7
        mthi    $6
        maddu   $ac0,$5,$4
        mflo    $7
        mfhi    $6
        move    $2,$6
        j       $31
        move    $3,$7

Regards,
Chao-ying

> -----Original Message-----
> From: gcc-owner@gcc.gnu.org [mailto:gcc-owner@gcc.gnu.org]On Behalf Of
> Richard Sandiford
> Sent: Friday, April 20, 2007 8:05 AM
> To: Stephens, Nigel
> Cc: Fu, Chao-Ying; gcc@gcc.gnu.org; Thekkath, Radhika
> Subject: Re: [MIPS] MADD issue
> 
> 
> Nigel Stephens <nigel@mips.com> writes:
> > OK, so maybe as the person who removed adddi3 from the MIPS 
> backend, and 
> > the main  proponent of the new fused opcodes, you get to 
> volunteer to 
> > implement this? :)
> 
> Hey, I was pretty happy with the status quo ;)
> 
> Richard
>

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