On Tue, 4 Feb 2014, Jakub Jelinek wrote:
> Hi!
>
> Apparently ia64 has mulv8qi3 and addv8qi3 insns, but not ashlv8qi3
> nor vashlv8qi3, thus the vectorizer can create or vector generic lowering
> keep a V8QImode multiplication by constant, but expand_mult if it is
> multiplied by a scalar (CONST_VECTOR with the same CONST_INT everywhere)
> attempts to expand it as left shift (if power of 8) or tests various costs
> and attempts to emit it as combination of left shift and add etc.
> I think there are no targets that have vector multiply but not vector add
> for the same mode, and similarly it doesn't make sense to test for scalar
> left shifts, those are pretty much assumed everywhere in the compiler,
> so this patch just ensures we emit normal vector multiply if there is no
> vector left shift (be it with scalar or vector shift count).
>
> Bootstrapped/regtested on i686-linux and Andreas has bootstrapped/regtested
> it on ia64-linux. Ok for trunk?
Ok.
Thanks,
Richard.
> 2014-02-04 Jakub Jelinek <ja...@redhat.com>
>
> PR middle-end/59261
> * expmed.c (expand_mult): For MODE_VECTOR_INT multiplication
> if there is no vashl<mode>3 or ashl<mode>3 insn, skip_synth.
>
> * gcc.dg/pr59261.c: New test.
>
> --- gcc/expmed.c.jj 2014-01-03 11:40:57.000000000 +0100
> +++ gcc/expmed.c 2014-02-03 19:06:30.459304401 +0100
> @@ -3136,6 +3136,14 @@ expand_mult (enum machine_mode mode, rtx
> if (do_trapv)
> goto skip_synth;
>
> + /* If mode is integer vector mode, check if the backend supports
> + vector lshift (by scalar or vector) at all. If not, we can't use
> + synthetized multiply. */
> + if (GET_MODE_CLASS (mode) == MODE_VECTOR_INT
> + && optab_handler (vashl_optab, mode) == CODE_FOR_nothing
> + && optab_handler (ashl_optab, mode) == CODE_FOR_nothing)
> + goto skip_synth;
> +
> /* These are the operations that are potentially turned into
> a sequence of shifts and additions. */
> mode_bitsize = GET_MODE_UNIT_BITSIZE (mode);
> --- gcc/testsuite/gcc.dg/pr59261.c.jj 2014-02-03 19:14:39.457797016 +0100
> +++ gcc/testsuite/gcc.dg/pr59261.c 2014-02-03 19:14:20.000000000 +0100
> @@ -0,0 +1,17 @@
> +/* PR middle-end/59261 */
> +/* { dg-do compile } */
> +/* { dg-options "-O2" } */
> +
> +typedef signed char V __attribute__((vector_size (8)));
> +
> +void
> +foo (V *a, V *b)
> +{
> + *a = *b * 3;
> +}
> +
> +void
> +bar (V *a, V *b)
> +{
> + *a = *b * 4;
> +}
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE / SUSE Labs
SUSE LINUX Products GmbH - Nuernberg - AG Nuernberg - HRB 16746
GF: Jeff Hawn, Jennifer Guild, Felix Imend"orffer
