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Re: [PATCH, rs6000] Gimple folding of splat_uX
- From: Richard Biener <richard dot guenther at gmail dot com>
- To: will_schmidt at vnet dot ibm dot com
- Cc: GCC Patches <gcc-patches at gcc dot gnu dot org>, Segher Boessenkool <segher at kernel dot crashing dot org>, Bill Schmidt <wschmidt at linux dot vnet dot ibm dot com>, David Edelsohn <dje dot gcc at gmail dot com>
- Date: Thu, 7 Dec 2017 12:21:03 +0100
- Subject: Re: [PATCH, rs6000] Gimple folding of splat_uX
- Authentication-results: sourceware.org; auth=none
- References: <1512578218.11602.59.camel@brimstone.rchland.ibm.com>
On Wed, Dec 6, 2017 at 5:36 PM, Will Schmidt <will_schmidt@vnet.ibm.com> wrote:
> Hi,
> Add support for gimple folding of splat_u{8,16,32}.
> Testcase coverage is primarily handled by existing tests
> testsuite/gcc.target/powerpc/fold-vec-splat_*.c
>
> One new test added to verify we continue to receive
> an 'invalid argument, must be a 5-bit immediate' error
> when we try to splat a non-constant value.
>
> Regtests currently running across assorted power systems.
> OK for trunk with successful results?
>
> Thanks
> -Will
>
> [gcc]
>
> 2017-12-05 Will Schmidt <will_schmidt@vnet.ibm.com>
>
> * config/rs6000/rs6000.c (rs6000_gimple_fold_builtin): Add support for
> early folding of splat_u{8,16,32}.
>
> [testsuite]
>
> 2017-12-05 Will Schmidt <will_schmidt@vnet.ibm.com>
>
> * gcc.target/powerpc/fold-vec-splat-misc-invalid.c: New.
>
> diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
> index 045a014..1470557 100644
> --- a/gcc/config/rs6000/rs6000.c
> +++ b/gcc/config/rs6000/rs6000.c
> @@ -16614,10 +16614,33 @@ rs6000_gimple_fold_builtin (gimple_stmt_iterator *gsi)
> case VSX_BUILTIN_CMPLE_2DI:
> case VSX_BUILTIN_CMPLE_U2DI:
> fold_compare_helper (gsi, LE_EXPR, stmt);
> return true;
>
> + /* flavors of vec_splat_[us]{8,16,32}. */
> + case ALTIVEC_BUILTIN_VSPLTISB:
> + case ALTIVEC_BUILTIN_VSPLTISH:
> + case ALTIVEC_BUILTIN_VSPLTISW:
> + {
> + arg0 = gimple_call_arg (stmt, 0);
> + lhs = gimple_call_lhs (stmt);
> + /* Only fold the vec_splat_*() if arg0 is constant. */
> + if ( TREE_CODE (arg0) != INTEGER_CST)
> + return false;
Is there a reason to not do this for non-constants? (even not for
float constants?)
You should probably double-check there is a LHS, folding runs before DCE.
> + tree splat_value = build_int_cst (TREE_TYPE (TREE_TYPE (lhs)),
> + TREE_INT_CST_LOW (arg0));
> + vec<constructor_elt, va_gc> *ctor_elts = NULL;
> + unsigned int n_elts = TYPE_VECTOR_SUBPARTS (TREE_TYPE (lhs));
> + for (unsigned int i=0; i < n_elts ; i++)
> + CONSTRUCTOR_APPEND_ELT (ctor_elts, NULL_TREE, splat_value);
> + tree splat_tree = build_constructor (TREE_TYPE (lhs), ctor_elts);
Just use
tree slat_tree = build_vector_from_val (splat_value);
that would also work for non-constants btw.
> + g = gimple_build_assign (lhs, splat_tree);
> + gimple_set_location (g, gimple_location (stmt));
> + gsi_replace (gsi, g, true);
> + return true;
> + }
> +
> default:
> if (TARGET_DEBUG_BUILTIN)
> fprintf (stderr, "gimple builtin intrinsic not matched:%d %s %s\n",
> fn_code, fn_name1, fn_name2);
> break;
> diff --git a/gcc/testsuite/gcc.target/powerpc/fold-vec-splat-misc-invalid.c b/gcc/testsuite/gcc.target/powerpc/fold-vec-splat-misc-invalid.c
> new file mode 100644
> index 0000000..20f5b05
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/fold-vec-splat-misc-invalid.c
> @@ -0,0 +1,33 @@
> +/* Verify that overloaded built-ins for vec_splat_s8 and vec_splat_s16
> + generate errors as expected when we attempt to use invalid inputs. */
> +
> +/* { dg-do compile } */
> +/* { dg-require-effective-target powerpc_vsx_ok } */
> +/* { dg-options "-mvsx -O2" } */
> +
> +#include <altivec.h>
> +
> +vector signed short
> +testss_1 (unsigned int ui)
> +{
> + return vec_splat_s16 (ui);/* { dg-error "argument 1 must be a 5-bit signed literal" } */
> +}
> +
> +vector unsigned short
> +testss_2 (signed int si)
> +{
> + return vec_splat_u16 (si);/* { dg-error "argument 1 must be a 5-bit signed literal" } */
> +}
> +
> +vector signed char
> +testsc_1 (unsigned int ui)
> +{
> + return vec_splat_s8 (ui); /* { dg-error "argument 1 must be a 5-bit signed literal" } */
> +}
> +
> +vector unsigned char
> +testsc_2 (signed int si)
> +{
> + return vec_splat_u8 (si);/* { dg-error "argument 1 must be a 5-bit signed literal" } */
> +}
> +
>
>