[rs6000] (v2) Gimple folding of splat_uX

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.
    
V2 updates include..
  Use the gimple_convert() helper.
  Use the build_vector_from_val() helper.
  whitespace fix-ups.
Those changes actually simplify the code here significantly, which is good. :-)
    
Per comments from last iteration, regarding the early exit for
arg0 != INTEGER_CST, if I remove the early exit when arg0 is not constant,
the code appears to handle things OK, and the generated code looks
reasonable, but this is a behavior change with respect to when folding is
disabled, which is to error out with an ("argument 1 must be a 5-bit signed
literal") error.  For that reason, I'm planning to leave that check in place.
I'll defer to Bill/Segher/David, etc on whether it would be appropriate to
change that behavior.
    
This intrinsic only takes INTegral types, so no need to check for FLOAT_CST.
(The other vec_splat* intrinsics will deal more with floats, those are later
in my queue).
    
Regtests across assorted power systems look clean.
OK for trunk?
    
Thanks,
-Will
    
[gcc]

2017-12-08  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]

2017-12-08  Will Schmidt  <will_schmidt@vnet.ibm.com>

	* gcc.target/powerpc/fold-vec-splat-misc-invalid.c: New.

On Dec 8, 2017, at 11:08 AM, 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.
> 
> V2 updates include..
>  Use the gimple_convert() helper.
>  Use the build_vector_from_val() helper.
>  whitespace fix-ups.
> Those changes actually simplify the code here significantly, which is good. :-)
> 
> Per comments from last iteration, regarding the early exit for
> arg0 != INTEGER_CST, if I remove the early exit when arg0 is not constant,
> the code appears to handle things OK, and the generated code looks
> reasonable, but this is a behavior change with respect to when folding is
> disabled, which is to error out with an ("argument 1 must be a 5-bit signed
> literal") error.  For that reason, I'm planning to leave that check in place.
> I'll defer to Bill/Segher/David, etc on whether it would be appropriate to
> change that behavior.

RIght -- the long-documented behavior of these built-ins requires a constant
value.  Until such time as we change that documentation, if we feel it's a
good idea to do so, I would like to error out for non-constant values.

Thanks,
Bill

> 
> This intrinsic only takes INTegral types, so no need to check for FLOAT_CST.
> (The other vec_splat* intrinsics will deal more with floats, those are later
> in my queue).
> 
> Regtests across assorted power systems look clean.
> OK for trunk?
> 
> Thanks,
> -Will
> 
> [gcc]
> 
> 2017-12-08  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]
> 
> 2017-12-08  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..8972d80 100644
> --- a/gcc/config/rs6000/rs6000.c
> +++ b/gcc/config/rs6000/rs6000.c
> @@ -16614,10 +16614,32 @@ 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;
> +	 gimple_seq stmts = NULL;
> +	 location_t loc = gimple_location (stmt);
> +	 tree splat_value = gimple_convert (&stmts, loc,
> +					    TREE_TYPE (TREE_TYPE (lhs)), arg0);
> +	 gsi_insert_seq_before (gsi, stmts, GSI_SAME_STMT);
> +	 tree splat_tree = build_vector_from_val (TREE_TYPE (lhs), splat_value);
> +	 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" } */
> +}
> +
> 
>

Hi!

On Fri, Dec 08, 2017 at 11:08:26AM -0600, Will Schmidt wrote:
> 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.
>     
> V2 updates include..
>   Use the gimple_convert() helper.
>   Use the build_vector_from_val() helper.
>   whitespace fix-ups.
> Those changes actually simplify the code here significantly, which is good. :-)

:-)

> 2017-12-08  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]
> 
> 2017-12-08  Will Schmidt  <will_schmidt@vnet.ibm.com>
> 
> 	* gcc.target/powerpc/fold-vec-splat-misc-invalid.c: New.


> +    /* 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);

The indent here is wrong (should be two spaces, is three).

Looks fine otherwise.  Okay for trunk with that fixed.  Thanks!


Segher