Re: [PATCH 13/13] rs6000, remove vector set and vector init built-ins.

["Kewen.Lin" <linkw@linux.ibm.com>]

Hi,

on 2024/4/20 05:18, Carl Love wrote:
> rs6000, remove vector set and vector init built-ins.
> 
> The vector init built-ins:
> 
>   __builtin_vec_init_v16qi, __builtin_vec_init_v8hi,
>   __builtin_vec_init_v4si, __builtin_vec_init_v4sf,
>   __builtin_vec_init_v2di, __builtin_vec_init_v2df,
>   __builtin_vec_set_v1ti
> 
> perform the same operation as initializing the vector in C code.  For
> example:
> 
>   result_v4si = __builtin_vec_init_v4si (1, 2, 3, 4);
>   result_v4si = {1, 2, 3, 4};
> 
> These two constructs were tested and verified they generate identical
> assembly instructions with no optimization and -O3 optimization.
> 
> The vector set built-ins:
> 
>   __builtin_vec_set_v16qi, __builtin_vec_set_v8hi.
>   __builtin_vec_set_v4si, __builtin_vec_set_v4sf
> 
> perform the same operation as setting a specific element in the vector in
> C code.  For example:
> 
>   src_v4si = __builtin_vec_set_v4si (src_v4si, int_val, index);
>   src_v4si[index] = int_val;
> 
> The built-in actually generates more instructions than the inline C code
> with no optimization but is identical with -O3 optimizations.
> 
> All of the above built-ins that are removed do not have test cases and
> are not documented.
> 
> Built-ins   __builtin_vec_set_v1ti __builtin_vec_set_v2di,
> __builtin_vec_set_v2df are not removed as they are used in function
> resolve_vec_insert() in file rs6000-c.cc.

I think we can replace these calls with the equivalent gimple codes
(early expanding it) and then we can get rid of these instances.

BR,
Kewen

> 
> The built-ins are removed as they don't provide any benefit over just
> using C code.
> 
> gcc/ChangeLog:
> 	* config/rs6000/rs6000-builtins.def (__builtin_vec_init_v16qi,
> 	 __builtin_vec_init_v8hi, __builtin_vec_init_v4si,
> 	__builtin_vec_init_v4sf, __builtin_vec_init_v2di,
> 	__builtin_vec_init_v2df, __builtin_vec_set_v1ti,
> 	__builtin_vec_set_v16qi, __builtin_vec_set_v8hi.
> 	__builtin_vec_set_v4si, __builtin_vec_set_v4sf,
> 	__builtin_vec_set_v2di, __builtin_vec_set_v2df,
> 	__builtin_vec_set_v1ti): Remove built-in definitions.
> ---
>  gcc/config/rs6000/rs6000-builtins.def | 42 ++-------------------------
>  1 file changed, 2 insertions(+), 40 deletions(-)
> 
> diff --git a/gcc/config/rs6000/rs6000-builtins.def b/gcc/config/rs6000/rs6000-builtins.def
> index 19d05b8043a..d04ad4ce7e5 100644
> --- a/gcc/config/rs6000/rs6000-builtins.def
> +++ b/gcc/config/rs6000/rs6000-builtins.def
> @@ -1115,37 +1115,6 @@
>    const signed short __builtin_vec_ext_v8hi (vss, signed int);
>      VEC_EXT_V8HI nothing {extract}
>  
> -  const vsc __builtin_vec_init_v16qi (signed char, signed char, signed char, \
> -            signed char, signed char, signed char, signed char, signed char, \
> -            signed char, signed char, signed char, signed char, signed char, \
> -            signed char, signed char, signed char);
> -    VEC_INIT_V16QI nothing {init}
> -
> -  const vf __builtin_vec_init_v4sf (float, float, float, float);
> -    VEC_INIT_V4SF nothing {init}
> -
> -  const vsi __builtin_vec_init_v4si (signed int, signed int, signed int, \
> -                                     signed int);
> -    VEC_INIT_V4SI nothing {init}
> -
> -  const vss __builtin_vec_init_v8hi (signed short, signed short, signed short,\
> -             signed short, signed short, signed short, signed short, \
> -             signed short);
> -    VEC_INIT_V8HI nothing {init}
> -
> -  const vsc __builtin_vec_set_v16qi (vsc, signed char, const int<4>);
> -    VEC_SET_V16QI nothing {set}
> -
> -  const vf __builtin_vec_set_v4sf (vf, float, const int<2>);
> -    VEC_SET_V4SF nothing {set}
> -
> -  const vsi __builtin_vec_set_v4si (vsi, signed int, const int<2>);
> -    VEC_SET_V4SI nothing {set}
> -
> -  const vss __builtin_vec_set_v8hi (vss, signed short, const int<3>);
> -    VEC_SET_V8HI nothing {set}
> -
> -
>  ; Cell builtins.
>  [cell]
>    pure vsc __builtin_altivec_lvlx (signed long, const void *);
> @@ -1292,15 +1261,8 @@
>    const signed long long __builtin_vec_ext_v2di (vsll, signed int);
>      VEC_EXT_V2DI nothing {extract}
>  
> -  const vsq __builtin_vec_init_v1ti (signed __int128);
> -    VEC_INIT_V1TI nothing {init}
> -
> -  const vd __builtin_vec_init_v2df (double, double);
> -    VEC_INIT_V2DF nothing {init}
> -
> -  const vsll __builtin_vec_init_v2di (signed long long, signed long long);
> -    VEC_INIT_V2DI nothing {init}
> -
> +;; VEC_SET_V1TI, VEC_SET_V2DF and VEC_SET_V2DI are used in
> +;; resolve_vec_insert(), rs6000-c.cc
>    const vsq __builtin_vec_set_v1ti (vsq, signed __int128, const int<0,0>);
>      VEC_SET_V1TI nothing {set}
>