[PATCH] move x86 to use gather/scatter internal functions

[Richard Biener]

This is an attempt to start moving the x86 backend to use
standard pattern names for [mask_]gather_load and [mask_]scatter_store
rather than using the builtin_{gather,scatter} target hooks.

I've started with AVX2 gathers and given x86 only supports masked
gather I only implemented mask_gather_load.  Note while for
the builtin_gather case the vectorizer will provide an all-true
mask operand for non-masked gathers this capability does not
exist for the IFN path yet, so only testcases with actual masked
gathers will work.

If this looks reasonable on the backend side I'll see to first
complete the vectorizer part, ripping out the target hook and
arranging for the missing pieces.  Another one is the support
for SImode indices with DFmode data which requires unpacking
the index vector and actually recognizing the IFN.

2021-08-17  Richard Biener  <rguenther@suse.de>

	* tree-vect-data-refs.c (vect_check_gather_scatter):
	Always use internal functions.
	* config/i386/sse.md
	(mask_gather_load<mode><vec_gather_idxsi>): New expander.
	(mask_gather_load<mode><vec_gather_idxdi>): Likewise.
---
 gcc/config/i386/sse.md    | 56 +++++++++++++++++++++++++++++++++++++++
 gcc/tree-vect-data-refs.c |  4 +--
 2 files changed, 57 insertions(+), 3 deletions(-)

diff --git a/gcc/config/i386/sse.md b/gcc/config/i386/sse.md
index 3957c86c3df..40bec98d9f7 100644
--- a/gcc/config/i386/sse.md
+++ b/gcc/config/i386/sse.md
@@ -23232,12 +23232,22 @@
 		       (V2DF "V4SI") (V4DF "V4SI") (V8DF "V8SI")
 		       (V4SI "V4SI") (V8SI "V8SI") (V16SI "V16SI")
 		       (V4SF "V4SI") (V8SF "V8SI") (V16SF "V16SI")])
+(define_mode_attr vec_gather_idxsi
+		      [(V2DI "v4si") (V4DI "v4si") (V8DI "v8si")
+		       (V2DF "v4si") (V4DF "v4si") (V8DF "v8si")
+		       (V4SI "v4si") (V8SI "v8si") (V16SI "v16si")
+		       (V4SF "v4si") (V8SF "v8si") (V16SF "v16si")])
 
 (define_mode_attr VEC_GATHER_IDXDI
 		      [(V2DI "V2DI") (V4DI "V4DI") (V8DI "V8DI")
 		       (V2DF "V2DI") (V4DF "V4DI") (V8DF "V8DI")
 		       (V4SI "V2DI") (V8SI "V4DI") (V16SI "V8DI")
 		       (V4SF "V2DI") (V8SF "V4DI") (V16SF "V8DI")])
+(define_mode_attr vec_gather_idxdi
+		      [(V2DI "v2di") (V4DI "v4di") (V8DI "v8di")
+		       (V2DF "v2di") (V4DF "v4di") (V8DF "v8di")
+		       (V4SI "v2di") (V8SI "v4di") (V16SI "v8di")
+		       (V4SF "v2di") (V8SF "v4di") (V16SF "v8di")])
 
 (define_mode_attr VEC_GATHER_SRCDI
 		      [(V2DI "V2DI") (V4DI "V4DI") (V8DI "V8DI")
@@ -23245,6 +23255,29 @@
 		       (V4SI "V4SI") (V8SI "V4SI") (V16SI "V8SI")
 		       (V4SF "V4SF") (V8SF "V4SF") (V16SF "V8SF")])
 
+(define_expand "mask_gather_load<mode><vec_gather_idxsi>"
+  [(parallel [(set (match_operand:VEC_GATHER_MODE 0 "register_operand")
+		   (unspec:VEC_GATHER_MODE
+		     [(pc)
+		      (mem:<ssescalarmode>
+			(match_par_dup 6
+			  [(match_operand 1 "vsib_address_operand")
+			   (match_operand:<VEC_GATHER_IDXSI>
+			      2 "register_operand")
+			   (match_operand:SI 4 "const1248_operand")
+			   (match_operand:SI 3 "const0_operand")]))
+		      (mem:BLK (scratch))
+		      (match_operand:<sseintvecmode> 5 "register_operand")]
+		     UNSPEC_GATHER))
+	      (clobber (match_scratch:VEC_GATHER_MODE 7))])]
+  "TARGET_AVX2 && TARGET_USE_GATHER"
+{
+  operands[5] = gen_lowpart_SUBREG (<MODE>mode, operands[5]);
+  operands[6]
+    = gen_rtx_UNSPEC (Pmode, gen_rtvec (3, operands[2], operands[3],
+					operands[5]), UNSPEC_VSIBADDR);
+})
+
 (define_expand "avx2_gathersi<mode>"
   [(parallel [(set (match_operand:VEC_GATHER_MODE 0 "register_operand")
 		   (unspec:VEC_GATHER_MODE
@@ -23306,6 +23339,29 @@
    (set_attr "prefix" "vex")
    (set_attr "mode" "<sseinsnmode>")])
 
+(define_expand "mask_gather_load<mode><vec_gather_idxdi>"
+  [(parallel [(set (match_operand:VEC_GATHER_MODE 0 "register_operand")
+		   (unspec:VEC_GATHER_MODE
+		     [(pc)
+		      (mem:<ssescalarmode>
+			(match_par_dup 6
+			  [(match_operand 1 "vsib_address_operand")
+			   (match_operand:<VEC_GATHER_IDXDI>
+			      2 "register_operand")
+			   (match_operand:SI 4 "const1248_operand ")
+			   (match_operand:SI 3 "const0_operand")]))
+		      (mem:BLK (scratch))
+		      (match_operand:<sseintvecmode> 5 "register_operand")]
+		     UNSPEC_GATHER))
+	      (clobber (match_scratch:VEC_GATHER_MODE 7))])]
+  "TARGET_AVX2 && TARGET_USE_GATHER"
+{
+  operands[5] = gen_lowpart_SUBREG (<VEC_GATHER_SRCDI>mode, operands[5]);
+  operands[6]
+    = gen_rtx_UNSPEC (Pmode, gen_rtvec (3, operands[1], operands[2],
+					operands[4]), UNSPEC_VSIBADDR);
+})
+
 (define_expand "avx2_gatherdi<mode>"
   [(parallel [(set (match_operand:VEC_GATHER_MODE 0 "register_operand")
 		   (unspec:VEC_GATHER_MODE
diff --git a/gcc/tree-vect-data-refs.c b/gcc/tree-vect-data-refs.c
index d594c0a1b1e..67564b45c32 100644
--- a/gcc/tree-vect-data-refs.c
+++ b/gcc/tree-vect-data-refs.c
@@ -3824,9 +3824,7 @@ vect_check_gather_scatter (stmt_vec_info stmt_info, loop_vec_info loop_vinfo,
 
   /* True if we should aim to use internal functions rather than
      built-in functions.  */
-  bool use_ifn_p = (DR_IS_READ (dr)
-		    ? supports_vec_gather_load_p ()
-		    : supports_vec_scatter_store_p ());
+  bool use_ifn_p = true;
 
   base = DR_REF (dr);
   /* For masked loads/stores, DR_REF (dr) is an artificial MEM_REF,
-- 
2.31.1