AArch64: Undo vec_widen_<sur>shiftl optabs [PR106346]

In GCC 11 we implemented the vectorizer optab for widening left shifts,
however this optab is only supported for uniform shift constants.

At the moment GCC still has two loop vectorization strategy (classical loop and
SLP based loop vec) and the optab is implemented as a scalar pattern.

This means that when we apply it to a non-uniform constant inside a loop we only
find out during SLP build that the constants aren't uniform.  At this point it's
too late and we lose SLP entirely.

Over the years I've tried various options but none of it works well:

1. Dissolving patterns during SLP built (problematic, also dissolves them for
non-slp).
2. Optionally ignoring patterns for SLP build (problematic, ends up interfearing
with relevancy detection).
3. Relaxing contraint on SLP build to allow non-constant values and dissolving
them after SLP build using an SLP pattern.  (problematic, ends up breaking
shift reassociation).

As a result we've concluded that for now this pattern should just be removed
and formed during RTL.

The plan is to move this to an SLP only pattern once we remove classical loop
vectorization support from GCC, at which time we can also properly support SVE's
Top and Bottom variants.

This removes the optab and reworks the RTL to recognize both the vector variant
and the intrinsics variant.  Also just simplifies all these patterns.

gcc/ChangeLog:

	PR target/106346
	* config/aarch64/aarch64-simd.md (vec_widen_<sur>shiftl_lo_<mode>,
	vec_widen_<sur>shiftl_hi_<mode>): Remove.
	(aarch64_<sur>shll<mode>_internal): Renamed to...
	(aarch64_<su>shll<mode>): .. This.
	(aarch64_<sur>shll2<mode>_internal): Renamed to...
	(aarch64_<su>shll2<mode>): .. This.
	(aarch64_<sur>shll_n<mode>, aarch64_<sur>shll2_n<mode>): Re-use new
	optabs.
	* config/aarch64/constraints.md (D2, DL): New.
	* config/aarch64/predicates.md (aarch64_simd_shll_imm_vec): New.

gcc/testsuite/ChangeLog:

	PR target/106346
	* gcc.target/aarch64/pr98772.c: Adjust assembly.
	* gcc.target/aarch64/vect-widen-shift.c: New test.

diff --git a/gcc/config/aarch64/aarch64-simd.md b/gcc/config/aarch64/aarch64-simd.md
index d95394101470446e55f25a2397dd112239b6a54d..f67eb70577d0c2d9911d8c867d38a4d0b390337c 100644 (file)
--- a/gcc/config/aarch64/aarch64-simd.md
+++ b/gcc/config/aarch64/aarch64-simd.md
@@ -6387,105 +6387,67 @@
   [(set_attr "type" "neon_sat_shift_reg<q>")]
 )
 
-(define_expand "vec_widen_<sur>shiftl_lo_<mode>"
-  [(set (match_operand:<VWIDE> 0 "register_operand" "=w")
-       (unspec:<VWIDE> [(match_operand:VQW 1 "register_operand" "w")
-                        (match_operand:SI 2
-                          "aarch64_simd_shift_imm_bitsize_<ve_mode>" "i")]
-                        VSHLL))]
-  "TARGET_SIMD"
-  {
-    rtx p = aarch64_simd_vect_par_cnst_half (<MODE>mode, <nunits>, false);
-    emit_insn (gen_aarch64_<sur>shll<mode>_internal (operands[0], operands[1],
-                                                    p, operands[2]));
-    DONE;
-  }
-)
-
-(define_expand "vec_widen_<sur>shiftl_hi_<mode>"
-   [(set (match_operand:<VWIDE> 0 "register_operand")
-       (unspec:<VWIDE> [(match_operand:VQW 1 "register_operand" "w")
-                        (match_operand:SI 2
-                          "immediate_operand" "i")]
-                         VSHLL))]
-   "TARGET_SIMD"
-   {
-    rtx p = aarch64_simd_vect_par_cnst_half (<MODE>mode, <nunits>, true);
-    emit_insn (gen_aarch64_<sur>shll2<mode>_internal (operands[0], operands[1],
-                                                     p, operands[2]));
-    DONE;
-   }
-)
-
 ;; vshll_n
 
-(define_insn "aarch64_<sur>shll<mode>_internal"
-  [(set (match_operand:<VWIDE> 0 "register_operand" "=w")
-       (unspec:<VWIDE> [(vec_select:<VHALF>
-                           (match_operand:VQW 1 "register_operand" "w")
-                           (match_operand:VQW 2 "vect_par_cnst_lo_half" ""))
-                        (match_operand:SI 3
-                          "aarch64_simd_shift_imm_bitsize_<ve_mode>" "i")]
-                        VSHLL))]
+(define_insn "aarch64_<su>shll<mode>"
+  [(set (match_operand:<VWIDE> 0 "register_operand")
+       (ashift:<VWIDE> (ANY_EXTEND:<VWIDE>
+                           (match_operand:VD_BHSI 1 "register_operand"))
+                        (match_operand:<VWIDE> 2
+                          "aarch64_simd_shll_imm_vec")))]
   "TARGET_SIMD"
-  {
-    if (INTVAL (operands[3]) == GET_MODE_UNIT_BITSIZE (<MODE>mode))
-      return "shll\\t%0.<Vwtype>, %1.<Vhalftype>, %3";
-    else
-      return "<sur>shll\\t%0.<Vwtype>, %1.<Vhalftype>, %3";
+  {@ [cons: =0, 1, 2]
+     [w, w, D2] shll\t%0.<Vwtype>, %1.<Vtype>, %I2
+     [w, w, DL] <su>shll\t%0.<Vwtype>, %1.<Vtype>, %I2
   }
   [(set_attr "type" "neon_shift_imm_long")]
 )
 
-(define_insn "aarch64_<sur>shll2<mode>_internal"
-  [(set (match_operand:<VWIDE> 0 "register_operand" "=w")
-       (unspec:<VWIDE> [(vec_select:<VHALF>
-                           (match_operand:VQW 1 "register_operand" "w")
-                           (match_operand:VQW 2 "vect_par_cnst_hi_half" ""))
-                        (match_operand:SI 3
-                          "aarch64_simd_shift_imm_bitsize_<ve_mode>" "i")]
+(define_expand "aarch64_<sur>shll_n<mode>"
+  [(set (match_operand:<VWIDE> 0 "register_operand")
+       (unspec:<VWIDE> [(match_operand:VD_BHSI 1 "register_operand")
+                        (match_operand:SI 2
+                          "aarch64_simd_shift_imm_bitsize_<ve_mode>")]
                         VSHLL))]
   "TARGET_SIMD"
   {
-    if (INTVAL (operands[3]) == GET_MODE_UNIT_BITSIZE (<MODE>mode))
-      return "shll2\\t%0.<Vwtype>, %1.<Vtype>, %3";
-    else
-      return "<sur>shll2\\t%0.<Vwtype>, %1.<Vtype>, %3";
+    rtx shft = gen_const_vec_duplicate (<VWIDE>mode, operands[2]);
+    emit_insn (gen_aarch64_<sur>shll<mode> (operands[0], operands[1], shft));
+    DONE;
   }
-  [(set_attr "type" "neon_shift_imm_long")]
 )
 
-(define_insn "aarch64_<sur>shll_n<mode>"
-  [(set (match_operand:<VWIDE> 0 "register_operand" "=w")
-       (unspec:<VWIDE> [(match_operand:VD_BHSI 1 "register_operand" "w")
-                        (match_operand:SI 2
-                          "aarch64_simd_shift_imm_bitsize_<ve_mode>" "i")]
-                         VSHLL))]
+;; vshll_high_n
+
+(define_insn "aarch64_<su>shll2<mode>"
+  [(set (match_operand:<VWIDE> 0 "register_operand")
+       (ashift:<VWIDE> (ANY_EXTEND:<VWIDE>
+                         (vec_select:<VHALF>
+                           (match_operand:VQW 1 "register_operand")
+                           (match_operand:VQW 2 "vect_par_cnst_hi_half")))
+                        (match_operand:<VWIDE> 3
+                          "aarch64_simd_shll_imm_vec")))]
   "TARGET_SIMD"
-  {
-    if (INTVAL (operands[2]) == GET_MODE_UNIT_BITSIZE (<MODE>mode))
-      return "shll\\t%0.<Vwtype>, %1.<Vtype>, %2";
-    else
-      return "<sur>shll\\t%0.<Vwtype>, %1.<Vtype>, %2";
+  {@ [cons: =0, 1, 2, 3]
+     [w, w, , D2] shll2\t%0.<Vwtype>, %1.<Vtype>, %I3
+     [w, w, , DL] <su>shll2\t%0.<Vwtype>, %1.<Vtype>, %I3
   }
   [(set_attr "type" "neon_shift_imm_long")]
 )
 
-;; vshll_high_n
-
-(define_insn "aarch64_<sur>shll2_n<mode>"
-  [(set (match_operand:<VWIDE> 0 "register_operand" "=w")
-       (unspec:<VWIDE> [(match_operand:VQW 1 "register_operand" "w")
-                        (match_operand:SI 2 "immediate_operand" "i")]
-                         VSHLL))]
+(define_expand "aarch64_<sur>shll2_n<mode>"
+  [(set (match_operand:<VWIDE> 0 "register_operand")
+       (unspec:<VWIDE> [(match_operand:VQW 1 "register_operand")
+                        (match_operand:SI 2
+                          "aarch64_simd_shift_imm_bitsize_<ve_mode>")]
+                        VSHLL))]
   "TARGET_SIMD"
   {
-    if (INTVAL (operands[2]) == GET_MODE_UNIT_BITSIZE (<MODE>mode))
-      return "shll2\\t%0.<Vwtype>, %1.<Vtype>, %2";
-    else
-      return "<sur>shll2\\t%0.<Vwtype>, %1.<Vtype>, %2";
+    rtx shft = gen_const_vec_duplicate (<VWIDE>mode, operands[2]);
+    rtx p = aarch64_simd_vect_par_cnst_half (<MODE>mode, <nunits>, true);
+    emit_insn (gen_aarch64_<sur>shll2<mode> (operands[0], operands[1], p, shft));
+    DONE;
   }
-  [(set_attr "type" "neon_shift_imm_long")]
 )
 
 ;; vrshr_n

diff --git a/gcc/config/aarch64/constraints.md b/gcc/config/aarch64/constraints.md
index 6df1dbec2a8097abe9783ed1670c77a8fad4ca57..371a00827d84d8ea4a06ba2b00a761d3b179ae90 100644 (file)
--- a/gcc/config/aarch64/constraints.md
+++ b/gcc/config/aarch64/constraints.md
@@ -468,6 +468,20 @@
                        GET_MODE_UNIT_BITSIZE (mode) - 1,
                        GET_MODE_UNIT_BITSIZE (mode) - 1)")))
 
+(define_constraint "D2"
+  "@internal
+ A constraint that matches vector of immediates that is bits(mode)/2."
+ (and (match_code "const,const_vector")
+      (match_test "aarch64_simd_shift_imm_vec_exact_top (op, mode)")))
+
+(define_constraint "DL"
+  "@internal
+ A constraint that matches vector of immediates for left shift long.
+ That is immediates between 0 to (bits(mode)/2)-1."
+ (and (match_code "const,const_vector")
+      (match_test "aarch64_const_vec_all_same_in_range_p (op, 0,
+                       (GET_MODE_UNIT_BITSIZE (mode) / 2) - 1)")))
+
 (define_constraint "Dr"
   "@internal
  A constraint that matches vector of immediates for right shifts."

diff --git a/gcc/config/aarch64/predicates.md b/gcc/config/aarch64/predicates.md
index d5a4a1cd9bf8cde8e779de6e0afa531f04892a7b..2d8d1fe25c1de35cb5a2386058cb2901ee46cd82 100644 (file)
--- a/gcc/config/aarch64/predicates.md
+++ b/gcc/config/aarch64/predicates.md
@@ -638,6 +638,11 @@
                                HOST_WIDE_INT_1U
                                << (GET_MODE_UNIT_BITSIZE  (mode) / 2 - 1))")))
 
+(define_predicate "aarch64_simd_shll_imm_vec"
+  (and (match_code "const_vector")
+       (match_test "aarch64_const_vec_all_same_in_range_p (op, 0,
+                               GET_MODE_UNIT_BITSIZE (mode) / 2)")))
+
 (define_predicate "aarch64_simd_shift_imm_bitsize_qi"
   (and (match_code "const_int")
        (match_test "IN_RANGE (INTVAL (op), 0, 8)")))

diff --git a/gcc/testsuite/gcc.target/aarch64/pr98772.c b/gcc/testsuite/gcc.target/aarch64/pr98772.c
index 8259251a7c0b64ae8362ea29ec3cf1d2a9d63547..52ad012dcfe72721b8c987bb826c0ffb8ba3f31e 100644 (file)
--- a/gcc/testsuite/gcc.target/aarch64/pr98772.c
+++ b/gcc/testsuite/gcc.target/aarch64/pr98772.c
@@ -155,4 +155,4 @@ int main ()
 /* { dg-final { scan-assembler-times "uaddl\\tv" 2 } } */
 /* { dg-final { scan-assembler-times "usubl\\tv" 2 } } */
 /* { dg-final { scan-assembler-times "umull\\tv" 2 } } */
-/* { dg-final { scan-assembler-times "shl\\tv" 2 } } */
+/* { dg-final { scan-assembler-times "shll\\tv" 2 } } */

diff --git a/gcc/testsuite/gcc.target/aarch64/vect-widen-shift.c b/gcc/testsuite/gcc.target/aarch64/vect-widen-shift.c
new file mode 100644 (file)
index 0000000..6ee41f6
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/vect-widen-shift.c
@@ -0,0 +1,50 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -save-temps" } */
+/* { dg-final { check-function-bodies "**" "" "" } } */
+#include <stdint.h>
+#include <string.h>
+
+#pragma GCC target "+nosve"
+
+#define ARR_SIZE 1024
+
+/* Should produce an shll,shll2 pair*/
+/*
+** sshll_opt1:
+**     ...
+**     shll    v[0-9]+.4s, v[0-9]+.4h, 16
+**     shll2   v[0-9]+.4s, v[0-9]+.8h, 16
+**     ...
+*/
+void sshll_opt1 (int32_t *foo, int16_t *a, int16_t *b)
+{
+    for( int i = 0; i < ARR_SIZE - 3;i=i+4)
+    {
+        foo[i]   = a[i]   << 16;
+        foo[i+1] = a[i+1] << 16;
+        foo[i+2] = a[i+2] << 16;
+        foo[i+3] = a[i+3] << 16;
+    }
+}
+
+/*
+** sshll_opt2:
+**     ...
+**     sxtl    v[0-9]+.4s, v[0-9]+.4h
+**     sxtl2   v[0-9]+.4s, v[0-9]+.8h
+**     sshl    v[0-9]+.4s, v[0-9]+.4s, v[0-9]+.4s
+**     sshl    v[0-9]+.4s, v[0-9]+.4s, v[0-9]+.4s
+**     ...
+*/
+void sshll_opt2 (int32_t *foo, int16_t *a, int16_t *b)
+{
+    for( int i = 0; i < ARR_SIZE - 3;i=i+4)
+    {
+        foo[i]   = a[i]   << 16;
+        foo[i+1] = a[i+1] << 15;
+        foo[i+2] = a[i+2] << 14;
+        foo[i+3] = a[i+3] << 17;
+    }
+}
+
+