Re: [PATCH] Fix MMX/SSE/AVX* shifts by non-immediate scalar (PR target/80286)

[Jakub Jelinek <jakub@redhat.com>]

On Thu, Apr 06, 2017 at 09:33:58AM +0200, Uros Bizjak wrote:
> Newly introduced alternatives (x/x) and (v/v) are valid also for
> 32-bit targets, so we have to adjust insn constraint of
> *vec_extractv4si_0_zext and enable alternatives accordingly. After the

That is true.  But if we provide just the x/x and v/v alternatives in
*vec_extractv4si_0_zext, then it will be forced to always do the zero
extraction on the SSE registers in 32-bit mode.  Is that what we want?

As for the define_insn_and_split that would transform sign extensions
used solely by the vector shifts by scalar shift count, did you mean
something like following (for every shift pattern)?

--- sse.md.jj1	2017-04-04 19:51:01.000000000 +0200
+++ sse.md	2017-04-06 10:26:26.877545109 +0200
@@ -10696,6 +10696,22 @@
    (set_attr "prefix" "orig,vex")
    (set_attr "mode" "<sseinsnmode>")])
 
+(define_insn_and_split "*<shift_insn><mode>3<mask_name>_1"
+  [(set (match_operand:VI2_AVX2_AVX512BW 0 "register_operand")
+	(any_lshift:VI2_AVX2_AVX512BW
+	  (match_operand:VI2_AVX2_AVX512BW 1 "register_operand")
+	  (sign_extend:DI (match_operand:SI 2 "nonmemory_operand"))))]
+  "TARGET_SSE2 && <mask_mode512bit_condition> && <mask_avx512bw_condition>
+   && can_create_pseudo_p ()"
+  "#"
+  "&& 1"
+  [(set (match_dup 3) (zero_extend:DI (match_dup 2)))
+   (set (match_dup 0) (any_lshift:VI2_AVX2_AVX512BW
+			(match_dup 1) (match_dup 3)))]
+{
+  operands[3] = gen_reg_rtx (DImode);
+})
+
 (define_insn "<shift_insn><mode>3<mask_name>"
   [(set (match_operand:VI48_AVX2 0 "register_operand" "=x,x,v")
 	(any_lshift:VI48_AVX2

The problem with that is that apparently our infrastructure doesn't support
define_subst for define_insn_and_split (and define_split), so either we'd
need to have separate define_insn_and_split for masked and for non-masked,
or we'd need to extend the define_subst infrastructure for
define_insn_and_split somehow.  Looking say at
(define_subst "mask"
  [(set (match_operand:SUBST_V 0)
        (match_operand:SUBST_V 1))]
  "TARGET_AVX512F"
  [(set (match_dup 0)
        (vec_merge:SUBST_V
          (match_dup 1)
          (match_operand:SUBST_V 2 "vector_move_operand" "0C")
          (match_operand:<avx512fmaskmode> 3 "register_operand" "Yk")))])
that is a transformation we want to do on the define_insn part of
define_insn_and_split, but not exactly what we want to do on the split
part of the insn - there we want literaly match_dup 0, match_dup 1,
and instead of the 2 other match_operand match_dup 2 and match_dup 3.

	Jakub