Add combine splitter to transform vashr/vlshr/vashl_optab to...

Add combine splitter to transform vashr/vlshr/vashl_optab to ashr/lshr/ashl_optab for const vector duplicate operand.

gcc/ChangeLog:

	PR target/101796
	* config/i386/predicates.md (const_vector_operand):
	Add new predicate.
	* config/i386/sse.md(<insn><mode>3<mask_name>):
	Add new define_split below.

gcc/testsuite/ChangeLog:

	PR target/101796
	* gcc.target/i386/pr101796-1.c: New test.

gcc/config/i386/predicates.md

@@ -1844,6 +1844,19 @@
   return true;
 })
 
+;; Return true if OP is a const vector with duplicate value.
+(define_predicate "const_vector_duplicate_operand"
+  (match_code "const_vector")
+{
+  rtx elt = XVECEXP (op, 0, 0);
+  int i, nelt = XVECLEN (op, 0);
+
+  for (i = 1; i < nelt; ++i)
+    if (!rtx_equal_p (elt, XVECEXP (op, 0, i)))
+      return false;
+  return true;
+})
+
 ;; Return true if OP is a parallel for a vbroadcast permute.
 (define_predicate "avx_vbroadcast_operand"
   (and (match_code "parallel")

gcc/config/i386/sse.md

@@ -15287,6 +15287,20 @@
        (const_string "0")))
    (set_attr "mode" "<sseinsnmode>")])
+;; PR target/101796: Transfrom movl+vpbranchcastw+vpsravw to vpsraw
+;; when COUNT is immediate.
+(define_split
+  [(set (match_operand:VI248_AVX512BW 0 "register_operand")
+	(any_shift:VI248_AVX512BW
+	  (match_operand:VI248_AVX512BW 1 "nonimmediate_operand")
+	  (match_operand:VI248_AVX512BW 2 "const_vector_duplicate_operand")))]
+  "TARGET_AVX512F && GET_MODE_UNIT_BITSIZE (<MODE>mode)
+   > INTVAL (XVECEXP (operands[2], 0, 0))"
+  [(set (match_dup 0)
+	(any_shift:VI248_AVX512BW
+	  (match_dup 1)
+	  (match_dup 3)))]
+  "operands[3] = XVECEXP (operands[2], 0, 0);")
 (define_expand "vec_shl_<mode>"
   [(set (match_dup 3)

gcc/testsuite/gcc.target/i386/pr101796-1.c

+/* { dg-do compile } */
+/* { dg-options "-O2 -mavx512bw" } */
+/* { dg-final {scan-assembler-times "vpsrlw\[ \\t\]" 1 } } */
+/* { dg-final {scan-assembler-times "vpsllw\[ \\t\]" 1 } } */
+/* { dg-final {scan-assembler-times "vpsraw\[ \\t\]" 1 } } */
+/* { dg-final {scan-assembler-not "vpbroadcastw\[ \\t\]" } } */
+/* { dg-final {scan-assembler-not "vpsrlvw\[ \\t\]" } } */
+/* { dg-final {scan-assembler-not "vpsllvw\[ \\t\]" } } */
+/* { dg-final {scan-assembler-not "vpsravw\[ \\t\]" } } */
+#include <immintrin.h>
+
+volatile __m512i a, b;
+
+void
+foo()
+{
+  b = _mm512_srlv_epi16 (a, _mm512_set1_epi16 (3));
+  b = _mm512_sllv_epi16 (a, _mm512_set1_epi16 (4));
+  b = _mm512_srav_epi16 (a, _mm512_set1_epi16 (5));
+}