Support udot_prodv*qi with emulation sdot_prodv*hi

Like r14-5990-gb4a7c1c8c59d19, but the patch optimized for udot_prod.

Since (zero_extend) (unsigned char)-> int is equal
to (zero_extend)(unsigned char) -> short
+ (sign_extend) (short) -> int

It should be safe to emulate udot_prodv*qi with

     vec_unpacku_lo_v32qi
     vec_unpacku_lo_v32qi
     vec_unpacku_hi_v32qi
     vec_unpacku_hi_v32qi
     sdot_prodv16hi
     sdot_prodv16hi
     add3v8si

gcc/ChangeLog:

	* config/i386/sse.md (udot_prodv64qi): New expander.
	(udot_prod<mode>): Emulates with VEC_UNPACKU_EXPR +
	DOT_PROD (short, int).

gcc/testsuite/ChangeLog:

	* gcc.target/i386/udotprodint8_emulate.c: New test.

2 files changed, 85 insertions, 12 deletions

diff --git a/gcc/config/i386/sse.md b/gcc/config/i386/sse.md
index 0df3341..4c81f66 100644
--- a/gcc/config/i386/sse.md
+++ b/gcc/config/i386/sse.md
@@ -30838,20 +30838,78 @@
 
 (define_expand "udot_prod<mode>"
   [(match_operand:<ssedvecmode> 0 "register_operand")
-   (match_operand:VI1 1 "register_operand")
-   (match_operand:VI1 2 "register_operand")
+   (match_operand:VI1_AVX2 1 "register_operand")
+   (match_operand:VI1_AVX2 2 "register_operand")
    (match_operand:<ssedvecmode> 3 "register_operand")]
-  "TARGET_AVXVNNIINT8"
+  "TARGET_SSE2"
 {
-  operands[1] = lowpart_subreg (<ssedvecmode>mode,
-                                force_reg (<MODE>mode, operands[1]),
-                                <MODE>mode);
-  operands[2] = lowpart_subreg (<ssedvecmode>mode,
-                                force_reg (<MODE>mode, operands[2]),
-                                <MODE>mode);
-  emit_insn (gen_rtx_SET (operands[0], operands[3]));
-  emit_insn (gen_vpdpbuud_<ssedvecmodelower> (operands[0], operands[3],
-				   operands[1], operands[2]));
+  if (TARGET_AVXVNNIINT8)
+    {
+      operands[1] = lowpart_subreg (<ssedvecmode>mode,
+				    force_reg (<MODE>mode, operands[1]),
+				    <MODE>mode);
+      operands[2] = lowpart_subreg (<ssedvecmode>mode,
+				    force_reg (<MODE>mode, operands[2]),
+				    <MODE>mode);
+      emit_insn (gen_rtx_SET (operands[0], operands[3]));
+      emit_insn (gen_vpdpbuud_<ssedvecmodelower> (operands[0], operands[3],
+						  operands[1], operands[2]));
+   }
+ else
+   {
+     /* Emulate with vpdpwssd.  */
+     rtx op1_lo = gen_reg_rtx (<sseunpackmode>mode);
+     rtx op1_hi = gen_reg_rtx (<sseunpackmode>mode);
+     rtx op2_lo = gen_reg_rtx (<sseunpackmode>mode);
+     rtx op2_hi = gen_reg_rtx (<sseunpackmode>mode);
+
+     emit_insn (gen_vec_unpacku_lo_<mode> (op1_lo, operands[1]));
+     emit_insn (gen_vec_unpacku_lo_<mode> (op2_lo, operands[2]));
+     emit_insn (gen_vec_unpacku_hi_<mode> (op1_hi, operands[1]));
+     emit_insn (gen_vec_unpacku_hi_<mode> (op2_hi, operands[2]));
+
+     rtx res1 = gen_reg_rtx (<ssedvecmode>mode);
+     rtx res2 = gen_reg_rtx (<ssedvecmode>mode);
+     rtx sum = gen_reg_rtx (<ssedvecmode>mode);
+
+     emit_move_insn (sum, CONST0_RTX (<ssedvecmode>mode));
+     emit_insn (gen_sdot_prod<sseunpackmodelower> (res1, op1_lo,
+						    op2_lo, sum));
+     emit_insn (gen_sdot_prod<sseunpackmodelower> (res2, op1_hi,
+						    op2_hi, operands[3]));
+     emit_insn (gen_add<ssedvecmodelower>3 (operands[0], res1, res2));
+   }
+
+  DONE;
+})
+
+(define_expand "udot_prodv64qi"
+  [(match_operand:V16SI 0 "register_operand")
+   (match_operand:V64QI 1 "register_operand")
+   (match_operand:V64QI 2 "register_operand")
+   (match_operand:V16SI 3 "register_operand")]
+  "(TARGET_AVX512VNNI || TARGET_AVX512BW) && TARGET_EVEX512"
+{
+  /* Emulate with vpdpwssd.  */
+  rtx op1_lo = gen_reg_rtx (V32HImode);
+  rtx op1_hi = gen_reg_rtx (V32HImode);
+  rtx op2_lo = gen_reg_rtx (V32HImode);
+  rtx op2_hi = gen_reg_rtx (V32HImode);
+
+  emit_insn (gen_vec_unpacku_lo_v64qi (op1_lo, operands[1]));
+  emit_insn (gen_vec_unpacku_lo_v64qi (op2_lo, operands[2]));
+  emit_insn (gen_vec_unpacku_hi_v64qi (op1_hi, operands[1]));
+  emit_insn (gen_vec_unpacku_hi_v64qi (op2_hi, operands[2]));
+
+  rtx res1 = gen_reg_rtx (V16SImode);
+  rtx res2 = gen_reg_rtx (V16SImode);
+  rtx sum = gen_reg_rtx (V16SImode);
+
+  emit_move_insn (sum, CONST0_RTX (V16SImode));
+  emit_insn (gen_sdot_prodv32hi (res1, op1_lo, op2_lo, sum));
+  emit_insn (gen_sdot_prodv32hi (res2, op1_hi, op2_hi, operands[3]));
+
+  emit_insn (gen_addv16si3 (operands[0], res1, res2));
   DONE;
 })
 
diff --git a/gcc/testsuite/gcc.target/i386/udotprodint8_emulate.c b/gcc/testsuite/gcc.target/i386/udotprodint8_emulate.c
new file mode 100644
index 0000000..1e8f2cf
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/udotprodint8_emulate.c
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-mavxvnni -O2 -fdump-tree-optimized" } */
+/* { dg-final { scan-tree-dump-times "DOT_PROD_EXPR" 1 "optimized" } } */
+/* { dg-final { scan-assembler-times "vpdpwssd" 2 } } */
+
+int
+foo (unsigned char* a, unsigned char* b)
+{
+  int sum = 0;
+  for (int i = 0; i != 16; i++)
+    {
+      sum += a[i] * b[i];
+    }
+  return sum;
+}