AVX512BF16: Do not allow permutation with vcvtne2ps2bf16 [PR115889]

According to the instruction spec of AVX512BF16, the convert from float
to BF16 is not a simple truncation. It has special handling for
denormal/nan, even for normal float it will add an extra bias according
to the least significant bit for bf number. This means we cannot use the
vcvtne2ps2bf16 for any bf16 vector shuffle.
The optimization introduced in r15-1368 adds a specific split to convert
HImode permutation with this instruction, so remove it and treat the
BFmode permutation same as HFmode.

gcc/ChangeLog:

	PR target/115889
	* config/i386/predicates.md (vcvtne2ps2bf_parallel): Remove.
	* config/i386/sse.md (hi_cvt_bf): Remove.
	(HI_CVT_BF): Likewise.
	(vpermt2_sepcial_bf16_shuffle_<mode>):Likewise.

gcc/testsuite/ChangeLog:

	PR target/115889
	* gcc.target/i386/vpermt2-special-bf16-shufflue.c: Adjust output
	scan.

3 files changed, 1 insertions, 48 deletions

diff --git a/gcc/config/i386/predicates.md b/gcc/config/i386/predicates.md
index a894847..5d0bb1e 100644
--- a/gcc/config/i386/predicates.md
+++ b/gcc/config/i386/predicates.md
@@ -2327,14 +2327,3 @@
 
   return true;
 })
-
-;; Check that each element is odd and incrementally increasing from 1
-(define_predicate "vcvtne2ps2bf_parallel"
-  (and (match_code "const_vector")
-       (match_code "const_int" "a"))
-{
-  for (int i = 0; i < XVECLEN (op, 0); ++i)
-    if (INTVAL (XVECEXP (op, 0, i)) != (2 * i + 1))
-      return false;
-  return true;
-})
diff --git a/gcc/config/i386/sse.md b/gcc/config/i386/sse.md
index b3b4697..c134494 100644
--- a/gcc/config/i386/sse.md
+++ b/gcc/config/i386/sse.md
@@ -31460,38 +31460,3 @@
   "TARGET_AVXVNNIINT16"
   "vpdp<vpdpwprodtype>\t{%3, %2, %0|%0, %2, %3}"
    [(set_attr "prefix" "vex")])
-
-(define_mode_attr hi_cvt_bf
-  [(V8HI "v8bf") (V16HI "v16bf") (V32HI "v32bf")])
-
-(define_mode_attr HI_CVT_BF
-  [(V8HI "V8BF") (V16HI "V16BF") (V32HI "V32BF")])
-
-(define_insn_and_split "vpermt2_sepcial_bf16_shuffle_<mode>"
-  [(set (match_operand:VI2_AVX512F 0 "register_operand")
-	(unspec:VI2_AVX512F
-	  [(match_operand:VI2_AVX512F 1 "vcvtne2ps2bf_parallel")
-	   (match_operand:VI2_AVX512F 2 "register_operand")
-	   (match_operand:VI2_AVX512F 3 "nonimmediate_operand")]
-	   UNSPEC_VPERMT2))]
-  "TARGET_AVX512VL && TARGET_AVX512BF16 && ix86_pre_reload_split ()"
-  "#"
-  "&& 1"
-  [(const_int 0)]
-{
-  rtx op0 = gen_reg_rtx (<HI_CVT_BF>mode);
-  operands[2] = lowpart_subreg (<ssePSmode>mode,
-				force_reg (<MODE>mode, operands[2]),
-				<MODE>mode);
-  operands[3] = lowpart_subreg (<ssePSmode>mode,
-				force_reg (<MODE>mode, operands[3]),
-				<MODE>mode);
-
-  emit_insn (gen_avx512f_cvtne2ps2bf16_<hi_cvt_bf>(op0,
-						   operands[3],
-						   operands[2]));
-  emit_move_insn (operands[0], lowpart_subreg (<MODE>mode, op0,
-					       <HI_CVT_BF>mode));
-  DONE;
-}
-[(set_attr "mode" "<sseinsnmode>")])
diff --git a/gcc/testsuite/gcc.target/i386/vpermt2-special-bf16-shufflue.c b/gcc/testsuite/gcc.target/i386/vpermt2-special-bf16-shufflue.c
index 5c65f2a..e504f3f 100755
--- a/gcc/testsuite/gcc.target/i386/vpermt2-special-bf16-shufflue.c
+++ b/gcc/testsuite/gcc.target/i386/vpermt2-special-bf16-shufflue.c
@@ -1,7 +1,6 @@
 /* { dg-do compile } */
 /* { dg-options "-O2 -mavx512bf16 -mavx512vl" } */
-/* { dg-final { scan-assembler-not "vpermi2b" } } */
-/* { dg-final { scan-assembler-times "vcvtne2ps2bf16" 3 } } */
+/* { dg-final { scan-assembler-times "vpermi2w" 3 } } */
 
 typedef __bf16 v8bf __attribute__((vector_size(16)));
 typedef __bf16 v16bf __attribute__((vector_size(32)));