[gcc r14-2007] Use intermiediate integer type for float_expr/fix_trunc_expr when direct optab is not existed.

[hongtao Liu <liuhongt@gcc.gnu.org>]

https://gcc.gnu.org/g:6f19cf7526168f840fd22f6af3f0cb67efb90dc8

commit r14-2007-g6f19cf7526168f840fd22f6af3f0cb67efb90dc8
Author: liuhongt <hongtao.liu@intel.com>
Date:   Wed May 31 11:20:46 2023 +0800

    Use intermiediate integer type for float_expr/fix_trunc_expr when direct optab is not existed.
    
    We have already use intermidate type in case WIDEN, but not for NONE,
    this patch extended that.
    
    gcc/ChangeLog:
    
            PR target/110018
            * tree-vect-stmts.cc (vectorizable_conversion): Use
            intermiediate integer type for float_expr/fix_trunc_expr when
            direct optab is not existed.
    
    gcc/testsuite/ChangeLog:
    
            * gcc.target/i386/pr110018-1.c: New test.

Diff:
---
 gcc/testsuite/gcc.target/i386/pr110018-1.c | 94 ++++++++++++++++++++++++++++++
 gcc/tree-vect-stmts.cc                     | 66 ++++++++++++++++++++-
 2 files changed, 158 insertions(+), 2 deletions(-)

diff --git a/gcc/testsuite/gcc.target/i386/pr110018-1.c b/gcc/testsuite/gcc.target/i386/pr110018-1.c
new file mode 100644
index 00000000000..b1baffd7af1
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr110018-1.c
@@ -0,0 +1,94 @@
+/* { dg-do compile } */
+/* { dg-options "-mavx512fp16 -mavx512vl -O2 -mavx512dq" } */
+/* { dg-final { scan-assembler-times {(?n)vcvttp[dsh]2[dqw]} 5 } } */
+/* { dg-final { scan-assembler-times {(?n)vcvt[dqw]*2p[dsh]} 5 } } */
+
+void
+foo (double* __restrict a, char* b)
+{
+  a[0] = b[0];
+  a[1] = b[1];
+}
+
+void
+foo1 (float* __restrict a, char* b)
+{
+  a[0] = b[0];
+  a[1] = b[1];
+  a[2] = b[2];
+  a[3] = b[3];
+}
+
+void
+foo2 (_Float16* __restrict a, char* b)
+{
+  a[0] = b[0];
+  a[1] = b[1];
+  a[2] = b[2];
+  a[3] = b[3];
+  a[4] = b[4];
+  a[5] = b[5];
+  a[6] = b[6];
+  a[7] = b[7];
+}
+
+void
+foo3 (double* __restrict a, short* b)
+{
+  a[0] = b[0];
+  a[1] = b[1];
+}
+
+void
+foo4 (float* __restrict a, char* b)
+{
+  a[0] = b[0];
+  a[1] = b[1];
+  a[2] = b[2];
+  a[3] = b[3];
+}
+
+void
+foo5 (double* __restrict b, char* a)
+{
+  a[0] = b[0];
+  a[1] = b[1];
+}
+
+void
+foo6 (float* __restrict b, char* a)
+{
+  a[0] = b[0];
+  a[1] = b[1];
+  a[2] = b[2];
+  a[3] = b[3];
+}
+
+void
+foo7 (_Float16* __restrict b, char* a)
+{
+  a[0] = b[0];
+  a[1] = b[1];
+  a[2] = b[2];
+  a[3] = b[3];
+  a[4] = b[4];
+  a[5] = b[5];
+  a[6] = b[6];
+  a[7] = b[7];
+}
+
+void
+foo8 (double* __restrict b, short* a)
+{
+  a[0] = b[0];
+  a[1] = b[1];
+}
+
+void
+foo9 (float* __restrict b, char* a)
+{
+  a[0] = b[0];
+  a[1] = b[1];
+  a[2] = b[2];
+  a[3] = b[3];
+}
diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
index 056a0ecb2be..ae24f3e66e6 100644
--- a/gcc/tree-vect-stmts.cc
+++ b/gcc/tree-vect-stmts.cc
@@ -5041,7 +5041,7 @@ vectorizable_conversion (vec_info *vinfo,
   tree scalar_dest;
   tree op0, op1 = NULL_TREE;
   loop_vec_info loop_vinfo = dyn_cast <loop_vec_info> (vinfo);
-  tree_code tc1;
+  tree_code tc1, tc2;
   code_helper code, code1, code2;
   code_helper codecvt1 = ERROR_MARK, codecvt2 = ERROR_MARK;
   tree new_temp;
@@ -5249,6 +5249,57 @@ vectorizable_conversion (vec_info *vinfo,
 	code1 = tc1;
 	break;
       }
+
+      /* For conversions between float and smaller integer types try whether we
+	 can use intermediate signed integer types to support the
+	 conversion.  */
+      if ((code == FLOAT_EXPR
+	   && GET_MODE_SIZE (lhs_mode) > GET_MODE_SIZE (rhs_mode))
+	  || (code == FIX_TRUNC_EXPR
+	      && GET_MODE_SIZE (rhs_mode) > GET_MODE_SIZE (lhs_mode)))
+	{
+	  bool float_expr_p = code == FLOAT_EXPR;
+	  scalar_mode imode = float_expr_p ? rhs_mode : lhs_mode;
+	  fltsz = GET_MODE_SIZE (float_expr_p ? lhs_mode : rhs_mode);
+	  code1 = float_expr_p ? code : NOP_EXPR;
+	  codecvt1 = float_expr_p ? NOP_EXPR : code;
+	  FOR_EACH_2XWIDER_MODE (rhs_mode_iter, imode)
+	    {
+	      imode = rhs_mode_iter.require ();
+	      if (GET_MODE_SIZE (imode) > fltsz)
+		break;
+
+	      cvt_type
+		= build_nonstandard_integer_type (GET_MODE_BITSIZE (imode),
+						  0);
+	      cvt_type = get_vectype_for_scalar_type (vinfo, cvt_type,
+						      slp_node);
+	      /* This should only happened for SLP as long as loop vectorizer
+		 only supports same-sized vector.  */
+	      if (cvt_type == NULL_TREE
+		  || maybe_ne (TYPE_VECTOR_SUBPARTS (cvt_type), nunits_in)
+		  || !supportable_convert_operation ((tree_code) code1,
+						     vectype_out,
+						     cvt_type, &tc1)
+		  || !supportable_convert_operation ((tree_code) codecvt1,
+						     cvt_type,
+						     vectype_in, &tc2))
+		continue;
+
+	      found_mode = true;
+	      break;
+	    }
+
+	  if (found_mode)
+	    {
+	      multi_step_cvt++;
+	      interm_types.safe_push (cvt_type);
+	      cvt_type = NULL_TREE;
+	      code1 = tc1;
+	      codecvt1 = tc2;
+	      break;
+	    }
+	}
       /* FALLTHRU */
     unsupported:
       if (dump_enabled_p ())
@@ -5513,7 +5564,18 @@ vectorizable_conversion (vec_info *vinfo,
       FOR_EACH_VEC_ELT (vec_oprnds0, i, vop0)
 	{
 	  /* Arguments are ready, create the new vector stmt.  */
-	  gimple *new_stmt = vect_gimple_build (vec_dest, code1, vop0);
+	  gimple* new_stmt;
+	  if (multi_step_cvt)
+	    {
+	      gcc_assert (multi_step_cvt == 1);
+	      new_stmt = vect_gimple_build (vec_dest, codecvt1, vop0);
+	      new_temp = make_ssa_name (vec_dest, new_stmt);
+	      gimple_assign_set_lhs (new_stmt, new_temp);
+	      vect_finish_stmt_generation (vinfo, stmt_info, new_stmt, gsi);
+	      vop0 = new_temp;
+	      vec_dest = vec_dsts[0];
+	    }
+	  new_stmt = vect_gimple_build (vec_dest, code1, vop0);
 	  new_temp = make_ssa_name (vec_dest, new_stmt);
 	  gimple_set_lhs (new_stmt, new_temp);
 	  vect_finish_stmt_generation (vinfo, stmt_info, new_stmt, gsi);