[PATCH-1, expand] Enable vector mode for compare_by_pieces [PR111449]

[PATCH-1, expand] Enable vector mode for compare_by_pieces [PR111449]

[HAO CHEN GUI]

Hi,
  Vector mode instructions are efficient on some targets (e.g. ppc64).
This patch enables vector mode for compare_by_pieces. The non-member
function widest_fixed_size_mode_for_size takes by_pieces_operation
as the second argument and decide whether vector mode is enabled or
not by the type of operations. Currently only set and compare enabled
vector mode and do the optab checking correspondingly.

  The test case is in the second patch which is rs6000 specific.

  Bootstrapped and tested on x86 and powerpc64-linux BE and LE with no
regressions.

Thanks
Gui Haochen

ChangeLog
Expand: Enable vector mode for pieces compare

Vector mode compare instructions are efficient for equality compare on
rs6000. This patch refactors the codes of pieces operation to enable
vector mode for compare.

gcc/
	PR target/111449
	* expr.cc (widest_fixed_size_mode_for_size): Enable vector mode
	for compare.  Replace the second argument with the type of pieces
	operation.  Add optab checks for vector mode used in compare.
	(by_pieces_ninsns): Pass the type of pieces operation to
	widest_fixed_size_mode_for_size.
	(class op_by_pieces_d): Add virtual function
	widest_fixed_size_mode_for_size.
	(op_by_pieces_d::op_by_pieces_d): Call outer function
	widest_fixed_size_mode_for_size.
	(op_by_pieces_d::get_usable_mode): Call class function
	widest_fixed_size_mode_for_size.
	(op_by_pieces_d::run): Likewise.
	(class move_by_pieces_d): Declare function
	widest_fixed_size_mode_for_size.
	(move_by_pieces_d::widest_fixed_size_mode_for_size): Implement.
	(class store_by_pieces_d): Declare function
	widest_fixed_size_mode_for_size.
	(store_by_pieces_d::widest_fixed_size_mode_for_size): Implement.
	(can_store_by_pieces): Pass the type of pieces operation to
	widest_fixed_size_mode_for_size.
	(class compare_by_pieces_d): Declare function
	widest_fixed_size_mode_for_size.
	(compare_by_pieces_d::compare_by_pieces_d): Set m_qi_vector_mode
	to true.
	(compare_by_pieces_d::widest_fixed_size_mode_for_size): Implement.

patch.diff
diff --git a/gcc/expr.cc b/gcc/expr.cc
index d87346dc07f..9885404ee9c 100644
--- a/gcc/expr.cc
+++ b/gcc/expr.cc
@@ -992,8 +992,9 @@ alignment_for_piecewise_move (unsigned int max_pieces, unsigned int align)
    that is narrower than SIZE bytes.  */

 static fixed_size_mode
-widest_fixed_size_mode_for_size (unsigned int size, bool qi_vector)
+widest_fixed_size_mode_for_size (unsigned int size, by_pieces_operation op)
 {
+  bool qi_vector = ((op == COMPARE_BY_PIECES) || op == SET_BY_PIECES);
   fixed_size_mode result = NARROWEST_INT_MODE;

   gcc_checking_assert (size > 1);
@@ -1009,8 +1010,13 @@ widest_fixed_size_mode_for_size (unsigned int size, bool qi_vector)
 	  {
 	    if (GET_MODE_SIZE (candidate) >= size)
 	      break;
-	    if (optab_handler (vec_duplicate_optab, candidate)
-		!= CODE_FOR_nothing)
+	    if ((op == SET_BY_PIECES
+		 && optab_handler (vec_duplicate_optab, candidate)
+		   != CODE_FOR_nothing)
+		 || (op == COMPARE_BY_PIECES
+		     && optab_handler (mov_optab, mode)
+			!= CODE_FOR_nothing
+		     && can_compare_p (EQ, mode, ccp_jump)))
 	      result = candidate;
 	  }

@@ -1061,8 +1067,7 @@ by_pieces_ninsns (unsigned HOST_WIDE_INT l, unsigned int align,
     {
       /* NB: Round up L and ALIGN to the widest integer mode for
 	 MAX_SIZE.  */
-      mode = widest_fixed_size_mode_for_size (max_size,
-					      op == SET_BY_PIECES);
+      mode = widest_fixed_size_mode_for_size (max_size, op);
       if (optab_handler (mov_optab, mode) != CODE_FOR_nothing)
 	{
 	  unsigned HOST_WIDE_INT up = ROUND_UP (l, GET_MODE_SIZE (mode));
@@ -1076,8 +1081,7 @@ by_pieces_ninsns (unsigned HOST_WIDE_INT l, unsigned int align,

   while (max_size > 1 && l > 0)
     {
-      mode = widest_fixed_size_mode_for_size (max_size,
-					      op == SET_BY_PIECES);
+      mode = widest_fixed_size_mode_for_size (max_size, op);
       enum insn_code icode;

       unsigned int modesize = GET_MODE_SIZE (mode);
@@ -1327,6 +1331,8 @@ class op_by_pieces_d
   virtual void finish_mode (machine_mode)
   {
   }
+  virtual fixed_size_mode widest_fixed_size_mode_for_size (unsigned int size)
+    = 0;

  public:
   op_by_pieces_d (unsigned int, rtx, bool, rtx, bool, by_pieces_constfn,
@@ -1375,8 +1381,7 @@ op_by_pieces_d::op_by_pieces_d (unsigned int max_pieces, rtx to,
     {
       /* Find the mode of the largest comparison.  */
       fixed_size_mode mode
-	= widest_fixed_size_mode_for_size (m_max_size,
-					   m_qi_vector_mode);
+	= ::widest_fixed_size_mode_for_size (m_max_size, COMPARE_BY_PIECES);

       m_from.decide_autoinc (mode, m_reverse, len);
       m_to.decide_autoinc (mode, m_reverse, len);
@@ -1401,7 +1406,7 @@ op_by_pieces_d::get_usable_mode (fixed_size_mode mode, unsigned int len)
       if (len >= size && prepare_mode (mode, m_align))
 	break;
       /* widest_fixed_size_mode_for_size checks SIZE > 1.  */
-      mode = widest_fixed_size_mode_for_size (size, m_qi_vector_mode);
+      mode = widest_fixed_size_mode_for_size (size);
     }
   while (1);
   return mode;
@@ -1451,7 +1456,7 @@ op_by_pieces_d::run ()

   /* widest_fixed_size_mode_for_size checks M_MAX_SIZE > 1.  */
   fixed_size_mode mode
-    = widest_fixed_size_mode_for_size (m_max_size, m_qi_vector_mode);
+    = widest_fixed_size_mode_for_size (m_max_size);
   mode = get_usable_mode (mode, length);

   by_pieces_prev to_prev = { nullptr, mode };
@@ -1516,8 +1521,7 @@ op_by_pieces_d::run ()
       else
 	{
 	  /* widest_fixed_size_mode_for_size checks SIZE > 1.  */
-	  mode = widest_fixed_size_mode_for_size (size,
-						  m_qi_vector_mode);
+	  mode = widest_fixed_size_mode_for_size (size);
 	  mode = get_usable_mode (mode, length);
 	}
     }
@@ -1538,6 +1542,8 @@ class move_by_pieces_d : public op_by_pieces_d
   insn_gen_fn m_gen_fun;
   void generate (rtx, rtx, machine_mode) final override;
   bool prepare_mode (machine_mode, unsigned int) final override;
+  fixed_size_mode widest_fixed_size_mode_for_size (unsigned int)
+    final override;

  public:
   move_by_pieces_d (rtx to, rtx from, unsigned HOST_WIDE_INT len,
@@ -1626,14 +1632,23 @@ move_by_pieces (rtx to, rtx from, unsigned HOST_WIDE_INT len,
     return to;
 }

+fixed_size_mode
+move_by_pieces_d::widest_fixed_size_mode_for_size (unsigned int size)
+{
+  return ::widest_fixed_size_mode_for_size (size, MOVE_BY_PIECES);
+}
+
 /* Derived class from op_by_pieces_d, providing support for block move
    operations.  */

 class store_by_pieces_d : public op_by_pieces_d
 {
   insn_gen_fn m_gen_fun;
+
   void generate (rtx, rtx, machine_mode) final override;
   bool prepare_mode (machine_mode, unsigned int) final override;
+  fixed_size_mode widest_fixed_size_mode_for_size (unsigned int)
+    final override;

  public:
   store_by_pieces_d (rtx to, by_pieces_constfn cfn, void *cfn_data,
@@ -1686,6 +1701,13 @@ store_by_pieces_d::finish_retmode (memop_ret retmode)
   return m_to.adjust (QImode, m_offset);
 }

+fixed_size_mode
+store_by_pieces_d::widest_fixed_size_mode_for_size (unsigned int size)
+{
+  return ::widest_fixed_size_mode_for_size (size,
+	     m_qi_vector_mode ? SET_BY_PIECES : STORE_BY_PIECES);
+}
+
 /* Determine whether the LEN bytes generated by CONSTFUN can be
    stored to memory using several move instructions.  CONSTFUNDATA is
    a pointer which will be passed as argument in every CONSTFUN call.
@@ -1730,7 +1752,8 @@ can_store_by_pieces (unsigned HOST_WIDE_INT len,
       while (max_size > 1 && l > 0)
 	{
 	  fixed_size_mode mode
-	    = widest_fixed_size_mode_for_size (max_size, memsetp);
+	    = widest_fixed_size_mode_for_size (max_size,
+		memsetp ? SET_BY_PIECES : STORE_BY_PIECES);

 	  icode = optab_handler (mov_optab, mode);
 	  if (icode != CODE_FOR_nothing
@@ -1832,12 +1855,15 @@ class compare_by_pieces_d : public op_by_pieces_d
   void generate (rtx, rtx, machine_mode) final override;
   bool prepare_mode (machine_mode, unsigned int) final override;
   void finish_mode (machine_mode) final override;
+  fixed_size_mode widest_fixed_size_mode_for_size (unsigned int)
+    final override;
+
  public:
   compare_by_pieces_d (rtx op0, rtx op1, by_pieces_constfn op1_cfn,
 		       void *op1_cfn_data, HOST_WIDE_INT len, int align,
 		       rtx_code_label *fail_label)
     : op_by_pieces_d (COMPARE_MAX_PIECES, op0, true, op1, true, op1_cfn,
-		      op1_cfn_data, len, align, false)
+		      op1_cfn_data, len, align, false, true)
   {
     m_fail_label = fail_label;
   }
@@ -1943,6 +1969,13 @@ compare_by_pieces (rtx arg0, rtx arg1, unsigned HOST_WIDE_INT len,

   return target;
 }
+
+fixed_size_mode
+compare_by_pieces_d::widest_fixed_size_mode_for_size (unsigned int size)
+{
+  return ::widest_fixed_size_mode_for_size (size, COMPARE_BY_PIECES);
+}
+
 \f
 /* Emit code to move a block Y to a block X.  This may be done with
    string-move instructions, with multiple scalar move instructions,