re PR tree-optimization/92645 (Hand written vector code is 450 times slower when compiled with GCC compared to Clang)

2019-11-27  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/92645
	* tree-ssa-forwprop.c (simplify_vector_constructor): Handle
	CTORs with just a subset of the original vectors.

	* gcc.target/i386/pr92645-2.c: New testcase.
	* gcc.target/i386/pr92645-3.c: Likewise.

From-SVN: r278758

1 files changed, 91 insertions, 47 deletions

diff --git a/gcc/tree-ssa-forwprop.c b/gcc/tree-ssa-forwprop.c
index 386406f..7202d4a 100644
--- a/gcc/tree-ssa-forwprop.c
+++ b/gcc/tree-ssa-forwprop.c
@@ -2037,6 +2037,7 @@ simplify_vector_constructor (gimple_stmt_iterator *gsi)
   tree op, op2, orig[2], type, elem_type;
   unsigned elem_size, i;
   unsigned HOST_WIDE_INT nelts;
+  unsigned HOST_WIDE_INT refnelts;
   enum tree_code conv_code;
   constructor_elt *elt;
   bool maybe_ident;
@@ -2052,7 +2053,6 @@ simplify_vector_constructor (gimple_stmt_iterator *gsi)
   elem_type = TREE_TYPE (type);
   elem_size = TREE_INT_CST_LOW (TYPE_SIZE (elem_type));
 
-  vec_perm_builder sel (nelts, nelts, 1);
   orig[0] = NULL;
   orig[1] = NULL;
   conv_code = ERROR_MARK;
@@ -2061,6 +2061,7 @@ simplify_vector_constructor (gimple_stmt_iterator *gsi)
   tree one_nonconstant = NULL_TREE;
   auto_vec<tree> constants;
   constants.safe_grow_cleared (nelts);
+  auto_vec<std::pair<unsigned, unsigned>, 64> elts;
   FOR_EACH_VEC_SAFE_ELT (CONSTRUCTOR_ELTS (op), i, elt)
     {
       tree ref, op1;
@@ -2079,7 +2080,8 @@ simplify_vector_constructor (gimple_stmt_iterator *gsi)
 					TREE_TYPE (TREE_TYPE (ref)))
 	  && known_eq (bit_field_size (op1), elem_size)
 	  && constant_multiple_p (bit_field_offset (op1),
-				  elem_size, &elem))
+				  elem_size, &elem)
+	  && TYPE_VECTOR_SUBPARTS (TREE_TYPE (ref)).is_constant (&refnelts))
 	{
 	  unsigned int j;
 	  for (j = 0; j < 2; ++j)
@@ -2098,11 +2100,9 @@ simplify_vector_constructor (gimple_stmt_iterator *gsi)
 	  if (j < 2)
 	    {
 	      orig[j] = ref;
-	      if (j)
-		elem += nelts;
-	      if (elem != i)
+	      if (elem != i || j != 0)
 		maybe_ident = false;
-	      sel.quick_push (elem);
+	      elts.safe_push (std::make_pair (j, elem));
 	      continue;
 	    }
 	  /* Else fallthru.  */
@@ -2131,28 +2131,41 @@ simplify_vector_constructor (gimple_stmt_iterator *gsi)
 	  else if (!operand_equal_p (one_nonconstant, elt->value, 0))
 	    return false;
 	}
-      sel.quick_push (i + nelts);
+      elts.safe_push (std::make_pair (1, i));
       maybe_ident = false;
     }
   if (i < nelts)
     return false;
 
   if (! orig[0]
-      || ! VECTOR_TYPE_P (TREE_TYPE (orig[0]))
-      || maybe_ne (TYPE_VECTOR_SUBPARTS (type),
-		   TYPE_VECTOR_SUBPARTS (TREE_TYPE (orig[0]))))
-    return false;
-
-  tree tem;
-  if (conv_code != ERROR_MARK
-      && (! supportable_convert_operation (conv_code, type,
-					   TREE_TYPE (orig[0]),
-					   &tem, &conv_code)
-	  || conv_code == CALL_EXPR))
+      || ! VECTOR_TYPE_P (TREE_TYPE (orig[0])))
     return false;
+  refnelts = TYPE_VECTOR_SUBPARTS (TREE_TYPE (orig[0])).to_constant ();
 
   if (maybe_ident)
     {
+      tree conv_src_type
+	= (nelts != refnelts
+	   ? (conv_code != ERROR_MARK
+	      ? build_vector_type (TREE_TYPE (TREE_TYPE (orig[0])), nelts)
+	      : type)
+	   : TREE_TYPE (orig[0]));
+      tree tem;
+      if (conv_code != ERROR_MARK
+	  && (!supportable_convert_operation (conv_code, type, conv_src_type,
+					      &tem, &conv_code)
+	      || conv_code == CALL_EXPR))
+	return false;
+      if (nelts != refnelts)
+	{
+	  gassign *lowpart
+	    = gimple_build_assign (make_ssa_name (conv_src_type),
+				   build3 (BIT_FIELD_REF, conv_src_type,
+					   orig[0], TYPE_SIZE (conv_src_type),
+					   bitsize_zero_node));
+	  gsi_insert_before (gsi, lowpart, GSI_SAME_STMT);
+	  orig[0] = gimple_assign_lhs (lowpart);
+	}
       if (conv_code == ERROR_MARK)
 	gimple_assign_set_rhs_from_tree (gsi, orig[0]);
       else
@@ -2161,34 +2174,66 @@ simplify_vector_constructor (gimple_stmt_iterator *gsi)
     }
   else
     {
-      tree mask_type;
+      tree mask_type, perm_type, conv_src_type;
+      if (orig[1] == error_mark_node && conv_code != ERROR_MARK)
+	{
+	  /* ???  For subsetting a larger vector we need to permute the original
+	     but then the constants are in the converted type already which is
+	     why for that case we first convert and then permute.  */
+	  if (nelts != refnelts)
+	    return false;
+	  conv_src_type = TREE_TYPE (orig[0]);
+	  perm_type = type;
+	}
+      else
+	{
+	  perm_type = TREE_TYPE (orig[0]);
+	  conv_src_type = (nelts == refnelts
+			   ? perm_type
+			   : build_vector_type (TREE_TYPE (perm_type), nelts));
+	}
+      tree tem;
+      if (conv_code != ERROR_MARK
+	  && (!supportable_convert_operation (conv_code, type, conv_src_type,
+					      &tem, &conv_code)
+	      || conv_code == CALL_EXPR))
+	return false;
 
-      vec_perm_indices indices (sel, orig[1] ? 2 : 1, nelts);
-      if (!can_vec_perm_const_p (TYPE_MODE (type), indices))
+      /* Now that we know the number of elements of the source build the
+	 permute vector.  */
+      vec_perm_builder sel (refnelts, refnelts, 1);
+      for (i = 0; i < elts.length (); ++i)
+	sel.quick_push (elts[i].second + elts[i].first * refnelts);
+      /* And fill the tail with "something".  It's really don't care,
+         and ideally we'd allow VEC_PERM to have a smaller destination
+	 vector.  */
+      for (; i < refnelts; ++i)
+	sel.quick_push (i - elts.length ());
+      vec_perm_indices indices (sel, orig[1] ? 2 : 1, refnelts);
+      if (!can_vec_perm_const_p (TYPE_MODE (perm_type), indices))
 	return false;
       mask_type
 	= build_vector_type (build_nonstandard_integer_type (elem_size, 1),
-			     nelts);
+			     refnelts);
       if (GET_MODE_CLASS (TYPE_MODE (mask_type)) != MODE_VECTOR_INT
 	  || maybe_ne (GET_MODE_SIZE (TYPE_MODE (mask_type)),
-		       GET_MODE_SIZE (TYPE_MODE (type))))
+		       GET_MODE_SIZE (TYPE_MODE (perm_type))))
 	return false;
       op2 = vec_perm_indices_to_tree (mask_type, indices);
       bool convert_orig0 = false;
+      gimple_seq stmts = NULL;
       if (!orig[1])
 	orig[1] = orig[0];
       else if (orig[1] == error_mark_node
 	       && one_nonconstant)
 	{
-	  gimple_seq seq = NULL;
-	  orig[1] = gimple_build_vector_from_val (&seq, UNKNOWN_LOCATION,
-						  type, one_nonconstant);
-	  gsi_insert_seq_before (gsi, seq, GSI_SAME_STMT);
-	  convert_orig0 = true;
+	  orig[1] = gimple_build_vector_from_val (&stmts, UNKNOWN_LOCATION,
+						  perm_type, one_nonconstant);
+	  convert_orig0 = conv_code != ERROR_MARK;
 	}
       else if (orig[1] == error_mark_node)
 	{
-	  tree_vector_builder vec (type, nelts, 1);
+	  tree_vector_builder vec (perm_type, nelts, 1);
 	  for (unsigned i = 0; i < nelts; ++i)
 	    if (constants[i])
 	      vec.quick_push (constants[i]);
@@ -2196,30 +2241,29 @@ simplify_vector_constructor (gimple_stmt_iterator *gsi)
 	      /* ??? Push a don't-care value.  */
 	      vec.quick_push (one_constant);
 	  orig[1] = vec.build ();
-	  convert_orig0 = true;
+	  convert_orig0 = conv_code != ERROR_MARK;
 	}
-      if (conv_code == ERROR_MARK)
-	gimple_assign_set_rhs_with_ops (gsi, VEC_PERM_EXPR, orig[0],
-					orig[1], op2);
-      else if (convert_orig0)
+      tree res;
+      if (convert_orig0)
 	{
-	  gimple *conv
-	    = gimple_build_assign (make_ssa_name (type), conv_code, orig[0]);
-	  orig[0] = gimple_assign_lhs (conv);
-	  gsi_insert_before (gsi, conv, GSI_SAME_STMT);
-	  gimple_assign_set_rhs_with_ops (gsi, VEC_PERM_EXPR,
-					  orig[0], orig[1], op2);
+	  gcc_assert (nelts == refnelts);
+	  res = gimple_build (&stmts, conv_code, type, orig[0]);
+	  res = gimple_build (&stmts, VEC_PERM_EXPR, perm_type,
+			      res, orig[1], op2);
 	}
       else
 	{
-	  gimple *perm
-	    = gimple_build_assign (make_ssa_name (TREE_TYPE (orig[0])),
-				   VEC_PERM_EXPR, orig[0], orig[1], op2);
-	  orig[0] = gimple_assign_lhs (perm);
-	  gsi_insert_before (gsi, perm, GSI_SAME_STMT);
-	  gimple_assign_set_rhs_with_ops (gsi, conv_code, orig[0],
-					  NULL_TREE, NULL_TREE);
+	  res = gimple_build (&stmts, VEC_PERM_EXPR, perm_type,
+			      orig[0], orig[1], op2);
+	  if (nelts != refnelts)
+	    res = gimple_build (&stmts, BIT_FIELD_REF,
+				conv_code != ERROR_MARK ? conv_src_type : type,
+				res, TYPE_SIZE (type), bitsize_zero_node);
+	  if (conv_code != ERROR_MARK)
+	    res = gimple_build (&stmts, conv_code, type, res);
 	}
+      gsi_insert_seq_before (gsi, stmts, GSI_SAME_STMT);
+      gimple_assign_set_rhs_with_ops (gsi, SSA_NAME, res);
     }
   update_stmt (gsi_stmt (*gsi));
   return true;