[9b/n] PR85694: Make vect_is_simple_use look through pattern statements

As suggested by Richard B., this patch makes vect_is_simple_use check
whether a defining statement has been replaced by a pattern statement,
and if so returns the pattern statement instead.

The reason for doing this is that the main patch for PR85694
makes over_widening handle more general cases.  These over-widened
patterns can still be useful when matching later statements;
e.g. an overwidened MULT_EXPR could be the input to a DOT_PROD_EXPR.

The patch doesn't do anything with the STMT_VINFO_IN_PATTERN_P checks
in vect_recog_over_widening_pattern or vect_recog_widen_shift_pattern
since later patches rewrite them anyway.

Doing this fixed an XFAIL in vect-reduc-dot-u16b.c.

2018-06-30  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* tree-vect-loop.c (vectorizable_reduction): Assert that the
	phi is not a pattern statement and has not been replaced by
	a pattern statement.
	* tree-vect-patterns.c (type_conversion_p): Don't check
	STMT_VINFO_IN_PATTERN_P.
	(vect_recog_vector_vector_shift_pattern): Likewise.
	(vect_recog_dot_prod_pattern): Expect vect_is_simple_use to return
	the pattern statement rather than the original statement; check
	directly for a WIDEN_MULT_EXPR here.
	* tree-vect-slp.c (vect_get_and_check_slp_defs): Expect
	vect_is_simple_use to return the pattern statement rather
	than the original statement; use is_pattern_stmt_p to check
	for such a pattern statement.
	* tree-vect-stmts.c (process_use): Expect vect_is_simple_use
	to return the pattern statement rather than the original statement;
	don't do the same transformation here.
	(vect_is_simple_use): If the defining statement has been replaced
	by a pattern statement, return the pattern statement instead.
	Remove the corresponding (local) transformation from the vectype
	overload.

gcc/testsuite/
	* gcc.dg/vect/vect-reduc-dot-u16b.c: Remove xfail and update the
	test for vectorization along the lines described in the comment.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@262273 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 6 insertions, 21 deletions

diff --git a/gcc/tree-vect-patterns.c b/gcc/tree-vect-patterns.c
index 6fb07fd1265..6926c849f13 100644
--- a/gcc/tree-vect-patterns.c
+++ b/gcc/tree-vect-patterns.c
@@ -193,13 +193,6 @@ type_conversion_p (tree name, gimple *use_stmt, bool check_sign,
   if (!*def_stmt)
     return false;
 
-  if (dt == vect_internal_def)
-    {
-      stmt_vec_info def_vinfo = vinfo_for_stmt (*def_stmt);
-      if (STMT_VINFO_IN_PATTERN_P (def_vinfo))
-	return false;
-    }
-
   if (!is_gimple_assign (*def_stmt))
     return false;
 
@@ -383,20 +376,11 @@ vect_recog_dot_prod_pattern (vec<gimple *> *stmts, tree *type_out)
   /* FORNOW.  Can continue analyzing the def-use chain when this stmt in a phi
      inside the loop (in case we are analyzing an outer-loop).  */
   gassign *mult = dyn_cast <gassign *> (mult_vinfo->stmt);
-  if (!mult || gimple_assign_rhs_code (mult) != MULT_EXPR)
+  if (!mult)
     return NULL;
-  if (STMT_VINFO_IN_PATTERN_P (mult_vinfo))
+  if (gimple_assign_rhs_code (mult) == WIDEN_MULT_EXPR)
     {
       /* Has been detected as a widening multiplication?  */
-
-      mult = dyn_cast <gassign *> (STMT_VINFO_RELATED_STMT (mult_vinfo));
-      if (!mult || gimple_assign_rhs_code (mult) != WIDEN_MULT_EXPR)
-        return NULL;
-      STMT_VINFO_PATTERN_DEF_SEQ (stmt_vinfo)
-	= STMT_VINFO_PATTERN_DEF_SEQ (mult_vinfo);
-      mult_vinfo = vinfo_for_stmt (mult);
-      gcc_assert (mult_vinfo);
-      gcc_assert (STMT_VINFO_DEF_TYPE (mult_vinfo) == vect_internal_def);
       oprnd00 = gimple_assign_rhs1 (mult);
       oprnd01 = gimple_assign_rhs2 (mult);
     }
@@ -406,6 +390,9 @@ vect_recog_dot_prod_pattern (vec<gimple *> *stmts, tree *type_out)
       gimple *def_stmt;
       tree oprnd0, oprnd1;
 
+      if (gimple_assign_rhs_code (mult) != MULT_EXPR)
+	return NULL;
+
       oprnd0 = gimple_assign_rhs1 (mult);
       oprnd1 = gimple_assign_rhs2 (mult);
       if (!type_conversion_p (oprnd0, mult, true, &half_type0, &def_stmt,
@@ -2050,9 +2037,7 @@ vect_recog_vector_vector_shift_pattern (vec<gimple *> *stmts, tree *type_out)
 
   tree def = NULL_TREE;
   gassign *def_stmt = dyn_cast <gassign *> (def_vinfo->stmt);
-  if (!STMT_VINFO_IN_PATTERN_P (def_vinfo)
-      && def_stmt
-      && gimple_assign_cast_p (def_stmt))
+  if (def_stmt && gimple_assign_cast_p (def_stmt))
     {
       tree rhs1 = gimple_assign_rhs1 (def_stmt);
       if (TYPE_MODE (TREE_TYPE (rhs1)) == TYPE_MODE (TREE_TYPE (oprnd0))