re PR tree-optimization/66948 (Performance regression in bit manipulation code)

2015-07-21  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/66948
	* genmatch.c (capture_info::walk_match): Also recurse to
	captures.  Properly compute expr state from captures of
	captures.
	* match.pd: Add single-use guards to
	(X & C2) >> C1 into (X >> C1) & (C2 >> C1) transform.

From-SVN: r226041

gcc/ChangeLog

+2015-07-21  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/66948
+	* genmatch.c (capture_info::walk_match): Also recurse to
+	captures.  Properly compute expr state from captures of
+	captures.
+	* match.pd: Add single-use guards to
+	(X & C2) >> C1 into (X >> C1) & (C2 >> C1) transform.
+
 2015-07-21  Nathan Sidwell  <nathan@codesourcery.com>
 
 	* config/nvptx/mkoffload.c (process): Add static destructor call.

gcc/genmatch.c

@@ -1622,17 +1622,28 @@ capture_info::walk_match (operand *o, unsigned toplevel_arg,
 {
   if (capture *c = dyn_cast <capture *> (o))
     {
-      info[c->where].toplevel_msk |= 1 << toplevel_arg;
-      info[c->where].force_no_side_effects_p |= conditional_p;
-      info[c->where].cond_expr_cond_p |= cond_expr_cond_p;
-      /* Mark expr (non-leaf) captures and recurse.  */
+      unsigned where = c->where;
+      info[where].toplevel_msk |= 1 << toplevel_arg;
+      info[where].force_no_side_effects_p |= conditional_p;
+      info[where].cond_expr_cond_p |= cond_expr_cond_p;
+      if (!c->what)
+	return;
+      /* Recurse to exprs and captures.  */
+      if (is_a <capture *> (c->what)
+	  || is_a <expr *> (c->what))
+	walk_match (c->what, toplevel_arg, conditional_p, false);
+      /* We need to look past multiple captures to find a captured
+	 expression as with conditional converts two captures
+	 can be collapsed onto the same expression.  */
+      while (c->what && is_a <capture *> (c->what))
+	c = as_a <capture *> (c->what);
+      /* Mark expr (non-leaf) captures and forced single-use exprs.  */
       expr *e;
       if (c->what
 	  && (e = dyn_cast <expr *> (c->what)))
 	{
-	  info[c->where].expr_p = true;
-	  info[c->where].force_single_use |= e->force_single_use;
-	  walk_match (c->what, toplevel_arg, conditional_p, false);
+	  info[where].expr_p = true;
+	  info[where].force_single_use |= e->force_single_use;
 	}
     }
   else if (expr *e = dyn_cast <expr *> (o))

gcc/match.pd

@@ -1052,7 +1052,7 @@ along with GCC; see the file COPYING3.  If not see
    (X & C2) >> C1 into (X >> C1) & (C2 >> C1).  */
 (for shift (lshift rshift)
  (simplify
-  (shift (convert? (bit_and @0 INTEGER_CST@2)) INTEGER_CST@1)
+  (shift (convert?:s (bit_and:s @0 INTEGER_CST@2)) INTEGER_CST@1)
   (if (tree_nop_conversion_p (type, TREE_TYPE (@0)))
    (with { tree mask = int_const_binop (shift, fold_convert (type, @2), @1); }
     (bit_and (shift (convert @0) @1) { mask; })))))