[PATCH] Warn about duplicate patterns in match.pd

[PATCH] Warn about duplicate patterns in match.pd

[Richard Biener]

This teaches genmatch to warn about multiple patterns that match
the exact same expressions (you should usually merge those otherwise
the first one wins always).

It also removes some existing (harmless) duplicates (the first one
is the one that should have matched).  This reduces the amount of
generated code.

Bootstrap/regtest running on x86_64-unknown-linux-gnu.

Richard.

2015-10-09  Richard Biener  <rguenther@suse.de>

	* genmatch.c (print_operand): Fix formatting.
	(dt_node::append_simplify): Warn for multiple simplifiers
	that match the same pattern.
	* match.pd (log (exp @0)): Remove duplicates.

Index: gcc/genmatch.c
===================================================================
--- gcc/genmatch.c	(revision 228635)
+++ gcc/genmatch.c	(working copy)
@@ -731,11 +731,10 @@ print_operand (operand *o, FILE *f = std
 
       if (flattened == false)
 	{
-	  putc (' ', f);
 	  for (unsigned i = 0; i < e->ops.length (); ++i)
 	    {
-	      print_operand (e->ops[i], f, flattened);
 	      putc (' ', f);
+	      print_operand (e->ops[i], f, flattened);
 	    }
 	}
       putc (')', f);
@@ -1563,6 +1562,16 @@ dt_node::append_simplify (simplify *s, u
 			  dt_operand **indexes)
 {
   dt_simplify *n = new dt_simplify (s, pattern_no, indexes);
+  for (unsigned i = 0; i < kids.length (); ++i)
+    if (dt_simplify *s2 = dyn_cast <dt_simplify *> (kids[i]))
+      {
+	warning_at (s->match->location, "duplicate pattern");
+	print_operand (s->match, stderr);
+	fprintf (stderr, "\n");
+	warning_at (s2->s->match->location, "previous pattern defined here");
+	print_operand (s2->s->match, stderr);
+	fprintf (stderr, "\n");
+      }
   return append_node (n);
 }
 
Index: gcc/match.pd
===================================================================
--- gcc/match.pd	(revision 228635)
+++ gcc/match.pd	(working copy)
@@ -2169,18 +2181,16 @@ (define_operator_list CEXPI BUILT_IN_CEX
    (mult @0 (POW @1 (negate @2))))
 
  /* Special case, optimize logN(expN(x)) = x.  */
- (for logs (LOG LOG2 LOG10)
-      exps (EXP EXP2 EXP10)
+ (for logs (LOG LOG2 LOG10 LOG10)
+      exps (EXP EXP2 EXP10 POW10)
   (simplify
    (logs (exps @0))
     @0))
  /* Optimize logN(func()) for various exponential functions.  We
     want to determine the value "x" and the power "exponent" in
     order to transform logN(x**exponent) into exponent*logN(x).  */
- (for logs (LOG LOG LOG LOG
-            LOG2 LOG2 LOG2 LOG2
-	    LOG10 LOG10 LOG10 LOG10)
-      exps (EXP EXP2 EXP10 POW10)
+ (for logs (LOG  LOG   LOG   LOG2 LOG2  LOG2  LOG10 LOG10)
+      exps (EXP2 EXP10 POW10 EXP  EXP10 POW10 EXP   EXP2)
   (simplify
    (logs (exps @0))
    (with {