Some minor HONOR_NANS improvements to match.pd

Tweak the constant folding of X CMP X in when X can't be a NaN.

2022-03-16  Roger Sayle  <roger@nextmovesoftware.com>

gcc/ChangeLog
	* match.pd (X CMP X -> true): Test tree_expr_maybe_nan_p
	instead of HONOR_NANS.
	(X LTGT X -> false): Enable if X is not tree_expr_maybe_nan_p, as
	this can't trap/signal.

diff --git a/gcc/match.pd b/gcc/match.pd
index 7d619f4..6d691d3 100644 (file)
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -4743,7 +4743,7 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
  (simplify
   (cmp @0 @0)
   (if (! FLOAT_TYPE_P (TREE_TYPE (@0))
-       || ! HONOR_NANS (@0))
+       || ! tree_expr_maybe_nan_p (@0))
    { constant_boolean_node (true, type); }
    (if (cmp != EQ_EXPR
        /* With -ftrapping-math conversion to EQ loses an exception.  */
@@ -4755,7 +4755,7 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
   (cmp @0 @0)
   (if (cmp != NE_EXPR
        || ! FLOAT_TYPE_P (TREE_TYPE (@0))
-       || ! HONOR_NANS (@0))
+       || ! tree_expr_maybe_nan_p (@0))
    { constant_boolean_node (false, type); })))
 (for cmp (unle unge uneq)
  (simplify
@@ -4767,7 +4767,7 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
   (unordered @0 @0)))
 (simplify
  (ltgt @0 @0)
- (if (!flag_trapping_math)
+ (if (!flag_trapping_math || !tree_expr_maybe_nan_p (@0))
   { constant_boolean_node (false, type); }))
 
 /* x == ~x -> false */