* Makefile.in: rtlanal.o now depends upon real.h.

	* flags.h [flag_signaling_nans]: New flag.
	[HONOR_SNANS]: New macro.

	* toplev.c [flag_signaling_nans]: Initialize to false.
        (f_options): Add processing for "-fsignaling-nans".
	(set_fast_math_flags): Clear flag_signaling_nans with -ffast-math.
	(process_options): flag_signaling_nans implies flag_trapping_math.

	* c-common.c (cb_register_builtins): Define __SUPPORT_SNAN__
	when -fsignaling-nans.  First step to implementing WG14's N965.

	* fold-const.c (fold) [MULT_EXPR]: Conditionalize transforming
	1.0 * x into x, and -1.0 * x into -x on !HONOR_SNANS.
	[RDIV_EXPR]: Conditionalize x/1.0 into x on !HONOR_SNANS.

	* simplify-rtx.c (simplify_relational_operation): Conditionalize
	transforming abs(x) < 0.0 into false on !HONOR_SNANS.

	* rtlanal.c: #include real.c for TARGET_FLOAT_FORMAT definitions
	required by HONOR_SNANS.  (may_trap_p): Floating point DIV, MOD,
	UDIV, UMOD, GE, GT, LE, LT and COMPARE may always trap with
	-fsignaling_nans.  EQ and NE only trap for flag_signaling_nans
	not flag_trapping_math (i.e. HONOR_SNANS but not HONOR_NANS).

	* doc/invoke.texi: Document new -fsignaling-nans compiler option.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@55804 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 8 insertions, 11 deletions

diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 3dafe0afb31..49c53cc0857 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -5476,16 +5476,13 @@ fold (expr)
 	      && !HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg0)))
 	      && real_zerop (arg1))
 	    return omit_one_operand (type, arg1, arg0);
-	  /* In IEEE floating point, x*1 is not equivalent to x for snans.
-	     However, ANSI says we can drop signals,
-	     so we can do this anyway.  */
-	  if (real_onep (arg1))
+	  /* In IEEE floating point, x*1 is not equivalent to x for snans.  */
+	  if (!HONOR_SNANS (TYPE_MODE (TREE_TYPE (arg0)))
+	      && real_onep (arg1))
 	    return non_lvalue (convert (type, arg0));
 
-	  /* Transform x * -1.0 into -x.  This should be safe for NaNs,
-	     signed zeros and signed infinities, but is currently
-	     restricted to "unsafe math optimizations" just in case.  */
-	  if (flag_unsafe_math_optimizations
+	  /* Transform x * -1.0 into -x.  */
+	  if (!HONOR_SNANS (TYPE_MODE (TREE_TYPE (arg0)))
 	      && real_minus_onep (arg1))
 	    return fold (build1 (NEGATE_EXPR, type, arg0));
 
@@ -5620,9 +5617,9 @@ fold (expr)
 	return fold (build (RDIV_EXPR, type, TREE_OPERAND (arg0, 0),
 			    TREE_OPERAND (arg1, 0)));
 
-      /* In IEEE floating point, x/1 is not equivalent to x for snans.
-	 However, ANSI says we can drop signals, so we can do this anyway.  */
-      if (real_onep (arg1))
+      /* In IEEE floating point, x/1 is not equivalent to x for snans.  */
+      if (!HONOR_SNANS (TYPE_MODE (TREE_TYPE (arg0)))
+	  && real_onep (arg1))
 	return non_lvalue (convert (type, arg0));
 
       /* If ARG1 is a constant, we can convert this to a multiply by the