🚀 go-pugleaf

For the program:

	double normalize(x) double x; { return x ? x : 0; }
	main() { printf("%g\n", normalize(-0.0)); }

GCC 2.2.2 (sparc, SunOS 4.1.2, with the -O option) generates code that outputs
`-0'.  It should output `0'.  The problem is that X?X:0 is being optimized to
X; but this optimization is incorrect when X is -0.0, because -0.0?-0.0:0
should yield 0.  Here is a patch.

Tue Aug 11 04:02:51 1992  Paul Eggert  (eggert@twinsun.com)

	* fold-const.c (fold):  Don't fold (A op B ? A : C) if A is IEEE
	floating point, because A might be -0.0 or NaN.

===================================================================
RCS file: fold-const.c,v
retrieving revision 2.2.2.1
diff -c -r2.2.2.1 fold-const.c
*** fold-const.c	1992/07/03 19:36:20	2.2.2.1
--- fold-const.c	1992/08/11 04:02:51
***************
*** 3729,3737 ****
  
        /* If we have A op B ? A : C, we may be able to convert this to a
  	 simpler expression, depending on the operation and the values
! 	 of B and C.  */
  
        if (TREE_CODE_CLASS (TREE_CODE (arg0)) == '<'
  	  && operand_equal_for_comparison_p (TREE_OPERAND (arg0, 0),
  					     arg1, TREE_OPERAND (arg0, 1)))
  	{
--- 3729,3740 ----
  
        /* If we have A op B ? A : C, we may be able to convert this to a
  	 simpler expression, depending on the operation and the values
! 	 of B and C.  IEEE floating point prevents this though,
! 	 because A or B might be -0.0 or a NaN.  */
  
        if (TREE_CODE_CLASS (TREE_CODE (arg0)) == '<'
+ 	  && (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
+ 	      || TREE_CODE (TREE_TYPE (TREE_OPERAND (arg0, 0))) != REAL_TYPE)
  	  && operand_equal_for_comparison_p (TREE_OPERAND (arg0, 0),
  					     arg1, TREE_OPERAND (arg0, 1)))
  	{