[PATCH, middle-end]: Prevent invalid transformations for modes with signed zeros.

[Uros Bizjak]

Hello!

Current gcc transforms "x >= 0.0 ? x : -x" into fabs(), which is wrong
for modes with signed zeros [when x equals -0.0, this code returns
-0.0, where fabs() returns 0.0]. Attached patch fixes a couple of
places where this wrong transformation is performed, including
transforms to ABS_EXPR, MAX_EXPR and MIN_EXPR.

2008-03-04  Uros Bizjak  <ubizjak@gmail.com>

	PR middle-end/35456
	* fold-const.c (fold_cond_expr_with_comparison): Prevent
	transformations for modes that have signed zeros.
	* ifcvt.c (noce_try_abs): Ditto.

2008-03-04  Uros Bizjak  <ubizjak@gmail.com>

	PR middle-end/35456
	* gcc.c-torture/execute/pr35456.c: New test.

Patch was bootstrapped and regression tested on i686-pc-linux-gnu. OK
for mainline?

Uros.
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