re PR tree-optimization/23109 (compiler generates wrong code leading to spurious...

re PR tree-optimization/23109 (compiler generates wrong code leading to spurious division by zero with -funsafe-math-optimizations (instead of -ftrapping-math))

2005-08-01  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/23109
	* tree-ssa-math-opts.c (execute_cse_reciprocals_1):
	If trapping math is in effect, use post-dominator information
	to check if we'd in any case reach a trapping point before
	doing the reciprocal insertion.
	(execute_cse_reciprocals): Compute post-dominators, if necessary.
	* tree-ssa-loop-im.c (determine_invariantness_stmt): RDIV
	expressions are invariant only if trapping math is not in effect.

From-SVN: r102627