backport: re PR tree-optimization/32044 (final value replacement too aggressive for...

backport: re PR tree-optimization/32044 (final value replacement too aggressive for e.g. targets with no native div/mod insns)

2009-05-26  Richard Guenther  <rguenther@suse.de>

	Backport from mainline
	2008-12-12  Zdenek Dvorak  <ook@ucw.cz>

	PR tree-optimization/32044
	* tree-scalar-evolution.h (expression_expensive_p): Declare.
	* tree-scalar-evolution.c (expression_expensive_p): New function.
	(scev_const_prop): Avoid introducing expensive expressions.
	* tree-ssa-loop-ivopts.c (may_eliminate_iv): Ditto.

	* gcc.dg/pr34027-1.c: Change outcome.
	* gcc.dg/tree-ssa/pr32044.c: New test.

From-SVN: r147865