re PR tree-optimization/42108 (50% performance regression)

re PR tree-optimization/42108 (50% performance regression)

2009-12-19  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/42108
	* tree-ssa-sccvn.c (last_vuse_ptr): New variable.
	(vn_reference_lookup_2): Update last seen VUSE.
	(vn_reference_lookup_3): Avoid updating last seen VUSE after
	translating.
	(visit_reference_op_load): Use last seen VUSE from the first
	lookup when entering into the table.

	* gfortran.dg/pr42108.f90: New testcase.

From-SVN: r155360