2012-08-21  Marc Glisse  <marc.glisse@inria.fr>

gcc/
	* fold-const.c (fold_ternary_loc): Detect identity permutations.
	Canonicalize permutations more.
	* tree-ssa-forwprop.c (is_combined_permutation_identity): New function.
	(simplify_permutation): Likewise.
	(ssa_forward_propagate_and_combine): Call it.

gcc/testsuite/
	* gcc.dg/tree-ssa/forwprop-19.c: New testcase.
	* gcc.dg/fold-perm.c: Likewise.

From-SVN: r190561