re PR tree-optimization/87977 (ICE: verify_ssa failed (error: definition in block 4 follows the use))

	PR tree-optimization/87977
	* tree-ssa-math-opts.c (optimize_recip_sqrt): Don't reuse division
	stmt, build a new one and replace the old one with it.  Formatting fix.
	Call release_ssa_name (x) if !has_other_use and !delete_div.
	(pass_cse_reciprocals::execute): Before calling optimize_recip_sqrt
	verify lhs of stmt is still def.

	* gcc.dg/recip_sqrt_mult_1.c: Add -fcompare-debug to dg-options.
	* gcc.dg/recip_sqrt_mult_2.c: Likewise.
	* gcc.dg/recip_sqrt_mult_3.c: Likewise.
	* gcc.dg/recip_sqrt_mult_4.c: Likewise.
	* gcc.dg/recip_sqrt_mult_5.c: Likewise.

From-SVN: r266098