re PR tree-optimization/60280 (gcc.target/arm/ivopts.c and gcc.target/arm/ivopts...

re PR tree-optimization/60280 (gcc.target/arm/ivopts.c and gcc.target/arm/ivopts-2.c failed caused by preserving loop structure.)

	PR target/60280
	* tree-cfgcleanup.c (tree_forwarder_block_p): Protect loop
	preheaders and latches only if requested.  Fix latch if it
	is removed.
	* tree-ssa-dom.c (tree_ssa_dominator_optimize): Set
	LOOPS_HAVE_PREHEADERS.

	PR target/60280
	* gnat.dg/renaming5.adb: Change to two expected gotos.
	* gcc.dg/tree-ssa/pr21559.c: Change back to three expected
	jump threads.
	* gcc.dg/tree-prof/update-loopch.c: Check two "Invalid sum"
	messages for removed basic block.
	* gcc.dg/tree-ssa/ivopt_1.c: Fix unreliable scanning string.
	* gcc.dg/tree-ssa/ivopt_2.c: Ditto.
	* gcc.dg/tree-ssa/ivopt_3.c: Ditto.
	* gcc.dg/tree-ssa/ivopt_4.c: Ditto.

From-SVN: r208165