re PR middle-end/48770 (wrong code with -O -fprofile-arcs -fPIC -fno-dce -fno-forward...

re PR middle-end/48770 (wrong code with -O -fprofile-arcs -fPIC -fno-dce -fno-forward-propagate -fno-tree-forwprop)

	PR middle-end/48770
	* reload.h (reload): Change to return a bool.
	* ira.c (ira): If requested by reload, run a fast DCE pass after
	reload has completed.  Fix comment typo.
	* reload1.c (need_dce): New file scoped static.
	(reload): Set reload_completed here.  Return whether or not a DCE
	pass after reload is needed.
	(delete_dead_insn): Set need_dce as needed.

	PR middle-end/48770
	* gcc.dg/pr48770.c: New test.

From-SVN: r175353