PR tree-optimization/44508

	PR tree-optimization/44508
	* tree-ssa-propagate.h (substitute_and_fold): Add DO_DCE
	argument.
	* tree-ssa-propagate.c (substitute_and_fold): If !DO_DCE,
	don't eliminate trivially dead stmts.
	* tree-vrp.c (vrp_finalize): Pass false as last argument
	to substitute_and_fold.
	* tree-ssa-copy.c (fini_copy_prop): Pass true as last argument
	to substitute_and_fold.
	* tree-ssa-ccp.c (ccp_finalize): Likewise.

	* gcc.dg/tree-ssa/pr21086.c: Adjust.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@160749 138bc75d-0d04-0410-961f-82ee72b054a4