re PR c/10175 (-Wunreachable-code doesn't work for single lines)

re PR c/10175 (-Wunreachable-code doesn't work for single lines)

2003-04-16  Roger Sayle  <roger@eyesopen.com>

	* c-semantics.c (find_reachable_label): New function to find a
	potentially reachable label in an expression.
	(expand_unreachable_if_stmt): Similar to expand_if_stmt but
	assumes the start of the IF_STMT is unreachable (dead) code.
	(expand_unreachable_stmt): Similar to expand_stmt but assumes
	the start of the statement list is unreachable (dead) code.
	(genrtl_if_stmt):  If the controlling expression of the IF
	is constant, use expand_unreachable_stmt for the THEN or ELSE
	clause as appropriate.
	(genrtl_switch_stmt):  Use expand_unreachable_stmt to expand
	the body of a SWITCH statement.
	(expand_stmt): The code immediately following a "return",
	"break", "continue" or "goto" is unreachable.
	* Makefile.in (c-semantics.o): Depend upon tree-inline.h.

	* gcc.dg/Wunreachable-5.c: New test case for PR c/10175.
	* gcc.c-torture/execute/medce-1.c: New test case.
	* gcc.c-torture/execute/medce-2.c: New test case.

From-SVN: r65715