combine: Fix PR83393

combine: Fix PR83393

In move_deaths we move a REG_DEAD note if the instruction combination
has extended the lifetime of a register so that the existing note is
no longer valid.  We find that note using reg_stat, but what that finds
can refer to a later insn.  If so, we cannot use the cached value.  This
patch implements that.

	PR rtl-optimization/83393
	* combine.c (move_deaths): If reg_stat points to a too new insn in
	last_death, do not use it: find the proper insn instead.

gcc/testsuite/
	PR rtl-optimization/83393
	* gcc.dg/pr83393.c: New testcase.

From-SVN: r255606