gcc/
	* dse.c (find_shift_sequence): Allow word as well as subword shifts.
	Do the tentative shift expansion with the DF_NO_INSN_RESCAN flag set.
	Fix the call to insn_rtx_cost.  Skip access sizes that require a
	real truncation of the store register.  Use convert_move instead
	of gen_lowpart when narrowing the result.
	(replace_read): Use convert_move instead of gen_lowpart when
	narrowing the store rhs.

gcc/testsuite/
	* gcc.target/mips/dse-1.c: New test.

From-SVN: r128530