Use FOR_EACH_IMM_USE_FAST in gimple-ssa-backprop.c

[Jeff Law]

On 10/8/18 11:27 AM, Richard Sandiford wrote:
> As pointed out by Richard in PR63155.  It speeds up the testcase a few %.
> 
> Tested on aarch64-linux-gnu.  OK to install?
> 
> Richard
> 
> 
> 2018-10-08  Richard Sandiford  <richard.sandiford@arm.com>
> 
> gcc/
> 	PR middle-end/63155
> 	* gimple-ssa-backprop.c (backprop::intersect_uses): Use
> 	FOR_EACH_IMM_USE_FAST instead of FOR_EACH_IMM_USE_STMT.
OK.
jeff