[PATH][GCC][mid-end] Check the alternate cost model just as costs_lt_p

[Jeff Law]

On 05/02/2017 08:34 AM, Tamar Christina wrote:
> Hi all,
> 
> When comparing costs, the rtl function costs_lt_p compares the costs of
> A and B such that if they are the same and we were checking for speed,
> compare the size and use that as determining factor.
> 
> This applies the same principle to the comparison done for the costing
> of expr expansions. Potentially makes -Osize code faster and -Ospeed code
> smaller.
> 
> Bootstrapped on aarch64-none-linux-gnu and x86_64-linux
> and reg-tested on aarch64-none-linux-gnu with no regressions.
> 
> OK for trunk?
> 
> Thanks,
> Tamar
> 
> 
> gcc/
> 2017-04-26  Tamar Christina  <tamar.christina@arm.com>
> 
> 	* expr.c (expand_expr_real_2): Re-cost if previous costs are the same.
OK
jeff