[PATCH] Handle LSHIFTRT in try_widen_shift_mode

[Jeff Law]

Adam Nemet wrote:
> This adds the LSHIFTRT counterpart of the ASHIFTRT changes from my previous
> patch:
>
>   http://gcc.gnu.org/ml/gcc-patches/2009-07/msg00406.html
>
> The assembly change on gcc.c-torture/execute for MIPS is:
>
>  7 files changed, 187 insertions(+), 324 deletions(-)
>
> and for x86_64:
>
>  6 files changed, 13 insertions(+), 21 deletions(-)
>
> Boostrapped and regtested on {mips64octeon,x86_64}-linux.  Also regtested on
> mipsisa64r2-elf.
>
> OK after the previous patch?
>
> Adam
>
>
> 	* combine.c (try_widen_shift_mode) <LSHIFTRT>: Allow widening if the
> 	high-order bits are zero.
>   
OK.
jeff