[PING] [PATCH, ARM] Improve code-gen for multiple shifted accumulations in array indexing

[Yufeng Zhang]

Ping~

Original posted here:

https://gcc.gnu.org/ml/gcc-patches/2014-06/msg01492.html

Thanks,
Yufeng

On 06/18/14 17:35, Yufeng Zhang wrote:
> This time with patch... Apologize.
>
> Yufeng
>
> On 06/18/14 17:31, Yufeng Zhang wrote:
>> Hi,
>>
>> This patch improves the code-gen of -marm in the case of two-dimensional
>> array access.
>>
>> Given the following code:
>>
>> typedef struct { int x,y,a,b; } X;
>>
>> int
>> f7a(X p[][4], int x, int y)
>> {
>>      return p[x][y].a;
>> }
>>
>> The code-gen on -O2 -marm -mcpu=cortex-a15 is currently
>>
>>            mov     r2, r2, asl #4
>>            add     r1, r2, r1, asl #6
>>            add     r0, r0, r1
>>            ldr     r0, [r0, #8]
>>            bx      lr
>>
>> With the patch, we'll get:
>>
>>            add     r1, r0, r1, lsl #6
>>            add     r2, r1, r2, lsl #4
>>            ldr     r0, [r2, #8]
>>            bx      lr
>>
>> The -mthumb code-gen had been OK.
>>
>> The patch has passed the bootstrapping on cortex-a15 and the
>> arm-none-eabi regtest, with no code-gen difference in spec2k
>> (unfortunately).
>>
>> OK for the trunk?
>>
>> Thanks,
>> Yufeng
>>
>> gcc/
>>
>> 	* config/arm/arm.c (arm_reassoc_shifts_in_address): New declaration
>> 	and new function.
>> 	(arm_legitimize_address): Call the new functions.
>> 	(thumb_legitimize_address): Prefix the declaration with static.
>>
>> gcc/testsuite/
>>
>> 	* gcc.target/arm/shifted-add-1.c: New test.
>> 	* gcc.target/arm/shifted-add-2.c: Ditto.
>>
>>