[Mesa-dev] [PATCH 5/9] i965: Combine assembly annotations if possible.

[Matt Turner]

On Mon, Oct 26, 2015 at 5:08 AM, Pohjolainen, Topi
<topi.pohjolainen at intel.com> wrote:
> On Wed, Oct 21, 2015 at 03:58:13PM -0700, Matt Turner wrote:
>> Often annotations are identical between sets of consecutive
>> instructions. We can perhaps avoid some memory allocations by reusing
>> the previous annotation.
>> ---
>>  src/mesa/drivers/dri/i965/intel_asm_annotation.c | 19 ++++++++++++++-----
>>  1 file changed, 14 insertions(+), 5 deletions(-)
>>
>> diff --git a/src/mesa/drivers/dri/i965/intel_asm_annotation.c b/src/mesa/drivers/dri/i965/intel_asm_annotation.c
>> index f87a9bb..58830db 100644
>> --- a/src/mesa/drivers/dri/i965/intel_asm_annotation.c
>> +++ b/src/mesa/drivers/dri/i965/intel_asm_annotation.c
>> @@ -112,6 +112,20 @@ void annotate(const struct brw_device_info *devinfo,
>>        ann->block_start = cfg->blocks[annotation->cur_block];
>>     }
>>
>> +   if (bblock_end(cfg->blocks[annotation->cur_block]) == inst) {
>> +      ann->block_end = cfg->blocks[annotation->cur_block];
>> +      annotation->cur_block++;
>> +   }
>> +
>> +   /* Merge this annotation with the previous if possible. */
>> +   struct annotation *prev = &annotation->ann[annotation->ann_count - 2];
>
> What guarantees that annotation->ann_count is always at least two at this
> point?

Nothing! Good catch :)

I'll add "annotation->ann_count >= 2 &&" as the first part of the
conditional immediately below.

>> +   if (ann->ir == prev->ir &&
>> +       ann->annotation == prev->annotation &&
>> +       ann->block_start == NULL) {
>> +      annotation->ann_count--;
>> +      return;
>> +   }
>> +