[Mesa-dev] [PATCH 18/20] i965/fs: Preserve CFG in the SEL peephole.

[Matt Turner]

On Mon, Aug 18, 2014 at 8:34 AM, Pohjolainen, Topi
<topi.pohjolainen at intel.com> wrote:
> On Thu, Jul 24, 2014 at 07:54:25PM -0700, Matt Turner wrote:
>> ---
>>  src/mesa/drivers/dri/i965/brw_fs_sel_peephole.cpp | 15 +++++++++------
>>  1 file changed, 9 insertions(+), 6 deletions(-)
>>
>> diff --git a/src/mesa/drivers/dri/i965/brw_fs_sel_peephole.cpp b/src/mesa/drivers/dri/i965/brw_fs_sel_peephole.cpp
>> index d64cd98..f609138 100644
>> --- a/src/mesa/drivers/dri/i965/brw_fs_sel_peephole.cpp
>> +++ b/src/mesa/drivers/dri/i965/brw_fs_sel_peephole.cpp
>> @@ -212,23 +212,26 @@ fs_visitor::opt_peephole_sel()
>>        if (brw->gen == 6 && if_inst->conditional_mod) {
>>           fs_inst *cmp_inst = CMP(reg_null_d, if_inst->src[0], if_inst->src[1],
>>                                   if_inst->conditional_mod);
>> -         if_inst->insert_before(cmp_inst);
>> +         if_inst->insert_before(block, cmp_inst);
>>        }
>>
>> +      bblock_t *then_block = (bblock_t *)block->link.next;
>> +      bblock_t *else_block = (bblock_t *)block->else_block->link.next;
>
> Isn't this a pointer to the endif-block? I thought else-block would be
>
>          bblock_t *else_block = (bblock_t *)block->then_block->link.next;
>
> or simply just
>
>          bblock_t *else_block = (bblock_t *)block->else_block;

It's the block immediately following the ELSE instruction (containing
the MOVs). E.g.,

B0: ...
    IF
B1: MOV
    MOV
    ELSE
B2: MOV
    MOV
B3: ENDIF
    ...

then_block is B1, and else_block is B2. I can name them something else
if that would make it clearer.