[Mesa-dev] [PATCH 2/2] i965/cfg: Remove if_block/else_block.

[Jason Ekstrand]

One more comment: These and the other two CFG fixes should probably be
promoted to stable.

On Tue, Nov 11, 2014 at 7:37 AM, Jason Ekstrand <jason at jlekstrand.net>
wrote:

> Two questions: Does it fix the bug? And did you ever figure out what was
> going on there?
> On Nov 11, 2014 6:58 AM, "Jason Ekstrand" <jason at jlekstrand.net> wrote:
>
>> Both patches are Reviewed-by: Jason Ekstrand <jason.ekstrand at intel.com>
>> On Nov 10, 2014 11:37 PM, "Matt Turner" <mattst88 at gmail.com> wrote:
>>
>>> I used these in the SEL peephole, but they require extra tracking and
>>> fix ups. The SEL peephole can pretty easily find the blocks it needs
>>> without these.
>>> ---
>>>  src/mesa/drivers/dri/i965/brw_cfg.cpp               | 15 +--------------
>>>  src/mesa/drivers/dri/i965/brw_cfg.h                 |  8 --------
>>>  src/mesa/drivers/dri/i965/brw_dead_control_flow.cpp |  8 --------
>>>  3 files changed, 1 insertion(+), 30 deletions(-)
>>>
>>> diff --git a/src/mesa/drivers/dri/i965/brw_cfg.cpp
>>> b/src/mesa/drivers/dri/i965/brw_cfg.cpp
>>> index bb49a0a..02149e2 100644
>>> --- a/src/mesa/drivers/dri/i965/brw_cfg.cpp
>>> +++ b/src/mesa/drivers/dri/i965/brw_cfg.cpp
>>> @@ -51,8 +51,7 @@ link(void *mem_ctx, bblock_t *block)
>>>  }
>>>
>>>  bblock_t::bblock_t(cfg_t *cfg) :
>>> -   cfg(cfg), start_ip(0), end_ip(0), num(0),
>>> -   if_block(NULL), else_block(NULL)
>>> +   cfg(cfg), start_ip(0), end_ip(0), num(0)
>>>  {
>>>     instructions.make_empty();
>>>     parents.make_empty();
>>> @@ -136,7 +135,6 @@ bblock_t::combine_with(bblock_t *that)
>>>     }
>>>
>>>     this->end_ip = that->end_ip;
>>> -   this->else_block = that->else_block;
>>>     this->instructions.append_list(&that->instructions);
>>>
>>>     this->cfg->remove_block(that);
>>> @@ -238,17 +236,6 @@ cfg_t::cfg_t(exec_list *instructions)
>>>           assert(cur_if->end()->opcode == BRW_OPCODE_IF);
>>>           assert(!cur_else || cur_else->end()->opcode ==
>>> BRW_OPCODE_ELSE);
>>>
>>> -         cur_if->if_block = cur_if;
>>> -         cur_if->else_block = cur_else;
>>> -
>>> -        if (cur_else) {
>>> -            cur_else->if_block = cur_if;
>>> -            cur_else->else_block = cur_else;
>>> -         }
>>> -
>>> -         cur->if_block = cur_if;
>>> -         cur->else_block = cur_else;
>>> -
>>>          /* Pop the stack so we're in the previous if/else/endif */
>>>          cur_if = pop_stack(&if_stack);
>>>          cur_else = pop_stack(&else_stack);
>>> diff --git a/src/mesa/drivers/dri/i965/brw_cfg.h
>>> b/src/mesa/drivers/dri/i965/brw_cfg.h
>>> index 388d29e..48bca9f 100644
>>> --- a/src/mesa/drivers/dri/i965/brw_cfg.h
>>> +++ b/src/mesa/drivers/dri/i965/brw_cfg.h
>>> @@ -89,14 +89,6 @@ struct bblock_t {
>>>     struct exec_list parents;
>>>     struct exec_list children;
>>>     int num;
>>> -
>>> -   /* If the current basic block ends in an IF or ELSE instruction,
>>> these will
>>> -    * point to the basic blocks containing the other associated
>>> instruction.
>>> -    *
>>> -    * Otherwise they are NULL.
>>> -    */
>>> -   struct bblock_t *if_block;
>>> -   struct bblock_t *else_block;
>>>  };
>>>
>>>  static inline struct backend_instruction *
>>> diff --git a/src/mesa/drivers/dri/i965/brw_dead_control_flow.cpp
>>> b/src/mesa/drivers/dri/i965/brw_dead_control_flow.cpp
>>> index 4c9d7b9..03f838d 100644
>>> --- a/src/mesa/drivers/dri/i965/brw_dead_control_flow.cpp
>>> +++ b/src/mesa/drivers/dri/i965/brw_dead_control_flow.cpp
>>> @@ -85,7 +85,6 @@ dead_control_flow_eliminate(backend_visitor *v)
>>>           }
>>>
>>>           if (else_inst) {
>>> -            else_block->if_block->else_block = NULL;
>>>              else_inst->remove(else_block);
>>>           }
>>>
>>> @@ -102,13 +101,6 @@ dead_control_flow_eliminate(backend_visitor *v)
>>>           if (earlier_block &&
>>> earlier_block->can_combine_with(later_block)) {
>>>              earlier_block->combine_with(later_block);
>>>
>>> -            foreach_block (block, v->cfg) {
>>> -               if (block->if_block == later_block)
>>> -                  block->if_block = earlier_block;
>>> -               if (block->else_block == later_block)
>>> -                  block->else_block = earlier_block;
>>> -            }
>>> -
>>>              /* If ENDIF was in its own block, then we've now deleted it
>>> and
>>>               * merged the two surrounding blocks, the latter of which
>>> the
>>>               * __next block pointer was pointing to.
>>> --
>>> 2.0.4
>>>
>>>
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