How did you test this? Do we have piglit execution tests that actually
hit this path? I'm assuming you didn't play Serious Sam 3 looking for
rendering errors. ;)
On 09/08/2014 12:21 PM, Matt Turner wrote:
> Helps a handful of programs in Serious Sam 3 that use do-while loops.
>
> instructions in affected programs: 16114 -> 16075 (-0.24%)
> ---
> This patch depends on the save-cfg series.
>
> .../dri/i965/brw_fs_peephole_predicated_break.cpp | 37
> ++++++++++++++++++++++
> 1 file changed, 37 insertions(+)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_fs_peephole_predicated_break.cpp
> b/src/mesa/drivers/dri/i965/brw_fs_peephole_predicated_break.cpp
> index 31b287a..66440d4 100644
> --- a/src/mesa/drivers/dri/i965/brw_fs_peephole_predicated_break.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_fs_peephole_predicated_break.cpp
> @@ -38,6 +38,18 @@
> *
> * This peephole pass removes the IF and ENDIF instructions and predicates
> the
> * BREAK, dropping two instructions from the loop body.
> + *
> + * If the loop was a DO { ... } WHILE loop, it looks like
> + *
> + * loop:
> + * ...
> + * CMP.f0
> + * (+f0) IF
> + * BREAK
> + * ENDIF
> + * WHILE loop
> + *
> + * and we can remove the BREAK instruction and predicate the WHILE.
> */
>
> bool
> @@ -107,6 +119,31 @@ fs_visitor::opt_peephole_predicated_break()
> block = earlier_block;
> }
>
> + /* Now look at the first instruction of the block following the BREAK.
> If
> + * it's a WHILE, we can delete the break, predicate the WHILE, and join
> + * the two basic blocks.
> + */
> + bblock_t *while_block = earlier_block->next();
> + fs_inst *while_inst = (fs_inst *)while_block->start();
> +
> + if (jump_inst->opcode == BRW_OPCODE_BREAK &&
> + while_inst->opcode == BRW_OPCODE_WHILE &&
> + while_inst->predicate == BRW_PREDICATE_NONE) {
> + jump_inst->remove(earlier_block);
> + while_inst->predicate = jump_inst->predicate;
> + while_inst->predicate_inverse = !jump_inst->predicate_inverse;
> +
> + earlier_block->children.make_empty();
> + earlier_block->add_successor(cfg->mem_ctx, while_block);
> +
> + assert(earlier_block->can_combine_with(while_block));
> + earlier_block->combine_with(while_block);
> +
> + earlier_block->next()->parents.make_empty();
> + earlier_block->add_successor(cfg->mem_ctx, earlier_block->next());
> + }
> +
> +
> progress = true;
> }
>
>
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