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i965/fs: Extend predicated break pass to predicate WHILE.

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Helps a handful of programs in Serious Sam 3 that use do-while loops.

instructions in affected programs:     16114 -> 16075 (-0.24%)

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
This commit is contained in:
Matt Turner 2014-09-04 13:25:15 -07:00
parent 6e7d36fd2c
commit d13bcdb3a9
1 changed files with 36 additions and 0 deletions
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36
src/mesa/drivers/dri/i965/brw_fs_peephole_predicated_break.cpp
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@ -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 +119,30 @@ 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;
}