0,0 → 1,170 |
/* |
* Copyright © 2014 Intel Corporation |
* |
* Permission is hereby granted, free of charge, to any person obtaining a |
* copy of this software and associated documentation files (the "Software"), |
* to deal in the Software without restriction, including without limitation |
* the rights to use, copy, modify, merge, publish, distribute, sublicense, |
* and/or sell copies of the Software, and to permit persons to whom the |
* Software is furnished to do so, subject to the following conditions: |
* |
* The above copyright notice and this permission notice (including the next |
* paragraph) shall be included in all copies or substantial portions of the |
* Software. |
* |
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING |
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS |
* IN THE SOFTWARE. |
*/ |
|
#include "brw_fs.h" |
#include "brw_fs_live_variables.h" |
#include "brw_cfg.h" |
|
/** @file brw_fs_cmod_propagation.cpp |
* |
* Implements a pass that propagates the conditional modifier from a CMP x 0.0 |
* instruction into the instruction that generated x. For instance, in this |
* sequence |
* |
* add(8) g70<1>F g69<8,8,1>F 4096F |
* cmp.ge.f0(8) null g70<8,8,1>F 0F |
* |
* we can do the comparison as part of the ADD instruction directly: |
* |
* add.ge.f0(8) g70<1>F g69<8,8,1>F 4096F |
* |
* If there had been a use of the flag register and another CMP using g70 |
* |
* add.ge.f0(8) g70<1>F g69<8,8,1>F 4096F |
* (+f0) sel(8) g71<F> g72<8,8,1>F g73<8,8,1>F |
* cmp.ge.f0(8) null g70<8,8,1>F 0F |
* |
* we can recognize that the CMP is generating the flag value that already |
* exists and therefore remove the instruction. |
*/ |
|
static bool |
opt_cmod_propagation_local(bblock_t *block) |
{ |
bool progress = false; |
int ip = block->end_ip + 1; |
|
foreach_inst_in_block_reverse_safe(fs_inst, inst, block) { |
ip--; |
|
if ((inst->opcode != BRW_OPCODE_AND && |
inst->opcode != BRW_OPCODE_CMP && |
inst->opcode != BRW_OPCODE_MOV) || |
inst->predicate != BRW_PREDICATE_NONE || |
!inst->dst.is_null() || |
inst->src[0].file != GRF || |
inst->src[0].abs) |
continue; |
|
/* Only an AND.NZ can be propagated. Many AND.Z instructions are |
* generated (for ir_unop_not in fs_visitor::emit_bool_to_cond_code). |
* Propagating those would require inverting the condition on the CMP. |
* This changes both the flag value and the register destination of the |
* CMP. That result may be used elsewhere, so we can't change its value |
* on a whim. |
*/ |
if (inst->opcode == BRW_OPCODE_AND && |
!(inst->src[1].is_one() && |
inst->conditional_mod == BRW_CONDITIONAL_NZ && |
!inst->src[0].negate)) |
continue; |
|
if (inst->opcode == BRW_OPCODE_CMP && !inst->src[1].is_zero()) |
continue; |
|
if (inst->opcode == BRW_OPCODE_MOV && |
inst->conditional_mod != BRW_CONDITIONAL_NZ) |
continue; |
|
bool read_flag = false; |
foreach_inst_in_block_reverse_starting_from(fs_inst, scan_inst, inst, |
block) { |
if (scan_inst->overwrites_reg(inst->src[0])) { |
if (scan_inst->is_partial_write() || |
scan_inst->dst.reg_offset != inst->src[0].reg_offset) |
break; |
|
/* CMP's result is the same regardless of dest type. */ |
if (inst->conditional_mod == BRW_CONDITIONAL_NZ && |
scan_inst->opcode == BRW_OPCODE_CMP && |
(inst->dst.type == BRW_REGISTER_TYPE_D || |
inst->dst.type == BRW_REGISTER_TYPE_UD)) { |
inst->remove(block); |
progress = true; |
break; |
} |
|
/* If the AND wasn't handled by the previous case, it isn't safe |
* to remove it. |
*/ |
if (inst->opcode == BRW_OPCODE_AND) |
break; |
|
/* Comparisons operate differently for ints and floats */ |
if (scan_inst->dst.type != inst->dst.type && |
(scan_inst->dst.type == BRW_REGISTER_TYPE_F || |
inst->dst.type == BRW_REGISTER_TYPE_F)) |
break; |
|
/* If the instruction generating inst's source also wrote the |
* flag, and inst is doing a simple .nz comparison, then inst |
* is redundant - the appropriate value is already in the flag |
* register. Delete inst. |
*/ |
if (inst->conditional_mod == BRW_CONDITIONAL_NZ && |
!inst->src[0].negate && |
scan_inst->writes_flag()) { |
inst->remove(block); |
progress = true; |
break; |
} |
|
/* Otherwise, try propagating the conditional. */ |
enum brw_conditional_mod cond = |
inst->src[0].negate ? brw_swap_cmod(inst->conditional_mod) |
: inst->conditional_mod; |
|
if (scan_inst->can_do_cmod() && |
((!read_flag && scan_inst->conditional_mod == BRW_CONDITIONAL_NONE) || |
scan_inst->conditional_mod == cond)) { |
scan_inst->conditional_mod = cond; |
inst->remove(block); |
progress = true; |
} |
break; |
} |
|
if (scan_inst->writes_flag()) |
break; |
|
read_flag = read_flag || scan_inst->reads_flag(); |
} |
} |
|
return progress; |
} |
|
bool |
fs_visitor::opt_cmod_propagation() |
{ |
bool progress = false; |
|
foreach_block_reverse(block, cfg) { |
progress = opt_cmod_propagation_local(block) || progress; |
} |
|
if (progress) |
invalidate_live_intervals(); |
|
return progress; |
} |