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/*
* Copyright © 2015 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.
*
*/
/** @file brw_vec4_cmod_propagation.cpp
*
* Really similar to brw_fs_cmod_propagation but adapted to vec4 needs. Check
* brw_fs_cmod_propagation for further details on the rationale behind this
* optimization.
*/
#include "brw_vec4.h"
#include "brw_cfg.h"
#include "brw_eu.h"
namespace brw {
static bool
writemasks_incompatible(const vec4_instruction *earlier,
const vec4_instruction *later)
{
return (earlier->dst.writemask != WRITEMASK_X &&
earlier->dst.writemask != WRITEMASK_XYZW) ||
(earlier->dst.writemask == WRITEMASK_XYZW &&
later->src[0].swizzle != BRW_SWIZZLE_XYZW) ||
(later->dst.writemask & ~earlier->dst.writemask) != 0;
}
static bool
opt_cmod_propagation_local(bblock_t *block)
{
bool progress = false;
int ip = block->end_ip + 1;
foreach_inst_in_block_reverse_safe(vec4_instruction, 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 != VGRF && inst->src[0].file != ATTR &&
inst->src[0].file != UNIFORM))
continue;
/* An ABS source modifier can only be handled when processing a compare
* with a value other than zero.
*/
if (inst->src[0].abs &&
(inst->opcode != BRW_OPCODE_CMP || inst->src[1].is_zero()))
continue;
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_MOV &&
inst->conditional_mod != BRW_CONDITIONAL_NZ)
continue;
bool read_flag = false;
foreach_inst_in_block_reverse_starting_from(vec4_instruction, scan_inst, inst) {
/* A CMP with a second source of zero can match with anything. A CMP
* with a second source that is not zero can only match with an ADD
* instruction.
*/
if (inst->opcode == BRW_OPCODE_CMP && !inst->src[1].is_zero()) {
bool negate;
if (scan_inst->opcode != BRW_OPCODE_ADD)
goto not_match;
if (writemasks_incompatible(scan_inst, inst))
goto not_match;
/* A CMP is basically a subtraction. The result of the
* subtraction must be the same as the result of the addition.
* This means that one of the operands must be negated. So (a +
* b) vs (a == -b) or (a + -b) vs (a == b).
*/
if ((inst->src[0].equals(scan_inst->src[0]) &&
inst->src[1].negative_equals(scan_inst->src[1])) ||
(inst->src[0].equals(scan_inst->src[1]) &&
inst->src[1].negative_equals(scan_inst->src[0]))) {
negate = false;
} else if ((inst->src[0].negative_equals(scan_inst->src[0]) &&
inst->src[1].equals(scan_inst->src[1])) ||
(inst->src[0].negative_equals(scan_inst->src[1]) &&
inst->src[1].equals(scan_inst->src[0]))) {
negate = true;
} else {
goto not_match;
}
if (scan_inst->exec_size != inst->exec_size ||
scan_inst->group != inst->group)
goto not_match;
/* From the Sky Lake PRM Vol. 7 "Assigning Conditional Mods":
*
* * Note that the [post condition signal] bits generated at
* the output of a compute are before the .sat.
*
* So we don't have to bail if scan_inst has saturate.
*/
/* Otherwise, try propagating the conditional. */
const enum brw_conditional_mod cond =
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 (regions_overlap(inst->src[0], inst->size_read(0),
scan_inst->dst, scan_inst->size_written)) {
if ((scan_inst->predicate && scan_inst->opcode != BRW_OPCODE_SEL) ||
scan_inst->dst.offset != inst->src[0].offset ||
writemasks_incompatible(scan_inst, inst) ||
scan_inst->exec_size != inst->exec_size ||
scan_inst->group != inst->group) {
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;
}
/* The conditional mod of the CMP/CMPN instructions behaves
* specially because the flag output is not calculated from the
* result of the instruction, but the other way around, which
* means that even if the condmod to propagate and the condmod
* from the CMP instruction are the same they will in general give
* different results because they are evaluated based on different
* inputs.
*/
if (scan_inst->opcode == BRW_OPCODE_CMP ||
scan_inst->opcode == BRW_OPCODE_CMPN)
break;
/* From the Sky Lake PRM Vol. 7 "Assigning Conditional Mods":
*
* * Note that the [post condition signal] bits generated at
* the output of a compute are before the .sat.
*/
if (scan_inst->saturate)
break;
/* From the Sky Lake PRM, Vol 2a, "Multiply":
*
* "When multiplying integer data types, if one of the sources
* is a DW, the resulting full precision data is stored in
* the accumulator. However, if the destination data type is
* either W or DW, the low bits of the result are written to
* the destination register and the remaining high bits are
* discarded. This results in undefined Overflow and Sign
* flags. Therefore, conditional modifiers and saturation
* (.sat) cannot be used in this case.
*
* We just disallow cmod propagation on all integer multiplies.
*/
if (!brw_reg_type_is_floating_point(scan_inst->dst.type) &&
scan_inst->opcode == BRW_OPCODE_MUL)
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;
}
not_match:
if (scan_inst->writes_flag())
break;
read_flag = read_flag || scan_inst->reads_flag();
}
}
return progress;
}
bool
vec4_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;
}
} /* namespace brw */
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