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7463d50580
No shader-db change on Sky Lake. Reviewed-by: Matt Turner <mattst88@gmail.com> Cc: mesa-stable@lists.freedesktop.org
208 lines
7.9 KiB
C++
208 lines
7.9 KiB
C++
/*
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* Copyright © 2014 Intel Corporation
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice (including the next
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* paragraph) shall be included in all copies or substantial portions of the
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* Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*/
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#include "brw_fs.h"
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#include "brw_cfg.h"
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#include "brw_eu.h"
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/** @file brw_fs_cmod_propagation.cpp
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*
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* Implements a pass that propagates the conditional modifier from a CMP x 0.0
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* instruction into the instruction that generated x. For instance, in this
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* sequence
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*
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* add(8) g70<1>F g69<8,8,1>F 4096F
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* cmp.ge.f0(8) null g70<8,8,1>F 0F
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*
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* we can do the comparison as part of the ADD instruction directly:
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*
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* add.ge.f0(8) g70<1>F g69<8,8,1>F 4096F
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*
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* If there had been a use of the flag register and another CMP using g70
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*
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* add.ge.f0(8) g70<1>F g69<8,8,1>F 4096F
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* (+f0) sel(8) g71<F> g72<8,8,1>F g73<8,8,1>F
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* cmp.ge.f0(8) null g70<8,8,1>F 0F
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*
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* we can recognize that the CMP is generating the flag value that already
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* exists and therefore remove the instruction.
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*/
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static bool
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opt_cmod_propagation_local(const gen_device_info *devinfo, bblock_t *block)
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{
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bool progress = false;
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int ip = block->end_ip + 1;
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foreach_inst_in_block_reverse_safe(fs_inst, inst, block) {
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ip--;
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if ((inst->opcode != BRW_OPCODE_AND &&
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inst->opcode != BRW_OPCODE_CMP &&
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inst->opcode != BRW_OPCODE_MOV) ||
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inst->predicate != BRW_PREDICATE_NONE ||
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!inst->dst.is_null() ||
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inst->src[0].file != VGRF ||
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inst->src[0].abs)
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continue;
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/* Only an AND.NZ can be propagated. Many AND.Z instructions are
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* generated (for ir_unop_not in fs_visitor::emit_bool_to_cond_code).
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* Propagating those would require inverting the condition on the CMP.
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* This changes both the flag value and the register destination of the
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* CMP. That result may be used elsewhere, so we can't change its value
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* on a whim.
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*/
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if (inst->opcode == BRW_OPCODE_AND &&
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!(inst->src[1].is_one() &&
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inst->conditional_mod == BRW_CONDITIONAL_NZ &&
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!inst->src[0].negate))
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continue;
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if (inst->opcode == BRW_OPCODE_CMP && !inst->src[1].is_zero())
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continue;
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if (inst->opcode == BRW_OPCODE_MOV &&
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inst->conditional_mod != BRW_CONDITIONAL_NZ)
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continue;
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bool read_flag = false;
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foreach_inst_in_block_reverse_starting_from(fs_inst, scan_inst, inst) {
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if (regions_overlap(scan_inst->dst, scan_inst->size_written,
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inst->src[0], inst->size_read(0))) {
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if (scan_inst->is_partial_write() ||
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scan_inst->dst.offset != inst->src[0].offset ||
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scan_inst->exec_size != inst->exec_size)
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break;
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/* CMP's result is the same regardless of dest type. */
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if (inst->conditional_mod == BRW_CONDITIONAL_NZ &&
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scan_inst->opcode == BRW_OPCODE_CMP &&
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(inst->dst.type == BRW_REGISTER_TYPE_D ||
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inst->dst.type == BRW_REGISTER_TYPE_UD)) {
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inst->remove(block);
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progress = true;
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break;
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}
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/* If the AND wasn't handled by the previous case, it isn't safe
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* to remove it.
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*/
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if (inst->opcode == BRW_OPCODE_AND)
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break;
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/* Comparisons operate differently for ints and floats */
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if (scan_inst->dst.type != inst->dst.type &&
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(scan_inst->dst.type == BRW_REGISTER_TYPE_F ||
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inst->dst.type == BRW_REGISTER_TYPE_F))
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break;
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/* If the instruction generating inst's source also wrote the
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* flag, and inst is doing a simple .nz comparison, then inst
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* is redundant - the appropriate value is already in the flag
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* register. Delete inst.
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*/
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if (inst->conditional_mod == BRW_CONDITIONAL_NZ &&
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!inst->src[0].negate &&
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scan_inst->flags_written()) {
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inst->remove(block);
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progress = true;
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break;
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}
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/* The conditional mod of the CMP/CMPN instructions behaves
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* specially because the flag output is not calculated from the
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* result of the instruction, but the other way around, which
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* means that even if the condmod to propagate and the condmod
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* from the CMP instruction are the same they will in general give
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* different results because they are evaluated based on different
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* inputs.
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*/
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if (scan_inst->opcode == BRW_OPCODE_CMP ||
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scan_inst->opcode == BRW_OPCODE_CMPN)
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break;
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/* From the Sky Lake PRM Vol. 7 "Assigning Conditional Mods":
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*
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* * Note that the [post condition signal] bits generated at
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* the output of a compute are before the .sat.
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*/
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if (scan_inst->saturate)
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break;
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/* From the Sky Lake PRM, Vol 2a, "Multiply":
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*
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* "When multiplying integer data types, if one of the sources
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* is a DW, the resulting full precision data is stored in
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* the accumulator. However, if the destination data type is
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* either W or DW, the low bits of the result are written to
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* the destination register and the remaining high bits are
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* discarded. This results in undefined Overflow and Sign
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* flags. Therefore, conditional modifiers and saturation
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* (.sat) cannot be used in this case."
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*
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* We just disallow cmod propagation on all integer multiplies.
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*/
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if (!brw_reg_type_is_floating_point(scan_inst->dst.type) &&
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scan_inst->opcode == BRW_OPCODE_MUL)
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break;
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/* Otherwise, try propagating the conditional. */
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enum brw_conditional_mod cond =
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inst->src[0].negate ? brw_swap_cmod(inst->conditional_mod)
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: inst->conditional_mod;
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if (scan_inst->can_do_cmod() &&
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((!read_flag && scan_inst->conditional_mod == BRW_CONDITIONAL_NONE) ||
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scan_inst->conditional_mod == cond)) {
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scan_inst->conditional_mod = cond;
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inst->remove(block);
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progress = true;
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}
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break;
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}
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if (scan_inst->flags_written())
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break;
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read_flag = read_flag || scan_inst->flags_read(devinfo);
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}
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}
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return progress;
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}
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bool
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fs_visitor::opt_cmod_propagation()
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{
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bool progress = false;
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foreach_block_reverse(block, cfg) {
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progress = opt_cmod_propagation_local(devinfo, block) || progress;
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}
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if (progress)
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invalidate_live_intervals();
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return progress;
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}
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