[Mesa-dev] [PATCH 2/5] i965/vec4: adding vec4_cmod_propagation optimization
Jason Ekstrand
jason at jlekstrand.net
Sat Oct 10 07:54:14 PDT 2015
On Sat, Oct 10, 2015 at 4:24 AM, Alejandro Piñeiro <apinheiro at igalia.com> wrote:
> vec4 port of fs_cmod_propagation.
>
> Shader-db results:
> total instructions in shared programs: 6241226 -> 6224469 (-0.27%)
> instructions in affected programs: 498213 -> 481456 (-3.36%)
> helped: 3082
> HURT: 0
Would you mind cherry-picking this back onto
4e0a8e0a50c9ac91cb7a70b92b8d9c6fcc02b7aa (the commit right before we
made NIR non-optional) and get some GLSL IR vs. NIR vec4-only numbers
with this patch? I'd like to know what it does to that delta as well.
Thanks!
--Jason
> ---
>
> The final outcome is really similar to fs_brw_cmod_propagation. In
> fact the only difference is that on fs we have this:
> 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;
>
> And on vec4 (this commit) we have this:
> if (inst->src[0].in_range(scan_inst->dst,
> scan_inst->regs_written)) {
>
> if ((scan_inst->predicate && scan_inst->opcode != BRW_OPCODE_SEL) ||
> scan_inst->dst.reg_offset != inst->src[0].reg_offset ||
> (scan_inst->dst.writemask != WRITEMASK_X && scan_inst->dst.writemask != WRITEMASK_XYZW))
> break;
>
> if (scan_inst->dst.writemask == WRITEMASK_XYZW &&
> inst->src[0].swizzle != BRW_SWIZZLE_XYZW) {
> break;
> }
>
> So at some point I thought about refactoring it and having one common,
> like with opt_predicated_break, but that one was possible with just
> backend_instructions, while here we would need to deal with
> vec4_instructions and fs_inst, that could be somewhat messy, so
> I'm leaving this as it is.
>
> src/mesa/drivers/dri/i965/Makefile.sources | 1 +
> src/mesa/drivers/dri/i965/brw_vec4.cpp | 1 +
> src/mesa/drivers/dri/i965/brw_vec4.h | 1 +
> .../drivers/dri/i965/brw_vec4_cmod_propagation.cpp | 163 +++++++++++++++++++++
> 4 files changed, 166 insertions(+)
> create mode 100644 src/mesa/drivers/dri/i965/brw_vec4_cmod_propagation.cpp
>
> diff --git a/src/mesa/drivers/dri/i965/Makefile.sources b/src/mesa/drivers/dri/i965/Makefile.sources
> index 81ef628..c1836d6 100644
> --- a/src/mesa/drivers/dri/i965/Makefile.sources
> +++ b/src/mesa/drivers/dri/i965/Makefile.sources
> @@ -56,6 +56,7 @@ i965_compiler_FILES = \
> brw_util.c \
> brw_util.h \
> brw_vec4_builder.h \
> + brw_vec4_cmod_propagation.cpp \
> brw_vec4_copy_propagation.cpp \
> brw_vec4.cpp \
> brw_vec4_cse.cpp \
> diff --git a/src/mesa/drivers/dri/i965/brw_vec4.cpp b/src/mesa/drivers/dri/i965/brw_vec4.cpp
> index e966b96..55e381b 100644
> --- a/src/mesa/drivers/dri/i965/brw_vec4.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_vec4.cpp
> @@ -1867,6 +1867,7 @@ vec4_visitor::run()
> OPT(dead_code_eliminate);
> OPT(dead_control_flow_eliminate, this);
> OPT(opt_copy_propagation);
> + OPT(opt_cmod_propagation);
> OPT(opt_cse);
> OPT(opt_algebraic);
> OPT(opt_register_coalesce);
> diff --git a/src/mesa/drivers/dri/i965/brw_vec4.h b/src/mesa/drivers/dri/i965/brw_vec4.h
> index 5e3500c..3c1711d 100644
> --- a/src/mesa/drivers/dri/i965/brw_vec4.h
> +++ b/src/mesa/drivers/dri/i965/brw_vec4.h
> @@ -149,6 +149,7 @@ public:
> int var_range_start(unsigned v, unsigned n) const;
> int var_range_end(unsigned v, unsigned n) const;
> bool virtual_grf_interferes(int a, int b);
> + bool opt_cmod_propagation();
> bool opt_copy_propagation(bool do_constant_prop = true);
> bool opt_cse_local(bblock_t *block);
> bool opt_cse();
> diff --git a/src/mesa/drivers/dri/i965/brw_vec4_cmod_propagation.cpp b/src/mesa/drivers/dri/i965/brw_vec4_cmod_propagation.cpp
> new file mode 100644
> index 0000000..7e39d2b
> --- /dev/null
> +++ b/src/mesa/drivers/dri/i965/brw_vec4_cmod_propagation.cpp
> @@ -0,0 +1,163 @@
> +/*
> + * 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.
> + *
> + * Authors:
> + * Alejandro Piñeiro Iglesias <apinheiro at igalia.com>
> + *
> + * Based on brw_fs_cmod_propagation.cpp
> + */
> +
> +/** @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"
> +
> +namespace brw {
> +
> +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 != GRF ||
> + inst->src[0].abs)
> + 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_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(vec4_instruction, scan_inst, inst,
> + block) {
> + if (inst->src[0].in_range(scan_inst->dst,
> + scan_inst->regs_written)) {
> +
> + if ((scan_inst->predicate && scan_inst->opcode != BRW_OPCODE_SEL) ||
> + scan_inst->dst.reg_offset != inst->src[0].reg_offset ||
> + (scan_inst->dst.writemask != WRITEMASK_X && scan_inst->dst.writemask != WRITEMASK_XYZW))
> + break;
> +
> + if (scan_inst->dst.writemask == WRITEMASK_XYZW &&
> + inst->src[0].swizzle != BRW_SWIZZLE_XYZW) {
> + 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
> +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 */
> --
> 2.1.4
>
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