[Mesa-dev] [PATCH 2/5] i965/fs: Add support for copy propagation.
Kenneth Graunke
kenneth at whitecape.org
Wed May 9 00:32:00 PDT 2012
On 05/08/2012 05:59 PM, Eric Anholt wrote:
> We could do more by handling abs/negate and non-GRF sources, but this is
> a good start.
>
> Total instructions: 208032 -> 207184
> 60/1246 programs affected (4.8%)
> 23286 -> 22438 instructions in affected programs (3.6% reduction)
> ---
> src/mesa/drivers/dri/i965/Makefile.sources | 1 +
> src/mesa/drivers/dri/i965/brw_fs.cpp | 1 +
> src/mesa/drivers/dri/i965/brw_fs.h | 5 +
> src/mesa/drivers/dri/i965/brw_fs_cfg.cpp | 1 +
> .../drivers/dri/i965/brw_fs_copy_propagation.cpp | 135 ++++++++++++++++++++
> 5 files changed, 143 insertions(+)
> create mode 100644 src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
>
> diff --git a/src/mesa/drivers/dri/i965/Makefile.sources b/src/mesa/drivers/dri/i965/Makefile.sources
> index c564d95..8156f31 100644
> --- a/src/mesa/drivers/dri/i965/Makefile.sources
> +++ b/src/mesa/drivers/dri/i965/Makefile.sources
> @@ -115,6 +115,7 @@ i965_CXX_FILES = \
> brw_cubemap_normalize.cpp \
> brw_fs.cpp \
> brw_fs_cfg.cpp \
> + brw_fs_copy_propagation.cpp \
> brw_fs_emit.cpp \
> brw_fs_live_variables.cpp \
> brw_fs_visitor.cpp \
> diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
> index fd67318..a723cd8 100644
> --- a/src/mesa/drivers/dri/i965/brw_fs.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
> @@ -1681,6 +1681,7 @@ fs_visitor::run()
>
> progress = propagate_constants() || progress;
> progress = opt_algebraic() || progress;
> + progress = opt_copy_propagate() || progress;
> progress = register_coalesce() || progress;
> progress = compute_to_mrf() || progress;
> progress = dead_code_eliminate() || progress;
> diff --git a/src/mesa/drivers/dri/i965/brw_fs.h b/src/mesa/drivers/dri/i965/brw_fs.h
> index 6b45c4e..8ae855e 100644
> --- a/src/mesa/drivers/dri/i965/brw_fs.h
> +++ b/src/mesa/drivers/dri/i965/brw_fs.h
> @@ -49,6 +49,8 @@ extern "C" {
> #include "glsl/glsl_types.h"
> #include "glsl/ir.h"
>
> +class fs_bblock;
> +
> enum register_file {
> BAD_FILE,
> ARF,
> @@ -507,6 +509,9 @@ public:
> void calculate_live_intervals();
> bool propagate_constants();
> bool opt_algebraic();
> + bool opt_copy_propagate();
> + bool opt_copy_propagate_local(void *mem_ctx, fs_bblock *block,
> + exec_list *acp);
> bool register_coalesce();
> bool compute_to_mrf();
> bool dead_code_eliminate();
> diff --git a/src/mesa/drivers/dri/i965/brw_fs_cfg.cpp b/src/mesa/drivers/dri/i965/brw_fs_cfg.cpp
> index 7c4c481..acc0085 100644
> --- a/src/mesa/drivers/dri/i965/brw_fs_cfg.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_fs_cfg.cpp
> @@ -25,6 +25,7 @@
> *
> */
>
> +#include "brw_fs.h"
> #include "brw_fs_cfg.h"
>
> /** @file brw_fs_cfg.cpp
> diff --git a/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp b/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
> new file mode 100644
> index 0000000..3c9768f
> --- /dev/null
> +++ b/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
> @@ -0,0 +1,135 @@
> +/*
> + * Copyright © 2012 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_cfg.h"
> +
> +struct acp_entry : public exec_node {
> + fs_reg dst;
> + fs_reg src;
> +};
Slightly worried about a clash between opt_copy_propagation_elements and
this. For paranoia, please wrap it in an anonymous namespace:
namespace {
struct acp_entry : public exec_node {
fs_reg dst;
fs_reg src;
};
}
> +
> +/** @file brw_fs_copy_propagation.cpp
> + *
> + * Support for local copy propagation by walking the list of instructions
> + * and maintaining the ACP table of available copies for propagation.
> + *
> + * See Muchnik's Advanced Compiler Design and Implementation, section
> + * 12.5 (p356).
> + */
Nice :) I read the section and yes, this is exactly that algorithm.
With the namespace change:
Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>
> +
> +/* Walks a basic block and does copy propagation on it using the acp
> + * list.
> + */
> +bool
> +fs_visitor::opt_copy_propagate_local(void *mem_ctx,
> + fs_bblock *block, exec_list *acp)
> +{
> + bool progress = false;
> +
> + for (fs_inst *inst = block->start;
> + inst != block->end->next;
> + inst = (fs_inst *)inst->next) {
> +
> + /* Try propagating into this instruction. */
> + foreach_list(entry_node, acp) {
> + acp_entry *entry = (acp_entry *)entry_node;
> +
> + for (int i = 0; i< 3; i++) {
> + if (inst->src[i].file == entry->dst.file&&
> + inst->src[i].reg == entry->dst.reg&&
> + inst->src[i].reg_offset == entry->dst.reg_offset) {
> + inst->src[i].reg = entry->src.reg;
> + inst->src[i].reg_offset = entry->src.reg_offset;
> + progress = true;
> + }
> + }
> + }
> +
> + /* kill the destination from the ACP */
> + if (inst->dst.file == GRF) {
> + int start_offset = inst->dst.reg_offset;
> + int end_offset = start_offset + inst->regs_written();
> +
> + foreach_list_safe(entry_node, acp) {
> + acp_entry *entry = (acp_entry *)entry_node;
> +
> + if (entry->dst.file == GRF&&
> + entry->dst.reg == inst->dst.reg&&
> + entry->dst.reg_offset>= start_offset&&
> + entry->dst.reg_offset< end_offset) {
> + entry->remove();
> + continue;
> + }
> + if (entry->src.file == GRF&&
> + entry->src.reg == inst->dst.reg&&
> + entry->src.reg_offset>= start_offset&&
> + entry->src.reg_offset< end_offset) {
> + entry->remove();
> + }
> + }
> + }
> +
> + /* If this instruction is a raw copy, add it to the ACP. */
> + if (inst->opcode == BRW_OPCODE_MOV&&
> + inst->dst.file == GRF&&
> + inst->src[0].file == GRF&&
> + (inst->src[0].reg != inst->dst.reg ||
> + inst->src[0].reg_offset != inst->dst.reg_offset)&&
> + inst->src[0].type == inst->dst.type&&
> + !inst->saturate&&
> + !inst->predicated&&
> + !inst->force_uncompressed&&
> + !inst->force_sechalf&&
> + inst->src[0].smear == -1&&
> + !inst->src[0].abs&&
> + !inst->src[0].negate) {
> + acp_entry *entry = ralloc(mem_ctx, acp_entry);
> + entry->dst = inst->dst;
> + entry->src = inst->src[0];
> + acp->push_tail(entry);
> + }
> + }
> +
> + return progress;
> +}
> +
> +bool
> +fs_visitor::opt_copy_propagate()
> +{
> + bool progress = false;
> + void *mem_ctx = ralloc_context(this->mem_ctx);
> +
> + fs_cfg cfg(this);
> +
> + for (int b = 0; b< cfg.num_blocks; b++) {
> + fs_bblock *block = cfg.blocks[b];
> + exec_list acp;
> +
> + progress = opt_copy_propagate_local(mem_ctx, block,&acp) || progress;
> + }
> +
> + ralloc_free(mem_ctx);
> +
> + return progress;
> +}
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