[Mesa-dev] [PATCH 1/4] i965/vec4: Add basic common subexpression elimination.
Matt Turner
mattst88 at gmail.com
Wed Jun 25 14:12:11 PDT 2014
From: Kenneth Graunke <kenneth at whitecape.org>
[mattst88]: Modified to perform CSE on instructions with
the same writemask. Offered no improvement before.
total instructions in shared programs: 1995633 -> 1995185 (-0.02%)
instructions in affected programs: 14410 -> 13962 (-3.11%)
Reviewed-by: Matt Turner <mattst88 at gmail.com>
Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
---
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 | 2 +
src/mesa/drivers/dri/i965/brw_vec4_cse.cpp | 237 +++++++++++++++++++++++++++++
4 files changed, 241 insertions(+)
create mode 100644 src/mesa/drivers/dri/i965/brw_vec4_cse.cpp
diff --git a/src/mesa/drivers/dri/i965/Makefile.sources b/src/mesa/drivers/dri/i965/Makefile.sources
index 2570059..8f1d272 100644
--- a/src/mesa/drivers/dri/i965/Makefile.sources
+++ b/src/mesa/drivers/dri/i965/Makefile.sources
@@ -102,6 +102,7 @@ i965_FILES = \
brw_util.c \
brw_vec4.cpp \
brw_vec4_copy_propagation.cpp \
+ brw_vec4_cse.cpp \
brw_vec4_generator.cpp \
brw_vec4_gs.c \
brw_vec4_gs_visitor.cpp \
diff --git a/src/mesa/drivers/dri/i965/brw_vec4.cpp b/src/mesa/drivers/dri/i965/brw_vec4.cpp
index 24903f9..0d57399 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4.cpp
@@ -1747,6 +1747,7 @@ vec4_visitor::run()
progress = dead_control_flow_eliminate(this) || progress;
progress = opt_copy_propagation() || progress;
progress = opt_algebraic() || progress;
+ progress = opt_cse() || progress;
progress = opt_register_coalesce() || progress;
} while (progress);
diff --git a/src/mesa/drivers/dri/i965/brw_vec4.h b/src/mesa/drivers/dri/i965/brw_vec4.h
index 366198c..4a8eabb 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4.h
+++ b/src/mesa/drivers/dri/i965/brw_vec4.h
@@ -426,6 +426,8 @@ public:
bool dead_code_eliminate();
bool virtual_grf_interferes(int a, int b);
bool opt_copy_propagation();
+ bool opt_cse_local(bblock_t *, exec_list *);
+ bool opt_cse();
bool opt_algebraic();
bool opt_register_coalesce();
void opt_set_dependency_control();
diff --git a/src/mesa/drivers/dri/i965/brw_vec4_cse.cpp b/src/mesa/drivers/dri/i965/brw_vec4_cse.cpp
new file mode 100644
index 0000000..33c7430
--- /dev/null
+++ b/src/mesa/drivers/dri/i965/brw_vec4_cse.cpp
@@ -0,0 +1,237 @@
+/*
+ * Copyright © 2012, 2013, 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_vec4.h"
+#include "brw_cfg.h"
+
+using namespace brw;
+
+/** @file brw_vec4_cse.cpp
+ *
+ * Support for local common subexpression elimination.
+ *
+ * See Muchnick's Advanced Compiler Design and Implementation, section
+ * 13.1 (p378).
+ */
+
+namespace {
+struct aeb_entry : public exec_node {
+ /** The instruction that generates the expression value. */
+ vec4_instruction *generator;
+
+ /** The temporary where the value is stored. */
+ src_reg tmp;
+};
+}
+
+static bool
+is_expression(const vec4_instruction *const inst)
+{
+ switch (inst->opcode) {
+ case BRW_OPCODE_SEL:
+ case BRW_OPCODE_NOT:
+ case BRW_OPCODE_AND:
+ case BRW_OPCODE_OR:
+ case BRW_OPCODE_XOR:
+ case BRW_OPCODE_SHR:
+ case BRW_OPCODE_SHL:
+ case BRW_OPCODE_ASR:
+ case BRW_OPCODE_ADD:
+ case BRW_OPCODE_MUL:
+ case BRW_OPCODE_FRC:
+ case BRW_OPCODE_RNDU:
+ case BRW_OPCODE_RNDD:
+ case BRW_OPCODE_RNDE:
+ case BRW_OPCODE_RNDZ:
+ case BRW_OPCODE_LINE:
+ case BRW_OPCODE_PLN:
+ case BRW_OPCODE_MAD:
+ case BRW_OPCODE_LRP:
+ return true;
+ case SHADER_OPCODE_RCP:
+ case SHADER_OPCODE_RSQ:
+ case SHADER_OPCODE_SQRT:
+ case SHADER_OPCODE_EXP2:
+ case SHADER_OPCODE_LOG2:
+ case SHADER_OPCODE_POW:
+ case SHADER_OPCODE_INT_QUOTIENT:
+ case SHADER_OPCODE_INT_REMAINDER:
+ case SHADER_OPCODE_SIN:
+ case SHADER_OPCODE_COS:
+ return inst->mlen == 0;
+ default:
+ return false;
+ }
+}
+
+static bool
+is_expression_commutative(enum opcode op)
+{
+ switch (op) {
+ case BRW_OPCODE_AND:
+ case BRW_OPCODE_OR:
+ case BRW_OPCODE_XOR:
+ case BRW_OPCODE_ADD:
+ case BRW_OPCODE_MUL:
+ return true;
+ default:
+ return false;
+ }
+}
+
+static bool
+operands_match(enum opcode op, src_reg *xs, src_reg *ys)
+{
+ if (!is_expression_commutative(op)) {
+ return xs[0].equals(ys[0]) && xs[1].equals(ys[1]) && xs[2].equals(ys[2]);
+ } else {
+ return (xs[0].equals(ys[0]) && xs[1].equals(ys[1])) ||
+ (xs[1].equals(ys[0]) && xs[0].equals(ys[1]));
+ }
+}
+
+static bool
+instructions_match(vec4_instruction *a, vec4_instruction *b)
+{
+ return a->opcode == b->opcode &&
+ a->saturate == b->saturate &&
+ a->conditional_mod == b->conditional_mod &&
+ a->dst.type == b->dst.type &&
+ a->dst.writemask == b->dst.writemask &&
+ operands_match(a->opcode, a->src, b->src);
+}
+
+bool
+vec4_visitor::opt_cse_local(bblock_t *block, exec_list *aeb)
+{
+ bool progress = false;
+
+ void *cse_ctx = ralloc_context(NULL);
+
+ for (vec4_instruction *inst = (vec4_instruction *)block->start;
+ inst != block->end->next;
+ inst = (vec4_instruction *) inst->next) {
+
+ /* Skip some cases. */
+ if (is_expression(inst) && !inst->predicate && inst->mlen == 0 &&
+ !inst->conditional_mod)
+ {
+ bool found = false;
+
+ aeb_entry *entry;
+ foreach_list(entry_node, aeb) {
+ entry = (aeb_entry *) entry_node;
+
+ /* Match current instruction's expression against those in AEB. */
+ if (instructions_match(inst, entry->generator)) {
+ found = true;
+ progress = true;
+ break;
+ }
+ }
+
+ if (!found) {
+ /* Our first sighting of this expression. Create an entry. */
+ aeb_entry *entry = ralloc(cse_ctx, aeb_entry);
+ entry->tmp = src_reg(); /* file will be BAD_FILE */
+ entry->generator = inst;
+ aeb->push_tail(entry);
+ } else {
+ /* This is at least our second sighting of this expression.
+ * If we don't have a temporary already, make one.
+ */
+ bool no_existing_temp = entry->tmp.file == BAD_FILE;
+ if (no_existing_temp) {
+ entry->tmp = src_reg(this, glsl_type::float_type);
+ entry->tmp.type = inst->dst.type;
+ entry->tmp.swizzle = BRW_SWIZZLE_XYZW;
+
+ vec4_instruction *copy = MOV(entry->generator->dst, entry->tmp);
+ entry->generator->insert_after(copy);
+ entry->generator->dst = dst_reg(entry->tmp);
+ }
+
+ /* dest <- temp */
+ assert(inst->dst.type == entry->tmp.type);
+ vec4_instruction *copy = MOV(inst->dst, entry->tmp);
+ copy->force_writemask_all = inst->force_writemask_all;
+ inst->insert_before(copy);
+
+ /* Set our iterator so that next time through the loop inst->next
+ * will get the instruction in the basic block after the one we've
+ * removed.
+ */
+ vec4_instruction *prev = (vec4_instruction *)inst->prev;
+
+ inst->remove();
+
+ /* Appending an instruction may have changed our bblock end. */
+ if (inst == block->end) {
+ block->end = prev;
+ }
+
+ inst = prev;
+ }
+ }
+
+ foreach_list_safe(entry_node, aeb) {
+ aeb_entry *entry = (aeb_entry *)entry_node;
+
+ for (int i = 0; i < 3; i++) {
+ /* Kill all AEB entries that use the destination we just
+ * overwrote.
+ */
+ if (inst->dst.file == entry->generator->src[i].file &&
+ inst->dst.reg == entry->generator->src[i].reg) {
+ entry->remove();
+ ralloc_free(entry);
+ break;
+ }
+ }
+ }
+ }
+
+ ralloc_free(cse_ctx);
+
+ if (progress)
+ invalidate_live_intervals();
+
+ return progress;
+}
+
+bool
+vec4_visitor::opt_cse()
+{
+ bool progress = false;
+
+ cfg_t cfg(&instructions);
+
+ for (int b = 0; b < cfg.num_blocks; b++) {
+ bblock_t *block = cfg.blocks[b];
+ exec_list aeb;
+
+ progress = opt_cse_local(block, &aeb) || progress;
+ }
+
+ return progress;
+}
--
1.8.3.2
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