[Mesa-dev] [PATCH 2/4] i965/vs: Copy the live intervals calculation over from the FS.
Eric Anholt
eric at anholt.net
Thu Aug 18 11:38:43 PDT 2011
This is a rather pessimistic calculation, since it doesn't distinguish
individual channels of a vec4, or elements of an array, but should be
a minimum start for register allocation.
---
src/mesa/drivers/dri/i965/Makefile | 1 +
src/mesa/drivers/dri/i965/brw_vec4.cpp | 130 ++++++++++++++++++++++++
src/mesa/drivers/dri/i965/brw_vec4.h | 5 +
src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp | 3 +
4 files changed, 139 insertions(+), 0 deletions(-)
create mode 100644 src/mesa/drivers/dri/i965/brw_vec4.cpp
diff --git a/src/mesa/drivers/dri/i965/Makefile b/src/mesa/drivers/dri/i965/Makefile
index 45a5350..d9c885d 100644
--- a/src/mesa/drivers/dri/i965/Makefile
+++ b/src/mesa/drivers/dri/i965/Makefile
@@ -125,6 +125,7 @@ CXX_SOURCES = \
brw_fs_schedule_instructions.cpp \
brw_fs_vector_splitting.cpp \
brw_shader.cpp \
+ brw_vec4.cpp \
brw_vec4_emit.cpp \
brw_vec4_reg_allocate.cpp \
brw_vec4_visitor.cpp
diff --git a/src/mesa/drivers/dri/i965/brw_vec4.cpp b/src/mesa/drivers/dri/i965/brw_vec4.cpp
new file mode 100644
index 0000000..a3ed31a
--- /dev/null
+++ b/src/mesa/drivers/dri/i965/brw_vec4.cpp
@@ -0,0 +1,130 @@
+/*
+ * Copyright © 2011 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"
+extern "C" {
+#include "main/macros.h"
+#include "program/prog_parameter.h"
+}
+
+#define MAX_INSTRUCTION (1 << 30)
+
+namespace brw {
+
+void
+vec4_visitor::calculate_live_intervals()
+{
+ int *def = ralloc_array(mem_ctx, int, virtual_grf_count);
+ int *use = ralloc_array(mem_ctx, int, virtual_grf_count);
+ int loop_depth = 0;
+ int loop_start = 0;
+
+ if (this->live_intervals_valid)
+ return;
+
+ for (int i = 0; i < virtual_grf_count; i++) {
+ def[i] = MAX_INSTRUCTION;
+ use[i] = -1;
+ }
+
+ int ip = 0;
+ foreach_list(node, &this->instructions) {
+ vec4_instruction *inst = (vec4_instruction *)node;
+
+ if (inst->opcode == BRW_OPCODE_DO) {
+ if (loop_depth++ == 0)
+ loop_start = ip;
+ } else if (inst->opcode == BRW_OPCODE_WHILE) {
+ loop_depth--;
+
+ if (loop_depth == 0) {
+ /* Patches up the use of vars marked for being live across
+ * the whole loop.
+ */
+ for (int i = 0; i < virtual_grf_count; i++) {
+ if (use[i] == loop_start) {
+ use[i] = ip;
+ }
+ }
+ }
+ } else {
+ for (unsigned int i = 0; i < 3; i++) {
+ if (inst->src[i].file == GRF) {
+ int reg = inst->src[i].reg;
+
+ if (!loop_depth) {
+ use[reg] = ip;
+ } else {
+ def[reg] = MIN2(loop_start, def[reg]);
+ use[reg] = loop_start;
+
+ /* Nobody else is going to go smash our start to
+ * later in the loop now, because def[reg] now
+ * points before the bb header.
+ */
+ }
+ }
+ }
+ if (inst->dst.file == GRF) {
+ int reg = inst->dst.reg;
+
+ if (!loop_depth) {
+ def[reg] = MIN2(def[reg], ip);
+ } else {
+ def[reg] = MIN2(def[reg], loop_start);
+ }
+ }
+ }
+
+ ip++;
+ }
+
+ ralloc_free(this->virtual_grf_def);
+ ralloc_free(this->virtual_grf_use);
+ this->virtual_grf_def = def;
+ this->virtual_grf_use = use;
+
+ this->live_intervals_valid = true;
+}
+
+bool
+vec4_visitor::virtual_grf_interferes(int a, int b)
+{
+ int start = MAX2(this->virtual_grf_def[a], this->virtual_grf_def[b]);
+ int end = MIN2(this->virtual_grf_use[a], this->virtual_grf_use[b]);
+
+ /* We can't handle dead register writes here, without iterating
+ * over the whole instruction stream to find every single dead
+ * write to that register to compare to the live interval of the
+ * other register. Just assert that dead_code_eliminate() has been
+ * called.
+ */
+ assert((this->virtual_grf_use[a] != -1 ||
+ this->virtual_grf_def[a] == MAX_INSTRUCTION) &&
+ (this->virtual_grf_use[b] != -1 ||
+ this->virtual_grf_def[b] == MAX_INSTRUCTION));
+
+ return start < end;
+}
+
+} /* namespace brw */
diff --git a/src/mesa/drivers/dri/i965/brw_vec4.h b/src/mesa/drivers/dri/i965/brw_vec4.h
index 620b055..77a28c7 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4.h
+++ b/src/mesa/drivers/dri/i965/brw_vec4.h
@@ -320,6 +320,9 @@ public:
int virtual_grf_count;
int virtual_grf_array_size;
int first_non_payload_grf;
+ int *virtual_grf_def;
+ int *virtual_grf_use;
+ bool live_intervals_valid;
dst_reg *variable_storage(ir_variable *var);
@@ -377,6 +380,8 @@ public:
void reg_allocate_trivial();
void reg_allocate();
void move_grf_array_access_to_scratch();
+ void calculate_live_intervals();
+ bool virtual_grf_interferes(int a, int b);
vec4_instruction *emit(enum opcode opcode);
diff --git a/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp b/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
index a60fc5f..b3a07bd 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
@@ -2109,9 +2109,12 @@ vec4_visitor::vec4_visitor(struct brw_vs_compile *c,
hash_table_pointer_hash,
hash_table_pointer_compare);
+ this->virtual_grf_def = NULL;
+ this->virtual_grf_use = NULL;
this->virtual_grf_sizes = NULL;
this->virtual_grf_count = 0;
this->virtual_grf_array_size = 0;
+ this->live_intervals_valid = false;
this->uniforms = 0;
--
1.7.5.4
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