[Mesa-dev] [PATCH 3/3] i965: Add a pass to remove dead control flow.
Matt Turner
mattst88 at gmail.com
Sat Nov 16 15:23:31 PST 2013
Removes IF/ENDIF and IF/ELSE/ENDIF with no intervening instructions.
total instructions in shared programs: 1360393 -> 1360387 (-0.00%)
instructions in affected programs: 157 -> 151 (-3.82%)
(no change in vertex shaders)
Reviewed-by: Paul Berry <stereotype441 at gmail.com>
Reviewed-by: Eric Anholt <eric at anholt.net>
---
src/mesa/drivers/dri/i965/Makefile.sources | 1 +
.../drivers/dri/i965/brw_dead_control_flow.cpp | 83 ++++++++++++++++++++++
src/mesa/drivers/dri/i965/brw_dead_control_flow.h | 26 +++++++
src/mesa/drivers/dri/i965/brw_fs.cpp | 2 +
src/mesa/drivers/dri/i965/brw_vec4.cpp | 2 +
5 files changed, 114 insertions(+)
create mode 100644 src/mesa/drivers/dri/i965/brw_dead_control_flow.cpp
create mode 100644 src/mesa/drivers/dri/i965/brw_dead_control_flow.h
diff --git a/src/mesa/drivers/dri/i965/Makefile.sources b/src/mesa/drivers/dri/i965/Makefile.sources
index 5724458..ac1363c 100644
--- a/src/mesa/drivers/dri/i965/Makefile.sources
+++ b/src/mesa/drivers/dri/i965/Makefile.sources
@@ -44,6 +44,7 @@ i965_FILES = \
brw_context.c \
brw_cubemap_normalize.cpp \
brw_curbe.c \
+ brw_dead_control_flow.cpp \
brw_device_info.c \
brw_disasm.c \
brw_draw.c \
diff --git a/src/mesa/drivers/dri/i965/brw_dead_control_flow.cpp b/src/mesa/drivers/dri/i965/brw_dead_control_flow.cpp
new file mode 100644
index 0000000..8bdf094
--- /dev/null
+++ b/src/mesa/drivers/dri/i965/brw_dead_control_flow.cpp
@@ -0,0 +1,83 @@
+/*
+ * Copyright © 2013 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.
+ */
+
+/** @file brw_dead_control_flow.cpp
+ *
+ * This file implements the dead control flow elimination optimization pass.
+ */
+
+#include "brw_shader.h"
+#include "brw_cfg.h"
+
+/* Look for and eliminate dead control flow:
+ *
+ * - if/endif
+ * - if/else/endif
+ */
+bool
+dead_control_flow_eliminate(backend_visitor *v)
+{
+ bool progress = false;
+
+ cfg_t cfg(v);
+
+ for (int b = 0; b < cfg.num_blocks; b++) {
+ bblock_t *block = cfg.blocks[b];
+ bool found = false;
+
+ /* ENDIF instructions, by definition, can only be found at the ends of
+ * basic blocks.
+ */
+ backend_instruction *endif_inst = block->end;
+ if (endif_inst->opcode != BRW_OPCODE_ENDIF)
+ continue;
+
+ backend_instruction *if_inst = NULL, *else_inst = NULL;
+ backend_instruction *prev_inst = (backend_instruction *) endif_inst->prev;
+ if (prev_inst->opcode == BRW_OPCODE_IF) {
+ if_inst = prev_inst;
+ found = true;
+ } else if (prev_inst->opcode == BRW_OPCODE_ELSE) {
+ else_inst = prev_inst;
+
+ prev_inst = (backend_instruction *) prev_inst->prev;
+ if (prev_inst->opcode == BRW_OPCODE_IF) {
+ if_inst = prev_inst;
+ found = true;
+ }
+ }
+
+ if (found) {
+ if_inst->remove();
+ if (else_inst)
+ else_inst->remove();
+ endif_inst->remove();
+ progress = true;
+ }
+ }
+
+ if (progress)
+ v->invalidate_live_intervals();
+
+ return progress;
+}
diff --git a/src/mesa/drivers/dri/i965/brw_dead_control_flow.h b/src/mesa/drivers/dri/i965/brw_dead_control_flow.h
new file mode 100644
index 0000000..57a4dab
--- /dev/null
+++ b/src/mesa/drivers/dri/i965/brw_dead_control_flow.h
@@ -0,0 +1,26 @@
+/*
+ * Copyright © 2013 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_shader.h"
+
+bool dead_control_flow_eliminate(backend_visitor *v);
diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
index f89390c..0d78918 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -46,6 +46,7 @@ extern "C" {
#include "brw_wm.h"
}
#include "brw_fs.h"
+#include "brw_dead_control_flow.h"
#include "main/uniforms.h"
#include "brw_fs_live_variables.h"
#include "glsl/glsl_types.h"
@@ -3276,6 +3277,7 @@ fs_visitor::run()
progress = opt_copy_propagate() || progress;
progress = dead_code_eliminate() || progress;
progress = dead_code_eliminate_local() || progress;
+ progress = dead_control_flow_eliminate(this) || progress;
progress = register_coalesce() || progress;
progress = register_coalesce_2() || progress;
progress = compute_to_mrf() || progress;
diff --git a/src/mesa/drivers/dri/i965/brw_vec4.cpp b/src/mesa/drivers/dri/i965/brw_vec4.cpp
index e7cfab2..73f91a0 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4.cpp
@@ -24,6 +24,7 @@
#include "brw_vec4.h"
#include "brw_cfg.h"
#include "brw_vs.h"
+#include "brw_dead_control_flow.h"
extern "C" {
#include "main/macros.h"
@@ -1498,6 +1499,7 @@ vec4_visitor::run()
do {
progress = false;
progress = dead_code_eliminate() || progress;
+ progress = dead_control_flow_eliminate(this) || progress;
progress = opt_copy_propagation() || progress;
progress = opt_algebraic() || progress;
progress = opt_register_coalesce() || progress;
--
1.8.3.2
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