Flattening of nested if blocks is a form of if-simplification.
Also, it shares the same visitor pattern, and we can possibly
simplify an if statement further while we are at it. So if we
merge them we get multiple benefits.
---
src/compiler/Makefile.sources | 1 -
src/compiler/glsl/glsl_parser_extras.cpp | 1 -
src/compiler/glsl/ir_optimization.h | 1 -
src/compiler/glsl/opt_flatten_nested_if_blocks.cpp | 103 ---------------------
src/compiler/glsl/opt_if_simplification.cpp | 45 +++++++++
5 files changed, 45 insertions(+), 106 deletions(-)
delete mode 100644 src/compiler/glsl/opt_flatten_nested_if_blocks.cpp
diff --git a/src/compiler/Makefile.sources b/src/compiler/Makefile.sources
index 8b4245612b..5197c31bb3 100644
--- a/src/compiler/Makefile.sources
+++ b/src/compiler/Makefile.sources
@@ -125,7 +125,6 @@ LIBGLSL_FILES = \
glsl/opt_dead_code.cpp \
glsl/opt_dead_code_local.cpp \
glsl/opt_dead_functions.cpp \
- glsl/opt_flatten_nested_if_blocks.cpp \
glsl/opt_flip_matrices.cpp \
glsl/opt_function_inlining.cpp \
glsl/opt_if_simplification.cpp \
diff --git a/src/compiler/glsl/glsl_parser_extras.cpp
b/src/compiler/glsl/glsl_parser_extras.cpp
index 53fcb0e45a..307e0d6215 100644
--- a/src/compiler/glsl/glsl_parser_extras.cpp
+++ b/src/compiler/glsl/glsl_parser_extras.cpp
@@ -2139,7 +2139,6 @@ do_common_optimization(exec_list *ir, bool linked,
}
propagate_invariance(ir);
OPT(do_if_simplification, ir);
- OPT(opt_flatten_nested_if_blocks, ir);
OPT(opt_conditional_discard, ir);
OPT(do_copy_propagation, ir);
OPT(do_copy_propagation_elements, ir);
diff --git a/src/compiler/glsl/ir_optimization.h
b/src/compiler/glsl/ir_optimization.h
index 65d3b3e0db..5d57ca85fd 100644
--- a/src/compiler/glsl/ir_optimization.h
+++ b/src/compiler/glsl/ir_optimization.h
@@ -114,7 +114,6 @@ bool do_function_inlining(exec_list *instructions);
bool do_lower_jumps(exec_list *instructions, bool pull_out_jumps = true, bool
lower_sub_return = true, bool lower_main_return = false, bool lower_continue =
false, bool lower_break = false);
bool do_lower_texture_projection(exec_list *instructions);
bool do_if_simplification(exec_list *instructions);
-bool opt_flatten_nested_if_blocks(exec_list *instructions);
bool do_discard_simplification(exec_list *instructions);
bool lower_if_to_cond_assign(gl_shader_stage stage, exec_list *instructions,
unsigned max_depth = 0, unsigned min_branch_cost
= 0);
diff --git a/src/compiler/glsl/opt_flatten_nested_if_blocks.cpp
b/src/compiler/glsl/opt_flatten_nested_if_blocks.cpp
deleted file mode 100644
index 66d55ae5c1..0000000000
--- a/src/compiler/glsl/opt_flatten_nested_if_blocks.cpp
+++ /dev/null
@@ -1,103 +0,0 @@
-/*
- * 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 opt_flatten_nested_if_blocks.cpp
- *
- * Flattens nested if blocks such as:
- *
- * if (x) {
- * if (y) {
- * ...
- * }
- * }
- *
- * into a single if block with a combined condition:
- *
- * if (x && y) {
- * ...
- * }
- */
-
-#include "ir.h"
-#include "ir_builder.h"
-
-using namespace ir_builder;
-
-namespace {
-
-class nested_if_flattener : public ir_hierarchical_visitor {
-public:
- nested_if_flattener()
- {
- progress = false;
- }
-
- ir_visitor_status visit_leave(ir_if *);
- ir_visitor_status visit_enter(ir_assignment *);
-
- bool progress;
-};
-
-} /* unnamed namespace */
-
-/* We only care about the top level "if" instructions, so don't
- * descend into expressions.
- */
-ir_visitor_status
-nested_if_flattener::visit_enter(ir_assignment *ir)
-{
- (void) ir;
- return visit_continue_with_parent;
-}
-
-bool
-opt_flatten_nested_if_blocks(exec_list *instructions)
-{
- nested_if_flattener v;
-
- v.run(instructions);
- return v.progress;
-}
-
-
-ir_visitor_status
-nested_if_flattener::visit_leave(ir_if *ir)
-{
- /* Only handle a single ir_if within the then clause of an ir_if. No extra
- * instructions, no else clauses, nothing.
- */
- if (ir->then_instructions.is_empty() || !ir->else_instructions.is_empty())
- return visit_continue;
-
- ir_if *inner = ((ir_instruction *)
ir->then_instructions.get_head_raw())->as_if();
- if (!inner || !inner->next->is_tail_sentinel() ||
- !inner->else_instructions.is_empty())
- return visit_continue;
-
- ir->condition = logic_and(ir->condition, inner->condition);
- inner->then_instructions.move_nodes_to(&ir->then_instructions);
-
- progress = true;
- return visit_continue;
-}
diff --git a/src/compiler/glsl/opt_if_simplification.cpp
b/src/compiler/glsl/opt_if_simplification.cpp
index e05f03190a..05159319ba 100644
--- a/src/compiler/glsl/opt_if_simplification.cpp
+++ b/src/compiler/glsl/opt_if_simplification.cpp
@@ -30,6 +30,9 @@
*/
#include "ir.h"
+#include "ir_builder.h"
+
+using namespace ir_builder;
namespace {
@@ -68,9 +71,51 @@ do_if_simplification(exec_list *instructions)
}
+/**
+ *
+ * Flattens nested if blocks such as:
+ *
+ * if (x) {
+ * if (y) {
+ * ...
+ * }
+ * }
+ *
+ * into a single if block with a combined condition:
+ *
+ * if (x && y) {
+ * ...
+ * }
+ */
+static bool
+opt_flatten_nested_if_blocks(ir_if *ir)
+{
+ /* Only handle a single ir_if within the then clause of an ir_if. No extra
+ * instructions, no else clauses, nothing.
+ */
+ if (ir->then_instructions.is_empty() || !ir->else_instructions.is_empty())
+ return visit_continue;
+
+ ir_if *inner = ((ir_instruction *)
ir->then_instructions.get_head_raw())->as_if();
+ if (!inner || !inner->next->is_tail_sentinel() ||
+ !inner->else_instructions.is_empty())
+ return visit_continue;
+
+ ir->condition = logic_and(ir->condition, inner->condition);
+ inner->then_instructions.move_nodes_to(&ir->then_instructions);
+
+ return true;
+}
+
ir_visitor_status
ir_if_simplification_visitor::visit_leave(ir_if *ir)
{
+ /* If we flattened an if expression, we can still possibly simplify
+ * it further. Therefore we continue on instead of returning.
+ */
+ if (opt_flatten_nested_if_blocks(ir))
+ this->made_progress = true;
+
/* If the if statement has nothing on either side, remove it. */
if (ir->then_instructions.is_empty() &&
ir->else_instructions.is_empty()) {
--
2.11.1
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