[Mesa-dev] [PATCH 7/8] glsl: Optimize "if (cond) discard; " to a conditional discard.
Jason Ekstrand
jason at jlekstrand.net
Tue Feb 24 07:53:48 PST 2015
On Tue, Feb 24, 2015 at 2:19 AM, Kenneth Graunke <kenneth at whitecape.org>
wrote:
> st_glsl_to_tgsi and ir_to_mesa have handled conditional discards for a
> long time; the previous patch added that capability to i965.
>
> i965 (Haswell) shader-db stats:
>
> Without NIR:
> total instructions in shared programs: 5792133 -> 5776360 (-0.27%)
> instructions in affected programs: 737585 -> 721812 (-2.14%)
> helped: 6300
> HURT: 68
> GAINED: 2
>
> With NIR:
> total instructions in shared programs: 5787538 -> 5769569 (-0.31%)
> instructions in affected programs: 767843 -> 749874 (-2.34%)
> helped: 6522
> HURT: 35
> GAINED: 6
>
What all do you have in that branch? Last I checked (10 minutes ago), NIR
wasn't beating GLSL IR yet.
--Jason
> Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
> ---
> src/glsl/Makefile.sources | 1 +
> src/glsl/glsl_parser_extras.cpp | 1 +
> src/glsl/ir_optimization.h | 1 +
> src/glsl/opt_conditional_discard.cpp | 81
> ++++++++++++++++++++++++++++++++++++
> 4 files changed, 84 insertions(+)
> create mode 100644 src/glsl/opt_conditional_discard.cpp
>
> diff --git a/src/glsl/Makefile.sources b/src/glsl/Makefile.sources
> index d0210d1..b876642 100644
> --- a/src/glsl/Makefile.sources
> +++ b/src/glsl/Makefile.sources
> @@ -157,6 +157,7 @@ LIBGLSL_FILES = \
> lower_ubo_reference.cpp \
> opt_algebraic.cpp \
> opt_array_splitting.cpp \
> + opt_conditional_discard.cpp \
> opt_constant_folding.cpp \
> opt_constant_propagation.cpp \
> opt_constant_variable.cpp \
> diff --git a/src/glsl/glsl_parser_extras.cpp
> b/src/glsl/glsl_parser_extras.cpp
> index 9f79313..f19804b 100644
> --- a/src/glsl/glsl_parser_extras.cpp
> +++ b/src/glsl/glsl_parser_extras.cpp
> @@ -1627,6 +1627,7 @@ do_common_optimization(exec_list *ir, bool linked,
> }
> progress = do_if_simplification(ir) || progress;
> progress = opt_flatten_nested_if_blocks(ir) || progress;
> + progress = opt_conditional_discard(ir) || progress;
> progress = do_copy_propagation(ir) || progress;
> progress = do_copy_propagation_elements(ir) || progress;
>
> diff --git a/src/glsl/ir_optimization.h b/src/glsl/ir_optimization.h
> index 7eb861a..e6939f3 100644
> --- a/src/glsl/ir_optimization.h
> +++ b/src/glsl/ir_optimization.h
> @@ -77,6 +77,7 @@ bool do_common_optimization(exec_list *ir, bool linked,
> bool do_rebalance_tree(exec_list *instructions);
> bool do_algebraic(exec_list *instructions, bool native_integers,
> const struct gl_shader_compiler_options *options);
> +bool opt_conditional_discard(exec_list *instructions);
> bool do_constant_folding(exec_list *instructions);
> bool do_constant_variable(exec_list *instructions);
> bool do_constant_variable_unlinked(exec_list *instructions);
> diff --git a/src/glsl/opt_conditional_discard.cpp
> b/src/glsl/opt_conditional_discard.cpp
> new file mode 100644
> index 0000000..0905188
> --- /dev/null
> +++ b/src/glsl/opt_conditional_discard.cpp
> @@ -0,0 +1,81 @@
> +/*
> + * Copyright © 2010 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_conditional_discard.cpp
> + *
> + * Replace
> + *
> + * if (cond) discard;
> + *
> + * with
> + *
> + * (discard <condition>)
> + */
> +
> +#include "glsl_types.h"
> +#include "ir.h"
> +
> +namespace {
> +
> +class opt_conditional_discard_visitor : public ir_hierarchical_visitor {
> +public:
> + opt_conditional_discard_visitor()
> + {
> + progress = false;
> + }
> +
> + ir_visitor_status visit_leave(ir_if *);
> +
> + bool progress;
> +};
> +
> +} /* anonymous namespace */
> +
> +bool
> +opt_conditional_discard(exec_list *instructions)
> +{
> + opt_conditional_discard_visitor v;
> + v.run(instructions);
> + return v.progress;
> +}
> +
> +ir_visitor_status
> +opt_conditional_discard_visitor::visit_leave(ir_if *ir)
> +{
> + /* Look for "if (...) discard" with no else clause or extra
> statements. */
> + if (ir->then_instructions.is_empty() ||
> + !ir->then_instructions.head->next->is_tail_sentinel() ||
> + !((ir_instruction *) ir->then_instructions.head)->as_discard() ||
> + !ir->else_instructions.is_empty())
> + return visit_continue;
> +
> + /* Move the condition and replace the ir_if with the ir_discard. */
> + ir_discard *discard = (ir_discard *) ir->then_instructions.head;
> + discard->condition = ir->condition;
> + ir->replace_with(discard);
> +
> + progress = true;
> +
> + return visit_continue;
> +}
> --
> 2.2.2
>
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