[Mesa-dev] [RFC 12/12] nir: Add a pass to inline functions
Connor Abbott
cwabbott0 at gmail.com
Sun Dec 27 10:15:16 PST 2015
On Sat, Dec 26, 2015 at 2:09 PM, Jason Ekstrand <jason at jlekstrand.net> wrote:
> This commit adds a new NIR pass that lowers all function calls away by
> inlining the functions.
> ---
>
> There are still two things missing here:
>
> 1) We really shouldn't do the inline recursively. We should keep a
> hash-table of inlined versions or something.
I don't think we need anything so complicated. We're collapsing the
DAG of functions, so we just need a simple DFS: we should inline the
callees before inlining the caller. We could keep a record of the
already-inlined functions, but if we visit an already-inlined function
we wouldn't do anything so it would only save us the cost of walking
over that function.
>
> 2) It doesn't properly handle things like samplers as parameters. Since
> those can only be "in" parameters, I had thought about treating the
> variable as a "proxy" and going through and rewriting all of the derefs
> that use it. We could do the same thing for regular parameters when a
> shadow isn't needed.
>
> Still, I thought it was worth sending out because it does work for most
> cases.
>
> src/glsl/Makefile.sources | 1 +
> src/glsl/nir/nir.h | 3 +
> src/glsl/nir/nir_inline_functions.c | 138 ++++++++++++++++++++++++++++++++++++
> 3 files changed, 142 insertions(+)
> create mode 100644 src/glsl/nir/nir_inline_functions.c
>
> diff --git a/src/glsl/Makefile.sources b/src/glsl/Makefile.sources
> index fa3868c..c271afd 100644
> --- a/src/glsl/Makefile.sources
> +++ b/src/glsl/Makefile.sources
> @@ -35,6 +35,7 @@ NIR_FILES = \
> nir/nir_dominance.c \
> nir/nir_from_ssa.c \
> nir/nir_gs_count_vertices.c \
> + nir/nir_inline_functions.c \
> nir/nir_intrinsics.c \
> nir/nir_intrinsics.h \
> nir/nir_instr_set.c \
> diff --git a/src/glsl/nir/nir.h b/src/glsl/nir/nir.h
> index 2e29617..437f63a 100644
> --- a/src/glsl/nir/nir.h
> +++ b/src/glsl/nir/nir.h
> @@ -1938,6 +1938,9 @@ bool nir_split_var_copies(nir_shader *shader);
> bool nir_lower_returns_impl(nir_function_impl *impl);
> bool nir_lower_returns(nir_shader *shader);
>
> +bool nir_inline_functions_impl(nir_function_impl *impl);
> +bool nir_inline_functions(nir_shader *shader);
> +
> void nir_lower_var_copy_instr(nir_intrinsic_instr *copy, void *mem_ctx);
> void nir_lower_var_copies(nir_shader *shader);
>
> diff --git a/src/glsl/nir/nir_inline_functions.c b/src/glsl/nir/nir_inline_functions.c
> new file mode 100644
> index 0000000..e7e17ca
> --- /dev/null
> +++ b/src/glsl/nir/nir_inline_functions.c
> @@ -0,0 +1,138 @@
> +/*
> + * Copyright © 2015 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 "nir.h"
> +#include "nir_builder.h"
> +#include "nir_control_flow.h"
> +
> +struct inline_functions_state {
> + nir_function_impl *impl;
> + nir_builder builder;
> + bool progress;
> +};
> +
> +static bool
> +inline_functions_block(nir_block *block, void *void_state)
> +{
> + struct inline_functions_state *state = void_state;
> +
> + nir_builder *b = &state->builder;
> +
> + /* This is tricky. We're iterating over instructions in a block but, as
> + * we go, the block and its instruction list are being split into
> + * pieces. However, this *should* be safe since foreach_safe always
> + * stashes the next thing in the iteration. That next thing will
> + * properly get moved to the next block when it gets split, and we
> + * continue iterating there.
> + */
> + nir_foreach_instr_safe(block, instr) {
> + if (instr->type != nir_instr_type_call)
> + continue;
> +
> + state->progress = true;
> +
> + nir_call_instr *call = nir_instr_as_call(instr);
> + assert(call->callee->impl);
> +
> + nir_function_impl *callee_copy =
> + nir_function_impl_clone(call->callee->impl);
> +
> + exec_list_append(&state->impl->locals, &callee_copy->locals);
> + exec_list_append(&state->impl->registers, &callee_copy->registers);
> +
> + b->cursor = nir_before_instr(&call->instr);
> +
> + /* Add copies of all in parameters */
> + assert(call->num_params == callee_copy->num_params);
> + for (unsigned i = 0; i < callee_copy->num_params; i++) {
> + /* Only in or inout parameters */
> + if (call->callee->params[i].param_type == nir_parameter_out)
> + continue;
> +
> + nir_copy_deref_var(b, nir_deref_var_create(b->shader,
> + callee_copy->params[i]),
> + call->params[i]);
> + }
> +
> + /* Pluck the body out of the function and place it here */
> + nir_cf_list body;
> + nir_cf_list_extract(&body, &callee_copy->body);
> + nir_cf_reinsert(&body, b->cursor);
> +
> + b->cursor = nir_before_instr(&call->instr);
> +
> + /* Add copies of all out parameters and the return */
> + assert(call->num_params == callee_copy->num_params);
> + for (unsigned i = 0; i < callee_copy->num_params; i++) {
> + /* Only out or inout parameters */
> + if (call->callee->params[i].param_type == nir_parameter_in)
> + continue;
> +
> + nir_copy_deref_var(b, call->params[i],
> + nir_deref_var_create(b->shader,
> + callee_copy->params[i]));
> + }
> + if (!glsl_type_is_void(call->callee->return_type)) {
> + nir_copy_deref_var(b, call->return_deref,
> + nir_deref_var_create(b->shader,
> + callee_copy->return_var));
> + }
> +
> + nir_instr_remove(&call->instr);
> + }
> +
> + return true;
> +}
> +
> +bool
> +nir_inline_functions_impl(nir_function_impl *impl)
> +{
> + struct inline_functions_state state;
> +
> + state.progress = false;
> + state.impl = impl;
> + nir_builder_init(&state.builder, impl);
> +
> + nir_foreach_block(impl, inline_functions_block, &state);
> +
> + /* SSA and register indices are completely messed up now */
> + nir_index_ssa_defs(impl);
> + nir_index_local_regs(impl);
> +
> + nir_metadata_preserve(impl, nir_metadata_none);
> +
> + return state.progress;
> +}
> +
> +bool
> +nir_inline_functions(nir_shader *shader)
> +{
> + bool progress = false;
> +
> + nir_foreach_function(shader, function) {
> + if (function->impl)
> + progress = nir_inline_functions_impl(function->impl) || progress;
> + }
> +
> + return progress;
> +}
> --
> 2.5.0.400.gff86faf
>
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