[Mesa-dev] [PATCH v2 3/7] nir: add some helpers for doing linking
Timothy Arceri
tarceri at itsqueeze.com
Tue Sep 26 01:23:09 UTC 2017
The initial helpers as support for removing unused varyings between
stages.
V2:
- made the io mask helper function into this file rather than
nir.h so it's not used elsewhere considering it doesn't handle
all corner cases.
- Use bitmask rather than hash table to handle tcs ouputs (Ken)
---
src/compiler/Makefile.sources | 1 +
src/compiler/nir/nir.h | 3 +
src/compiler/nir/nir_linking_helpers.c | 147 +++++++++++++++++++++++++++++++++
3 files changed, 151 insertions(+)
create mode 100644 src/compiler/nir/nir_linking_helpers.c
diff --git a/src/compiler/Makefile.sources b/src/compiler/Makefile.sources
index 0e9a84e87cb..36906f41dd5 100644
--- a/src/compiler/Makefile.sources
+++ b/src/compiler/Makefile.sources
@@ -202,6 +202,7 @@ NIR_FILES = \
nir/nir_instr_set.h \
nir/nir_intrinsics.c \
nir/nir_intrinsics.h \
+ nir/nir_linking_helpers.c \
nir/nir_liveness.c \
nir/nir_loop_analyze.c \
nir/nir_loop_analyze.h \
diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
index fab2110f619..bb5aba605a1 100644
--- a/src/compiler/nir/nir.h
+++ b/src/compiler/nir/nir.h
@@ -2417,6 +2417,9 @@ void nir_shader_gather_info(nir_shader *shader, nir_function_impl *entrypoint);
void nir_assign_var_locations(struct exec_list *var_list, unsigned *size,
int (*type_size)(const struct glsl_type *));
+/* Some helpers to do very simple linking */
+bool nir_remove_unused_varyings(nir_shader *producer, nir_shader *consumer);
+
typedef enum {
/* If set, this forces all non-flat fragment shader inputs to be
* interpolated as if with the "sample" qualifier. This requires
diff --git a/src/compiler/nir/nir_linking_helpers.c b/src/compiler/nir/nir_linking_helpers.c
new file mode 100644
index 00000000000..838054e42a4
--- /dev/null
+++ b/src/compiler/nir/nir_linking_helpers.c
@@ -0,0 +1,147 @@
+/*
+ * 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 "util/set.h"
+#include "util/hash_table.h"
+
+/* This file contains various little helpers for doing simple linking in
+ * NIR. Eventually, we'll probably want a full-blown varying packing
+ * implementation in here. Right now, it just deletes unused things.
+ */
+
+/**
+ * Returns the bits in the inputs_read, outputs_written, or
+ * system_values_read bitfield corresponding to this variable.
+ */
+static uint64_t
+get_variable_io_mask(nir_variable *var, gl_shader_stage stage)
+{
+ /* TODO: add support for tess patches */
+ if (var->data.patch || var->data.location < 0)
+ return 0;
+
+ assert(var->data.mode == nir_var_shader_in ||
+ var->data.mode == nir_var_shader_out ||
+ var->data.mode == nir_var_system_value);
+ assert(var->data.location >= 0);
+
+ const struct glsl_type *type = var->type;
+ if (nir_is_per_vertex_io(var, stage)) {
+ assert(glsl_type_is_array(type));
+ type = glsl_get_array_element(type);
+ }
+
+ unsigned slots = glsl_count_attribute_slots(type, false);
+ return ((1ull << slots) - 1) << var->data.location;
+}
+
+static uint64_t
+tcs_output_read_bitmask(nir_shader *shader)
+{
+ uint64_t read = 0;
+
+ nir_foreach_function(function, shader) {
+ if (function->impl) {
+ nir_foreach_block(block, function->impl) {
+ nir_foreach_instr(instr, block) {
+ if (instr->type != nir_instr_type_intrinsic)
+ continue;
+
+ nir_intrinsic_instr *intrin_instr =
+ nir_instr_as_intrinsic(instr);
+ if (intrin_instr->intrinsic == nir_intrinsic_load_var &&
+ intrin_instr->variables[0]->var->data.mode ==
+ nir_var_shader_out) {
+ read |= get_variable_io_mask(intrin_instr->variables[0]->var,
+ shader->stage);
+ }
+ }
+ }
+ }
+ }
+
+ return read;
+}
+
+static bool
+remove_unused_io_vars(nir_shader *shader, struct exec_list *var_list,
+ uint64_t used_by_other_stage)
+{
+ bool progress = false;
+
+ nir_foreach_variable_safe(var, var_list) {
+ /* TODO: add patch support */
+ if (var->data.patch)
+ continue;
+
+ if (var->data.location < VARYING_SLOT_VAR0 && var->data.location >= 0)
+ continue;
+
+ if (var->data.always_active_io)
+ continue;
+
+ if (!(used_by_other_stage & get_variable_io_mask(var, shader->stage))) {
+ /* This one is invalid, make it a global variable instead */
+ var->data.location = 0;
+ var->data.mode = nir_var_global;
+
+ exec_node_remove(&var->node);
+ exec_list_push_tail(&shader->globals, &var->node);
+
+ progress = true;
+ }
+ }
+
+ return progress;
+}
+
+bool
+nir_remove_unused_varyings(nir_shader *producer, nir_shader *consumer)
+{
+ assert(producer->stage != MESA_SHADER_FRAGMENT);
+ assert(consumer->stage != MESA_SHADER_VERTEX);
+
+ uint64_t read = 0, written = 0;
+
+ nir_foreach_variable(var, &producer->outputs)
+ written |= get_variable_io_mask(var, producer->stage);
+
+ nir_foreach_variable(var, &consumer->inputs)
+ read |= get_variable_io_mask(var, consumer->stage);
+
+ /* Each TCS invocation can read data written by other TCS invocations,
+ * so even if the outputs are not used by the TES we must also make
+ * sure they are not read by the TCS before demoting them to globals.
+ */
+ if (producer->stage == MESA_SHADER_TESS_CTRL)
+ read |= tcs_output_read_bitmask(producer);
+
+ bool progress = false;
+ progress = remove_unused_io_vars(producer, &producer->outputs, read);
+
+ progress =
+ remove_unused_io_vars(consumer, &consumer->inputs, written) || progress;
+
+ return progress;
+}
--
2.13.5
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