*/
/*
- * Implements a pass that lowers output variables to a temporary plus an
- * output variable with a single copy at each exit point of the shader.
- * This way the output variable is only ever written.
+ * Implements a pass that lowers output and/or input variables to a
+ * temporary plus an output variable with a single copy at each exit
+ * point of the shader and/or an input variable with a single copy
+ * at the entrance point of the shader. This way the output variable
+ * is only ever written once and/or input is only read once, and there
+ * are no indirect outut/input accesses.
*/
#include "nir.h"
+#include "nir_builder.h"
+#include "nir_deref.h"
struct lower_io_state {
nir_shader *shader;
+ nir_function_impl *entrypoint;
struct exec_list old_outputs;
+ struct exec_list old_inputs;
+ struct exec_list new_outputs;
+ struct exec_list new_inputs;
+
+ /* map from temporary to new input */
+ struct hash_table *input_map;
};
static void
-emit_output_copies(nir_cursor cursor, struct lower_io_state *state)
+emit_copies(nir_builder *b, struct exec_list *dest_vars,
+ struct exec_list *src_vars)
+{
+ assert(exec_list_length(dest_vars) == exec_list_length(src_vars));
+
+ foreach_two_lists(dest_node, dest_vars, src_node, src_vars) {
+ nir_variable *dest = exec_node_data(nir_variable, dest_node, node);
+ nir_variable *src = exec_node_data(nir_variable, src_node, node);
+
+ /* No need to copy the contents of a non-fb_fetch_output output variable
+ * to the temporary allocated for it, since its initial value is
+ * undefined.
+ */
+ if (src->data.mode == nir_var_shader_out &&
+ !src->data.fb_fetch_output)
+ continue;
+
+ /* Can't copy the contents of the temporary back to a read-only
+ * interface variable. The value of the temporary won't have been
+ * modified by the shader anyway.
+ */
+ if (dest->data.read_only)
+ continue;
+
+ nir_copy_var(b, dest, src);
+ }
+}
+
+static void
+emit_output_copies_impl(struct lower_io_state *state, nir_function_impl *impl)
+{
+ nir_builder b;
+ nir_builder_init(&b, impl);
+
+ if (state->shader->info.stage == MESA_SHADER_GEOMETRY) {
+ /* For geometry shaders, we have to emit the output copies right
+ * before each EmitVertex call.
+ */
+ nir_foreach_block(block, impl) {
+ nir_foreach_instr(instr, block) {
+ if (instr->type != nir_instr_type_intrinsic)
+ continue;
+
+ nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
+ if (intrin->intrinsic == nir_intrinsic_emit_vertex ||
+ intrin->intrinsic == nir_intrinsic_emit_vertex_with_counter) {
+ b.cursor = nir_before_instr(&intrin->instr);
+ emit_copies(&b, &state->new_outputs, &state->old_outputs);
+ }
+ }
+ }
+ } else if (impl == state->entrypoint) {
+ b.cursor = nir_before_block(nir_start_block(impl));
+ emit_copies(&b, &state->old_outputs, &state->new_outputs);
+
+ /* For all other shader types, we need to do the copies right before
+ * the jumps to the end block.
+ */
+ set_foreach(impl->end_block->predecessors, block_entry) {
+ struct nir_block *block = (void *)block_entry->key;
+ b.cursor = nir_after_block_before_jump(block);
+ emit_copies(&b, &state->new_outputs, &state->old_outputs);
+ }
+ }
+}
+
+/* For fragment shader inputs, when we lower to temporaries we'll invalidate
+ * interpolateAt*() because now they'll be pointing to the temporary instead
+ * of the actual variable. Since the caller presumably doesn't support
+ * indirect indexing of inputs, we'll need to lower something like:
+ *
+ * in vec4 foo[3];
+ *
+ * ... = interpolateAtCentroid(foo[i]);
+ *
+ * to a sequence of interpolations that store to our temporary, then a
+ * load at the end:
+ *
+ * in vec4 foo[3];
+ * vec4 foo_tmp[3];
+ *
+ * foo_tmp[0] = interpolateAtCentroid(foo[0]);
+ * foo_tmp[1] = interpolateAtCentroid(foo[1]);
+ * ... = foo_tmp[i];
+ */
+
+/*
+ * Recursively emit the interpolation instructions. Here old_interp_deref
+ * refers to foo[i], temp_deref is foo_tmp[0/1], and new_interp_deref is
+ * foo[0/1].
+ */
+
+static void
+emit_interp(nir_builder *b, nir_deref_instr **old_interp_deref,
+ nir_deref_instr *temp_deref, nir_deref_instr *new_interp_deref,
+ nir_intrinsic_instr *interp)
+{
+ while (*old_interp_deref) {
+ switch ((*old_interp_deref)->deref_type) {
+ case nir_deref_type_struct:
+ temp_deref =
+ nir_build_deref_struct(b, temp_deref,
+ (*old_interp_deref)->strct.index);
+ new_interp_deref =
+ nir_build_deref_struct(b, new_interp_deref,
+ (*old_interp_deref)->strct.index);
+ break;
+ case nir_deref_type_array:
+ if (nir_src_is_const((*old_interp_deref)->arr.index)) {
+ temp_deref =
+ nir_build_deref_array(b, temp_deref,
+ (*old_interp_deref)->arr.index.ssa);
+ new_interp_deref =
+ nir_build_deref_array(b, new_interp_deref,
+ (*old_interp_deref)->arr.index.ssa);
+ break;
+ } else {
+ /* We have an indirect deref, so we have to emit interpolations
+ * for every index. Recurse in case we have an array of arrays.
+ */
+ unsigned length = glsl_get_length(temp_deref->type);
+ for (unsigned i = 0; i < length; i++) {
+ nir_deref_instr *new_temp =
+ nir_build_deref_array_imm(b, temp_deref, i);
+ nir_deref_instr *new_interp =
+ nir_build_deref_array_imm(b, new_interp_deref, i);
+
+ emit_interp(b, old_interp_deref + 1, new_temp, new_interp,
+ interp);
+ }
+
+ return;
+ }
+
+ case nir_deref_type_var:
+ case nir_deref_type_array_wildcard:
+ case nir_deref_type_ptr_as_array:
+ case nir_deref_type_cast:
+ unreachable("bad deref type");
+ }
+
+ old_interp_deref++;
+ }
+
+ /* Now that we've constructed a fully-qualified deref with all the indirect
+ * derefs replaced with direct ones, it's time to actually emit the new
+ * interpolation instruction.
+ */
+
+ nir_intrinsic_instr *new_interp =
+ nir_intrinsic_instr_create(b->shader, interp->intrinsic);
+
+ new_interp->src[0] = nir_src_for_ssa(&new_interp_deref->dest.ssa);
+ if (interp->intrinsic == nir_intrinsic_interp_deref_at_sample ||
+ interp->intrinsic == nir_intrinsic_interp_deref_at_offset ||
+ interp->intrinsic == nir_intrinsic_interp_deref_at_vertex) {
+ new_interp->src[1] = interp->src[1];
+ }
+
+ new_interp->num_components = interp->num_components;
+ nir_ssa_dest_init(&new_interp->instr, &new_interp->dest,
+ interp->dest.ssa.num_components,
+ interp->dest.ssa.bit_size, NULL);
+
+ nir_builder_instr_insert(b, &new_interp->instr);
+ nir_store_deref(b, temp_deref, &new_interp->dest.ssa,
+ (1 << interp->dest.ssa.num_components) - 1);
+}
+
+static void
+fixup_interpolation_instr(struct lower_io_state *state,
+ nir_intrinsic_instr *interp, nir_builder *b)
{
- assert(exec_list_length(&state->shader->outputs) ==
- exec_list_length(&state->old_outputs));
+ nir_deref_path interp_path;
+ nir_deref_path_init(&interp_path, nir_src_as_deref(interp->src[0]), NULL);
+
+ b->cursor = nir_before_instr(&interp->instr);
+
+ /* The original interpolation instruction should contain a deref path
+ * starting with the original variable, which is now the temporary.
+ */
+ nir_deref_instr *temp_root = interp_path.path[0];
- foreach_two_lists(out_node, &state->shader->outputs,
- temp_node, &state->old_outputs) {
- nir_variable *output = exec_node_data(nir_variable, out_node, node);
- nir_variable *temp = exec_node_data(nir_variable, temp_node, node);
+ /* Fish out the newly-created input variable. */
+ assert(temp_root->deref_type == nir_deref_type_var);
+ struct hash_entry *entry = _mesa_hash_table_search(state->input_map,
+ temp_root->var);
+ assert(entry);
+ nir_variable *input = entry->data;
+ nir_deref_instr *input_root = nir_build_deref_var(b, input);
- nir_intrinsic_instr *copy =
- nir_intrinsic_instr_create(state->shader, nir_intrinsic_copy_var);
- copy->variables[0] = nir_deref_var_create(copy, output);
- copy->variables[1] = nir_deref_var_create(copy, temp);
+ /* Emit the interpolation instructions. */
+ emit_interp(b, interp_path.path + 1, temp_root, input_root, interp);
- nir_instr_insert(cursor, ©->instr);
+ /* Now the temporary contains the interpolation results, and we can just
+ * load from it. We can reuse the original deref, since it points to the
+ * correct part of the temporary.
+ */
+ nir_ssa_def *load = nir_load_deref(b, nir_src_as_deref(interp->src[0]));
+ nir_ssa_def_rewrite_uses(&interp->dest.ssa, nir_src_for_ssa(load));
+ nir_instr_remove(&interp->instr);
+
+ nir_deref_path_finish(&interp_path);
+}
+
+static void
+fixup_interpolation(struct lower_io_state *state, nir_function_impl *impl,
+ nir_builder *b)
+{
+ nir_foreach_block(block, impl) {
+ nir_foreach_instr_safe(instr, block) {
+ if (instr->type != nir_instr_type_intrinsic)
+ continue;
+
+ nir_intrinsic_instr *interp = nir_instr_as_intrinsic(instr);
+
+ if (interp->intrinsic == nir_intrinsic_interp_deref_at_centroid ||
+ interp->intrinsic == nir_intrinsic_interp_deref_at_sample ||
+ interp->intrinsic == nir_intrinsic_interp_deref_at_offset ||
+ interp->intrinsic == nir_intrinsic_interp_deref_at_vertex) {
+ fixup_interpolation_instr(state, interp, b);
+ }
+ }
+ }
+}
+
+static void
+emit_input_copies_impl(struct lower_io_state *state, nir_function_impl *impl)
+{
+ if (impl == state->entrypoint) {
+ nir_builder b;
+ nir_builder_init(&b, impl);
+ b.cursor = nir_before_block(nir_start_block(impl));
+ emit_copies(&b, &state->old_inputs, &state->new_inputs);
+ if (state->shader->info.stage == MESA_SHADER_FRAGMENT)
+ fixup_interpolation(state, impl, &b);
+ }
+}
+
+static nir_variable *
+create_shadow_temp(struct lower_io_state *state, nir_variable *var)
+{
+ nir_variable *nvar = ralloc(state->shader, nir_variable);
+ memcpy(nvar, var, sizeof *nvar);
+ nvar->data.cannot_coalesce = true;
+
+ /* The original is now the temporary */
+ nir_variable *temp = var;
+
+ /* Reparent the name to the new variable */
+ ralloc_steal(nvar, nvar->name);
+
+ assert(nvar->constant_initializer == NULL && nvar->pointer_initializer == NULL);
+
+ /* Give the original a new name with @<mode>-temp appended */
+ const char *mode = (temp->data.mode == nir_var_shader_in) ? "in" : "out";
+ temp->name = ralloc_asprintf(var, "%s@%s-temp", mode, nvar->name);
+ temp->data.mode = nir_var_shader_temp;
+ temp->data.read_only = false;
+ temp->data.fb_fetch_output = false;
+ temp->data.compact = false;
+
+ return nvar;
+}
+
+static void
+move_variables_to_list(nir_shader *shader, nir_variable_mode mode,
+ struct exec_list *dst_list)
+{
+ nir_foreach_variable_with_modes_safe(var, shader, mode) {
+ exec_node_remove(&var->node);
+ exec_list_push_tail(dst_list, &var->node);
}
}
void
-nir_lower_io_to_temporaries(nir_shader *shader, nir_function *entrypoint)
+nir_lower_io_to_temporaries(nir_shader *shader, nir_function_impl *entrypoint,
+ bool outputs, bool inputs)
{
struct lower_io_state state;
- if (shader->stage == MESA_SHADER_TESS_CTRL)
+ if (shader->info.stage == MESA_SHADER_TESS_CTRL)
return;
state.shader = shader;
- exec_list_move_nodes_to(&shader->outputs, &state.old_outputs);
-
- /* Walk over all of the outputs turn each output into a temporary and
- * make a new variable for the actual output.
- */
- nir_foreach_variable(var, &state.old_outputs) {
- nir_variable *output = ralloc(shader, nir_variable);
- memcpy(output, var, sizeof *output);
+ state.entrypoint = entrypoint;
+ state.input_map = _mesa_pointer_hash_table_create(NULL);
- /* The orignal is now the temporary */
- nir_variable *temp = var;
+ exec_list_make_empty(&state.old_inputs);
+ if (inputs)
+ move_variables_to_list(shader, nir_var_shader_in, &state.old_inputs);
- /* Reparent the name to the new variable */
- ralloc_steal(output, output->name);
+ exec_list_make_empty(&state.old_outputs);
+ if (outputs)
+ move_variables_to_list(shader, nir_var_shader_out, &state.old_outputs);
- /* Reparent the constant initializer (if any) */
- ralloc_steal(output, output->constant_initializer);
+ exec_list_make_empty(&state.new_inputs);
+ exec_list_make_empty(&state.new_outputs);
- /* Give the output a new name with @out-temp appended */
- temp->name = ralloc_asprintf(var, "%s@out-temp", output->name);
- temp->data.mode = nir_var_global;
- temp->constant_initializer = NULL;
+ /* Walk over all of the outputs turn each output into a temporary and
+ * make a new variable for the actual output.
+ */
+ nir_foreach_variable_in_list(var, &state.old_outputs) {
+ nir_variable *output = create_shadow_temp(&state, var);
+ exec_list_push_tail(&state.new_outputs, &output->node);
+ }
- exec_list_push_tail(&shader->outputs, &output->node);
+ /* and same for inputs: */
+ nir_foreach_variable_in_list(var, &state.old_inputs) {
+ nir_variable *input = create_shadow_temp(&state, var);
+ exec_list_push_tail(&state.new_inputs, &input->node);
+ _mesa_hash_table_insert(state.input_map, var, input);
}
nir_foreach_function(function, shader) {
if (function->impl == NULL)
continue;
- if (shader->stage == MESA_SHADER_GEOMETRY) {
- /* For geometry shaders, we have to emit the output copies right
- * before each EmitVertex call.
- */
- nir_foreach_block(block, function->impl) {
- nir_foreach_instr(instr, block) {
- if (instr->type != nir_instr_type_intrinsic)
- continue;
-
- nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
- if (intrin->intrinsic == nir_intrinsic_emit_vertex) {
- emit_output_copies(nir_before_instr(&intrin->instr),
- &state);
- }
- }
- }
- } else if (function == entrypoint) {
- /* For all other shader types, we need to do the copies right before
- * the jumps to the end block.
- */
- struct set_entry *block_entry;
- set_foreach(function->impl->end_block->predecessors, block_entry) {
- struct nir_block *block = (void *)block_entry->key;
- emit_output_copies(nir_after_block_before_jump(block), &state);
- }
- }
+ if (inputs)
+ emit_input_copies_impl(&state, function->impl);
+
+ if (outputs)
+ emit_output_copies_impl(&state, function->impl);
nir_metadata_preserve(function->impl, nir_metadata_block_index |
nir_metadata_dominance);
}
- exec_list_append(&shader->globals, &state.old_outputs);
+ exec_list_append(&shader->variables, &state.old_inputs);
+ exec_list_append(&shader->variables, &state.old_outputs);
+ exec_list_append(&shader->variables, &state.new_inputs);
+ exec_list_append(&shader->variables, &state.new_outputs);
+
+ nir_fixup_deref_modes(shader);
+
+ _mesa_hash_table_destroy(state.input_map, NULL);
}
projects / mesa.git / blobdiff