[Mesa-dev] [PATCH v2 3/4] nir: rewrite varying component packing
Timothy Arceri
tarceri at itsqueeze.com
Mon Dec 10 00:31:00 UTC 2018
There are three reasons for the rewrite.
1. Adding support for packing tess patch varyings in a sane way.
2. Making use of qsort allowing the code to be much easier to
follow.
3. Allowing us to add a crude live range analysis for deciding
which components should be packed together. This support will
be added in a future patch.
v2: pack moveable components with the unmoveable components. The
new pass is now functionally the same as the old pass besides
the new support for packing patches.
---
src/compiler/nir/nir_linking_helpers.c | 305 ++++++++++++++++---------
1 file changed, 196 insertions(+), 109 deletions(-)
diff --git a/src/compiler/nir/nir_linking_helpers.c b/src/compiler/nir/nir_linking_helpers.c
index c26582ddec..8bd4acc2ee 100644
--- a/src/compiler/nir/nir_linking_helpers.c
+++ b/src/compiler/nir/nir_linking_helpers.c
@@ -247,22 +247,20 @@ is_packing_supported_for_type(const struct glsl_type *type)
return true;
}
+/* Packing arrays and dual slot varyings is difficult so to avoid complex
+ * algorithms this function marks these components as unmoveable.
+ */
static void
-get_slot_component_masks_and_interp_types(struct exec_list *var_list,
- uint8_t *comps,
- uint8_t *interp_type,
- uint8_t *interp_loc,
- gl_shader_stage stage,
- bool default_to_smooth_interp)
+get_unmoveable_components_masks(struct exec_list *var_list, uint8_t *comps,
+ gl_shader_stage stage,
+ bool default_to_smooth_interp)
{
nir_foreach_variable_safe(var, var_list) {
assert(var->data.location >= 0);
- /* Only remap things that aren't built-ins.
- * TODO: add TES patch support.
- */
+ /* Only remap things that aren't built-ins. */
if (var->data.location >= VARYING_SLOT_VAR0 &&
- var->data.location - VARYING_SLOT_VAR0 < 32) {
+ var->data.location - VARYING_SLOT_VAR0 < MAX_VARYINGS_INCL_PATCH) {
const struct glsl_type *type = var->type;
if (nir_is_per_vertex_io(var, stage)) {
@@ -270,6 +268,12 @@ get_slot_component_masks_and_interp_types(struct exec_list *var_list,
type = glsl_get_array_element(type);
}
+ /* If we can pack this varying then don't mark the components as
+ * used.
+ */
+ if (is_packing_supported_for_type(type))
+ continue;
+
unsigned location = var->data.location - VARYING_SLOT_VAR0;
unsigned elements =
glsl_get_vector_elements(glsl_without_array(type));
@@ -278,10 +282,6 @@ get_slot_component_masks_and_interp_types(struct exec_list *var_list,
unsigned slots = glsl_count_attribute_slots(type, false);
unsigned comps_slot2 = 0;
for (unsigned i = 0; i < slots; i++) {
- interp_type[location + i] =
- get_interp_type(var, type, default_to_smooth_interp);
- interp_loc[location + i] = get_interp_loc(var);
-
if (dual_slot) {
if (i & 1) {
comps[location + i] |= ((1 << comps_slot2) - 1);
@@ -413,32 +413,55 @@ remap_slots_and_components(struct exec_list *var_list, gl_shader_stage stage,
*p_out_slots_read = out_slots_read_tmp[1];
}
-/* If there are empty components in the slot compact the remaining components
- * as close to component 0 as possible. This will make it easier to fill the
- * empty components with components from a different slot in a following pass.
- */
-static void
-compact_components(nir_shader *producer, nir_shader *consumer, uint8_t *comps,
- uint8_t *interp_type, uint8_t *interp_loc,
- bool default_to_smooth_interp)
+struct varying_component {
+ nir_variable *var;
+ uint8_t interp_type;
+ uint8_t interp_loc;
+ bool is_patch;
+ bool initialised;
+};
+
+static int
+cmp_varying_component(const void *comp1_v, const void *comp2_v)
{
- struct exec_list *input_list = &consumer->inputs;
- struct exec_list *output_list = &producer->outputs;
- struct varying_loc remap[MAX_VARYINGS_INCL_PATCH][4] = {{{0}, {0}}};
+ struct varying_component *comp1 = (struct varying_component *) comp1_v;
+ struct varying_component *comp2 = (struct varying_component *) comp2_v;
- /* Create a cursor for each interpolation type */
- unsigned cursor[4] = {0};
+ /* We want patches to be order at the end of the array */
+ if (comp1->is_patch != comp2->is_patch)
+ return comp1->is_patch ? 1 : -1;
- /* We only need to pass over one stage and we choose the consumer as it seems
- * to cause a larger reduction in instruction counts (tested on i965).
+ /* We can only pack varyings with matching interpolation types so group
+ * them together.
*/
- nir_foreach_variable(var, input_list) {
+ if (comp1->interp_type != comp2->interp_type)
+ return comp1->interp_type - comp2->interp_type;
+
+ /* Interpolation loc must match also. */
+ if (comp1->interp_loc != comp2->interp_loc)
+ return comp1->interp_loc - comp2->interp_loc;
+
+ /* If everything else matches just use the original location to sort */
+ return comp1->var->data.location - comp2->var->data.location;
+}
+
+static void
+gather_varying_component_info(nir_shader *consumer,
+ struct varying_component **varying_comp_info,
+ unsigned *varying_comp_info_size,
+ bool default_to_smooth_interp)
+{
+ unsigned store_varying_info_idx[MAX_VARYINGS_INCL_PATCH][4] = {0};
+ unsigned num_of_comps_to_pack = 0;
- /* Only remap things that aren't builtins.
- * TODO: add TES patch support.
- */
+ /* Count the number of varying that can be packed and create a mapping
+ * of those varyings to the array we will pass to qsort.
+ */
+ nir_foreach_variable(var, &consumer->inputs) {
+
+ /* Only remap things that aren't builtins. */
if (var->data.location >= VARYING_SLOT_VAR0 &&
- var->data.location - VARYING_SLOT_VAR0 < 32) {
+ var->data.location - VARYING_SLOT_VAR0 < MAX_VARYINGS_INCL_PATCH) {
/* We can't repack xfb varyings. */
if (var->data.always_active_io)
@@ -450,88 +473,156 @@ compact_components(nir_shader *producer, nir_shader *consumer, uint8_t *comps,
type = glsl_get_array_element(type);
}
- /* Skip types that require more complex packing handling.
- * TODO: add support for these types.
- */
- if (glsl_type_is_array(type) ||
- glsl_type_is_dual_slot(type) ||
- glsl_type_is_matrix(type) ||
- glsl_type_is_struct(type) ||
- glsl_type_is_64bit(type))
+ if (!is_packing_supported_for_type(type))
continue;
- /* We ignore complex types above and all other vector types should
- * have been split into scalar variables by the lower_io_to_scalar
- * pass. The only exeption should by OpenGL xfb varyings.
- */
- if (glsl_get_vector_elements(type) != 1)
+ unsigned loc = var->data.location - VARYING_SLOT_VAR0;
+ store_varying_info_idx[loc][var->data.location_frac] =
+ ++num_of_comps_to_pack;
+ }
+ }
+
+ *varying_comp_info_size = num_of_comps_to_pack;
+ *varying_comp_info = rzalloc_array(NULL, struct varying_component,
+ num_of_comps_to_pack);
+
+ nir_function_impl *impl = nir_shader_get_entrypoint(consumer);
+
+ /* Walk over the shader and populate the varying component info array */
+ nir_foreach_block(block, impl) {
+ nir_foreach_instr(instr, block) {
+ if (instr->type != nir_instr_type_intrinsic)
continue;
- unsigned location = var->data.location - VARYING_SLOT_VAR0;
- uint8_t used_comps = comps[location];
+ nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
+ if (intr->intrinsic != nir_intrinsic_load_deref)
+ continue;
- /* If there are no empty components there is nothing more for us to do.
- */
- if (used_comps == 0xf)
+ nir_variable *in_var =
+ nir_deref_instr_get_variable(nir_src_as_deref(intr->src[0]));
+
+ if (in_var->data.mode != nir_var_shader_in)
continue;
- bool found_new_offset = false;
- uint8_t interp = get_interp_type(var, type, default_to_smooth_interp);
- for (; cursor[interp] < 32; cursor[interp]++) {
- uint8_t cursor_used_comps = comps[cursor[interp]];
+ /* We only remap things that aren't builtins. */
+ if (in_var->data.location < VARYING_SLOT_VAR0)
+ continue;
- /* We couldn't find anywhere to pack the varying continue on. */
- if (cursor[interp] == location &&
- (var->data.location_frac == 0 ||
- cursor_used_comps & ((1 << (var->data.location_frac)) - 1)))
- break;
+ unsigned location = in_var->data.location - VARYING_SLOT_VAR0;
+ if (location >= MAX_VARYINGS_INCL_PATCH)
+ continue;
- /* We can only pack varyings with matching interpolation types */
- if (interp_type[cursor[interp]] != interp)
- continue;
+ unsigned var_info_idx =
+ store_varying_info_idx[location][in_var->data.location_frac];
+ if (!var_info_idx)
+ continue;
- /* Interpolation loc must match also.
- * TODO: i965 can handle these if they don't match, but the
- * radeonsi nir backend handles everything as vec4s and so expects
- * this to be the same for all components. We could make this
- * check driver specfific or drop it if NIR ever become the only
- * radeonsi backend.
- */
- if (interp_loc[cursor[interp]] != get_interp_loc(var))
- continue;
+ struct varying_component *vc_info =
+ &(*varying_comp_info)[var_info_idx-1];
- /* If the slot is empty just skip it for now, compact_var_list()
- * can be called after this function to remove empty slots for us.
- * TODO: finish implementing compact_var_list() requires array and
- * matrix splitting.
- */
- if (!cursor_used_comps)
- continue;
+ if (!vc_info->initialised) {
+ const struct glsl_type *type = in_var->type;
+ if (nir_is_per_vertex_io(in_var, consumer->info.stage)) {
+ assert(glsl_type_is_array(type));
+ type = glsl_get_array_element(type);
+ }
- uint8_t unused_comps = ~cursor_used_comps;
+ vc_info->var = in_var;
+ vc_info->interp_type =
+ get_interp_type(in_var, type, default_to_smooth_interp);
+ vc_info->interp_loc = get_interp_loc(in_var);
+ vc_info->is_patch = in_var->data.patch;
+ }
+ }
+ }
+}
- for (unsigned i = 0; i < 4; i++) {
- uint8_t new_var_comps = 1 << i;
- if (unused_comps & new_var_comps) {
- remap[location][var->data.location_frac].component = i;
- remap[location][var->data.location_frac].location =
- cursor[interp] + VARYING_SLOT_VAR0;
+/* If there are empty components in the slot compact the remaining components
+ * as close to component 0 as possible. This will make it easier to fill the
+ * empty components with components from a different slot in a following pass.
+ */
+static void
+compact_components(nir_shader *producer, nir_shader *consumer,
+ uint8_t *unmoveable_comps, bool default_to_smooth_interp)
+{
+ struct exec_list *input_list = &consumer->inputs;
+ struct exec_list *output_list = &producer->outputs;
+ struct varying_loc remap[MAX_VARYINGS_INCL_PATCH][4] = {{{0}, {0}}};
+ struct varying_component *varying_comp_info;
+ unsigned varying_comp_info_size;
- found_new_offset = true;
+ /* Gather varying component info */
+ gather_varying_component_info(consumer, &varying_comp_info,
+ &varying_comp_info_size,
+ default_to_smooth_interp);
- /* Turn off the mask for the component we are remapping */
- if (comps[location] & 1 << var->data.location_frac) {
- comps[location] ^= 1 << var->data.location_frac;
- comps[cursor[interp]] |= new_var_comps;
- }
- break;
- }
+ /* Sort varying components. This attempts to reduce register pressure by
+ * packing components with a similar live range.
+ */
+ qsort(varying_comp_info, varying_comp_info_size,
+ sizeof(struct varying_component), cmp_varying_component);
+
+ unsigned cursor = 0;
+ unsigned comp = 0;
+ struct varying_component *prev_info = NULL;
+
+ /* Set the remap array based on the sorted components */
+ for (unsigned i = 0; i < varying_comp_info_size; i++ ) {
+ struct varying_component *info = &varying_comp_info[i];
+
+ /* Set the cursor to start at 32 for patches */
+ if (info->is_patch) {
+ if (!prev_info)
+ cursor = MAX_VARYING;
+ else if (info->is_patch != prev_info->is_patch)
+ cursor = MAX_VARYING;
+ }
+
+ for (; cursor < MAX_VARYINGS_INCL_PATCH; cursor++) {
+
+ while (comp < 4) {
+ if (unmoveable_comps[cursor] & (1 << comp)) {
+ comp++;
+ continue;
}
- if (found_new_offset)
- break;
+ break;
+ }
+
+ if (comp == 4) {
+ comp = 0;
+ continue;
}
+
+ /* We can only pack varyings with matching interpolation types */
+ if (prev_info && comp != 0 &&
+ info->interp_type != prev_info->interp_type) {
+ comp = 0;
+ continue;
+ }
+
+ /* Interpolation loc must match also.
+ * TODO: i965 can handle these if they don't match, but the
+ * radeonsi nir backend handles everything as vec4s and so expects
+ * this to be the same for all components. We could make this
+ * check driver specfific or drop it if NIR ever become the only
+ * radeonsi backend.
+ */
+ if (prev_info && comp != 0 &&
+ info->interp_loc != prev_info->interp_loc) {
+ comp = 0;
+ continue;
+ }
+
+ unsigned location = info->var->data.location - VARYING_SLOT_VAR0;
+ remap[location][info->var->data.location_frac].component = comp++;
+ remap[location][info->var->data.location_frac].location =
+ cursor + VARYING_SLOT_VAR0;
+
+ break;
}
+
+ prev_info = info;
}
uint64_t zero = 0;
@@ -563,20 +654,16 @@ nir_compact_varyings(nir_shader *producer, nir_shader *consumer,
assert(producer->info.stage != MESA_SHADER_FRAGMENT);
assert(consumer->info.stage != MESA_SHADER_VERTEX);
- uint8_t comps[32] = {0};
- uint8_t interp_type[32] = {0};
- uint8_t interp_loc[32] = {0};
+ uint8_t unmoveable_comps[MAX_VARYINGS_INCL_PATCH] = {0};
- get_slot_component_masks_and_interp_types(&producer->outputs, comps,
- interp_type, interp_loc,
- producer->info.stage,
- default_to_smooth_interp);
- get_slot_component_masks_and_interp_types(&consumer->inputs, comps,
- interp_type, interp_loc,
- consumer->info.stage,
- default_to_smooth_interp);
+ get_unmoveable_components_masks(&producer->outputs, unmoveable_comps,
+ producer->info.stage,
+ default_to_smooth_interp);
+ get_unmoveable_components_masks(&consumer->inputs, unmoveable_comps,
+ consumer->info.stage,
+ default_to_smooth_interp);
- compact_components(producer, consumer, comps, interp_type, interp_loc,
+ compact_components(producer, consumer, unmoveable_comps,
default_to_smooth_interp);
}
--
2.19.2
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