Mesa (master): zink: add alternate ubo loader in ntv
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Tue Dec 1 18:31:37 UTC 2020
Module: Mesa
Branch: master
Commit: 8366d23e7b342ed3d3f8251e6d970cc13d70e99f
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=8366d23e7b342ed3d3f8251e6d970cc13d70e99f
Author: Mike Blumenkrantz <michael.blumenkrantz at gmail.com>
Date: Fri Jun 26 15:53:30 2020 -0400
zink: add alternate ubo loader in ntv
This is a loader that handles more cases than the current vec4-based
loader, that is a bit easier to extend to more features.
Reviewed-by: Erik Faye-Lund <erik.faye-lund at collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7858>
---
.../drivers/zink/nir_to_spirv/nir_to_spirv.c | 92 ++++++++++++++++++++++
1 file changed, 92 insertions(+)
diff --git a/src/gallium/drivers/zink/nir_to_spirv/nir_to_spirv.c b/src/gallium/drivers/zink/nir_to_spirv/nir_to_spirv.c
index b2021694c19..d990bdc9af6 100644
--- a/src/gallium/drivers/zink/nir_to_spirv/nir_to_spirv.c
+++ b/src/gallium/drivers/zink/nir_to_spirv/nir_to_spirv.c
@@ -1525,6 +1525,94 @@ emit_load_const(struct ntv_context *ctx, nir_load_const_instr *load_const)
store_ssa_def(ctx, &load_const->def, constant);
}
+static void
+emit_load_ubo(struct ntv_context *ctx, nir_intrinsic_instr *intr)
+{
+ ASSERTED nir_const_value *const_block_index = nir_src_as_const_value(intr->src[0]);
+ assert(const_block_index); // no dynamic indexing for now
+
+ SpvId uint_type = get_uvec_type(ctx, 32, 1);
+ SpvId one = emit_uint_const(ctx, 32, 1);
+
+ /* number of components being loaded */
+ unsigned num_components = nir_dest_num_components(intr->dest);
+ SpvId constituents[num_components];
+ SpvId result;
+
+ /* destination type for the load */
+ SpvId type = get_dest_uvec_type(ctx, &intr->dest);
+ /* an id of the array stride in bytes */
+ SpvId vec4_size = emit_uint_const(ctx, 32, sizeof(uint32_t) * 4);
+ /* an id of an array member in bytes */
+ SpvId uint_size = emit_uint_const(ctx, 32, sizeof(uint32_t));
+
+ /* we grab a single array member at a time, so it's a pointer to a uint */
+ SpvId pointer_type = spirv_builder_type_pointer(&ctx->builder,
+ SpvStorageClassUniform,
+ uint_type);
+
+ /* our generated uniform has a memory layout like
+ *
+ * struct {
+ * vec4 base[array_size];
+ * };
+ *
+ * where 'array_size' is set as though every member of the ubo takes up a vec4,
+ * even if it's only a vec2 or a float.
+ *
+ * first, access 'base'
+ */
+ SpvId member = emit_uint_const(ctx, 32, 0);
+ /* this is the offset (in bytes) that we're accessing:
+ * it may be a const value or it may be dynamic in the shader
+ */
+ SpvId offset = get_src(ctx, &intr->src[1]);
+ /* convert offset to an array index for 'base' to determine which vec4 to access */
+ SpvId vec_offset = emit_binop(ctx, SpvOpUDiv, uint_type, offset, vec4_size);
+ /* use the remainder to calculate the byte offset in the vec, which tells us the member
+ * that we're going to access
+ */
+ SpvId vec_member_offset = emit_binop(ctx, SpvOpUDiv, uint_type,
+ emit_binop(ctx, SpvOpUMod, uint_type, offset, vec4_size),
+ uint_size);
+ /* OpAccessChain takes an array of indices that drill into a hierarchy based on the type:
+ * index 0 is accessing 'base'
+ * index 1 is accessing 'base[index 1]'
+ * index 2 is accessing 'base[index 1][index 2]'
+ *
+ * we must perform the access this way in case src[1] is dynamic because there's
+ * no other spirv method for using an id to access a member of a composite, as
+ * (composite|vector)_extract both take literals
+ */
+ for (unsigned i = 0; i < num_components; i++) {
+ SpvId indices[3] = { member, vec_offset, vec_member_offset };
+ SpvId ptr = spirv_builder_emit_access_chain(&ctx->builder, pointer_type,
+ ctx->ubos[const_block_index->u32], indices,
+ ARRAY_SIZE(indices));
+ /* load a single value into the constituents array */
+ constituents[i] = spirv_builder_emit_load(&ctx->builder, uint_type, ptr);
+ /* increment to the next vec4 member index for the next load */
+ vec_member_offset = emit_binop(ctx, SpvOpIAdd, uint_type, vec_member_offset, one);
+ }
+
+ /* if loading more than 1 value, reassemble the results into the desired type,
+ * otherwise just use the loaded result
+ */
+ if (num_components > 1) {
+ result = spirv_builder_emit_composite_construct(&ctx->builder,
+ type,
+ constituents,
+ num_components);
+ } else
+ result = constituents[0];
+
+ /* explicitly convert to a bool vector if the destination type is a bool */
+ if (nir_dest_bit_size(intr->dest) == 1)
+ result = uvec_to_bvec(ctx, result, num_components);
+
+ store_dest(ctx, &intr->dest, result, nir_type_uint);
+}
+
static void
emit_load_ubo_vec4(struct ntv_context *ctx, nir_intrinsic_instr *intr)
{
@@ -1721,6 +1809,10 @@ static void
emit_intrinsic(struct ntv_context *ctx, nir_intrinsic_instr *intr)
{
switch (intr->intrinsic) {
+ case nir_intrinsic_load_ubo:
+ emit_load_ubo(ctx, intr);
+ break;
+
case nir_intrinsic_load_ubo_vec4:
emit_load_ubo_vec4(ctx, intr);
break;
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