[Mesa-dev] [PATCH 16/36] glsl ubo/ssbo: Add lower_buffer_access class
Iago Toral
itoral at igalia.com
Mon Nov 16 04:27:55 PST 2015
On Sat, 2015-11-14 at 13:43 -0800, Jordan Justen wrote:
> This class has code that will be shared by lower_ubo_reference and
> lower_shared_reference. (lower_shared_reference will be used to
> support compute shader shared variables.)
>
> Signed-off-by: Jordan Justen <jordan.l.justen at intel.com>
> Cc: Samuel Iglesias Gonsalvez <siglesias at igalia.com>
> Cc: Iago Toral Quiroga <itoral at igalia.com>
> ---
> src/glsl/Makefile.sources | 1 +
> src/glsl/lower_buffer_access.cpp | 307 +++++++++++++++++++++++++++++++++++++++
> src/glsl/lower_buffer_access.h | 56 +++++++
> src/glsl/lower_ubo_reference.cpp | 180 +----------------------
> 4 files changed, 367 insertions(+), 177 deletions(-)
> create mode 100644 src/glsl/lower_buffer_access.cpp
> create mode 100644 src/glsl/lower_buffer_access.h
>
> diff --git a/src/glsl/Makefile.sources b/src/glsl/Makefile.sources
> index d4b02c1..f2c95c0 100644
> --- a/src/glsl/Makefile.sources
> +++ b/src/glsl/Makefile.sources
> @@ -155,6 +155,7 @@ LIBGLSL_FILES = \
> loop_analysis.h \
> loop_controls.cpp \
> loop_unroll.cpp \
> + lower_buffer_access.cpp \
> lower_clip_distance.cpp \
> lower_const_arrays_to_uniforms.cpp \
> lower_discard.cpp \
> diff --git a/src/glsl/lower_buffer_access.cpp b/src/glsl/lower_buffer_access.cpp
> new file mode 100644
> index 0000000..e0b5a2f
> --- /dev/null
> +++ b/src/glsl/lower_buffer_access.cpp
> @@ -0,0 +1,307 @@
> +/*
> + * Copyright (c) 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.
> + */
> +
> +/**
> + * \file lower_buffer_access.cpp
> + *
> + * Helper for IR lowering pass to replace dereferences of buffer object based
> + * shader variables with intrinsic function calls.
> + *
> + * This helper is used by lowering passes for UBOs, SSBOs and compute shader
> + * shared variables.
> + */
> +
> +#include "ir.h"
> +#include "ir_builder.h"
> +#include "ir_rvalue_visitor.h"
> +#include "main/macros.h"
> +#include "util/list.h"
> +#include "glsl_parser_extras.h"
> +#include "lower_buffer_access.h"
> +
> +using namespace ir_builder;
> +
> +namespace lower_buffer_access {
> +
> +static inline int
> +writemask_for_size(unsigned n)
> +{
> + return ((1 << n) - 1);
> +}
> +
> +/**
> + * Takes LHS and emits a series of assignments into its components
> + * from the shared variable storage.
I find this part of the comment a bit confusing. This function breaks a
dereference access into one or multiple accesses to the underlying
buffer storage. Such dereference could be in a RHS expression, and in
fact, that will always be the case for UBO and SSBO loads.
> + * Recursively calls itself to break the deref down to the point that
> + * the intrinsic calls are generated.
> + */
> +void
> +lower_buffer_access::emit_access(bool is_write,
> + ir_dereference *deref,
> + ir_variable *base_offset,
> + unsigned int deref_offset,
> + bool row_major,
> + int matrix_columns,
> + unsigned int packing,
> + unsigned int write_mask)
> +{
Why not pass mem_ctx as parameter instead of having it be a class
member? I find it a bit odd that this class defines mem_ctx but never
really takes care of initializing it, expecting that subclasses do that
for it, so in that case why not just make them actually take care of
passing the mem_ctx to use instead?
If you rather keep mem_ctx defined here I'd at least suggest to add an
assert to the functions that use it to check that it has indeed been
initialized by the subclass.
> + if (deref->type->is_record()) {
> + unsigned int field_offset = 0;
> +
> + for (unsigned i = 0; i < deref->type->length; i++) {
> + const struct glsl_struct_field *field =
> + &deref->type->fields.structure[i];
> + ir_dereference *field_deref =
> + new(mem_ctx) ir_dereference_record(deref->clone(mem_ctx, NULL),
> + field->name);
> +
> + field_offset =
> + glsl_align(field_offset,
> + field->type->std140_base_alignment(row_major));
> +
> + emit_access(is_write, field_deref, base_offset,
> + deref_offset + field_offset,
> + row_major, 1, packing,
> + writemask_for_size(field_deref->type->vector_elements));
> +
> + field_offset += field->type->std140_size(row_major);
> + }
> + return;
> + }
> +
> + if (deref->type->is_array()) {
> + unsigned array_stride = packing == GLSL_INTERFACE_PACKING_STD430 ?
> + deref->type->fields.array->std430_array_stride(row_major) :
> + glsl_align(deref->type->fields.array->std140_size(row_major), 16);
> +
> + for (unsigned i = 0; i < deref->type->length; i++) {
> + ir_constant *element = new(mem_ctx) ir_constant(i);
> + ir_dereference *element_deref =
> + new(mem_ctx) ir_dereference_array(deref->clone(mem_ctx, NULL),
> + element);
> + emit_access(is_write, element_deref, base_offset,
> + deref_offset + i * array_stride,
> + row_major, 1, packing,
> + writemask_for_size(element_deref->type->vector_elements));
> + }
> + return;
> + }
> +
> + if (deref->type->is_matrix()) {
> + for (unsigned i = 0; i < deref->type->matrix_columns; i++) {
> + ir_constant *col = new(mem_ctx) ir_constant(i);
> + ir_dereference *col_deref =
> + new(mem_ctx) ir_dereference_array(deref->clone(mem_ctx, NULL), col);
> +
> + if (row_major) {
> + /* For a row-major matrix, the next column starts at the next
> + * element.
> + */
> + int size_mul = deref->type->is_double() ? 8 : 4;
> + emit_access(is_write, col_deref, base_offset,
> + deref_offset + i * size_mul,
> + row_major, deref->type->matrix_columns, packing,
> + writemask_for_size(col_deref->type->vector_elements));
> + } else {
> + int size_mul;
> +
> + /* std430 doesn't round up vec2 size to a vec4 size */
> + if (packing == GLSL_INTERFACE_PACKING_STD430 &&
> + deref->type->vector_elements == 2 &&
> + !deref->type->is_double()) {
> + size_mul = 8;
> + } else {
> + /* std140 always rounds the stride of arrays (and matrices) to a
> + * vec4, so matrices are always 16 between columns/rows. With
> + * doubles, they will be 32 apart when there are more than 2 rows.
> + *
> + * For both std140 and std430, if the member is a
> + * three-'component vector with components consuming N basic
> + * machine units, the base alignment is 4N. For vec4, base
> + * alignment is 4N.
> + */
> + size_mul = (deref->type->is_double() &&
> + deref->type->vector_elements > 2) ? 32 : 16;
> + }
> +
> + emit_access(is_write, col_deref, base_offset,
> + deref_offset + i * size_mul,
> + row_major, deref->type->matrix_columns, packing,
> + writemask_for_size(col_deref->type->vector_elements));
> + }
> + }
> + return;
> + }
> +
> + assert(deref->type->is_scalar() || deref->type->is_vector());
> +
> + if (!row_major) {
> + ir_rvalue *offset =
> + add(base_offset, new(mem_ctx) ir_constant(deref_offset));
> + unsigned mask =
> + is_write ? write_mask : (1 << deref->type->vector_elements) - 1;
> + insert_buffer_access(deref, deref->type, offset, mask, -1);
> + } else {
> + unsigned N = deref->type->is_double() ? 8 : 4;
> +
> + /* We're dereffing a column out of a row-major matrix, so we
> + * gather the vector from each stored row.
> + */
> + assert(deref->type->base_type == GLSL_TYPE_FLOAT ||
> + deref->type->base_type == GLSL_TYPE_DOUBLE);
> + /* Matrices, row_major or not, are stored as if they were
> + * arrays of vectors of the appropriate size in std140.
> + * Arrays have their strides rounded up to a vec4, so the
> + * matrix stride is always 16. However a double matrix may either be 16
> + * or 32 depending on the number of columns.
> + */
> + assert(matrix_columns <= 4);
> + unsigned matrix_stride = 0;
> + /* Matrix stride for std430 mat2xY matrices are not rounded up to
> + * vec4 size. From OpenGL 4.3 spec, section 7.6.2.2 "Standard Uniform
> + * Block Layout":
> + *
> + * "2. If the member is a two- or four-component vector with components
> + * consuming N basic machine units, the base alignment is 2N or 4N,
> + * respectively." [...]
> + * "4. If the member is an array of scalars or vectors, the base alignment
> + * and array stride are set to match the base alignment of a single array
> + * element, according to rules (1), (2), and (3), and rounded up to the
> + * base alignment of a vec4." [...]
> + * "7. If the member is a row-major matrix with C columns and R rows, the
> + * matrix is stored identically to an array of R row vectors with C
> + * components each, according to rule (4)." [...]
> + * "When using the std430 storage layout, shader storage blocks will be
> + * laid out in buffer storage identically to uniform and shader storage
> + * blocks using the std140 layout, except that the base alignment and
> + * stride of arrays of scalars and vectors in rule 4 and of structures in
> + * rule 9 are not rounded up a multiple of the base alignment of a vec4."
> + */
> + if (packing == GLSL_INTERFACE_PACKING_STD430 && matrix_columns == 2)
> + matrix_stride = 2 * N;
> + else
> + matrix_stride = glsl_align(matrix_columns * N, 16);
> +
> + const glsl_type *deref_type = deref->type->base_type == GLSL_TYPE_FLOAT ?
> + glsl_type::float_type : glsl_type::double_type;
> +
> + for (unsigned i = 0; i < deref->type->vector_elements; i++) {
> + ir_rvalue *chan_offset =
> + add(base_offset,
> + new(mem_ctx) ir_constant(deref_offset + i * matrix_stride));
> + if (!is_write || ((1U << i) & write_mask))
> + insert_buffer_access(deref, deref_type, chan_offset, (1U << i), i);
> + }
> + }
> +}
> +
> +/**
> + * Determine if a thing being dereferenced is row-major
> + *
> + * There is some trickery here.
> + *
> + * If the thing being dereferenced is a member of uniform block \b without an
> + * instance name, then the name of the \c ir_variable is the field name of an
> + * interface type. If this field is row-major, then the thing referenced is
> + * row-major.
> + *
> + * If the thing being dereferenced is a member of uniform block \b with an
> + * instance name, then the last dereference in the tree will be an
> + * \c ir_dereference_record. If that record field is row-major, then the
> + * thing referenced is row-major.
> + */
> +static bool
> +is_dereferenced_thing_row_major(const ir_dereference *deref)
> +{
> + bool matrix = false;
> + const ir_rvalue *ir = deref;
> +
> + while (true) {
> + matrix = matrix || ir->type->without_array()->is_matrix();
> +
> + switch (ir->ir_type) {
> + case ir_type_dereference_array: {
> + const ir_dereference_array *const array_deref =
> + (const ir_dereference_array *) ir;
> +
> + ir = array_deref->array;
> + break;
> + }
> +
> + case ir_type_dereference_record: {
> + const ir_dereference_record *const record_deref =
> + (const ir_dereference_record *) ir;
> +
> + ir = record_deref->record;
> +
> + const int idx = ir->type->field_index(record_deref->field);
> + assert(idx >= 0);
> +
> + const enum glsl_matrix_layout matrix_layout =
> + glsl_matrix_layout(ir->type->fields.structure[idx].matrix_layout);
> +
> + switch (matrix_layout) {
> + case GLSL_MATRIX_LAYOUT_INHERITED:
> + break;
> + case GLSL_MATRIX_LAYOUT_COLUMN_MAJOR:
> + return false;
> + case GLSL_MATRIX_LAYOUT_ROW_MAJOR:
> + return matrix || deref->type->without_array()->is_record();
> + }
> +
> + break;
> + }
> +
> + case ir_type_dereference_variable: {
> + const ir_dereference_variable *const var_deref =
> + (const ir_dereference_variable *) ir;
> +
> + const enum glsl_matrix_layout matrix_layout =
> + glsl_matrix_layout(var_deref->var->data.matrix_layout);
> +
> + switch (matrix_layout) {
> + case GLSL_MATRIX_LAYOUT_INHERITED:
> + case GLSL_MATRIX_LAYOUT_COLUMN_MAJOR:
> + return false;
> + case GLSL_MATRIX_LAYOUT_ROW_MAJOR:
> + return matrix || deref->type->without_array()->is_record();
> + }
> +
> + unreachable("invalid matrix layout");
> + break;
> + }
> +
> + default:
> + return false;
> + }
> + }
> +
> + /* The tree must have ended with a dereference that wasn't an
> + * ir_dereference_variable. That is invalid, and it should be impossible.
> + */
> + unreachable("invalid dereference tree");
> + return false;
> +}
> +
> +} /* namespace lower_buffer_access */
> diff --git a/src/glsl/lower_buffer_access.h b/src/glsl/lower_buffer_access.h
> new file mode 100644
> index 0000000..3138963
> --- /dev/null
> +++ b/src/glsl/lower_buffer_access.h
> @@ -0,0 +1,56 @@
> +/*
> + * Copyright (c) 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.
> + */
> +
> +/**
> + * \file lower_buffer_access.h
> + *
> + * Helper for IR lowering pass to replace dereferences of buffer object based
> + * shader variables with intrinsic function calls.
> + *
> + * This helper is used by lowering passes for UBOs, SSBOs and compute shader
> + * shared variables.
> + */
> +
> +#pragma once
> +#ifndef LOWER_BUFFER_ACCESS_H
> +#define LOWER_BUFFER_ACCESS_H
> +
> +namespace lower_buffer_access {
> +
> +class lower_buffer_access : public ir_rvalue_enter_visitor {
> +public:
> + virtual void
> + insert_buffer_access(ir_dereference *deref, const glsl_type *type,
> + ir_rvalue *offset, unsigned mask, int channel) = 0;
> +
> + void emit_access(bool is_write, ir_dereference *deref,
> + ir_variable *base_offset, unsigned int deref_offset,
> + bool row_major, int matrix_columns,
> + unsigned int packing, unsigned int write_mask);
> +
> + void *mem_ctx;
> +};
> +
> +} /* namespace lower_buffer_access */
> +
> +#endif /* LOWER_BUFFER_ACCESS_H */
> diff --git a/src/glsl/lower_ubo_reference.cpp b/src/glsl/lower_ubo_reference.cpp
> index b8fcc8e..8de4f5e 100644
> --- a/src/glsl/lower_ubo_reference.cpp
> +++ b/src/glsl/lower_ubo_reference.cpp
> @@ -38,6 +38,7 @@
> #include "ir_rvalue_visitor.h"
> #include "main/macros.h"
> #include "glsl_parser_extras.h"
> +#include "lower_buffer_access.h"
>
> using namespace ir_builder;
>
> @@ -132,7 +133,8 @@ is_dereferenced_thing_row_major(const ir_rvalue *deref)
> }
>
> namespace {
> -class lower_ubo_reference_visitor : public ir_rvalue_enter_visitor {
> +class lower_ubo_reference_visitor :
> + public lower_buffer_access::lower_buffer_access {
> public:
> lower_ubo_reference_visitor(struct gl_shader *shader)
> : shader(shader)
> @@ -173,11 +175,6 @@ public:
> void insert_buffer_access(ir_dereference *deref, const glsl_type *type,
> ir_rvalue *offset, unsigned mask, int channel);
>
> - void emit_access(bool is_write, ir_dereference *deref,
> - ir_variable *base_offset, unsigned int deref_offset,
> - bool row_major, int matrix_columns,
> - unsigned packing, unsigned write_mask);
> -
> ir_visitor_status visit_enter(class ir_expression *);
> ir_expression *calculate_ssbo_unsized_array_length(ir_expression *expr);
> void check_ssbo_unsized_array_length_expression(class ir_expression *);
> @@ -195,7 +192,6 @@ public:
> ir_call *check_for_ssbo_atomic_intrinsic(ir_call *ir);
> ir_visitor_status visit_enter(ir_call *ir);
>
> - void *mem_ctx;
> struct gl_shader *shader;
> struct gl_uniform_buffer_variable *ubo_var;
> ir_rvalue *uniform_block;
> @@ -727,176 +723,6 @@ lower_ubo_reference_visitor::insert_buffer_access(ir_dereference *deref,
> }
> }
>
> -static inline int
> -writemask_for_size(unsigned n)
> -{
> - return ((1 << n) - 1);
> -}
> -
> -/**
> - * Takes a deref and recursively calls itself to break the deref down to the
> - * point that the reads or writes generated are contiguous scalars or vectors.
> - */
> -void
> -lower_ubo_reference_visitor::emit_access(bool is_write,
> - ir_dereference *deref,
> - ir_variable *base_offset,
> - unsigned int deref_offset,
> - bool row_major,
> - int matrix_columns,
> - unsigned packing,
> - unsigned write_mask)
> -{
> - if (deref->type->is_record()) {
> - unsigned int field_offset = 0;
> -
> - for (unsigned i = 0; i < deref->type->length; i++) {
> - const struct glsl_struct_field *field =
> - &deref->type->fields.structure[i];
> - ir_dereference *field_deref =
> - new(mem_ctx) ir_dereference_record(deref->clone(mem_ctx, NULL),
> - field->name);
> -
> - field_offset =
> - glsl_align(field_offset,
> - field->type->std140_base_alignment(row_major));
> -
> - emit_access(is_write, field_deref, base_offset,
> - deref_offset + field_offset,
> - row_major, 1, packing,
> - writemask_for_size(field_deref->type->vector_elements));
> -
> - field_offset += field->type->std140_size(row_major);
> - }
> - return;
> - }
> -
> - if (deref->type->is_array()) {
> - unsigned array_stride = packing == GLSL_INTERFACE_PACKING_STD430 ?
> - deref->type->fields.array->std430_array_stride(row_major) :
> - glsl_align(deref->type->fields.array->std140_size(row_major), 16);
> -
> - for (unsigned i = 0; i < deref->type->length; i++) {
> - ir_constant *element = new(mem_ctx) ir_constant(i);
> - ir_dereference *element_deref =
> - new(mem_ctx) ir_dereference_array(deref->clone(mem_ctx, NULL),
> - element);
> - emit_access(is_write, element_deref, base_offset,
> - deref_offset + i * array_stride,
> - row_major, 1, packing,
> - writemask_for_size(element_deref->type->vector_elements));
> - }
> - return;
> - }
> -
> - if (deref->type->is_matrix()) {
> - for (unsigned i = 0; i < deref->type->matrix_columns; i++) {
> - ir_constant *col = new(mem_ctx) ir_constant(i);
> - ir_dereference *col_deref =
> - new(mem_ctx) ir_dereference_array(deref->clone(mem_ctx, NULL), col);
> -
> - if (row_major) {
> - /* For a row-major matrix, the next column starts at the next
> - * element.
> - */
> - int size_mul = deref->type->is_double() ? 8 : 4;
> - emit_access(is_write, col_deref, base_offset,
> - deref_offset + i * size_mul,
> - row_major, deref->type->matrix_columns, packing,
> - writemask_for_size(col_deref->type->vector_elements));
> - } else {
> - int size_mul;
> -
> - /* std430 doesn't round up vec2 size to a vec4 size */
> - if (packing == GLSL_INTERFACE_PACKING_STD430 &&
> - deref->type->vector_elements == 2 &&
> - !deref->type->is_double()) {
> - size_mul = 8;
> - } else {
> - /* std140 always rounds the stride of arrays (and matrices) to a
> - * vec4, so matrices are always 16 between columns/rows. With
> - * doubles, they will be 32 apart when there are more than 2 rows.
> - *
> - * For both std140 and std430, if the member is a
> - * three-'component vector with components consuming N basic
> - * machine units, the base alignment is 4N. For vec4, base
> - * alignment is 4N.
> - */
> - size_mul = (deref->type->is_double() &&
> - deref->type->vector_elements > 2) ? 32 : 16;
> - }
> -
> - emit_access(is_write, col_deref, base_offset,
> - deref_offset + i * size_mul,
> - row_major, deref->type->matrix_columns, packing,
> - writemask_for_size(col_deref->type->vector_elements));
> - }
> - }
> - return;
> - }
> -
> - assert(deref->type->is_scalar() || deref->type->is_vector());
> -
> - if (!row_major) {
> - ir_rvalue *offset =
> - add(base_offset, new(mem_ctx) ir_constant(deref_offset));
> - unsigned mask =
> - is_write ? write_mask : (1 << deref->type->vector_elements) - 1;
> - insert_buffer_access(deref, deref->type, offset, mask, -1);
> - } else {
> - unsigned N = deref->type->is_double() ? 8 : 4;
> -
> - /* We're dereffing a column out of a row-major matrix, so we
> - * gather the vector from each stored row.
> - */
> - assert(deref->type->base_type == GLSL_TYPE_FLOAT ||
> - deref->type->base_type == GLSL_TYPE_DOUBLE);
> - /* Matrices, row_major or not, are stored as if they were
> - * arrays of vectors of the appropriate size in std140.
> - * Arrays have their strides rounded up to a vec4, so the
> - * matrix stride is always 16. However a double matrix may either be 16
> - * or 32 depending on the number of columns.
> - */
> - assert(matrix_columns <= 4);
> - unsigned matrix_stride = 0;
> - /* Matrix stride for std430 mat2xY matrices are not rounded up to
> - * vec4 size. From OpenGL 4.3 spec, section 7.6.2.2 "Standard Uniform
> - * Block Layout":
> - *
> - * "2. If the member is a two- or four-component vector with components
> - * consuming N basic machine units, the base alignment is 2N or 4N,
> - * respectively." [...]
> - * "4. If the member is an array of scalars or vectors, the base alignment
> - * and array stride are set to match the base alignment of a single array
> - * element, according to rules (1), (2), and (3), and rounded up to the
> - * base alignment of a vec4." [...]
> - * "7. If the member is a row-major matrix with C columns and R rows, the
> - * matrix is stored identically to an array of R row vectors with C
> - * components each, according to rule (4)." [...]
> - * "When using the std430 storage layout, shader storage blocks will be
> - * laid out in buffer storage identically to uniform and shader storage
> - * blocks using the std140 layout, except that the base alignment and
> - * stride of arrays of scalars and vectors in rule 4 and of structures in
> - * rule 9 are not rounded up a multiple of the base alignment of a vec4."
> - */
> - if (packing == GLSL_INTERFACE_PACKING_STD430 && matrix_columns == 2)
> - matrix_stride = 2 * N;
> - else
> - matrix_stride = glsl_align(matrix_columns * N, 16);
> -
> - const glsl_type *deref_type = deref->type->base_type == GLSL_TYPE_FLOAT ?
> - glsl_type::float_type : glsl_type::double_type;
> -
> - for (unsigned i = 0; i < deref->type->vector_elements; i++) {
> - ir_rvalue *chan_offset =
> - add(base_offset,
> - new(mem_ctx) ir_constant(deref_offset + i * matrix_stride));
> - if (!is_write || ((1U << i) & write_mask))
> - insert_buffer_access(deref, deref_type, chan_offset, (1U << i), i);
> - }
> - }
> -}
> -
> void
> lower_ubo_reference_visitor::write_to_memory(ir_dereference *deref,
> ir_variable *var,
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