Specifically, offset, stride (coming from arrays or matrices) and
row_major.
On GLSL, most of that info is computed using the layout qualifier, but
on ARB_gl_spirv they are explicit, and for Mesa, included on the
glsl_type.
From ARB_gl_spirv spec:
"Mapping of layouts
std140/std430 -> explicit *Offset*, *ArrayStride*, and
*MatrixStride* Decoration on struct members""
"7.6.2.spv SPIR-V Uniform Offsets and Strides
The SPIR-V decorations *GLSLShared* or *GLSLPacked* must not be
used. A variable in the *Uniform* Storage Class decorated as a
*Block* must be explicitly laid out using the *Offset*,
*ArrayStride*, and *MatrixStride* decorations"
For offset we needed to include the parent and index_in_parent while
processing the type, as the offset is maintained on glsl_struct_field
of the parent type, not on the type itself.
v2: Fix the default values for MATRIX_STRIDE, ARRAY_STRIDE and
ROW_MAJOR when the variable is not backed by a buffer object
(Antia Puentes).
v3: Update after Jason series "SPIR-V: Use NIR deref instructions for
UBO/SSBO access" that included just one explicit stride, instead
of a previous patch we wrote that had matrix_stride and
array_stride (Alejandro)
Signed-off-by: Antia Puentes <apuentes@igalia.com>
Signed-off-by: Alejandro Piñeiro <apinheiro@igalia.com>
Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>
Alejandro Piñeiro
de05a6ccf5