[Mesa-dev] [PATCH v2 3/9] nir/types: Add a natural size and alignment helper

[Jason Ekstrand]

The size and alignment are "natural" in the sense that everything is
aligned to a scalar.  This is a bit tighter than std430 where vec3s are
required to be aligned to a vec4.
---
 src/compiler/nir_types.cpp | 56 ++++++++++++++++++++++++++++++++++++++
 src/compiler/nir_types.h   |  6 ++++
 2 files changed, 62 insertions(+)

diff --git a/src/compiler/nir_types.cpp b/src/compiler/nir_types.cpp
index d2b2a93b207..2b932b1967e 100644
--- a/src/compiler/nir_types.cpp
+++ b/src/compiler/nir_types.cpp
@@ -477,3 +477,59 @@ glsl_channel_type(const glsl_type *t)
       unreachable("Unhandled base type glsl_channel_type()");
    }
 }
+
+void
+glsl_get_natural_size_align_bytes(const struct glsl_type *type,
+                                  unsigned *size, unsigned *align)
+{
+   switch (type->base_type) {
+   case GLSL_TYPE_UINT8:
+   case GLSL_TYPE_INT8:
+   case GLSL_TYPE_UINT16:
+   case GLSL_TYPE_INT16:
+   case GLSL_TYPE_FLOAT16:
+   case GLSL_TYPE_UINT:
+   case GLSL_TYPE_INT:
+   case GLSL_TYPE_FLOAT:
+   case GLSL_TYPE_BOOL:
+   case GLSL_TYPE_DOUBLE:
+   case GLSL_TYPE_UINT64:
+   case GLSL_TYPE_INT64: {
+      unsigned N = glsl_get_bit_size(type) / 8;
+      *size = N * type->components();
+      *align = N;
+      break;
+   }
+
+   case GLSL_TYPE_ARRAY: {
+      unsigned elem_size, elem_align;
+      glsl_get_natural_size_align_bytes(type->fields.array,
+                                        &elem_size, &elem_align);
+      *align = elem_align;
+      *size = type->length * ALIGN_POT(elem_size, elem_align);
+      break;
+   }
+
+   case GLSL_TYPE_STRUCT:
+      *size = 0;
+      *align = 0;
+      for (unsigned i = 0; i < type->length; i++) {
+         unsigned elem_size, elem_align;
+         glsl_get_natural_size_align_bytes(type->fields.structure[i].type,
+                                           &elem_size, &elem_align);
+         *align = MAX2(*align, elem_align);
+         *size = ALIGN_POT(*size, elem_align) + elem_size;
+      }
+      break;
+
+   case GLSL_TYPE_SAMPLER:
+   case GLSL_TYPE_ATOMIC_UINT:
+   case GLSL_TYPE_SUBROUTINE:
+   case GLSL_TYPE_IMAGE:
+   case GLSL_TYPE_VOID:
+   case GLSL_TYPE_ERROR:
+   case GLSL_TYPE_INTERFACE:
+   case GLSL_TYPE_FUNCTION:
+      unreachable("type does not have a natural size");
+   }
+}
diff --git a/src/compiler/nir_types.h b/src/compiler/nir_types.h
index 1107cfd73f2..67c4d7b5097 100644
--- a/src/compiler/nir_types.h
+++ b/src/compiler/nir_types.h
@@ -184,6 +184,12 @@ const struct glsl_type *glsl_transposed_type(const struct glsl_type *type);
 
 const struct glsl_type *glsl_channel_type(const struct glsl_type *type);
 
+typedef void (*glsl_type_size_align_func)(const struct glsl_type *type,
+                                          unsigned *size, unsigned *align);
+
+void glsl_get_natural_size_align_bytes(const struct glsl_type *type,
+                                       unsigned *size, unsigned *align);
+
 #ifdef __cplusplus
 }
 #endif
-- 
2.17.1