Mesa (master): glsl: apply align layout qualifier rules to block offsets
Timothy Arceri
tarceri at kemper.freedesktop.org
Sat Mar 5 08:39:30 UTC 2016
Module: Mesa
Branch: master
Commit: 037f68d81e192d954a188907fb37254a7b266502
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=037f68d81e192d954a188907fb37254a7b266502
Author: Timothy Arceri <timothy.arceri at collabora.com>
Date: Tue Jan 12 15:53:53 2016 +1100
glsl: apply align layout qualifier rules to block offsets
>From Section 4.4.5 (Uniform and Shader Storage Block Layout
Qualifiers) of the OpenGL 4.50 spec:
"The align qualifier makes the start of each block member have a
minimum byte alignment. It does not affect the internal layout
within each member, which will still follow the std140 or std430
rules. The specified alignment must be a power of 2, or a
compile-time error results.
The actual alignment of a member will be the greater of the
specified align alignment and the standard (e.g., std140) base
alignment for the member's type. The actual offset of a member is
computed as follows: If offset was declared, start with that
offset, otherwise start with the next available offset. If the
resulting offset is not a multiple of the actual alignment,
increase it to the first offset that is a multiple of the actual
alignment. This results in the actual offset the member will have.
When align is applied to an array, it affects only the start of
the array, not the array's internal stride. Both an offset and an
align qualifier can be specified on a declaration.
The align qualifier, when used on a block, has the same effect as
qualifying each member with the same align value as declared on
the block, and gets the same compile-time results and errors as if
this had been done. As described in general earlier, an individual
member can specify its own align, which overrides the block-level
align, but just for that member.
Reviewed-by: Ian Romanick <ian.d.romanick at intel.com>
Reviewed-by: Samuel Iglesias Gonsálvez <siglesias at igalia.com>
---
src/compiler/glsl/ast_to_hir.cpp | 51 +++++++++++++++++++++++++++++++++++++---
1 file changed, 48 insertions(+), 3 deletions(-)
diff --git a/src/compiler/glsl/ast_to_hir.cpp b/src/compiler/glsl/ast_to_hir.cpp
index 60b008c..d755a11 100644
--- a/src/compiler/glsl/ast_to_hir.cpp
+++ b/src/compiler/glsl/ast_to_hir.cpp
@@ -6244,7 +6244,8 @@ ast_process_struct_or_iface_block_members(exec_list *instructions,
ir_variable_mode var_mode,
ast_type_qualifier *layout,
unsigned block_stream,
- unsigned expl_location)
+ unsigned expl_location,
+ unsigned expl_align)
{
unsigned decl_count = 0;
unsigned next_offset = 0;
@@ -6507,6 +6508,34 @@ ast_process_struct_or_iface_block_members(exec_list *instructions,
}
} else {
fields[i].offset = -1;
+ }
+
+ if (qual->flags.q.explicit_align || expl_align != 0) {
+ unsigned offset = fields[i].offset != -1 ? fields[i].offset :
+ next_offset;
+ if (align == 0 || size == 0) {
+ _mesa_glsl_error(&loc, state, "align can only be used with "
+ "std430 and std140 layouts");
+ } else if (qual->flags.q.explicit_align) {
+ unsigned member_align;
+ if (process_qualifier_constant(state, &loc, "align",
+ qual->align, &member_align)) {
+ if (member_align == 0 ||
+ member_align & (member_align - 1)) {
+ _mesa_glsl_error(&loc, state, "align layout qualifier "
+ "in not a power of 2");
+ } else {
+ fields[i].offset = glsl_align(offset, member_align);
+ next_offset = glsl_align(fields[i].offset + size, align);
+ }
+ }
+ } else {
+ fields[i].offset = glsl_align(offset, expl_align);
+ next_offset = glsl_align(fields[i].offset + size, align);
+ }
+ }
+
+ if (!qual->flags.q.explicit_offset) {
if (align != 0 && size != 0)
next_offset = glsl_align(next_offset + size, align);
}
@@ -6605,7 +6634,8 @@ ast_struct_specifier::hir(exec_list *instructions,
ir_var_auto,
layout,
0, /* for interface only */
- expl_location);
+ expl_location,
+ 0 /* for interface only */);
validate_identifier(this->name, loc, state);
@@ -6773,6 +6803,20 @@ ast_interface_block::hir(exec_list *instructions,
}
}
+ unsigned expl_align = 0;
+ if (layout.flags.q.explicit_align) {
+ if (!process_qualifier_constant(state, &loc, "align",
+ layout.align, &expl_align)) {
+ return NULL;
+ } else {
+ if (expl_align == 0 || expl_align & (expl_align - 1)) {
+ _mesa_glsl_error(&loc, state, "align layout qualifier in not a "
+ "power of 2.");
+ return NULL;
+ }
+ }
+ }
+
unsigned int num_variables =
ast_process_struct_or_iface_block_members(&declared_variables,
state,
@@ -6784,7 +6828,8 @@ ast_interface_block::hir(exec_list *instructions,
var_mode,
&this->layout,
qual_stream,
- expl_location);
+ expl_location,
+ expl_align);
if (!redeclaring_per_vertex) {
validate_identifier(this->block_name, loc, state);
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