Explicitly give rules for SPIR-V uniform offsets. These changes will be
reflected in the next OpenGL 4.6 spec update as well, once that's
published.
diff --git a/extensions/ARB/ARB_gl_spirv.txt b/extensions/ARB/ARB_gl_spirv.txt
index 3583aa1..a7a4c9a 100644
--- a/extensions/ARB/ARB_gl_spirv.txt
+++ b/extensions/ARB/ARB_gl_spirv.txt
@@ -15,11 +15,11 @@
Contact Point for Bug Reports
- https://www.khronos.org/bugzilla/enter_bug.cgi?product=OpenGL
+ https://github.com/KhronosGroup/OpenGL-Registry/issues/
Notice
- Copyright (c) 2015-2016 The Khronos Group Inc. Copyright terms at
+ Copyright (c) 2015-2019 The Khronos Group Inc. Copyright terms at
http://www.khronos.org/registry/speccopyright.html
Status
@@ -29,8 +29,8 @@
Version
- Last Modified Date: December 10, 2018
- Revision: 41
+ Last Modified Date: January 9, 2019
+ Revision: 42
Number
@@ -358,7 +358,7 @@
NA -> OpAtomicCompareExchangeWeak
atomicCounterIncrement -> OpAtomicIIncrement
- atomicCounterDecrement -> OpAtomicIDecrement (with post decrement)
+ atomicCounterDecrement -> OpAtomicIDecrement
atomicCounter -> OpAtomicLoad
Mapping of other instructions
@@ -706,12 +706,51 @@
"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. If the variable is decorated as a *BufferBlock*, its offsets
- and strides must not contradict std430 alignment and minimum offset
- requirements. Otherwise, its offsets and strides must not contradict
- std140 alignment and minimum offset requirements."
+ variable in the *Uniform* Storage Class decorated as a *Block* or
+ *BufferBlock* must be explicitly laid out using the *Offset*, *ArrayStride*,
+ and *MatrixStride* decorations. These must follow the alignment rules listed
+ above, but not necessarily the packing rules. More specifically, explicit
+ SPIR-V offsets and strides must obey the following:
+
+ Define the /base alignment/ recursively as:
+
+ - A scalar of size N has a base alignment of N.
+
+ - A two-component vector, with components of size N, has a base alignment
+ of 2N.
+
+ - A three- or four-component vector, with components of size N, has a base
+ alignment of 4N.
+
+ - An array has a base alignment equal to the base alignment of its element
+ type, rounded up to a multiple of 16.
+
+ - A structure has a base alignment equal to the largest base alignment of
+ any of its members, rounded up to a multiple of 16.
+
+ - A row-major matrix of C columns has a base alignment equal to the base
+ alignment of a vector of C matrix components.
+
+ - A column-major matrix has a base alignment equal to the base alignment
+ of the matrix column type.
+
+ Given this definition, blocks must be laid out such that:
+
+ - The *Offset* decoration must be a multiple of its base alignment.
+
+ - Any *ArrayStride* or *MatrixStride* decoration must be an integer
+ multiple of the base alignment of the array or matrix.
+
+ - The *Offset* decoration of a member must not place it between the end of
+ a structure or an array and the next multiple of the base alignment of
+ that structure or array.
+
+ - The numeric order of *Offset* decorations need not follow member
+ declaration order.
+
+ With one exception: Variables in the *Uniform* storage class with a
+ decoration of *BufferBlock* do not need their base alignments rounded up
+ to a multiple of 16.
Modifications to Section 7.13 "Shader, Program, and Program Pipeline Queries"
@@ -2077,11 +2116,12 @@
Rev. Date Author Changes
---- ----------- ------------ ---------------------------------
+ 42 9-Jan-2019 JohnK Explicitly give rules for SPIR-V
+ uniform offsets (internal API issue
+ 92)
41 10-Dec-2018 Jon Leech Use 'workgroup' consistently
throughout (Bug 11723, internal API
issue 87).
- 40 29-May-2018 dgkoch note post decrement for atomicCounterDecrement
- mapping
39 25-Apr-2018 JohnK add mappings of barriers and atomics
38 10-Apr-2018 dgkoch OpImageQuerySizeLod and OpImageQuerylevels
only work with Sampled images
