This CL adds the necessary configuration to build glslang inside a
Chromium checkout. Two build warnings were fixed in the process to
make things compile.
the following warning gets emitted:
```
In file included from ./Vulkan/glslang/SPIRV/hex_float.h:39,
from ./Vulkan/glslang/SPIRV/SpvBuilder.cpp:49:
./Vulkan/glslang/SPIRV/bitutils.h: In instantiation of ‘Dest spvutils::BitwiseCast(Src) [with Dest = spvutils::Float16; Src = short unsigned int]’:
./Vulkan/glslang/SPIRV/hex_float.h:138:47: required from ‘T spvutils::FloatProxy<T>::getAsFloat() const [with T = spvutils::Float16]’
./Vulkan/glslang/SPIRV/hex_float.h:821:52: required from here
./Vulkan/glslang/SPIRV/bitutils.h:29:14: warning: ‘void* memcpy(void*, const void*, size_t)’ writing to an object of non-trivially copyable type ‘class spvutils::Float16’; use copy-assignment or copy-initialization instead [-Wclass-memaccess]
std::memcpy(&dest, &source, sizeof(dest));
~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from ./Vulkan/glslang/SPIRV/SpvBuilder.cpp:49:
./Vulkan/glslang/SPIRV/hex_float.h:43:7: note: ‘class spvutils::Float16’ declared here
class Float16 {
^~~~~~~
In file included from ./Vulkan/glslang/SPIRV/hex_float.h:39,
from ./Vulkan/glslang/SPIRV/SpvBuilder.cpp:49:
./Vulkan/glslang/SPIRV/bitutils.h: In instantiation of ‘Dest spvutils::BitwiseCast(Src) [with Dest = spvutils::FloatProxy<spvutils::Float16>; Src = short unsigned int]’:
./Vulkan/glslang/SPIRV/hex_float.h:431:28: required from ‘void spvutils::HexFloat<T, Traits>::setFromSignUnbiasedExponentAndNormalizedSignificand(bool, spvutils::HexFloat<T, Traits>::int_type, spvutils::HexFloat<T, Traits>::uint_type, bool) [with T = spvutils::FloatProxy<spvutils::Float16>; Traits = spvutils::HexFloatTraits<spvutils::FloatProxy<spvutils::Float16> >; spvutils::HexFloat<T, Traits>::int_type = short int; spvutils::HexFloat<T, Traits>::uint_type = short unsigned int]’
./Vulkan/glslang/SPIRV/hex_float.h:633:5: required from ‘void spvutils::HexFloat<T, Traits>::castTo(other_T&, spvutils::round_direction) [with other_T = spvutils::HexFloat<spvutils::FloatProxy<spvutils::Float16>, spvutils::HexFloatTraits<spvutils::FloatProxy<spvutils::Float16> > >; T = spvutils::FloatProxy<float>; Traits = spvutils::HexFloatTraits<spvutils::FloatProxy<float> >]’
./Vulkan/glslang/SPIRV/hex_float.h:817:39: required from here
./Vulkan/glslang/SPIRV/bitutils.h:29:14: warning: ‘void* memcpy(void*, const void*, size_t)’ copying an object of non-trivial type ‘class spvutils::FloatProxy<spvutils::Float16>’ from an array of ‘short unsigned int’ [-Wclass-memaccess]
std::memcpy(&dest, &source, sizeof(dest));
~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from ./Vulkan/glslang/SPIRV/SpvBuilder.cpp:49:
./Vulkan/glslang/SPIRV/hex_float.h:115:7: note: ‘class spvutils::FloatProxy<spvutils::Float16>’ declared here
class FloatProxy {
^~~~~~~~~~
```
When capabilities are needed for specific SPIR-V instructions, it is
fragile to do so based on GLSL/AST usage; it should be based on actual
instructions they got translated to.
When constructing a matrix from another matrix with smaller dimensions,
there's no need to extract the scalars out of columns and rebuild the
resulting matrix from scalars - instead, we can just construct shorter
vectors with OpShuffle and combine them to the final result.
This keeps the common casts such as mat3(mat4) in vector registers,
which may improve performance for some GPUs, and cleans up output of
translation tools like SPIRV-Cross.
Fixes#1412.
These introduce limited support for 8/16-bit types such that they can only be accessed in buffer memory and converted to/from 32-bit types.
Contributed from Khronos-internal work.
