Previously, when generating non-Vulkan GLSL, each use of a spec constant
would be subsituted for its default value and the declaration of the constant
itself would be omitted completely.
This change slightly alters this behavior. The uses of the constant are kept,
as well as the declaration, although the latter is stripped of the layout
qualifier. The declaration is also prepended with the following code:
#ifndef <constant name>_value
#define <constant name> <default constant value>
#endif
and the constant itself now looks like
const <constant type> <constant name> = <constant name>_value;
The rationale for this change is that it gives the user a way to provide
custom values for specialization constants even when the target does not
support them.
This is kinda tricky, because if we only conditionally write to a
function parameter variable it is implicitly preserved in SPIR-V, so we must force
an in qualifier on the parameter to get the same behavior in GLSL.
Previously, we would generate parentheses proactively when generating
binary ops, however, this leads to uglier code and hits warnings in
compilers when used as a conditional.
There was a potential problem if variables were invalidated and SPIR-V
read expressions which depended on other expression which in turn depended on the
invalidated variable.
Also fixes issue where variables were considered immutable if they were
forwardable. This allowed some incorrect optimizations to slip through.
This is now fixed in ESSL 3.10 backend of glslang, so we can remove the old workaround
of dropping full memory barriers.
Also fixes unrelated issue which newer glslang detects.
In some cases we need to bitcast when dealing with int vs. uint.
SPIR-V allows inputs to be of different integer signedness, so we need
to deal with this somehow.
Add testing system to test SPIR-V assembly.
For now, test all possible combination for all major cases.
- IAdd (which doesn't care about input type as long as they're equal)
- SDiv/UDiv operations which case about input type.
- Arith/Logical right shifts.
- IEqual to test outputs to bvec, which shouldn't get output cast. Also
tests casting in function-like calls.
