GLSL and RelaxedPrecision are quite different in what they affect.
RelaxedPrecision affects operations, while this is merely implied in
GLSL based on inputs.
This leads to situations where we have to promote mediump inputs to
highp, and the simplest approach is to force highp temporaries for
inputs which are consumed in a highp context. For completeness, we also
demote RelaxedPrecision inputs to mediump variables.
PHI is handled by copying the PHI into a temporary.
We have to be very careful with hoisted temporaries, since the child
temporary will not be analyzed up-front. We inherit the hoisted-ness
state and emit the hoisted child temporary as necessary. When faking the
temporaries with OpCopyObject, we make sure to block any variable
hoisting.
Hoisting children of PHI variables is fine, since PHIs are not hoisted with
the same framework as other temporaries.
Rolled the hashes used for glslang, SPIRV-Tools, and SPIRV-Headers to
HEAD, which includes the update to 1.5.
Added passing '--amb' to glslang, so I didn't have to explicitly set
bindings in a large number of test shaders that currently don't, and
now glslang considers them invalid.
Marked all shaders that no longer pass spirv-val as .invalid.
If this is computed *before* a `demote`, but used *after*, forwarding it
will produce the wrong value. This does make for uglier shaders, but
it's necessary right now to ensure correctness.
I needed to use an assembly shader to produce the test for this.
`spirv-opt` is not smart enough (or too smart?) to eliminate the
variable that would be used in GLSL to express this.
This extension provides a new operation which causes a fragment to be
discarded without terminating the fragment shader invocation. The
invocation for the discarded fragment becomes a helper invocation, so
that derivatives will remain defined. The old `HelperInvocation` builtin
becomes undefined when this occurs, so a second new instruction queries
the current helper invocation status.
This is only fully supported for GLSL. HLSL doesn't support the
`IsHelperInvocation` operation and MSL doesn't support the
`DemoteToHelperInvocation` op.
Fixes#1052.
Fix fallout from changes.
There's a bug in glslang that prevents `float16_t`, `[u]int16_t`, and
`[u]int8_t` constants from adding the corresponding SPIR-V capabilities.
SPIRV-Tools, meanwhile, tightened validation so that these constants are
only valid if the corresponding `Float16`, `Int16`, and `Int8` caps are
on. This affects the `16bit-constants.frag` test for GLSL and MSL.
Storage was in place already, so mostly just dealing with bitcasts and
constants.
Simplies some of the bitcasting logic, and this exposed some bugs in the
implementation. Refactor to use correct width integers with explicit bitcast opcodes.
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.
