Consider the following code:
layout(constant_id=0) const int Y = 1;
layout(constant_id=1) const int Z = 2;
layout(constant_id=3) const int X = Y + Z;
Previously, it would produce SPIR-V decorations like this:
Decorate 21(Y) SpecId 1
Decorate 22 SpecId 3
Decorate 33(Z) SpecId 0
This seems inaccurate, since the spec constant `X` that is dependent on
the two others did not get a name in the SPIR-V decorations. This behavior
may potentially negatively affect shader introspection capabilities.
This change alters the behavior to always add a name, which results in the code
above producing the following decorations:
Decorate 21(Y) SpecId 1
Decorate 22(X) SpecId 3
Decorate 33(Z) SpecId 0
Note: This required adding a new test mode to see the AST for vulkan tests.
This also required reworking some deeper parts of type creation, regarding
when storage qualification and constness is deduced bottom-up or dictated
top-down.
Fix issue: #237
1. The code generated for matrix constructor should 1) build column
vectors first, 2) build matrix with the vectors.
2. When there is only one scalar type constituent in vector's
constructor, we should populate the constituent to fill all the slots in
the vector. As for matrix, the single constituent should be populated to
the diagonal positions (top-left to bottom-right diagonal).
remove createSpvConstantFromConstSubTree()
Bool -> uint/int with OpSpecConstantOp OpSelect instruction.
uint <-> int conversion with OpSpecConstantOp OpIAdd instruction.
Note, implicit conversion: `const uint = an_int_spec_constant` is not
supported. Explicit type casting is required: `const uint =
uint(an_int_spec_constant)`
This is according to the expected KHR_vulkan_glsl without floating point.
So, floating-point spec-const operations no longer work, and that's
reflected in the tests.
Move SpecConstantOpModeGuard from makeSpvConstantFromConstSubTree() to
visitbinary() and visitunary(). Checking if the visiting node is a spec
constants, if so, turn on the SpecConstantOpMode, otherwise, stay in the
normal mode.
Approach:
Add a flag in `Builder` to indicate 'spec constant mode' and 'normal
mode'. When the builder is in 'normal mode', nothing changed. When the
builder is in 'spec constant mode', binary, unary and other instruction
creation rountines will be redirected to `createSpecConstantOp()` to
create instrution at module level with `OpSpecConstantOp <original
opcode> <operands>`.
'spec constant mode' should be enabled if and only if we are creating
spec constants. So a flager setter/recover guard is added when handling
binary/unary nodes in `createSpvConstantsFromConstSubTree()`.
Note when handling spec constants which are represented as ConstantUnion
Node, we should not use `OpSpecConstantOp` to initialize the composite
constant, so builder is set to 'normal mode'.
Tests:
Tests are added in Test/spv.specConstantOperations.vert, including:
1) Arithmetic, shift opeations for both scalar and composite type spec constants.
2) Size conversion from/to float and double for both scalar and vector.
3) Bitwise and/or/xor for both scalar and vector.
4) Unary negate/not for both scalar and vector.
5) Vector swizzles.
6) Comparisons for scalars.
7) == and != for composite type spec constants
Issues:
1) To implement == and != for composite type spec constants, the Spec needs
to allow OpAll, OpAny, OpFOrdEqual, OpFUnordEqual, OpOrdNotEqual,
OpFUnordNotEqual. Currently none of them are allowed in the Spec.
