Capability def parsing & codegen + disjoint sets (#3451)

* Capability def parsing & codegen + disjoint sets

This change adds a capability definition file, and a code generator
to produce C++ code that defines the capability enums and necessary
data structures around the capabilities.

Extends the existing CapabilitySet class to support expressing
disjoint sets of capabilities. This sets up for the next change
that will enhance our type checking with reasoning of capability
requirements.

* Fix cmake.

* Fix warning.

* Fix.

* Fix isBetterForTarget to prefer less specialized option.

* Fix.

* Fix premake.

* Fix intrinsic.

* Fix vs sln file.

---------

Co-authored-by: Yong He <yhe@nvidia.com>

1 files changed, 135 insertions, 0 deletions

diff --git a/source/slang/slang-capabilities.capdef b/source/slang/slang-capabilities.capdef
new file mode 100644
index 000000000..7e5931edf
--- /dev/null
+++ b/source/slang/slang-capabilities.capdef
@@ -0,0 +1,135 @@
+// This file is the single source of truth for all capabilities
+// supported by the Slang language.
+//
+// This file will be parsed and processed by the slang-capability-generator
+// tool during the build process to produce slang-generated-capability-defs.h
+// and slang-generated-capability-defs-impl.h files that constitute the final
+// C++ source of the compiler. New capabilties should be added by editing
+// this file instead of the generated .h files.
+//
+// A capability atom represent a basic unit that characterizes a single code-gen target or
+// a platform-specific API/feature, e.g. _GL_EXT_ray_tracing represents the GLSL ray tracing
+// extension, and `glsl` represents the GLSL code gen target.
+//
+// A capability name is defined by a unique disjunction of conjunction of capability atoms.
+// For example, `raytracing` is a name that expands to
+// glsl + _GL_EXT_ray_tracing | spirv_1_4 + _GL_EXT_ray_tracing | hlsl + _sm_6_4
+// which means it requires the `_GL_EXT_ray_tracing` extension when generating code for glsl
+// or spirv, and requires sm_6_4 when generating hlsl.
+//
+// There are three types of capability definitions:
+// - `def`: this will introduce an new capability atom. If there is an inheritance clause,
+//    the capability name will expand to all inherited atoms plus the newly introduced atom.
+// - `abstract`: an abstract capability does not introduce an actual atom, but it defines
+//   an implicit conflict group such that two capabilities inheriting the same abstract
+//   capability cannot be satisfied simultaneously. When used in an expression, `abstract`
+//   capability also expands into a disjunction (or) of all inherited capabilities.
+// - `alias`: this defines an alias and does not introduce actual atoms.
+
+// Several capabilities represent the target formats in which we generate code.
+// Because we can only generate code in one format at a time, all of these are
+// marked as conflicting with one another along the `TargetFormat` axis.
+//
+// Note: We are only including here the source code formats we initially generate
+// code in and not the formats that code might be translated into "downstream."
+// Trying to figure out how to integrate both kinds of formats into our capability
+// system will be an interesting challenge (e.g., can we compile code for `hlsl+spirv`
+// and for `glsl+spirv` or even just for `spirv`, and how should all of those impact
+// overloading).
+//
+def textualTarget;
+
+abstract target;
+def hlsl : target + textualTarget;
+def glsl : target + textualTarget;
+def c : target + textualTarget;
+def cpp : target + textualTarget;
+def cuda : target + textualTarget;
+
+// We have multiple capabilities for the various SPIR-V versions,
+// arranged so that they inherit from one another to represent which versions
+// provide a super-set of the features of earlier ones (e.g., SPIR-V 1.4 is
+// expressed as inheriting from SPIR-V 1.3).
+//
+def spirv_1_0 : target;
+def spirv_1_1 : spirv_1_0;
+def spirv_1_2 : spirv_1_1;
+def spirv_1_3 : spirv_1_2;
+def spirv_1_4 : spirv_1_3;
+def spirv_1_5 : spirv_1_4;
+def spirv_1_6 : spirv_1_5;
+alias spirv = spirv_1_0;
+alias spirv_latest = spirv_1_6;
+
+// Capabilities that stand for target spirv version for GLSL backend.
+// These are not compilation targets.
+def glsl_spirv_1_0;
+def glsl_spirv_1_1 : glsl_spirv_1_0;
+def glsl_spirv_1_2 : glsl_spirv_1_1;
+def glsl_spirv_1_3 : glsl_spirv_1_2;
+def glsl_spirv_1_4 : glsl_spirv_1_3;
+def glsl_spirv_1_5 : glsl_spirv_1_4;
+def glsl_spirv_1_6 : glsl_spirv_1_5;
+
+abstract stage;
+def vertex : stage;
+def fragment : stage;
+alias pixel = fragment;
+def compute : stage;
+def hull : stage;
+def domain : stage;
+def geometry : stage;
+def raygen : stage;
+def intersection : stage;
+def anyhit : stage;
+def closesthit: stage;
+def miss : stage;
+def mesh : stage;
+
+def _sm_5_1 : hlsl;
+def _sm_6_0 : _sm_5_1;
+def _sm_6_1 : _sm_6_0;
+def _sm_6_2 : _sm_6_1;
+def _sm_6_3 : _sm_6_2;
+def _sm_6_4 : _sm_6_3;
+def _sm_6_5 : _sm_6_4;
+def _sm_6_6 : _sm_6_5;
+def _sm_6_7 : _sm_6_6;
+
+// The following capabilities all pertain to how ray tracing shaders are translated
+// to GLSL, where there are two different extensions that can provide the core
+// functionality of `TraceRay` and the related operations.
+//
+// The two extensions are expressed as distinct capabilities that both are marked
+// as conflicting on the `RayTracingExtension` axis, so that a compilation target
+// cannot have both enabled at once.
+//
+// The `GL_EXT_ray_tracing` extension should be favored, so it has a rank of `1`
+// instead of `0`, which means that when comparing overloads that require these
+// extensions, the `EXT` extension will be favored over the `NV` extension, if
+// all other factors are equal.
+//
+def _GL_EXT_ray_tracing : glsl + glsl_spirv_1_4 = 1;
+def _GL_NV_ray_tracing : _GL_EXT_ray_tracing;
+def _SPV_KHR_ray_tracing : spirv_1_4;
+alias GL_NV_ray_tracing = _GL_NV_ray_tracing | _SPV_KHR_ray_tracing | _sm_6_4 | cuda;
+alias GL_EXT_ray_tracing = _GL_EXT_ray_tracing | _SPV_KHR_ray_tracing | _sm_6_4 | cuda;
+alias raytracing = GL_EXT_ray_tracing;
+
+def _GL_EXT_fragment_shader_barycentric : glsl + fragment;
+def _GL_NV_fragment_shader_barycentric : _GL_EXT_fragment_shader_barycentric;
+def _SPV_KHR_fragment_shader_barycentric : spirv_1_0 + fragment;
+alias GL_NV_fragment_shader_barycentric = _GL_NV_fragment_shader_barycentric | _SPV_KHR_fragment_shader_barycentric | hlsl + fragment;
+alias GL_EXT_fragment_shader_barycentric = _GL_EXT_fragment_shader_barycentric | _SPV_KHR_fragment_shader_barycentric | hlsl + fragment;
+
+// TODO: define what SM means for all supported targets.
+
+alias sm_5_1 = _sm_5_1;
+alias sm_6_0 = _sm_6_0;
+alias sm_6_1 = _sm_6_1;
+alias sm_6_2 = _sm_6_2;
+alias sm_6_3 = _sm_6_3;
+alias sm_6_4 = _sm_6_4 | raytracing;
+alias sm_6_5 = _sm_6_5;
+alias sm_6_6 = _sm_6_6;
+alias sm_6_7 = _sm_6_7;