kernels: add a function system_variants

This function lists all the variants that are available on the current
system.

Author: danieldk

kernels/src/kernels/variants.py

@@ -1,3 +1,4 @@
+import itertools
 import logging
 import platform
 import re
@@ -16,6 +17,7 @@
     XPU,
     Backend,
     ROCm,
+    _backend,
     _select_backend,
     parse_backend,
 )
@@ -28,32 +30,77 @@
 
 @dataclass(unsafe_hash=True)
 class Torch:
-    _VARIANT_REGEX: ClassVar[re.Pattern] = re.compile(r"torch(\d+?)(\d+)")
+    """Versioned Torch framework (arch variants)."""
 
-    version: Version | None
+    _VARIANT_REGEX: ClassVar[re.Pattern] = re.compile(
+        r"torch(\d+?)(\d+)(?:-(cxx11|cxx98))?"
+    )
+
+    version: Version
+    cxx11_abi: bool | None
+
+    @staticmethod
+    def possible_variants() -> list["Torch"]:
+        if has_torch:
+            import torch
+
+            torch_version = parse(torch.__version__)
+            torch_version = Version(f"{torch_version.major}.{torch_version.minor}")
+
+            os_ = platform.system().lower()
+            if os_ == "linux":
+                cxx11_abi = torch.compiled_with_cxx11_abi()
+                return [
+                    Torch(version=torch_version, cxx11_abi=cxx11_abi),
+                    Torch(version=torch_version, cxx11_abi=None),
+                ]
+            else:
+                return [Torch(version=torch_version, cxx11_abi=None)]
+        else:
+            return []
 
     @property
     def variant_str(self) -> str:
-        if self.version is None:
-            return "torch"
-        return f"torch{self.version.major}{self.version.minor}"
+        base = f"torch{self.version.major}{self.version.minor}"
+        if self.cxx11_abi is None:
+            return base
+        return f"{base}-{'cxx11' if self.cxx11_abi else 'cxx98'}"
 
     @staticmethod
     def parse(s: str) -> "Torch":
-        if s == "torch":
-            return Torch(version=None)
         m = Torch._VARIANT_REGEX.fullmatch(s)
         if not m:
             raise ValueError(f"Invalid Torch variant string: {s!r}")
-        return Torch(version=Version(f"{m.group(1)}.{m.group(2)}"))
+        version = Version(f"{m.group(1)}.{m.group(2)}")
+        abi_str = m.group(3)
+        if abi_str is None:
+            cxx11_abi = None
+        else:
+            cxx11_abi = abi_str != "cxx98"
+        return Torch(version=version, cxx11_abi=cxx11_abi)
 
 
 @dataclass(unsafe_hash=True)
 class TvmFfi:
+    """Versioned tvm-ffi framework (arch variants)."""
+
     _VARIANT_REGEX: ClassVar[re.Pattern] = re.compile(r"tvm-ffi(\d+?)(\d+)")
 
     version: Version
 
+    @staticmethod
+    def possible_variants() -> list["TvmFfi"]:
+        if has_tvm_ffi:
+            import tvm_ffi
+
+            tvm_ffi_version = parse(tvm_ffi.__version__)
+            tvm_ffi_version = Version(
+                f"{tvm_ffi_version.major}.{tvm_ffi_version.minor}"
+            )
+            return [TvmFfi(version=tvm_ffi_version)]
+        else:
+            return []
+
     @property
     def variant_str(self) -> str:
         return f"tvm-ffi{self.version.major}{self.version.minor}"
@@ -66,41 +113,60 @@ def parse(s: str) -> "TvmFfi":
         return TvmFfi(version=Version(f"{m.group(1)}.{m.group(2)}"))
 
 
+@strict
+@dataclass(unsafe_hash=True)
+class TorchNoarch:
+    """Versionless Torch framework (noarch variants)."""
+
+    @staticmethod
+    def possible_variants() -> list["TorchNoarch"]:
+        if has_torch:
+            return [TorchNoarch()]
+        else:
+            return []
+
+    @property
+    def variant_str(self) -> str:
+        return "torch"
+
+
 @strict
 @dataclass(unsafe_hash=True)
 class Arch:
-    """Aarch kernel information."""
+    """Arch kernel information."""
 
     backend: Backend
     platform: str
     os: str
-    cxx11_abi: bool | None
 
     @property
     def variant_str(self) -> str:
-        if self.cxx11_abi is None:
-            return f"{self.backend.variant_str}-{self.platform}-{self.os}"
-        else:
-            return f"{'cxx11' if self.cxx11_abi else 'cxx98'}-{self.backend.variant_str}-{self.platform}-{self.os}"
+        return f"{self.backend.variant_str}-{self.platform}-{self.os}"
+
+    @staticmethod
+    def possible_variants() -> list["Arch"]:
+        cpu = platform.machine()
+        os = platform.system().lower()
+
+        if os == "darwin":
+            cpu = "aarch64" if cpu == "arm64" else cpu
+        elif os == "windows":
+            cpu = "x86_64" if cpu == "AMD64" else cpu
+
+        backend = _backend()
+
+        return [Arch(backend=backend, platform=cpu, os=os)]
 
     @staticmethod
     def parse(parts: list[str]) -> "Arch":
-        # Handle Linux with cxx11 marker.
-        if len(parts) == 4:
-            # In the future, we want to remove the marker and use cxx11 as
-            # the default. We check on cxx98 for this reason.
-            cxx11_abi = parts[0] != "cxx98"
-            parts = parts[1:]
-        elif len(parts) == 3:
-            cxx11_abi = None
-        else:
+        if len(parts) != 3:
             raise ValueError(f"Invalid arch variant parts: {parts!r}")
 
         backend = parse_backend(parts[0])
         platform = parts[1]
         os = parts[2]
 
-        return Arch(backend=backend, platform=platform, os=os, cxx11_abi=cxx11_abi)
+        return Arch(backend=backend, platform=platform, os=os)
 
 
 @strict
@@ -110,6 +176,13 @@ class Noarch:
 
     backend_name: str
 
+    @staticmethod
+    def possible_variants() -> list["Noarch"]:
+        backend = _backend()
+        noarch_backend_name = "npu" if backend.name == "cann" else backend.name
+        names = {noarch_backend_name, "universal"}
+        return [Noarch(backend_name=name) for name in sorted(names)]
+
     @property
     def variant_str(self) -> str:
         return self.backend_name
@@ -121,37 +194,92 @@ def parse(s: str) -> "Noarch":
 
 @strict
 @dataclass(unsafe_hash=True)
-class Variant:
-    """Kernel build variant."""
+class ArchVariant:
+    """Arch kernel build variant."""
 
     framework: Torch | TvmFfi
-    arch: Arch | Noarch
+    arch: Arch
+
+    @staticmethod
+    def possible_variants() -> list["ArchVariant"]:
+        frameworks: list[Torch | TvmFfi] = (
+            Torch.possible_variants() + TvmFfi.possible_variants()
+        )
+        archs = Arch.possible_variants()
+        return [
+            ArchVariant(framework=fw, arch=arch)
+            for fw, arch in itertools.product(frameworks, archs)
+        ]
 
     @property
     def variant_str(self) -> str:
         return f"{self.framework.variant_str}-{self.arch.variant_str}"
 
+
+@strict
+@dataclass(unsafe_hash=True)
+class NoarchVariant:
+    """Noarch kernel build variant."""
+
+    framework: TorchNoarch
+    arch: Noarch
+
     @staticmethod
-    def parse(variant_str: str) -> "Variant":
-        parts = variant_str.split("-")
-
-        arch: Arch | Noarch
-        framework: Torch | TvmFfi
-
-        if parts[0] == "torch":
-            # noarch: e.g. "torch-cpu"
-            framework = Torch.parse(parts[0])
-            arch = Noarch.parse("-".join(parts[1:]))
-        elif parts[0].startswith("torch"):
-            framework = Torch.parse(parts[0])
-            arch = Arch.parse(parts[1:])
-        elif parts[0] == "tvm" and parts[1].startswith("ffi"):
-            framework = TvmFfi.parse(f"tvm-{parts[1]}")
-            arch = Arch.parse(parts[2:])
-        else:
-            raise ValueError(f"Unknown framework in variant string: {variant_str!r}")
+    def possible_variants() -> list["NoarchVariant"]:
+        frameworks = TorchNoarch.possible_variants()
+        archs = Noarch.possible_variants()
+        return [
+            NoarchVariant(framework=fw, arch=arch)
+            for fw, arch in itertools.product(frameworks, archs)
+        ]
+
+    @property
+    def variant_str(self) -> str:
+        return f"{self.framework.variant_str}-{self.arch.variant_str}"
+
 
-        return Variant(framework=framework, arch=arch)
+Variant = ArchVariant | NoarchVariant
+
+
+def system_variants() -> list[Variant]:
+    """Return all possible build variants for the current system.
+
+    Warning: this function should only be used internally (so don't export
+             at the top-level) and for informational purposes, such as user
+             feedback. When loading kernels, etc. rely what is on disk and
+             use `parse_variant` + `resolve_variant`, since this uses our
+             priority order, etc."""
+    result: list[Variant] = (
+        ArchVariant.possible_variants() + NoarchVariant.possible_variants()
+    )
+    return _sort_variants(result)
+
+
+def parse_variant(variant_str: str) -> Variant:
+    """Parse a variant string into an ArchVariant or NoarchVariant."""
+    parts = variant_str.split("-")
+
+    if parts[0] == "torch":
+        # noarch: e.g. "torch-cpu"
+        return NoarchVariant(
+            framework=TorchNoarch(), arch=Noarch.parse("-".join(parts[1:]))
+        )
+    elif parts[0].startswith("torch"):
+        if len(parts) >= 2 and parts[1] in ("cxx11", "cxx98"):
+            framework_str = f"{parts[0]}-{parts[1]}"
+            arch_parts = parts[2:]
+        else:
+            framework_str = parts[0]
+            arch_parts = parts[1:]
+        return ArchVariant(
+            framework=Torch.parse(framework_str), arch=Arch.parse(arch_parts)
+        )
+    elif parts[0] == "tvm" and len(parts) >= 2 and parts[1].startswith("ffi"):
+        return ArchVariant(
+            framework=TvmFfi.parse(f"tvm-{parts[1]}"), arch=Arch.parse(parts[2:])
+        )
+    else:
+        raise ValueError(f"Unknown framework in variant string: {variant_str!r}")
 
 
 def get_variants(api: HfApi, *, repo_id: str, revision: str) -> list[Variant]:
@@ -162,10 +290,10 @@ def get_variants(api: HfApi, *, repo_id: str, revision: str) -> list[Variant]:
         item.path.split("/")[-1] for item in tree if isinstance(item, RepoFolder)
     }
 
-    variants = []
+    variants: list[Variant] = []
     for variant_str in variant_strs:
         try:
-            variants.append(Variant.parse(variant_str))
+            variants.append(parse_variant(variant_str))
         except ValueError:
             logging.warning(
                 f"Repository {repo_id} (revision: {revision}) contains invalid build variant variant: {variant_str!r}"
@@ -181,10 +309,10 @@ def get_variants_local(repo_path: Path) -> list[Variant]:
     except Exception:
         return []
 
-    variants = []
+    variants: list[Variant] = []
     for variant_str in variant_strs:
         try:
-            variants.append(Variant.parse(variant_str))
+            variants.append(parse_variant(variant_str))
         except ValueError:
             pass
     return variants
@@ -228,7 +356,7 @@ def resolve_variants(
     if has_tvm_ffi:
         import tvm_ffi
 
-        # Parse Torch version and strip patch/tags.
+        # Parse tvm-ffi version and strip patch/tags.
         tvm_ffi_version = parse(tvm_ffi.__version__)
         tvm_ffi_version = Version(f"{tvm_ffi_version.major}.{tvm_ffi_version.minor}")
 
@@ -275,9 +403,9 @@ def _filter_variants(
     tvm_ffi_version: Version | None,
 ) -> list[Variant]:
     """Return only the variants applicable to the current system."""
-    result = []
+    result: list[Variant] = []
     for v in variants:
-        if isinstance(v.arch, Arch):
+        if isinstance(v, ArchVariant):
             # Skip non-matching CPU or OS.
             if v.arch.platform != cpu or v.arch.os != os:
                 continue
@@ -286,7 +414,10 @@ def _filter_variants(
             if isinstance(v.framework, Torch):
                 if v.framework.version != torch_version:
                     continue
-                if v.arch.cxx11_abi != torch_cxx11_abi:
+                if (
+                    v.framework.cxx11_abi is not None
+                    and v.framework.cxx11_abi != torch_cxx11_abi
+                ):
                     continue
             elif isinstance(v.framework, TvmFfi):
                 if v.framework.version != tvm_ffi_version:
@@ -302,8 +433,7 @@ def _filter_variants(
                     continue
             elif v.arch.backend.variant_str != selected_backend.variant_str:
                 continue
-        else:
-            assert isinstance(v.arch, Noarch)
+        elif isinstance(v, NoarchVariant):
             # Only noarch variants with a matching backend or "universal"
             # are applicable.
             noarch_backend_name = (
@@ -330,7 +460,7 @@ def _sort_variants(
     """
 
     def sort_key(v: Variant) -> tuple:
-        if isinstance(v.arch, Arch):
+        if isinstance(v, ArchVariant):
             framework_order = 0 if isinstance(v.framework, Torch) else 1
             if isinstance(v.arch.backend, (CUDA, ROCm, XPU, CANN)):
                 # Order by backend version in reverse (higher is better).
@@ -339,7 +469,7 @@ def sort_key(v: Variant) -> tuple:
                 backend_order = 0
             return (framework_order, backend_order)
         else:
-            assert isinstance(v.arch, Noarch)
+            assert isinstance(v, NoarchVariant)
             universal_order = 1 if v.arch.backend_name == "universal" else 0
             return (2, universal_order)