Add persistent program cache for Program.compile

cuda_core/cuda/core/_program.pxd

@@ -17,5 +17,6 @@ cdef class Program:
         object _compile_lock  # Per-instance lock for compile-time mutation
         bint _use_libdevice      # Flag for libdevice loading
         bint _libdevice_added
-        bytes _nvrtc_code       # Source code for NVRTC retry (PCH auto-resize)
+        bytes _code             # Source code as bytes: used for key derivation and NVRTC PCH retry
+        str _code_type          # Normalised code_type ("c++", "ptx", "nvvm")
         str _pch_status         # PCH creation outcome after compile

cuda_core/cuda/core/_program.pyx

@@ -85,7 +85,12 @@ cdef class Program:
         self._h_nvvm.reset()
 
     def compile(
-        self, target_type: str, name_expressions: tuple | list = (), logs = None
+        self,
+        target_type: str,
+        name_expressions: tuple | list = (),
+        logs=None,
+        *,
+        cache: "ProgramCacheResource | None" = None,
     ) -> ObjectCode:
         """Compile the program to the specified target type.
 
@@ -98,13 +103,126 @@ cdef class Program:
             Used for template instantiation and similar cases.
         logs : object, optional
             Object with a ``write`` method to receive compilation logs.
+            On a cache hit no compilation runs and ``logs`` receives
+            nothing -- callers that rely on log output to confirm a
+            compile happened should compile without ``cache=``.
+        cache : :class:`~cuda.core.utils.ProgramCacheResource`, optional
+            If provided, the compiled binary is looked up in ``cache`` via a
+            key derived from the program's code, options, and ``target_type``.
+            On a hit the cached bytes are wrapped in a fresh
+            :class:`~cuda.core.ObjectCode` (with the same ``target_type``
+            and ``ProgramOptions.name``) and returned without re-compiling;
+            on a miss the compile output is stored as raw bytes (the cache
+            extracts ``bytes(object_code.code)``). Passing a non-empty
+            ``name_expressions`` together with ``cache=`` raises
+            ``ValueError``: NVRTC populates
+            ``ObjectCode.symbol_mapping`` at compile time and that mapping
+            is not carried in the binary the cache stores, so cache hits
+            would silently miss ``get_kernel(name_expression)`` lookups.
+            Options that require an ``extra_digest`` (``include_path``,
+            ``pre_include``, ``pch``, ``use_pch``, ``pch_dir``, NVVM
+            ``use_libdevice=True``, or NVRTC ``options.name`` with a
+            directory component) raise ``ValueError`` via
+            :func:`~cuda.core.utils.make_program_cache_key`; for those
+            compiles, use the manual ``make_program_cache_key(...)``
+            pattern directly.
+
+            ``cache=`` is independent of ``ProgramOptions.no_cache``: the
+            former controls this program-level cache (compiled-output
+            reuse across calls), while ``no_cache`` is forwarded to the
+            Linker to disable its in-process JIT cache for cuLink/nvJitLink.
+            Setting ``options.no_cache=True`` does not bypass ``cache=``,
+            and vice-versa.
 
         Returns
         -------
         :class:`~cuda.core.ObjectCode`
             The compiled object code.
         """
-        return Program_compile(self, target_type, name_expressions, logs)
+        # Mirror Program_init's code_type normalization so callers can pass
+        # "PTX" or "Cubin" without confusing case-sensitive comparisons
+        # later in the dispatch (Program_compile_nvrtc keys on lowercase
+        # target_type, ``make_program_cache_key`` lowercases too).
+        if isinstance(target_type, str):
+            target_type = target_type.lower()
+
+        if cache is None:
+            return _program_compile_uncached(self, target_type, name_expressions, logs)
+
+        # Deferred import to avoid a circular import between _program and
+        # cuda.core.utils._program_cache (the cache module already imports
+        # ProgramOptions from this module). Import from the leaf module so
+        # tests that monkeypatch make_program_cache_key via that path
+        # intercept reliably.
+        from cuda.core.utils._program_cache import (
+            ProgramCacheResource,
+            make_program_cache_key,
+        )
+
+        if not isinstance(cache, ProgramCacheResource):
+            raise TypeError(
+                "cache must be an instance of "
+                "cuda.core.utils.ProgramCacheResource; got "
+                f"{type(cache).__name__}"
+            )
+
+        # ``name_expressions`` is incompatible with the cache: NVRTC
+        # populates ``ObjectCode.symbol_mapping`` from name-expression
+        # mangling at compile time, and that mapping isn't carried in
+        # the binary bytes the cache stores. Without this guard the
+        # first call (cache miss) would return an ObjectCode with
+        # symbol_mapping populated, while every subsequent call (hit)
+        # would return one without -- silently breaking later
+        # ``get_kernel(name_expression)`` lookups that work on the
+        # uncached path. Fail loud here instead.
+        if name_expressions:
+            raise ValueError(
+                "Program.compile(cache=...) does not support name_expressions: "
+                "ObjectCode.symbol_mapping is populated by NVRTC at compile "
+                "time and is not preserved across a cache round-trip, so cache "
+                "hits would silently break get_kernel(name_expression) lookups "
+                "that the uncached path supports. Compile without cache= when "
+                "name_expressions are needed, or look up mangled symbols by "
+                "hand from the cached ObjectCode."
+            )
+
+        # ``self._code`` is always stored as bytes (see ``Program_init``),
+        # but ``make_program_cache_key`` only accepts bytes when
+        # ``code_type == "nvvm"`` -- c++/ptx must be ``str``. The bytes
+        # came from ``code.encode()`` on a ``str`` Program_init validated
+        # via ``assert_type(code, str)``, so this round-trip is always
+        # safe; no try/except needed.
+        code_for_key = self._code if self._code_type == "nvvm" else self._code.decode("utf-8")
+
+        key = make_program_cache_key(
+            code=code_for_key,
+            code_type=self._code_type,
+            options=self._options,
+            target_type=target_type,
+        )
+        hit_bytes = cache.get(key)
+        if hit_bytes is not None:
+            # The uncached NVRTC path warns when the active driver can't
+            # load freshly-generated PTX; that loadability is a property
+            # of the driver, not of how the bytes were produced, so the
+            # warning applies equally to cached PTX. Mirror it here so a
+            # cache hit doesn't silently hide an incompatibility that the
+            # uncached call would have surfaced.
+            if (
+                self._backend == "NVRTC"
+                and target_type == "ptx"
+                and not _can_load_generated_ptx()
+            ):
+                warn(
+                    "The CUDA driver version is older than the backend version. "
+                    "The generated ptx will not be loadable by the current driver.",
+                    stacklevel=2,
+                    category=RuntimeWarning,
+                )
+            return ObjectCode._init(hit_bytes, target_type, name=self._options.name)
+        compiled = _program_compile_uncached(self, target_type, name_expressions, logs)
+        cache[key] = compiled
+        return compiled
 
     @property
     def pch_status(self) -> str | None:
@@ -503,6 +621,19 @@ class ProgramOptions:
 # Private Classes and Helper Functions
 # =============================================================================
 
+
+def _program_compile_uncached(program, target_type, name_expressions, logs):
+    """Run ``Program_compile`` without the cache wrapper.
+
+    Module-level Python function so tests can monkeypatch it from
+    ``cuda.core._program`` to avoid invoking NVRTC when exercising the cache
+    wrapper in :meth:`Program.compile`. ``Program`` itself is a ``cdef class``
+    and its methods cannot be reassigned from Python, so the seam must live
+    outside the class.
+    """
+    return Program_compile(program, target_type, name_expressions, logs)
+
+
 # Module-level state for NVVM lazy loading
 _nvvm_module = None
 _nvvm_import_attempted = False
@@ -618,6 +749,7 @@ cdef inline int Program_init(Program self, object code, str code_type, object op
 
     self._options = options = check_or_create_options(ProgramOptions, options, "Program options")
     code_type = code_type.lower()
+    self._code_type = code_type
     self._compile_lock = threading.Lock()
     self._use_libdevice = False
     self._libdevice_added = False
@@ -638,16 +770,18 @@ cdef inline int Program_init(Program self, object code, str code_type, object op
             HANDLE_RETURN_NVRTC(NULL, cynvrtc.nvrtcCreateProgram(
                 &nvrtc_prog, code_ptr, name_ptr, 0, NULL, NULL))
         self._h_nvrtc = create_nvrtc_program_handle(nvrtc_prog)
-        self._nvrtc_code = code_bytes
+        self._code = code_bytes
         self._backend = "NVRTC"
         self._linker = None
 
     elif code_type == "ptx":
         assert_type(code, str)
         if options.extra_sources is not None:
             raise ValueError("extra_sources is not supported by the PTX backend.")
+        code_bytes = code.encode()
+        self._code = code_bytes
         self._linker = Linker(
-            ObjectCode._init(code.encode(), code_type), options=_translate_program_options(options)
+            ObjectCode._init(code_bytes, code_type), options=_translate_program_options(options)
         )
         self._backend = self._linker.backend
 
@@ -657,10 +791,13 @@ cdef inline int Program_init(Program self, object code, str code_type, object op
             code = code.encode("utf-8")
         elif not isinstance(code, (bytes, bytearray)):
             raise TypeError("NVVM IR code must be provided as str, bytes, or bytearray")
+        self._code = bytes(code)  # Coerce bytearray -> bytes so retention type is stable
 
-        code_ptr = <const char*>(<bytes>code)
+        # Use self._code (strictly bytes) for the C pointer so a bytearray
+        # input doesn't trip the `<bytes>code` cast at runtime.
+        code_ptr = <const char*>self._code
         name_ptr = <const char*>options._name
-        code_len = len(code)
+        code_len = len(self._code)
 
         with nogil:
             HANDLE_RETURN_NVVM(NULL, cynvvm.nvvmCreateProgram(&nvvm_prog))
@@ -832,7 +969,7 @@ cdef object Program_compile_nvrtc(Program self, str target_type, object name_exp
         HANDLE_RETURN_NVRTC(NULL, cynvrtc.nvrtcSetPCHHeapSize(required))
 
     cdef cynvrtc.nvrtcProgram retry_prog
-    cdef const char* code_ptr = <const char*>self._nvrtc_code
+    cdef const char* code_ptr = <const char*>self._code
     cdef const char* name_ptr = <const char*>self._options._name
     with nogil:
         HANDLE_RETURN_NVRTC(NULL, cynvrtc.nvrtcCreateProgram(

cuda_core/cuda/core/utils/__init__.py

@@ -0,0 +1,23 @@
+# SPDX-FileCopyrightText: Copyright (c) 2024-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+from cuda.core._memoryview import (
+    StridedMemoryView,
+    args_viewable_as_strided_memory,
+)
+from cuda.core.utils._program_cache import (
+    FileStreamProgramCache,
+    InMemoryProgramCache,
+    ProgramCacheResource,
+    make_program_cache_key,
+)
+
+__all__ = [
+    "FileStreamProgramCache",
+    "InMemoryProgramCache",
+    "ProgramCacheResource",
+    "StridedMemoryView",
+    "args_viewable_as_strided_memory",
+    "make_program_cache_key",
+]

cuda_core/cuda/core/utils/_program_cache/__init__.py

@@ -0,0 +1,36 @@
+# SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+"""Persistent program cache for cuda.core.
+
+Public surface:
+
+* :class:`ProgramCacheResource` -- bytes-in / bytes-out ABC.
+* :class:`InMemoryProgramCache` -- thread-safe LRU dict-backed cache.
+* :class:`FileStreamProgramCache` -- atomic, multi-process directory cache.
+* :func:`make_program_cache_key` -- key derivation for arbitrary
+  ``Program`` configurations.
+
+The package is split into submodules by concern. Tests that need to
+monkeypatch internals (Windows flag, version probes, helpers, ...)
+should reach into the owning submodule (e.g.
+``_program_cache._file_stream._IS_WINDOWS``,
+``_program_cache._keys._linker_backend_and_version``) rather than the
+package object: the symbols re-exported here are only convenience
+aliases and don't intercept calls within the submodules.
+"""
+
+from __future__ import annotations
+
+from ._abc import ProgramCacheResource
+from ._file_stream import FileStreamProgramCache
+from ._in_memory import InMemoryProgramCache
+from ._keys import make_program_cache_key
+
+__all__ = [
+    "FileStreamProgramCache",
+    "InMemoryProgramCache",
+    "ProgramCacheResource",
+    "make_program_cache_key",
+]