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gh-112529: Use GC heaps for GC allocations in free-threaded builds (gh-114157)
* gh-112529: Use GC heaps for GC allocations in free-threaded builds The free-threaded build's garbage collector implementation will need to find GC objects by traversing mimalloc heaps. This hooks up the allocation calls with the correct heaps by using a thread-local "current_obj_heap" variable. * Refactor out setting heap based on type
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6 files changed

+85
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‎Include/internal/pycore_object_alloc.h

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#ifndef Py_INTERNAL_OBJECT_ALLOC_H
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#define Py_INTERNAL_OBJECT_ALLOC_H
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#include "pycore_object.h" // _PyType_HasFeature()
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#include "pycore_pystate.h" // _PyThreadState_GET()
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#include "pycore_tstate.h" // _PyThreadStateImpl
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#ifdef __cplusplus
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extern "C" {
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#endif
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#ifndef Py_BUILD_CORE
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# error "this header requires Py_BUILD_CORE define"
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#endif
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#ifdef Py_GIL_DISABLED
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static inline mi_heap_t *
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_PyObject_GetAllocationHeap(_PyThreadStateImpl *tstate, PyTypeObject *tp)
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{
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struct _mimalloc_thread_state *m = &tstate->mimalloc;
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if (_PyType_HasFeature(tp, Py_TPFLAGS_PREHEADER)) {
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return &m->heaps[_Py_MIMALLOC_HEAP_GC_PRE];
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}
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else if (_PyType_IS_GC(tp)) {
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return &m->heaps[_Py_MIMALLOC_HEAP_GC];
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}
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else {
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return &m->heaps[_Py_MIMALLOC_HEAP_OBJECT];
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}
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}
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#endif
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// Sets the heap used for PyObject_Malloc(), PyObject_Realloc(), etc. calls in
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// Py_GIL_DISABLED builds. We use different heaps depending on if the object
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// supports GC and if it has a pre-header. We smuggle the choice of heap
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// through the _mimalloc_thread_state. In the default build, this simply
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// calls PyObject_Malloc().
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static inline void *
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_PyObject_MallocWithType(PyTypeObject *tp, size_t size)
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{
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#ifdef Py_GIL_DISABLED
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_PyThreadStateImpl *tstate = (_PyThreadStateImpl *)_PyThreadState_GET();
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struct _mimalloc_thread_state *m = &tstate->mimalloc;
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m->current_object_heap = _PyObject_GetAllocationHeap(tstate, tp);
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#endif
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void *mem = PyObject_Malloc(size);
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#ifdef Py_GIL_DISABLED
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m->current_object_heap = &m->heaps[_Py_MIMALLOC_HEAP_OBJECT];
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#endif
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return mem;
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}
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static inline void *
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_PyObject_ReallocWithType(PyTypeObject *tp, void *ptr, size_t size)
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{
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#ifdef Py_GIL_DISABLED
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_PyThreadStateImpl *tstate = (_PyThreadStateImpl *)_PyThreadState_GET();
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struct _mimalloc_thread_state *m = &tstate->mimalloc;
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m->current_object_heap = _PyObject_GetAllocationHeap(tstate, tp);
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#endif
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void *mem = PyObject_Realloc(ptr, size);
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#ifdef Py_GIL_DISABLED
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m->current_object_heap = &m->heaps[_Py_MIMALLOC_HEAP_OBJECT];
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#endif
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return mem;
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}
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#ifdef __cplusplus
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}
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#endif
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#endif // !Py_INTERNAL_OBJECT_ALLOC_H

‎Makefile.pre.in

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@@ -1852,6 +1852,7 @@ PYTHON_HEADERS= \
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$(srcdir)/Include/internal/pycore_moduleobject.h \
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$(srcdir)/Include/internal/pycore_namespace.h \
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$(srcdir)/Include/internal/pycore_object.h \
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$(srcdir)/Include/internal/pycore_object_alloc.h \
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$(srcdir)/Include/internal/pycore_object_state.h \
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$(srcdir)/Include/internal/pycore_obmalloc.h \
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$(srcdir)/Include/internal/pycore_obmalloc_init.h \

‎Objects/typeobject.c

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@@ -11,6 +11,7 @@
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#include "pycore_modsupport.h" // _PyArg_NoKwnames()
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#include "pycore_moduleobject.h" // _PyModule_GetDef()
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#include "pycore_object.h" // _PyType_HasFeature()
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#include "pycore_object_alloc.h" // _PyObject_MallocWithType()
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#include "pycore_pyerrors.h" // _PyErr_Occurred()
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#include "pycore_pystate.h" // _PyThreadState_GET()
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#include "pycore_symtable.h" // _Py_Mangle()
@@ -1729,7 +1730,7 @@ _PyType_AllocNoTrack(PyTypeObject *type, Py_ssize_t nitems)
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const size_t size = _PyObject_VAR_SIZE(type, nitems+1);
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const size_t presize = _PyType_PreHeaderSize(type);
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char *alloc = PyObject_Malloc(size + presize);
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char *alloc = _PyObject_MallocWithType(type, size + presize);
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if (alloc == NULL) {
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return PyErr_NoMemory();
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}

‎PCbuild/pythoncore.vcxproj

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@@ -255,6 +255,7 @@
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<ClInclude Include="..\Include\internal\pycore_moduleobject.h" />
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<ClInclude Include="..\Include\internal\pycore_namespace.h" />
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<ClInclude Include="..\Include\internal\pycore_object.h" />
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<ClInclude Include="..\Include\internal\pycore_object_alloc.h" />
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<ClInclude Include="..\Include\internal\pycore_object_state.h" />
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<ClInclude Include="..\Include\internal\pycore_obmalloc.h" />
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<ClInclude Include="..\Include\internal\pycore_obmalloc_init.h" />

‎PCbuild/pythoncore.vcxproj.filters

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<ClInclude Include="..\Include\internal\pycore_object.h">
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<Filter>Include\internal</Filter>
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</ClInclude>
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<ClInclude Include="..\Include\internal\pycore_object_alloc.h">
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<Filter>Include\internal</Filter>
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</ClInclude>
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<ClInclude Include="..\Include\internal\pycore_object_state.h">
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<Filter>Include\internal</Filter>
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</ClInclude>

‎Python/gc.c

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@@ -9,6 +9,7 @@
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#include "pycore_initconfig.h"
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#include "pycore_interp.h" // PyInterpreterState.gc
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#include "pycore_object.h"
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#include "pycore_object_alloc.h" // _PyObject_MallocWithType()
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#include "pycore_pyerrors.h"
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#include "pycore_pystate.h" // _PyThreadState_GET()
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#include "pycore_weakref.h" // _PyWeakref_ClearRef()
@@ -1795,14 +1796,14 @@ _Py_RunGC(PyThreadState *tstate)
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}
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static PyObject *
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gc_alloc(size_t basicsize, size_t presize)
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gc_alloc(PyTypeObject *tp, size_t basicsize, size_t presize)
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{
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PyThreadState *tstate = _PyThreadState_GET();
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if (basicsize > PY_SSIZE_T_MAX - presize) {
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return _PyErr_NoMemory(tstate);
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}
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size_t size = presize + basicsize;
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char *mem = PyObject_Malloc(size);
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char *mem = _PyObject_MallocWithType(tp, size);
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if (mem == NULL) {
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return _PyErr_NoMemory(tstate);
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}
@@ -1817,7 +1818,7 @@ PyObject *
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_PyObject_GC_New(PyTypeObject *tp)
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{
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size_t presize = _PyType_PreHeaderSize(tp);
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PyObject *op = gc_alloc(_PyObject_SIZE(tp), presize);
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PyObject *op = gc_alloc(tp, _PyObject_SIZE(tp), presize);
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if (op == NULL) {
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return NULL;
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}
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}
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size_t presize = _PyType_PreHeaderSize(tp);
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size_t size = _PyObject_VAR_SIZE(tp, nitems);
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op = (PyVarObject *)gc_alloc(size, presize);
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op = (PyVarObject *)gc_alloc(tp, size, presize);
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if (op == NULL) {
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return NULL;
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}
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PyUnstable_Object_GC_NewWithExtraData(PyTypeObject *tp, size_t extra_size)
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{
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size_t presize = _PyType_PreHeaderSize(tp);
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PyObject *op = gc_alloc(_PyObject_SIZE(tp) + extra_size, presize);
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PyObject *op = gc_alloc(tp, _PyObject_SIZE(tp) + extra_size, presize);
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if (op == NULL) {
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return NULL;
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}
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return (PyVarObject *)PyErr_NoMemory();
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}
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char *mem = (char *)op - presize;
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mem = (char *)PyObject_Realloc(mem, presize + basicsize);
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mem = (char *)_PyObject_ReallocWithType(Py_TYPE(op), mem, presize + basicsize);
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if (mem == NULL) {
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return (PyVarObject *)PyErr_NoMemory();
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}

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