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22b0de2755
This PR sets up tagged pointers for CPython. The general idea is to create a separate struct _PyStackRef for everything on the evaluation stack to store the bits. This forces the C compiler to warn us if we try to cast things or pull things out of the struct directly. Only for free threading: We tag the low bit if something is deferred - that means we skip incref and decref operations on it. This behavior may change in the future if Mark's plans to defer all objects in the interpreter loop pans out. This implies a strict stack reference discipline is required. ALL incref and decref operations on stackrefs must use the stackref variants. It is unsafe to untag something then do normal incref/decref ops on it. The new incref and decref variants are called dup and close. They mimic a "handle" API operating on these stackrefs. Please read Include/internal/pycore_stackref.h for more information! --------- Co-authored-by: Mark Shannon <9448417+markshannon@users.noreply.github.com>
26 lines
1.1 KiB
C
26 lines
1.1 KiB
C
#include "Python.h"
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#include "pycore_ceval.h"
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#include "pycore_frame.h"
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#include "pycore_jit.h"
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// This is where the calling convention changes, on platforms that require it.
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// The actual change is patched in while the JIT compiler is being built, in
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// Tools/jit/_targets.py. On other platforms, this function compiles to nothing.
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_Py_CODEUNIT *
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_ENTRY(_PyInterpreterFrame *frame, _PyStackRef *stack_pointer, PyThreadState *tstate)
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{
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// This is subtle. The actual trace will return to us once it exits, so we
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// need to make sure that we stay alive until then. If our trace side-exits
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// into another trace, and this trace is then invalidated, the code for
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// *this function* will be freed and we'll crash upon return:
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PyAPI_DATA(void) _JIT_EXECUTOR;
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PyObject *executor = (PyObject *)(uintptr_t)&_JIT_EXECUTOR;
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Py_INCREF(executor);
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// Note that this is *not* a tail call:
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PyAPI_DATA(void) _JIT_CONTINUE;
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_Py_CODEUNIT *target = ((jit_func)&_JIT_CONTINUE)(frame, stack_pointer, tstate);
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Py_SETREF(tstate->previous_executor, executor);
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return target;
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}
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