02d830c035
This patch introduces the MICROPY_ENABLE_PYSTACK option (disabled by default) which enables a "Python stack" that allows to allocate and free memory in a scoped, or Last-In-First-Out (LIFO) way, similar to alloca(). A new memory allocation API is introduced along with this Py-stack. It includes both "local" and "nonlocal" LIFO allocation. Local allocation is intended to be equivalent to using alloca(), whereby the same function must free the memory. Nonlocal allocation is where another function may free the memory, so long as it's still LIFO. Follow-up patches will convert all uses of alloca() and VLA to the new scoped allocation API. The old behaviour (using alloca()) will still be available, but when MICROPY_ENABLE_PYSTACK is enabled then alloca() is no longer required or used. The benefits of enabling this option are (or will be once subsequent patches are made to convert alloca()/VLA): - Toolchains without alloca() can use this feature to obtain correct and efficient scoped memory allocation (compared to using the heap instead of alloca(), which is slower). - Even if alloca() is available, enabling the Py-stack gives slightly more efficient use of stack space when calling nested Python functions, due to the way that compilers implement alloca(). - Enabling the Py-stack with the stackless mode allows for even more efficient stack usage, as well as retaining high performance (because the heap is no longer used to build and destroy stackless code states). - With Py-stack and stackless enabled, Python-calling-Python is no longer recursive in the C mp_execute_bytecode function. The micropython.pystack_use() function is included to measure usage of the Python stack.
133 lines
4.2 KiB
C
133 lines
4.2 KiB
C
/*
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* This file is part of the MicroPython project, http://micropython.org/
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*
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* The MIT License (MIT)
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*
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* Copyright (c) 2013, 2014 Damien P. George
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#ifndef MICROPY_INCLUDED_PY_NLR_H
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#define MICROPY_INCLUDED_PY_NLR_H
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// non-local return
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// exception handling, basically a stack of setjmp/longjmp buffers
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#include <limits.h>
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#include <setjmp.h>
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#include <assert.h>
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#include "py/mpconfig.h"
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typedef struct _nlr_buf_t nlr_buf_t;
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struct _nlr_buf_t {
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// the entries here must all be machine word size
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nlr_buf_t *prev;
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void *ret_val; // always a concrete object (an exception instance)
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#if !defined(MICROPY_NLR_SETJMP) || !MICROPY_NLR_SETJMP
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#if defined(__i386__)
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void *regs[6];
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#elif defined(__x86_64__)
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#if defined(__CYGWIN__)
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void *regs[12];
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#else
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void *regs[8];
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#endif
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#elif defined(__thumb2__) || defined(__thumb__) || defined(__arm__)
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void *regs[10];
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#elif defined(__xtensa__)
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void *regs[10];
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#else
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#define MICROPY_NLR_SETJMP (1)
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//#warning "No native NLR support for this arch, using setjmp implementation"
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#endif
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#endif
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#if MICROPY_NLR_SETJMP
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jmp_buf jmpbuf;
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#endif
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#if MICROPY_ENABLE_PYSTACK
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void *pystack;
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#endif
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};
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// Helper macros to save/restore the pystack state
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#if MICROPY_ENABLE_PYSTACK
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#define MP_NLR_SAVE_PYSTACK(nlr_buf) (nlr_buf)->pystack = MP_STATE_THREAD(pystack_cur)
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#define MP_NLR_RESTORE_PYSTACK(nlr_buf) MP_STATE_THREAD(pystack_cur) = (nlr_buf)->pystack
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#else
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#define MP_NLR_SAVE_PYSTACK(nlr_buf) (void)nlr_buf
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#define MP_NLR_RESTORE_PYSTACK(nlr_buf) (void)nlr_buf
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#endif
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#if MICROPY_NLR_SETJMP
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#include "py/mpstate.h"
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NORETURN void nlr_setjmp_jump(void *val);
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// nlr_push() must be defined as a macro, because "The stack context will be
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// invalidated if the function which called setjmp() returns."
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#define nlr_push(buf) ( \
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(buf)->prev = MP_STATE_THREAD(nlr_top), \
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MP_NLR_SAVE_PYSTACK(buf), \
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MP_STATE_THREAD(nlr_top) = (buf), \
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setjmp((buf)->jmpbuf))
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#define nlr_pop() { MP_STATE_THREAD(nlr_top) = MP_STATE_THREAD(nlr_top)->prev; }
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#define nlr_jump(val) nlr_setjmp_jump(val)
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#else
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unsigned int nlr_push(nlr_buf_t *);
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void nlr_pop(void);
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NORETURN void nlr_jump(void *val);
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#endif
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// This must be implemented by a port. It's called by nlr_jump
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// if no nlr buf has been pushed. It must not return, but rather
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// should bail out with a fatal error.
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NORETURN void nlr_jump_fail(void *val);
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// use nlr_raise instead of nlr_jump so that debugging is easier
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#ifndef MICROPY_DEBUG_NLR
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#define nlr_raise(val) nlr_jump(MP_OBJ_TO_PTR(val))
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#else
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#include "mpstate.h"
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#define nlr_raise(val) \
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do { \
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/*printf("nlr_raise: nlr_top=%p\n", MP_STATE_THREAD(nlr_top)); \
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fflush(stdout);*/ \
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void *_val = MP_OBJ_TO_PTR(val); \
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assert(_val != NULL); \
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assert(mp_obj_is_exception_instance(val)); \
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nlr_jump(_val); \
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} while (0)
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#if !MICROPY_NLR_SETJMP
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#define nlr_push(val) \
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assert(MP_STATE_THREAD(nlr_top) != val),nlr_push(val)
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/*
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#define nlr_push(val) \
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printf("nlr_push: before: nlr_top=%p, val=%p\n", MP_STATE_THREAD(nlr_top), val),assert(MP_STATE_THREAD(nlr_top) != val),nlr_push(val)
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#endif
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*/
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#endif
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#endif
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#endif // MICROPY_INCLUDED_PY_NLR_H
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