2757acf6ed
NLR buffers are usually quite large (use lots of C stack) and expensive to push and pop. Some of the time they are only needed to perform clean up if an exception happens, and then they re-raise the exception. This commit allows optimizing that scenario by introducing a linked-list of NLR callbacks that are called automatically when an exception is raised. They are essentially a light-weight NLR handler that can implement a "finally" block, i.e. clean-up when an exception is raised, or (by passing `true` to nlr_pop_jump_callback) when execution leaves the scope. Signed-off-by: Damien George <damien@micropython.org>
89 lines
3.2 KiB
C
89 lines
3.2 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) 2013-2023 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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#include "py/mpstate.h"
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#if !MICROPY_NLR_SETJMP
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// When not using setjmp, nlr_push_tail is called from inline asm so needs special care
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#if MICROPY_NLR_X86 && MICROPY_NLR_OS_WINDOWS
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// On these 32-bit platforms make sure nlr_push_tail doesn't have a leading underscore
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unsigned int nlr_push_tail(nlr_buf_t *nlr) asm ("nlr_push_tail");
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#else
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// LTO can't see inside inline asm functions so explicitly mark nlr_push_tail as used
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__attribute__((used)) unsigned int nlr_push_tail(nlr_buf_t *nlr);
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#endif
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#endif
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unsigned int nlr_push_tail(nlr_buf_t *nlr) {
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nlr_buf_t **top = &MP_STATE_THREAD(nlr_top);
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nlr->prev = *top;
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MP_NLR_SAVE_PYSTACK(nlr);
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*top = nlr;
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return 0; // normal return
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}
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void nlr_pop(void) {
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nlr_buf_t **top = &MP_STATE_THREAD(nlr_top);
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*top = (*top)->prev;
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}
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void nlr_push_jump_callback(nlr_jump_callback_node_t *node, nlr_jump_callback_fun_t fun) {
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nlr_jump_callback_node_t **top = &MP_STATE_THREAD(nlr_jump_callback_top);
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node->prev = *top;
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node->fun = fun;
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*top = node;
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}
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void nlr_pop_jump_callback(bool run_callback) {
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nlr_jump_callback_node_t **top = &MP_STATE_THREAD(nlr_jump_callback_top);
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nlr_jump_callback_node_t *cur = *top;
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*top = (*top)->prev;
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if (run_callback) {
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cur->fun(cur);
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}
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}
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// This function pops and runs all callbacks that were registered after `nlr`
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// was pushed (via nlr_push). It assumes:
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// - a descending C stack,
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// - that all nlr_jump_callback_node_t's in the linked-list pointed to by
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// nlr_jump_callback_top are on the C stack
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// It works by popping each node in turn until the next node is NULL or above
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// the `nlr` pointer on the C stack (and so pushed before `nlr` was pushed).
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void nlr_call_jump_callbacks(nlr_buf_t *nlr) {
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nlr_jump_callback_node_t **top = &MP_STATE_THREAD(nlr_jump_callback_top);
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while (*top != NULL && (void *)*top < (void *)nlr) {
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nlr_pop_jump_callback(true);
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}
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}
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#if MICROPY_ENABLE_VM_ABORT
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NORETURN void nlr_jump_abort(void) {
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MP_STATE_THREAD(nlr_top) = MP_STATE_VM(nlr_abort);
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nlr_jump(NULL);
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}
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#endif
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