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esp32/gccollect: Make level arg volatile to force recursive function.

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Otherwise the compiler may inline the gc_collect_inner() function and/or
remove the recursion, which is necessary to spill all the windowed
registers to the C stack.

Signed-off-by: Damien George <damien@micropython.org>
This commit is contained in:
Damien George 2023-08-15 14:34:25 +10:00
parent 05dcb8be99
commit fa1ea21f75
1 changed files with 9 additions and 14 deletions
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23
ports/esp32/gccollect.c
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@ -39,30 +39,25 @@
#include "xtensa/hal.h"
static void gc_collect_inner(int level) {
// The level argument must be volatile to force the compiler to emit code that
// will call this function recursively, to nest the C stack.
static void gc_collect_inner(volatile unsigned int level) {
if (level < XCHAL_NUM_AREGS / 8) {
// Go deeper on the stack to spill more registers from the register window.
gc_collect_inner(level + 1);
if (level != 0) {
return;
}
}
if (level == XCHAL_NUM_AREGS / 8) {
// get the sp
} else {
// Deep enough so that all registers are on the C stack, now trace the stack.
volatile uint32_t sp = (uint32_t)esp_cpu_get_sp();
gc_collect_root((void **)sp, ((mp_uint_t)MP_STATE_THREAD(stack_top) - sp) / sizeof(uint32_t));
return;
}
// trace root pointers from any threads
#if MICROPY_PY_THREAD
mp_thread_gc_others();
#endif
}
void gc_collect(void) {
gc_collect_start();
gc_collect_inner(0);
#if MICROPY_PY_THREAD
mp_thread_gc_others();
#endif
gc_collect_end();
}