> If I read aarch64_emit_probe_stack_range correctly, these two > instructions are generated when (size <= PROBE_INTERVAL). If > size <= 4 * PROBE_INTERVAL, more instructions are generated, > > sub x9, sp, #16384 > str xzr, [x9] > > sub x9, x9, #PROBE_INTERVAL > str xzr, [x9] > ... /* At most two instances of these two insn. */ > > either > sub x9, x9, #PROBE_INTERVAL > str xzr, [x9, #offset] > or > str xzr, [x9, -16] > > > A probing loop uses both x9 and x10: > > sub x9, sp, #12288 > > sub x10, sp, #36864 > > > > LPSRL0: > > sub x9, x9, 4096 > > str xzr, [x9] > > cmp x9, x10 > > b.ne LPSRL0 > > The probing loop is used when size > 4 * PROBE_INTERVAL > > > with an optional last probe: > > str xzr, [x10,#-16] > > and there can be an optional instruction before the probe, > > sub x10, x10, #PROBE_INTERVAL > > Let me know if my understanding above is wrong.
That's correct, probes can come with a 'sub' instruction just before. > s/aarch64_output_probe_stack-range/aarch64_output_probe_stack_range Thanks, will fix. -- Eric Botcazou
