When we exit a block under icount with instructions left to execute we might need a shorter than normal block to take us to the next deterministic event. Instead of creating a throwaway block on demand we use the existing compile flags mechanism to ensure we fetch (or compile and fetch) a block with exactly the number of instructions we need.
Signed-off-by: Alex Bennée <alex.ben...@linaro.org> --- accel/tcg/cpu-exec.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c index d9ef69121c..7f477af891 100644 --- a/accel/tcg/cpu-exec.c +++ b/accel/tcg/cpu-exec.c @@ -730,16 +730,18 @@ static inline void cpu_loop_exec_tb(CPUState *cpu, TranslationBlock *tb, /* Ensure global icount has gone forward */ icount_update(cpu); /* Refill decrementer and continue execution. */ - insns_left = MIN(0xffff, cpu->icount_budget); + insns_left = MIN(CF_COUNT_MASK, cpu->icount_budget); cpu_neg(cpu)->icount_decr.u16.low = insns_left; cpu->icount_extra = cpu->icount_budget - insns_left; - if (!cpu->icount_extra && insns_left < tb->icount) { - /* Execute any remaining instructions, then let the main loop - * handle the next event. - */ - if (insns_left > 0) { - cpu_exec_nocache(cpu, insns_left, tb, false); - } + + /* + * If the next tb has more instructions than we have left to + * execute we need to ensure we find/generate a TB with exactly + * insns_left instructions in it. + */ + if (!cpu->icount_extra && insns_left > 0 && insns_left < tb->icount) { + g_assert(insns_left < CF_COUNT_MASK); + cpu->cflags_next_tb = (tb->cflags & ~CF_COUNT_MASK) | insns_left; } #endif } -- 2.20.1