mirror of https://gitee.com/openkylin/qemu.git
accel/tcg: avoid re-translating one-shot instructions
By definition a single instruction is capable of being an IO instruction. This avoids a problem of triggering a cpu_io_recompile on a non-recorded translation which then fails because it expects tcg_tb_lookup() to succeed unconditionally. The normal use case requires a TB to be able to resolve machine state. The other users of tcg_tb_lookup() are able to tolerate a missing TB if the machine state has been resolved by other means - which in the single-shot case is always true because machine state is synced at the start of a block. Reported-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Message-id: 20210415162454.22056-1-alex.bennee@linaro.org Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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@ -1863,7 +1863,7 @@ TranslationBlock *tb_gen_code(CPUState *cpu,
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if (phys_pc == -1) {
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/* Generate a one-shot TB with 1 insn in it */
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cflags = (cflags & ~CF_COUNT_MASK) | 1;
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cflags = (cflags & ~CF_COUNT_MASK) | CF_LAST_IO | 1;
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}
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max_insns = cflags & CF_COUNT_MASK;
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