Since commit
ba3e7926691ed3 it has been unnecessary for target code
to call gen_io_end() after an IO instruction in icount mode; it is
sufficient to call gen_io_start() before it and to force the end of
the TB.
Many now-unnecessary calls to gen_io_end() were removed in commit
9e9b10c6491153b, but some were missed or accidentally added later.
Remove unneeded calls from the arm target:
* the call in the handling of exception-return-via-LDM is
unnecessary, and the code is already forcing end-of-TB
* the call in the VFP access check code is more complicated:
we weren't ending the TB, so we need to add the code to
force that by setting DISAS_UPDATE
* the doc comment for ARM_CP_IO doesn't need to mention
gen_io_end() any more
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>
Message-id:
20200619170324.12093-1-peter.maydell@linaro.org
* migration or KVM state synchronization. (Typically this is for "registers"
* which are actually used as instructions for cache maintenance and so on.)
* IO indicates that this register does I/O and therefore its accesses
- * need to be surrounded by gen_io_start()/gen_io_end(). In particular,
+ * need to be marked with gen_io_start() and also end the TB. In particular,
* registers which implement clocks or timers require this.
* RAISES_EXC is for when the read or write hook might raise an exception;
* the generated code will synchronize the CPU state before calling the hook
if (s->v7m_lspact) {
/*
* Lazy state saving affects external memory and also the NVIC,
- * so we must mark it as an IO operation for icount.
+ * so we must mark it as an IO operation for icount (and cause
+ * this to be the last insn in the TB).
*/
if (tb_cflags(s->base.tb) & CF_USE_ICOUNT) {
+ s->base.is_jmp = DISAS_UPDATE;
gen_io_start();
}
gen_helper_v7m_preserve_fp_state(cpu_env);
- if (tb_cflags(s->base.tb) & CF_USE_ICOUNT) {
- gen_io_end();
- }
/*
* If the preserve_fp_state helper doesn't throw an exception
* then it will clear LSPACT; we don't need to repeat this for
gen_io_start();
}
gen_helper_cpsr_write_eret(cpu_env, tmp);
- if (tb_cflags(s->base.tb) & CF_USE_ICOUNT) {
- gen_io_end();
- }
tcg_temp_free_i32(tmp);
/* Must exit loop to check un-masked IRQs */
s->base.is_jmp = DISAS_EXIT;