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.mayd...@linaro.org> --- target/arm/cpu.h | 2 +- target/arm/translate-vfp.inc.c | 7 +++---- target/arm/translate.c | 3 --- 3 files changed, 4 insertions(+), 8 deletions(-) diff --git a/target/arm/cpu.h b/target/arm/cpu.h index 677584e5da0..cf66b8c7fb0 100644 --- a/target/arm/cpu.h +++ b/target/arm/cpu.h @@ -2334,7 +2334,7 @@ static inline uint64_t cpreg_to_kvm_id(uint32_t cpregid) * 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 diff --git a/target/arm/translate-vfp.inc.c b/target/arm/translate-vfp.inc.c index e1a90175983..bf31b186578 100644 --- a/target/arm/translate-vfp.inc.c +++ b/target/arm/translate-vfp.inc.c @@ -119,15 +119,14 @@ static bool full_vfp_access_check(DisasContext *s, bool ignore_vfp_enabled) 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 diff --git a/target/arm/translate.c b/target/arm/translate.c index 6d18892adee..2677eaeb1e1 100644 --- a/target/arm/translate.c +++ b/target/arm/translate.c @@ -8824,9 +8824,6 @@ static bool do_ldm(DisasContext *s, arg_ldst_block *a, int min_n) 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; -- 2.20.1