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>
---
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;