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accel/tcg: cache single instruction TB on pending replay exception 

Again there is no reason to jump through the nocache hoops to execute
a single instruction block. We do have to add an additional wrinkle to
the cpu_handle_interrupt case to ensure we let through a TB where we
have specifically disabled icount for the block.

As the last user of cpu_exec_nocache we can now remove the function.
Further clean-up will follow in subsequent patches.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20210213130325.14781-18-alex.bennee@linaro.org>
This commit is contained in:
Alex Bennée 2021-02-13 13:03:19 +00:00
parent bc662a3351
commit a11bbb6a23
1 changed files with 4 additions and 40 deletions
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44
accel/tcg/cpu-exec.c
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@ -224,40 +224,6 @@ cpu_tb_exec(CPUState *cpu, TranslationBlock *itb, int *tb_exit)
return last_tb;
}
#ifndef CONFIG_USER_ONLY
/* Execute the code without caching the generated code. An interpreter
could be used if available. */
static void cpu_exec_nocache(CPUState *cpu, int max_cycles,
TranslationBlock *orig_tb, bool ignore_icount)
{
TranslationBlock *tb;
uint32_t cflags = curr_cflags() | CF_NOCACHE;
int tb_exit;
if (ignore_icount) {
cflags &= ~CF_USE_ICOUNT;
}
/* Should never happen.
We only end up here when an existing TB is too long. */
cflags |= MIN(max_cycles, CF_COUNT_MASK);
mmap_lock();
tb = tb_gen_code(cpu, orig_tb->pc, orig_tb->cs_base,
orig_tb->flags, cflags);
tb->orig_tb = orig_tb;
mmap_unlock();
/* execute the generated code */
trace_exec_tb_nocache(tb, tb->pc);
cpu_tb_exec(cpu, tb, &tb_exit);
mmap_lock();
tb_phys_invalidate(tb, -1);
mmap_unlock();
tcg_tb_remove(tb);
}
#endif
static void cpu_exec_enter(CPUState *cpu)
{
@ -524,15 +490,12 @@ static inline bool cpu_handle_exception(CPUState *cpu, int *ret)
#ifndef CONFIG_USER_ONLY
if (replay_has_exception()
&& cpu_neg(cpu)->icount_decr.u16.low + cpu->icount_extra == 0) {
/* try to cause an exception pending in the log */
cpu_exec_nocache(cpu, 1, tb_find(cpu, NULL, 0, curr_cflags()), true);
/* Execute just one insn to trigger exception pending in the log */
cpu->cflags_next_tb = (curr_cflags() & ~CF_USE_ICOUNT) | 1;
}
#endif
if (cpu->exception_index < 0) {
return false;
}
return false;
}
if (cpu->exception_index >= EXCP_INTERRUPT) {
/* exit request from the cpu execution loop */
*ret = cpu->exception_index;
@ -688,6 +651,7 @@ static inline bool cpu_handle_interrupt(CPUState *cpu,
/* Finally, check if we need to exit to the main loop. */
if (unlikely(qatomic_read(&cpu->exit_request))
|| (icount_enabled()
&& (cpu->cflags_next_tb == -1 || cpu->cflags_next_tb & CF_USE_ICOUNT)
&& cpu_neg(cpu)->icount_decr.u16.low + cpu->icount_extra == 0)) {
qatomic_set(&cpu->exit_request, 0);
if (cpu->exception_index == -1) {