Re: [Qemu-devel] [PATCH] nios2: define tcg_env

[Richard Henderson]

On 10/10/2017 09:49 AM, Peter Maydell wrote:
> On 10 October 2017 at 16:18, Paolo Bonzini <address@hidden> wrote:
>> This should be done by all target and, since commit 53f6672bcf
>> ("gen-icount: use tcg_ctx.tcg_env instead of cpu_env", 2017-06-30),
>> is causing the NIOS2 target to hang.
>>
>> This is because the test for "should I exit to the main loop"
>> was being done with the correct offset to the icount decrementer,
>> but using TCG temporary 0 (the frame pointer) rather than the
>> env pointer.
>>
>> Cc: address@hidden
>> Cc: Marek Vasut <address@hidden>
>> Reported-by: Thomas Huth <address@hidden>
>> Signed-off-by: Paolo Bonzini <address@hidden>
>> ---
>>  target/nios2/translate.c | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/target/nios2/translate.c b/target/nios2/translate.c
>> index 6b0961837d..54fbe898df 100644
>> --- a/target/nios2/translate.c
>> +++ b/target/nios2/translate.c
>> @@ -948,6 +948,7 @@ void nios2_tcg_init(void)
>>      int i;
>>
>>      cpu_env = tcg_global_reg_new_ptr(TCG_AREG0, "env");
>> +    tcg_ctx.tcg_env = cpu_env;
>>
>>      for (i = 0; i < NUM_CORE_REGS; i++) {
>>          cpu_R[i] = tcg_global_mem_new(cpu_env,
>> --
> 
> Is there somewhere we could put an assert() so we can catch this
> error for future targets rather than them just silently generating
> bad code?

Yes, I can arrange for this.

That said, probably the best change we could make is to eliminate cpu_env
entirely, and create tcg_ctx.tcg_env generically (possibly renaming this to a
standalone global variable called cpu_env, minimizing the changes within
target/*).  It is, after all, the same for every target, and there is no longer
any other TCG_AREG* value that can be used.


r~