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Re: [qemu-s390x] [PATCH v3 8/9] target/s390x: Skip wout, cout helpers if
From: |
Richard Henderson |
Subject: |
Re: [qemu-s390x] [PATCH v3 8/9] target/s390x: Skip wout, cout helpers if op helper does not return |
Date: |
Thu, 11 Oct 2018 09:47:15 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.0 |
On 10/11/18 1:06 AM, David Hildenbrand wrote:
> On 03/10/2018 21:39, Richard Henderson wrote:
>> When op raises an exception, it may not have initialized the output
>> temps that would be written back by wout or cout.
>>
>> Cc: address@hidden
>> Signed-off-by: Richard Henderson <address@hidden>
>> ---
>> target/s390x/translate.c | 12 +++++++-----
>> 1 file changed, 7 insertions(+), 5 deletions(-)
>>
>> diff --git a/target/s390x/translate.c b/target/s390x/translate.c
>> index 7363aabf3a..7fad3ad8e9 100644
>> --- a/target/s390x/translate.c
>> +++ b/target/s390x/translate.c
>> @@ -6164,11 +6164,13 @@ static DisasJumpType translate_one(CPUS390XState
>> *env, DisasContext *s)
>> if (insn->help_op) {
>> ret = insn->help_op(s, &o);
>> }
>> - if (insn->help_wout) {
>> - insn->help_wout(s, &f, &o);
>> - }
>> - if (insn->help_cout) {
>> - insn->help_cout(s, &o);
>> + if (ret != DISAS_NORETURN) {
>> + if (insn->help_wout) {
>> + insn->help_wout(s, &f, &o);
>> + }
>> + if (insn->help_cout) {
>> + insn->help_cout(s, &o);
>> + }
>> }
>>
>> /* Free any temporaries created by the helpers. */
>>
>
> What about things like LPSW/LPWSE ? They certainly don't imply that we
> had an exception.
Exception in the tcg sense, not the guest architectural sense, in that we call
cpu_loop_exit from the helper, which performs a longjmp. (Incidentally,
there's no reason to do that for load_psw -- we could just exit the tb
normally.)
> (these two don't use wout/cout, so it is still fine, but I would prefer
> a comment somewhere because otherwise it is really easy to miss that
> DISAS_NORETURN makes us skip these handlers)
Where would you like me to place that comment? In the DisasInsn definition?
r~