Re: [PATCH] break gdb build on 32-bit host with ADI support

[Pedro Alves <palves@redhat.com>]

On 08/24/2017 08:09 PM, Wei-min Pan wrote:
> 
> 
> On 8/24/2017 11:07 AM, Pedro Alves wrote:
>> On 08/24/2017 06:23 PM, Weimin Pan wrote:
>>
>>> diff --git a/gdb/sparc64-tdep.c b/gdb/sparc64-tdep.c
>>> index 6f4fca7..0da2ae5 100644
>>> --- a/gdb/sparc64-tdep.c
>>> +++ b/gdb/sparc64-tdep.c
>>> @@ -90,12 +90,12 @@ static struct cmd_list_element *sparc64adilist =
>>> NULL;
>>>   typedef struct
>>>   {
>>>     /* The ADI block size.  */
>>> -  unsigned long blksize;
>>> +  unsigned long long blksize;
>>>       /* Number of bits used for an ADI version tag which can be
>>>      * used together with the shift value for an ADI version tag
>>>      * to encode or extract the ADI version value in a pointer.  */
>>> -  unsigned long nbits;
>>> +  unsigned long long nbits;
>> Do you really need to count 64-bit bits? :-P  :-)
> 
> Since the value of either nbits or blksize is between 0 and 64,
> no, I really don't. But without a 32-bit host, I'm simply play
> safe here so that the compiler won't bark.
>> (Formatting of comment is incorrect for GNU code, BTW.  No '*'
>> on each line.)
> 
> Corrected.
> 
>>>       /* The maximum ADI version tag value supported.  */
>>>     int max_version;
>>> @@ -223,9 +223,10 @@ adi_available (void)
>>>       proc->stat.checked_avail = true;
>>>     if (target_auxv_search (&current_target, AT_ADI_BLKSZ,
>>> -                          &proc->stat.blksize) <= 0)
>>> +                          (CORE_ADDR *)&proc->stat.blksize) <= 0)
>> Please don't introduce potential aliasing problems.  Also, missing
>> space before &.
>>
>> Either make blksize really be a CORE_ADDR or do
>>
>>      CORE_ADDR value;
>>      if (target_auxv_search (&current_target, AT_ADI_BLKSZ, &value) <= 0)
>>        return false;
>>      proc->stat.blksize = value;
> 
> Since neither blksize nor nbits is a CORE_ADDR, I'm taking your second
> suggestion.

Then you don't need the

 -  unsigned long nbits;
 +  unsigned long long nbits;

change anymore..

> 

>>> @@ -346,7 +347,8 @@ adi_read_versions (CORE_ADDR vaddr, size_t size,
>>> unsigned char *tags)
>>>     if (!adi_is_addr_mapped (vaddr, size))
>>>       {
>>>         adi_stat_t ast = get_adi_info (ptid_get_pid (inferior_ptid));
>>> -      error(_("Address at 0x%lx is not in ADI maps"),
>>> vaddr*ast.blksize);
>>> +      error(_("Address at 0x%llx is not in ADI maps"),
>>> +            (long long)(vaddr*ast.blksize));
>>>       }
>> Use paddress instead?  Also spaces around '*' and after the cast.
> 
> Where is paddress defined? I tried casting to "uint64" which yields to
> "unsigned long" on a 64-bit host and didn't bode well with %llx.

 $ grep paddress *.h
 utils.h:extern const char *paddress (struct gdbarch *gdbarch, CORE_ADDR addr);


>>> @@ -387,7 +390,7 @@ adi_print_versions (CORE_ADDR vaddr, size_t cnt,
>>> unsigned char *tags)
>>>     while (cnt > 0)
>>>       {
>>>         QUIT;
>>> -      printf_filtered ("0x%016lx:\t", vaddr * adi_stat.blksize);
>>> +      printf_filtered ("0x%016llx:\t", (long
>>> long)(vaddr*adi_stat.blksize));
>> paddress / hex_string / phex_nz ?
> 
> ??

Try grepping for those things.


>>   static CORE_ADDR
>>   adi_normalize_address (CORE_ADDR addr)
>>   {
>>     adi_stat_t ast = get_adi_info (ptid_get_pid (inferior_ptid));
>>
>>     if (ast.nbits)
>>       return ((CORE_ADDR)(((long)addr << ast.nbits) >> ast.nbits));
>>     return addr;
>>   }
>>
>> looks suspiciously bogus to me.  Consider a 32-bit host
>> remote/cross debugging a SPARC64 target machine.  Also consider
>> a Win64-hosted GDB.
> 
> Good point. Changing it to:
> 
>       return ((long long)(((long long)addr << ast.nbits) >> ast.nbits));
> 
> Thanks.

Still looks odd to me.  
Why are you shifting signed types, for instance?
Any why do you need the casts in the first place, BTW?

Thanks,
Pedro Alves