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

[Wei-min Pan <weimin.pan@oracle.com>]

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.

>> -  target_auxv_search (&current_target, AT_ADI_NBITS, &proc->stat.nbits);
>> +  target_auxv_search (&current_target, AT_ADI_NBITS,
>> +                      (CORE_ADDR *)&proc->stat.nbits);
>>     proc->stat.max_version = (1 << proc->stat.nbits) - 2;
>>     proc->stat.is_avail = true;
>>   
> Ditto.
>
>> @@ -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.

>>   
>>     int target_errno;
>> @@ -366,7 +368,8 @@ adi_write_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));
> Ditto.
>
>>       }
>>   
>>     int target_errno;
>> @@ -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 ?

??

>>         for (int i = maxelts; i > 0 && cnt > 0; i--, cnt--)
>>           {
>>             if (tags[v_idx] == 0xff)    /* no version tag */
>> @@ -418,7 +421,7 @@ do_examine (CORE_ADDR start, int bcnt)
>>     if (read_cnt == -1)
>>       error (_("No ADI information"));
>>     else if (read_cnt < cnt)
>> -    error(_("No ADI information at 0x%lx"), vaddr);
>> +    error(_("No ADI information at 0x%llx"), (long long)vaddr);
> padress.
>
>>   
>>     adi_print_versions (vstart, cnt, buf);
>>   
>> @@ -438,7 +441,7 @@ do_assign (CORE_ADDR start, size_t bcnt, int version)
>>     if (set_cnt == -1)
>>       error (_("No ADI information"));
>>     else if (set_cnt < cnt)
>> -    error(_("No ADI information at 0x%lx"), vaddr);
>> +    error(_("No ADI information at 0x%llx"), (long long)vaddr);
> paddress.
>
> BTW, this cast to long here:
>
>   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.

>
> Thanks,
> Pedro Alves
>