Re: Signedness of char in BTF

[Yonghong Song <yhs@fb.com>]

On 7/22/22 4:25 AM, Jose E. Marchesi wrote:
> 
>> The llvm and pahole generate BTF_INT_BOOL when the dwarf type has
>> attribute DW_ATE_boolean.
>> But BTF_INT_BOOL is actually used in libbpf to differentiate
>> configuration values (CONFIG_* = 'y' vs. CONFIG_* = <value>)
>>
>> In llvm,
>>    uint8_t BTFEncoding;
>>    switch (Encoding) {
>>    case dwarf::DW_ATE_boolean:
>>      BTFEncoding = BTF::INT_BOOL;
>>      break;
>>    case dwarf::DW_ATE_signed:
>>    case dwarf::DW_ATE_signed_char:
>>      BTFEncoding = BTF::INT_SIGNED;
>>      break;
>>    case dwarf::DW_ATE_unsigned:
>>    case dwarf::DW_ATE_unsigned_char:
>>      BTFEncoding = 0;
>>      break;
>>    default:
>>      llvm_unreachable("Unknown BTFTypeInt Encoding");
>>    }
> 
> I just sent a patch to make GCC behave the same way:
> https://gcc.gnu.org/pipermail/gcc-patches/2022-July/598702.html

Sounds good. Thanks!