[lld-macho] Change bitfield types to be identical.

[oontvoo]

Summary

Symbol's subclasses all have an additional bitfield of type uint8_t (RefState enum).
For the bitfields in the same block tomerge, they should be of the same type. (clang/gcc will work, but others like MSVC does not)

Eg., https://gcc.godbolt.org/z/9sPbzYsqG

[int3]

Oh yes, I remember seeing this issue. Thanks!

[thakis]

Bitfields can't be merged across classes in either abi: https://gcc.godbolt.org/z/n5Efxh551

Also, Defined doesn't have a refState field.

These fields are semantically bool, so I'd keep them that unless there's a reason to change it. In this case this doesn't buy anything as far as I can tell. (But if you have eg /usr/bin/time -f %M / /usr/bin/time -l numbers to back up a benefit, then changes like this are great of course.)

[oontvoo]

In D113040#3104059, @thakis wrote:

Bitfields can't be merged across classes in either abi: https://gcc.godbolt.org/z/n5Efxh551

Also, Defined doesn't have a refState field.

These fields are semantically bool, so I'd keep them that unless there's a reason to change it. In this case this doesn't buy anything as far as I can tell. (But if you have eg /usr/bin/time -f %M / /usr/bin/time -l numbers to back up a benefit, then changes like this are great of course.)

oops ... too late . will revert it.

re: benefit: nothing measured yet , I'd been seeing a few warnings in the vicinity warning: ‘lld::macho::DylibSymbol::refState’ is too small to hold all values of ‘enum class lld::macho::RefState’ so I started poking around an noticed this ...

lld/MachO/Symbols.h

protected:
 
   Kind symbolKind;
   const char *nameData;
   mutable uint32_t nameSize;
   InputFile *file;
 
 public:
   // True if this symbol was referenced by a regular (non-bitcode) object.
-  bool isUsedInRegularObj : 1;
+  uint8_t isUsedInRegularObj : 1;
 
   // True if an undefined or dylib symbol is used from a live section.
-  bool used : 1;
+  uint8_t used : 1;
 };
 
 class Defined : public Symbol {
 public:
   Defined(StringRefZ name, InputFile *file, InputSection *isec, uint64_t value,
           uint64_t size, bool isWeakDef, bool isExternal, bool isPrivateExtern,
           bool isThumb, bool isReferencedDynamically, bool noDeadStrip);