Put always_inline on adjustExpr

[silvas]

Summary

This function is incredibly hot (it is called unconditionally for every relocation) and so we need everything the compiler can give us for it. It is just a helper anyway.

This change is good for 3-4% speedup on clang-fsds with ld.lld -O1.

The compiler that needed this identifies itself as gcc (Ubuntu 5.4.0-6ubuntu1~16.04.4) 5.4.0 20160609

Also, this will allow us in the future to more accurately assess the benefits of PGO for building LLD. If we can get this speedup easily without PGO by just applying an attribute, we don't want this 3-4% to inflate the benefit of PGO when we try PGO.

[silvas]

Oh, sorry, I think I accidentally measured this on top of D27145 instead of vs master (so the speedup here is the speedup from D27145). My bad. No wonder the speedup was very similar.

ELF/Relocations.cpp

 }
 
 template <class ELFT>
-static RelExpr adjustExpr(const elf::ObjectFile<ELFT> &File, SymbolBody &Body,
-                          bool IsWrite, RelExpr Expr, uint32_t Type,
-                          const uint8_t *Data, InputSectionBase<ELFT> &S,
-                          typename ELFT::uint RelOff) {
+LLVM_ATTRIBUTE_ALWAYS_INLINE static inline RelExpr
+adjustExpr(const elf::ObjectFile<ELFT> &File, SymbolBody &Body, bool IsWrite,
+           RelExpr Expr, uint32_t Type, const uint8_t *Data,
+           InputSectionBase<ELFT> &S, typename ELFT::uint RelOff) {
   bool Preemptible = isPreemptible(Body, Type);
   if (Body.isGnuIFunc()) {
     Expr = toPlt(Expr);