labath accepted this revision.
labath added inline comments.

================
Comment at: source/Utility/ConstString.cpp:49
+      // pointer, we don't need the lock.
       const StringPoolEntryType &entry = GetStringMapEntryFromKeyData(ccstr);
       return entry.getKey().size();
----------------
labath wrote:
> scott.smith wrote:
> > zturner wrote:
> > > Why do we even have this function which digs into the `StringMap` 
> > > internals rather than just calling existing `StringMap` member functions? 
> > >  Can Can we just delete `GetStringMapEntryFromKeyData` entirely and use 
> > > `StringMap::find`?
> > Probably performance.  If we have to call Find, then we have to call hash, 
> > fault in the appropriate bucket, and then finally return the entry that we 
> > already have in hand.  Plus we'd need the lock.
> > 
> > Can we just delete GetStringMapEntryFromKeyData entirely and use 
> > StringMap::find?
> Unfortunately, I don't think that's possible. `StringMap::find` expects a 
> StringRef. In order to construct that, we need to know the length of the 
> string, and we're back where we started :(
> 
> In reality, this is doing a very different operation than find (which takes a 
> random string and checks whether it's in the map) -- this takes a string 
> which we know to be in the map and get its size.
> 
> It will take some rearchitecting of the ConstString class to get rid of this 
> hack. Probably it could be fixed by ConstString storing a StringMap::iterator 
> instead of the raw pointer. In any case, that seems out of scope of this 
> change.
Cool, I didn't notice that one when looking for it. I guess at this point we 
can just delete our copy of `GetStringMapEntryFromKeyData` completely and call 
the StringPool's version instead.


Repository:
  rL LLVM

https://reviews.llvm.org/D32306



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