[LLVMdev] GC patches again

[Chris Lattner]

>> Attached. This makes the last change set compatible with the new  
>> hand-written lexer—a whole one line change!
>>
>> See the readme file in the zip archive.

Hi Gordon, here's some feedback:

   include/llvm/Support/StringPool.h (+124)
   lib/Support/StringPool.cpp (+52)
A reference-counted string interning facility. Will be used by the
next patch.

This implementation is not as fast as it could be, I'd suggest  
switching to using StringMap<char> (char being a dummy).  However,  
this is a fine starting point, the implementation can be tuned later.

About the interface:

+    PooledStringPtr intern(const std::string &Str);

Instead of taking an std::string, please provide two versions:

     PooledStringPtr intern(const char *StrStart, const char *StrEnd);
and:
     PooledStringPtr intern(const char *CStr) { return intern(CStr,  
CStr+strlen(CStr); }

This discourages string abuse/copying: std::string is not very  
efficient.

Also, in PooledStringPtr, please make the accessor not return an  
std::string.


//===-- gc-5-funattr.patch (+120 -47) -------------------------===//

Adds these methods to Function and makes corresponding changes to
assembly and bitcode:
The assembly representation is as such:

   define void @f() gc "shadow-stack" { ...

Uses StringPool to unique collector names, which are extremely
likely to be unique per process.

This patch depends on gc-4-stringpool.


Can you please explain to me again why this is needed?  I'd like to  
avoid growing Function by another word for GC, is there another way?

-Chris
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