[llvm-commits] [llvm] r83082 - /llvm/trunk/include/llvm/ADT/StringRef.h

Chris Lattner clattner at apple.com
Tue Sep 29 11:59:29 PDT 2009

On Sep 29, 2009, at 11:57 AM, Devang Patel wrote:
> On Sep 29, 2009, at 11:53 AM, Chris Lattner wrote:
>> On Sep 29, 2009, at 11:39 AM, Devang Patel wrote:
>> Author: dpatel
>>> Date: Tue Sep 29 13:39:56 2009
>>> New Revision: 83082
>>> URL: http://llvm.org/viewvc/llvm-project?rev=83082&view=rev
>>> Log:
>>> Create empty StringRef is incoming cstring is NULL.
>> I don't think this is correct, StringRef shouldn't allow null  
>> cstrings to be passed in.
> I'm using it to pass optional strings. For example, linkage name in  
> debug info.
> Note, one can create empty StringRef by say
> 	SringRef foo;
> If this is not desirable then I'll update DebugInfo interface.

The reason I mention that is that stringref is frequently used for  
const char*'s, and this adds an extra branch to the common case.   
Doing something like:

   return ptr != 0 : StringRef(ptr) : StringRef();

in the debug info stuff would make it pay the cost locally instead of  
making all clients of stringref pay it.

What do you think Daniel?

BTW, getting rid of std::string from debug info is really really  


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