[llvm-commits] [llvm] r162888 - /llvm/trunk/lib/Transforms/Instrumentation/GCOVProfiling.cpp

[Bill Wendling]

On Aug 29, 2012, at 11:16 PM, David Blaikie <dblaikie at gmail.com> wrote:

> On Wed, Aug 29, 2012 at 6:32 PM, Bill Wendling <isanbard at gmail.com> wrote:
>> Author: void
>> Date: Wed Aug 29 20:32:31 2012
>> New Revision: 162888
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=162888&view=rev
>> Log:
>> Pass by pointer and not std::string.
> 
> Any particular reason for a c-style string rather than a StringRef or
> Twine? Looks like it's just being passed through to replace_extension
> which takes a Twine so you could expose that same flexibility.
> 
It's cheaper? :) It's passing through a string literal. I thought it best to use that instead of something else...

-bw

> (Ramble: not sure how I feel about something like replace_extension
> taking a Twine instead of a StringRef - it unconditionally evaluates
> the Twine anyway so it's not winning the "possibly avoid creating this
> string" benefit that (so far as I understand it) is the big win of
> Twine. On the other hand it'd be annoying for clients of this API not
> to be able to write simple string concatenation expressions, or pass
> other Twines through. (& having Twines be implicitly convertible to
> StringRefs is of course fraught with danger (works only for the life
> of a full expression since the Twine would have to store the thing the
> StringRef refers to) - or even implicitly convertible to std::string
> or similar isn't ideal (inefficient if you use a Twine multiple times
> in the body of a function - causing multiple repeated conversions)...
> meh, not sure what the right answer is)
> 
>> 
>> Modified:
>>    llvm/trunk/lib/Transforms/Instrumentation/GCOVProfiling.cpp
>> 
>> Modified: llvm/trunk/lib/Transforms/Instrumentation/GCOVProfiling.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Instrumentation/GCOVProfiling.cpp?rev=162888&r1=162887&r2=162888&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Transforms/Instrumentation/GCOVProfiling.cpp (original)
>> +++ llvm/trunk/lib/Transforms/Instrumentation/GCOVProfiling.cpp Wed Aug 29 20:32:31 2012
>> @@ -91,7 +91,7 @@
>>     void insertCounterWriteout(ArrayRef<std::pair<GlobalVariable*, MDNode*> >);
>>     void insertIndirectCounterIncrement();
>> 
>> -    std::string mangleName(DICompileUnit CU, std::string NewStem);
>> +    std::string mangleName(DICompileUnit CU, const char *NewStem);
>> 
>>     bool EmitNotes;
>>     bool EmitData;
>> @@ -328,7 +328,7 @@
>>   };
>> }
>> 
>> -std::string GCOVProfiler::mangleName(DICompileUnit CU, std::string NewStem) {
>> +std::string GCOVProfiler::mangleName(DICompileUnit CU, const char *NewStem) {
>>   if (NamedMDNode *GCov = M->getNamedMetadata("llvm.gcov")) {
>>     for (int i = 0, e = GCov->getNumOperands(); i != e; ++i) {
>>       MDNode *N = GCov->getOperand(i);
>> 
>> 
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