[analyzer] Avoid allocation in Std C function modelling.

[xazax.hun]

Summary

Avoid an allocation in modelling Std C functions to improve the performance.

[NoQ]

Thanks :o

I guess i was planning for C++ support here, but never reached that far.

Is it an actual performance problem? Cause i think i did somehow test the checker for performance regressions and it seemed all good.

[xazax.hun]

In D33095#752879, @NoQ wrote:

Is it an actual performance problem? Cause i think i did somehow test the checker for performance regressions and it seemed all good.

I did not measure it. Just spotted by skimming through the code. I think, this is not a performance problem, but since it is easy to avoid the allocation and this codepath might be executed for every call, it might be worth to fix this.

lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp

StdLibraryFunctionsChecker::findFunctionSummary(const FunctionDecl *FD,
 
   if (!FD)
     return None;
 
   SValBuilder &SVB = C.getSValBuilder();
   BasicValueFactory &BVF = SVB.getBasicValueFactory();
   initFunctionSummaries(BVF);
 
-  std::string Name = FD->getQualifiedNameAsString();
+  IdentifierInfo *II = FD->getIdentifier();
+  if (!II)
+    return None;
+  StringRef Name = II->getName();
   if (Name.empty() || !C.isCLibraryFunction(FD, Name))
     return None;
 
   auto FSMI = FunctionSummaryMap.find(Name);
   if (FSMI == FunctionSummaryMap.end())
     return None;
 
   // Verify that function signature matches the spec in advance.