Add coverage mapping generation.

This patch adds the '-fcoverage-mapping' option which
allows clang to generate the coverage mapping information
that can be used to provide code coverage analysis using
the execution counts obtained from the instrumentation 
based profiling (-fprofile-instr-generate).

llvm-svn: 214752

clang/lib/CodeGen/CodeGenFunction.cpp

@@ -829,6 +829,7 @@ void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn,
   StartFunction(GD, ResTy, Fn, FnInfo, Args, Loc, BodyRange.getBegin());
 
   // Generate the body of the function.
+  PGO.checkGlobalDecl(GD);
   PGO.assignRegionCounters(GD.getDecl(), CurFn);
   if (isa<CXXDestructorDecl>(FD))
     EmitDestructorBody(Args);