[C-API][DIBuilder] Use NameLen in LLVMDIBuilderCreateParameterVariable

[Wallbraker]

Summary

NameLen wasn't being used and caused the parameters in gdb to very long, in my case, crashes in others. Please also perform the correct magical incarnations to have this be applied to the LLVM 7 branch.

[CodaFi]

Thanks for catching this! On top of respecting our API contract, it's good to be safe around C strings.

llvm/trunk/lib/IR/DebugInfo.cpp

return wrap(unwrap(Builder)->createAutoVariable(
                   map_from_llvmDIFlags(Flags), AlignInBits));
 }
 
 LLVMMetadataRef LLVMDIBuilderCreateParameterVariable(
     LLVMDIBuilderRef Builder, LLVMMetadataRef Scope, const char *Name,
     size_t NameLen, unsigned ArgNo, LLVMMetadataRef File, unsigned LineNo,
     LLVMMetadataRef Ty, LLVMBool AlwaysPreserve, LLVMDIFlags Flags) {
   return wrap(unwrap(Builder)->createParameterVariable(
-                  unwrap<DIScope>(Scope), Name, ArgNo, unwrap<DIFile>(File),
+                  unwrap<DIScope>(Scope), {Name, NameLen}, ArgNo, unwrap<DIFile>(File),
                   LineNo, unwrap<DIType>(Ty), AlwaysPreserve,
                   map_from_llvmDIFlags(Flags)));
 }
 
 LLVMMetadataRef LLVMDIBuilderGetOrCreateSubrange(LLVMDIBuilderRef Builder,
                                                  int64_t Lo, int64_t Count) {
   return wrap(unwrap(Builder)->getOrCreateSubrange(Lo, Count));
 }