[NFC][CodeView] Use one unified access to the module in beginModule.

[cchen15]

Summary

Use the argument M throughout the function.

The current code can trigger warnings from a static checker as the checker may not be able to deduce that M is the same as MMI->getModule().

[rnk]

lgtm

[cchen15]

Thanks for the review, Reid.

llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp

default:
     // as it's very low level.
     return SourceLanguage::Masm;
   }
 }
 
 void CodeViewDebug::beginModule(Module *M) {
   // If module doesn't have named metadata anchors or COFF debug section
   // is not available, skip any debug info related stuff.
-  if (!M->getNamedMetadata("llvm.dbg.cu") ||
-      !Asm->getObjFileLowering().getCOFFDebugSymbolsSection()) {
+  NamedMDNode *CUs = M->getNamedMetadata("llvm.dbg.cu");
+  if (!CUs || !Asm->getObjFileLowering().getCOFFDebugSymbolsSection()) {
     Asm = nullptr;
     return;
   }
   // Tell MMI that we have and need debug info.
   MMI->setDebugInfoAvailability(true);
 
   TheCPU = mapArchToCVCPUType(Triple(M->getTargetTriple()).getArch());
 
   // Get the current source language.
-  NamedMDNode *CUs = MMI->getModule()->getNamedMetadata("llvm.dbg.cu");
   const MDNode *Node = *CUs->operands().begin();
   const auto *CU = cast<DICompileUnit>(Node);
 
   CurrentSourceLanguage = MapDWLangToCVLang(CU->getSourceLanguage());
 
   collectGlobalVariableInfo();
 
   // Check if we should emit type record hashes.