[DebugInfo] LLVM IR assembly writer for DILabel.

[HsiangKai]

Summary

Write out !DILabel(scope: , name: , file: , line: )

[chenwj]

LGTM. However, combining this one with D45025 would be better.

[HsiangKai]

In D45032#1052939, @chenwj wrote:

LGTM. However, combining this one with D45025 would be better.

Merged into D45024, this patch should be abandoned.

lib/IR/AsmWriter.cpp

static void writeDILocalVariable(raw_ostream &Out, const DILocalVariable *N,
   Printer.printMetadata("file", N->getRawFile());
   Printer.printInt("line", N->getLine());
   Printer.printMetadata("type", N->getRawType());
   Printer.printDIFlags("flags", N->getFlags());
   Printer.printInt("align", N->getAlignInBits());
   Out << ")";
 }
 
+static void writeDILabel(raw_ostream &Out, const DILabel *N,
+                         TypePrinting *TypePrinter,
+                         SlotTracker *Machine, const Module *Context) {
+  Out << "!DILabel(";
+  MDFieldPrinter Printer(Out, TypePrinter, Machine, Context);
+  Printer.printMetadata("scope", N->getRawScope(), /* ShouldSkipNull */ false);
+  Printer.printString("name", N->getName());
+  Printer.printMetadata("file", N->getRawFile());
+  Printer.printInt("line", N->getLine());
+  Out << ")";
+}
+
 static void writeDIExpression(raw_ostream &Out, const DIExpression *N,
                               TypePrinting *TypePrinter, SlotTracker *Machine,
                               const Module *Context) {
   Out << "!DIExpression(";
   FieldSeparator FS;
   if (N->isValid()) {
     for (auto I = N->expr_op_begin(), E = N->expr_op_end(); I != E; ++I) {
       auto OpStr = dwarf::OperationEncodingString(I->getOp());