[debug-info] refactor emitDwarfUnitLength

remove `Hi` `Lo` argument from `emitDwarfUnitLength`, so we
can make caller of emitDwarfUnitLength easier.

Reviewed By: MaskRay, dblaikie, ikudrin

Differential Revision: https://reviews.llvm.org/D96409

1 files changed, 9 insertions, 2 deletions

diff --git a/llvm/lib/MC/MCStreamer.cpp b/llvm/lib/MC/MCStreamer.cpp
index 4f2ec51..9b9e5b9 100644
--- a/llvm/lib/MC/MCStreamer.cpp
+++ b/llvm/lib/MC/MCStreamer.cpp
@@ -1006,12 +1006,19 @@ void MCStreamer::emitDwarfUnitLength(uint64_t Length, const Twine &Comment) {
   emitIntValue(Length, dwarf::getDwarfOffsetByteSize(Context.getDwarfFormat()));
 }
 
-void MCStreamer::emitDwarfUnitLength(const MCSymbol *Hi, const MCSymbol *Lo,
-                                     const Twine &Comment) {
+MCSymbol *MCStreamer::emitDwarfUnitLength(const Twine &Prefix,
+                                          const Twine &Comment) {
   maybeEmitDwarf64Mark();
   AddComment(Comment);
+  MCSymbol *Lo = Context.createTempSymbol(Prefix + "_start");
+  MCSymbol *Hi = Context.createTempSymbol(Prefix + "_end");
+
   emitAbsoluteSymbolDiff(
       Hi, Lo, dwarf::getDwarfOffsetByteSize(Context.getDwarfFormat()));
+  // emit the begin symbol after we generate the length field.
+  emitLabel(Lo);
+  // Return the Hi symbol to the caller.
+  return Hi;
 }
 
 void MCStreamer::emitAssignment(MCSymbol *Symbol, const MCExpr *Value) {