Revert "IR: Simplify DIBuilder's HeaderBuilder API, NFC"

This reverts commit r226540, since I hit an unexpected bot failure [1].
I'll investigate.

[1]: http://bb.pgr.jp/builders/cmake-llvm-x86_64-linux/builds/20244

llvm-svn: 226542

1 files changed, 5 insertions, 15 deletions

diff --git a/llvm/lib/IR/DIBuilder.cpp b/llvm/lib/IR/DIBuilder.cpp
index c6df3409a47..eb686aa4bec 100644
--- a/llvm/lib/IR/DIBuilder.cpp
+++ b/llvm/lib/IR/DIBuilder.cpp
@@ -25,23 +25,15 @@ using namespace llvm::dwarf;
 
 namespace {
 class HeaderBuilder {
-  /// \brief Whether there are any fields yet.
-  ///
-  /// Note that this is not equivalent to \c Chars.empty(), since \a concat()
-  /// may have been called already with an empty string.
-  bool IsEmpty;
   SmallVector<char, 256> Chars;
 
 public:
-  HeaderBuilder() : IsEmpty(true) {}
+  explicit HeaderBuilder(Twine T) { T.toVector(Chars); }
   HeaderBuilder(const HeaderBuilder &X) : Chars(X.Chars) {}
   HeaderBuilder(HeaderBuilder &&X) : Chars(std::move(X.Chars)) {}
 
   template <class Twineable> HeaderBuilder &concat(Twineable &&X) {
-    if (IsEmpty)
-      IsEmpty = false;
-    else
-      Chars.push_back(0);
+    Chars.push_back(0);
     Twine(X).toVector(Chars);
     return *this;
   }
@@ -51,7 +43,7 @@ public:
   }
 
   static HeaderBuilder get(unsigned Tag) {
-    return HeaderBuilder().concat("0x" + Twine::utohexstr(Tag));
+    return HeaderBuilder("0x" + Twine::utohexstr(Tag));
   }
 };
 }
@@ -747,10 +739,8 @@ static HeaderBuilder setTypeFlagsInHeader(StringRef Header,
     Flags = 0;
   Flags |= FlagsToSet;
 
-  return HeaderBuilder()
-      .concat(I.getPrefix())
-      .concat(Flags)
-      .concat(I.getSuffix());
+  return HeaderBuilder(Twine(I.getPrefix())).concat(Flags).concat(
+      I.getSuffix());
 }
 
 static DIType createTypeWithFlags(LLVMContext &Context, DIType Ty,