Make codeview::StringTable.

Previously we had knowledge of how to serialize and deserialize
a string table inside of DebugInfo/PDB, but the string table
that it serializes contains a piece that is actually considered
CodeView and can appear outside of a PDB.  We already have logic
in llvm-readobj and MCCodeView to read and write this format,
so it doesn't make sense to duplicate the logic in DebugInfoPDB
as well.

This patch makes codeview::StringTable (for writing) and
codeview::StringTableRef (for reading), updates DebugInfoPDB
to use these classes for its own writing, and updates llvm-readobj
to additionally use StringTableRef for reading.

It's a bit more difficult to get MCCodeView to use this for
writing, but it's a logical next step.

llvm-svn: 301986

1 files changed, 13 insertions, 0 deletions

diff --git a/llvm/lib/Support/BinaryStreamWriter.cpp b/llvm/lib/Support/BinaryStreamWriter.cpp
index d60b75642d0..d78dbc68f59 100644
--- a/llvm/lib/Support/BinaryStreamWriter.cpp
+++ b/llvm/lib/Support/BinaryStreamWriter.cpp
@@ -59,6 +59,19 @@ Error BinaryStreamWriter::writeStreamRef(BinaryStreamRef Ref, uint32_t Length) {
   return Error::success();
 }
 
+std::pair<BinaryStreamWriter, BinaryStreamWriter>
+BinaryStreamWriter::split(uint32_t Off) const {
+  assert(getLength() >= Off);
+
+  WritableBinaryStreamRef First = Stream.drop_front(Offset);
+
+  WritableBinaryStreamRef Second = First.drop_front(Off);
+  First = First.keep_front(Off);
+  BinaryStreamWriter W1{First};
+  BinaryStreamWriter W2{Second};
+  return std::make_pair(W1, W2);
+}
+
 Error BinaryStreamWriter::padToAlignment(uint32_t Align) {
   uint32_t NewOffset = alignTo(Offset, Align);
   if (NewOffset > getLength())