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/BinaryStreamReader.cpp b/llvm/lib/Support/BinaryStreamReader.cpp
index c7a2e0ddb17..702d98770e0 100644
--- a/llvm/lib/Support/BinaryStreamReader.cpp
+++ b/llvm/lib/Support/BinaryStreamReader.cpp
@@ -93,3 +93,16 @@ uint8_t BinaryStreamReader::peek() const {
   llvm::consumeError(std::move(EC));
   return Buffer[0];
 }
+
+std::pair<BinaryStreamReader, BinaryStreamReader>
+BinaryStreamReader::split(uint32_t Off) const {
+  assert(getLength() >= Off);
+
+  BinaryStreamRef First = Stream.drop_front(Offset);
+
+  BinaryStreamRef Second = First.drop_front(Off);
+  First = First.keep_front(Off);
+  BinaryStreamReader W1{First};
+  BinaryStreamReader W2{Second};
+  return std::make_pair(W1, W2);
+}
\ No newline at end of file