[Support] Add LEB128 support to BinaryStreamReader/Writer.

Summary:
This patch adds support for ULEB128 and SLEB128 encoding and decoding to
BinaryStreamWriter and BinaryStreamReader respectively.

Support for ULEB128/SLEB128 will be used for eh-frame parsing in the JITLink
library currently under development (see https://reviews.llvm.org/D58704).

Reviewers: zturner, dblaikie

Subscribers: kristina, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D60810

llvm-svn: 358584

1 files changed, 13 insertions, 0 deletions

diff --git a/llvm/lib/Support/BinaryStreamWriter.cpp b/llvm/lib/Support/BinaryStreamWriter.cpp
index 929968bf2e4..986e18da281 100644
--- a/llvm/lib/Support/BinaryStreamWriter.cpp
+++ b/llvm/lib/Support/BinaryStreamWriter.cpp
@@ -11,6 +11,7 @@
 #include "llvm/Support/BinaryStreamError.h"
 #include "llvm/Support/BinaryStreamReader.h"
 #include "llvm/Support/BinaryStreamRef.h"
+#include "llvm/Support/LEB128.h"
 
 using namespace llvm;
 
@@ -31,6 +32,18 @@ Error BinaryStreamWriter::writeBytes(ArrayRef<uint8_t> Buffer) {
   return Error::success();
 }
 
+Error BinaryStreamWriter::writeULEB128(uint64_t Value) {
+  uint8_t EncodedBytes[10] = {0};
+  unsigned Size = encodeULEB128(Value, &EncodedBytes[0]);
+  return writeBytes({EncodedBytes, Size});
+}
+
+Error BinaryStreamWriter::writeSLEB128(int64_t Value) {
+  uint8_t EncodedBytes[10] = {0};
+  unsigned Size = encodeSLEB128(Value, &EncodedBytes[0]);
+  return writeBytes({EncodedBytes, Size});
+}
+
 Error BinaryStreamWriter::writeCString(StringRef Str) {
   if (auto EC = writeFixedString(Str))
     return EC;