Add a lower level zlib::uncompress.

SmallVectors are convenient, but they don't cover every use case.

In particular, they are fairly large (3 pointers + one element) and
there is no way to take ownership of the buffer to put it somewhere
else.  This patch then adds a lower lever interface that works with
any buffer.

llvm-svn: 281082

1 files changed, 13 insertions, 6 deletions

diff --git a/llvm/lib/Support/Compression.cpp b/llvm/lib/Support/Compression.cpp
index b54613e92b8..7453071f1df 100644
--- a/llvm/lib/Support/Compression.cpp
+++ b/llvm/lib/Support/Compression.cpp
@@ -62,16 +62,23 @@ zlib::Status zlib::compress(StringRef InputBuffer,
   return Res;
 }
 
+zlib::Status zlib::uncompress(StringRef InputBuffer, char *UncompressedBuffer,
+                              size_t &UncompressedSize) {
+  Status Res = encodeZlibReturnValue(
+      ::uncompress((Bytef *)UncompressedBuffer, (uLongf *)&UncompressedSize,
+                   (const Bytef *)InputBuffer.data(), InputBuffer.size()));
+  // Tell MemorySanitizer that zlib output buffer is fully initialized.
+  // This avoids a false report when running LLVM with uninstrumented ZLib.
+  __msan_unpoison(UncompressedBuffer, UncompressedSize);
+  return Res;
+}
+
 zlib::Status zlib::uncompress(StringRef InputBuffer,
                               SmallVectorImpl<char> &UncompressedBuffer,
                               size_t UncompressedSize) {
   UncompressedBuffer.resize(UncompressedSize);
-  Status Res = encodeZlibReturnValue(::uncompress(
-      (Bytef *)UncompressedBuffer.data(), (uLongf *)&UncompressedSize,
-      (const Bytef *)InputBuffer.data(), InputBuffer.size()));
-  // Tell MemorySanitizer that zlib output buffer is fully initialized.
-  // This avoids a false report when running LLVM with uninstrumented ZLib.
-  __msan_unpoison(UncompressedBuffer.data(), UncompressedSize);
+  Status Res =
+      uncompress(InputBuffer, UncompressedBuffer.data(), UncompressedSize);
   UncompressedBuffer.resize(UncompressedSize);
   return Res;
 }