[PATCH] D24341: Add a lower level zlib::uncompress

[Rafael Ávila de Espíndola via llvm-commits]

rafael created this revision.
rafael added reviewers: dblaikie, ruiu.
rafael added a subscriber: llvm-commits.

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.


https://reviews.llvm.org/D24341

Files:
  include/llvm/Support/Compression.h
  lib/Support/Compression.cpp

Index: lib/Support/Compression.cpp
===================================================================
--- lib/Support/Compression.cpp
+++ lib/Support/Compression.cpp
@@ -62,16 +62,23 @@
   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;
 }
Index: include/llvm/Support/Compression.h
===================================================================
--- include/llvm/Support/Compression.h
+++ include/llvm/Support/Compression.h
@@ -43,6 +43,9 @@
 Status compress(StringRef InputBuffer, SmallVectorImpl<char> &CompressedBuffer,
                 CompressionLevel Level = DefaultCompression);
 
+Status uncompress(StringRef InputBuffer, char *UncompressedBuffer,
+                  size_t &UncompressedSize);
+
 Status uncompress(StringRef InputBuffer,
                   SmallVectorImpl<char> &UncompressedBuffer,
                   size_t UncompressedSize);


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