[llvm] add zstd to `llvm::compression` namespace

- add zstd to `llvm::compression` namespace
- add a CMake option `LLVM_ENABLE_ZSTD` with behavior mirroring that of `LLVM_ENABLE_ZLIB`
- add tests for zstd to `llvm/unittests/Support/CompressionTest.cpp`
- debian users should install libzstd when using `LLVM_ENABLE_ZSTD=FORCE_ON` from source due to this bug https://bugs.launchpad.net/ubuntu/+source/libzstd/+bug/1941956

Reviewed By: leonardchan, MaskRay

Differential Revision: https://reviews.llvm.org/D128465

1 files changed, 65 insertions, 0 deletions

diff --git a/llvm/lib/Support/Compression.cpp b/llvm/lib/Support/Compression.cpp
index 2119197..e8fb715 100644
--- a/llvm/lib/Support/Compression.cpp
+++ b/llvm/lib/Support/Compression.cpp
@@ -20,6 +20,9 @@
 #if LLVM_ENABLE_ZLIB
 #include <zlib.h>
 #endif
+#if LLVM_ENABLE_ZSTD
+#include <zstd.h>
+#endif
 
 using namespace llvm;
 using namespace llvm::compression;
@@ -100,3 +103,65 @@ Error zlib::uncompress(ArrayRef<uint8_t> Input,
   llvm_unreachable("zlib::uncompress is unavailable");
 }
 #endif
+
+#if LLVM_ENABLE_ZSTD
+
+bool zstd::isAvailable() { return true; }
+
+void zstd::compress(ArrayRef<uint8_t> Input,
+                    SmallVectorImpl<uint8_t> &CompressedBuffer, int Level) {
+  unsigned long CompressedBufferSize = ::ZSTD_compressBound(Input.size());
+  CompressedBuffer.resize_for_overwrite(CompressedBufferSize);
+  unsigned long CompressedSize =
+      ::ZSTD_compress((char *)CompressedBuffer.data(), CompressedBufferSize,
+                      (const char *)Input.data(), Input.size(), Level);
+  if (ZSTD_isError(CompressedSize))
+    report_bad_alloc_error("Allocation failed");
+  // Tell MemorySanitizer that zstd output buffer is fully initialized.
+  // This avoids a false report when running LLVM with uninstrumented ZLib.
+  __msan_unpoison(CompressedBuffer.data(), CompressedSize);
+  if (CompressedSize < CompressedBuffer.size())
+    CompressedBuffer.truncate(CompressedSize);
+}
+
+Error zstd::uncompress(ArrayRef<uint8_t> Input, uint8_t *UncompressedBuffer,
+                       size_t &UncompressedSize) {
+  const size_t Res =
+      ::ZSTD_decompress(UncompressedBuffer, UncompressedSize,
+                        (const uint8_t *)Input.data(), Input.size());
+  UncompressedSize = Res;
+  // Tell MemorySanitizer that zstd output buffer is fully initialized.
+  // This avoids a false report when running LLVM with uninstrumented ZLib.
+  __msan_unpoison(UncompressedBuffer, UncompressedSize);
+  return ZSTD_isError(Res) ? make_error<StringError>(ZSTD_getErrorName(Res),
+                                                     inconvertibleErrorCode())
+                           : Error::success();
+}
+
+Error zstd::uncompress(ArrayRef<uint8_t> Input,
+                       SmallVectorImpl<uint8_t> &UncompressedBuffer,
+                       size_t UncompressedSize) {
+  UncompressedBuffer.resize_for_overwrite(UncompressedSize);
+  Error E =
+      zstd::uncompress(Input, UncompressedBuffer.data(), UncompressedSize);
+  if (UncompressedSize < UncompressedBuffer.size())
+    UncompressedBuffer.truncate(UncompressedSize);
+  return E;
+}
+
+#else
+bool zstd::isAvailable() { return false; }
+void zstd::compress(ArrayRef<uint8_t> Input,
+                    SmallVectorImpl<uint8_t> &CompressedBuffer, int Level) {
+  llvm_unreachable("zstd::compress is unavailable");
+}
+Error zstd::uncompress(ArrayRef<uint8_t> Input, uint8_t *UncompressedBuffer,
+                       size_t &UncompressedSize) {
+  llvm_unreachable("zstd::uncompress is unavailable");
+}
+Error zstd::uncompress(ArrayRef<uint8_t> Input,
+                       SmallVectorImpl<uint8_t> &UncompressedBuffer,
+                       size_t UncompressedSize) {
+  llvm_unreachable("zstd::uncompress is unavailable");
+}
+#endif