Make llvm::crc32() work also for input sizes larger than 32 bits.

The problem was noticed by the Chrome OS toolchain folks
(crbug.com/1048445) because llvm-objcopy --add-gnu-debuglink would
insert the wrong checksum when processing a binary larger than 4 GB.
That use case regressed in 1e1e3ba2526 when we started using
llvm::crc32() in more places.

Differential revision: https://reviews.llvm.org/D74039

(cherry picked from commit 6c4a8bc0a9f6a466d90d542bef66d69550c1b041)

1 files changed, 9 insertions, 1 deletions

diff --git a/llvm/lib/Support/CRC.cpp b/llvm/lib/Support/CRC.cpp
index a3dba1a3aa1..2bc668beed3 100644
--- a/llvm/lib/Support/CRC.cpp
+++ b/llvm/lib/Support/CRC.cpp
@@ -85,7 +85,15 @@ uint32_t llvm::crc32(uint32_t CRC, ArrayRef<uint8_t> Data) {
 
 #include <zlib.h>
 uint32_t llvm::crc32(uint32_t CRC, ArrayRef<uint8_t> Data) {
-  return ::crc32(CRC, (const Bytef *)Data.data(), Data.size());
+  // Zlib's crc32() only takes a 32-bit length, so we have to iterate for larger
+  // sizes. One could use crc32_z() instead, but that's a recent (2017) addition
+  // and may not be available on all systems.
+  do {
+    ArrayRef<uint8_t> Slice = Data.take_front(UINT32_MAX);
+    CRC = ::crc32(CRC, (const Bytef *)Slice.data(), (uInt)Slice.size());
+    Data = Data.drop_front(Slice.size());
+  } while (Data.size() > 0);
+  return CRC;
 }
 
 #endif