Use a memcpy to avoid unaligned store UB.
On a 32-bit output, we may write LC_SOURCE_VERSION (which contains a uint64_t) to
an unaligned address. This changes it to use a memcpy instead which is UB safe.
llvm-svn: 264202
diff --git a/lld/lib/ReaderWriter/MachO/MachONormalizedFileBinaryWriter.cpp b/lld/lib/ReaderWriter/MachO/MachONormalizedFileBinaryWriter.cpp
index 03e081a..a0a3df4 100644
--- a/lld/lib/ReaderWriter/MachO/MachONormalizedFileBinaryWriter.cpp
+++ b/lld/lib/ReaderWriter/MachO/MachONormalizedFileBinaryWriter.cpp
@@ -928,12 +928,15 @@
// Add LC_SOURCE_VERSION
{
- source_version_command* sv = reinterpret_cast<source_version_command*>(lc);
- sv->cmd = LC_SOURCE_VERSION;
- sv->cmdsize = sizeof(source_version_command);
- sv->version = _file.sourceVersion;
+ // Note, using a temporary here to appease UB as we may not be aligned
+ // enough for a struct containing a uint64_t when emitting a 32-bit binary
+ source_version_command sv;
+ sv.cmd = LC_SOURCE_VERSION;
+ sv.cmdsize = sizeof(source_version_command);
+ sv.version = _file.sourceVersion;
if (_swap)
- swapStruct(*sv);
+ swapStruct(sv);
+ memcpy(lc, &sv, sizeof(source_version_command));
lc += sizeof(source_version_command);
}