jkorous-apple created this revision.
jkorous-apple added a project: clang-tools-extra.
Herald added subscribers: cfe-commits, ioeric, ilya-biryukov.
The current code is casting pointer to a misaligned type which is undefined
behavior.
Found by compiling with Undefined Behavior Sanitizer and running tests
(check-clang-tools).
AFAIK clang produces the same code for reinterpret_cast<>() and memcpy().
Follow-up to: https://reviews.llvm.org/D44575
Repository:
rCTE Clang Tools Extra
https://reviews.llvm.org/D44576
Files:
clangd/index/Index.h
Index: clangd/index/Index.h
===================================================================
--- clangd/index/Index.h
+++ clangd/index/Index.h
@@ -59,7 +59,9 @@
friend llvm::hash_code hash_value(const SymbolID &ID) {
// We already have a good hash, just return the first bytes.
static_assert(sizeof(size_t) <= HashByteLength, "size_t longer than
SHA1!");
- return *reinterpret_cast<const size_t *>(ID.HashValue.data());
+ size_t Result;
+ memcpy(&Result, ID.HashValue.data(), sizeof(size_t));
+ return llvm::hash_code(Result);
}
friend llvm::raw_ostream &operator<<(llvm::raw_ostream &OS,
const SymbolID &ID);
Index: clangd/index/Index.h
===================================================================
--- clangd/index/Index.h
+++ clangd/index/Index.h
@@ -59,7 +59,9 @@
friend llvm::hash_code hash_value(const SymbolID &ID) {
// We already have a good hash, just return the first bytes.
static_assert(sizeof(size_t) <= HashByteLength, "size_t longer than SHA1!");
- return *reinterpret_cast<const size_t *>(ID.HashValue.data());
+ size_t Result;
+ memcpy(&Result, ID.HashValue.data(), sizeof(size_t));
+ return llvm::hash_code(Result);
}
friend llvm::raw_ostream &operator<<(llvm::raw_ostream &OS,
const SymbolID &ID);
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