[clangd] Don't re-hash SymbolID in maps, just use the SHA1 data

llvm-svn: 321302

2 files changed, 4 insertions, 2 deletions

diff --git a/clang-tools-extra/clangd/index/Index.cpp b/clang-tools-extra/clangd/index/Index.cpp
index 95ecb6b18ec..cac3ceab6f1 100644
--- a/clang-tools-extra/clangd/index/Index.cpp
+++ b/clang-tools-extra/clangd/index/Index.cpp
@@ -24,7 +24,7 @@ llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, const SymbolID &ID) {
 
 void operator>>(llvm::StringRef Str, SymbolID &ID) {
   std::string HexString = fromHex(Str);
-  assert(HexString.size() == 20);
+  assert(HexString.size() == ID.HashValue.size());
   std::copy(HexString.begin(), HexString.end(), ID.HashValue.begin());
 }
 
diff --git a/clang-tools-extra/clangd/index/Index.h b/clang-tools-extra/clangd/index/Index.h
index f0414bf7b4c..1816d79fce1 100644
--- a/clang-tools-extra/clangd/index/Index.h
+++ b/clang-tools-extra/clangd/index/Index.h
@@ -52,7 +52,9 @@ public:
 
 private:
   friend llvm::hash_code hash_value(const SymbolID &ID) {
-    return hash_value(ArrayRef<uint8_t>(ID.HashValue));
+    // We already have a good hash, just return the first bytes.
+    static_assert(sizeof(size_t) <= 20, "size_t longer than SHA1!");
+    return *reinterpret_cast<const size_t *>(ID.HashValue.data());
   }
   friend llvm::raw_ostream &operator<<(llvm::raw_ostream &OS,
                                        const SymbolID &ID);