[CAS] Make CASConfiguration hashable (NFC)

Author: adrian-prantl

llvm/include/llvm/CAS/CASConfiguration.h

@@ -14,13 +14,15 @@
 #ifndef LLVM_CAS_CASCONFIGURATION_H
 #define LLVM_CAS_CASCONFIGURATION_H
 
+#include "llvm/ADT/Hashing.h"
 #include "llvm/ADT/IntrusiveRefCntPtr.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/VirtualFileSystem.h"
 #include <string>
 #include <vector>
 
-namespace llvm::cas {
+namespace llvm {
+namespace cas {
 
 class ActionCache;
 class ObjectStore;
@@ -72,8 +74,42 @@ class CASConfiguration {
   createFromSearchConfigFile(
       StringRef Path,
       llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS = nullptr);
+
+  /// DenseMap support \{
+  static cas::CASConfiguration getDenseMapEmptyKey() { return {}; }
+
+  static cas::CASConfiguration getDenseMapTombstoneKey() {
+    return {"$", "$", {}};
+  }
+  unsigned getHashValue() const {
+    return detail::combineHashValue(
+        DenseMapInfo<StringRef>::getHashValue(StringRef(CASPath)),
+        DenseMapInfo<StringRef>::getHashValue(StringRef(PluginPath)));
+  }
+  /// \}
+  operator bool() { return !CASPath.empty() || !PluginPath.empty(); }
 };
 
-} // namespace llvm::cas
+} // namespace cas
+
+template <> struct DenseMapInfo<cas::CASConfiguration> {
+  static cas::CASConfiguration getEmptyKey() {
+    return cas::CASConfiguration::getDenseMapEmptyKey();
+  }
+
+  static cas::CASConfiguration getTombstoneKey() {
+    return cas::CASConfiguration::getDenseMapTombstoneKey();
+  }
+
+  static unsigned getHashValue(const cas::CASConfiguration &config) {
+    return config.getHashValue();
+  }
+
+  static bool isEqual(const cas::CASConfiguration &LHS,
+                      const cas::CASConfiguration &RHS) {
+    return LHS == RHS;
+  }
+};
 
+} // namespace llvm
 #endif