[PATCH] D89719: [clang][Basic] Make SourceLocation usable as key in hash maps, NFCI

[Mikhail Maltsev via Phabricator via cfe-commits]

miyuki created this revision.
miyuki added a reviewer: dexonsmith.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.
miyuki requested review of this revision.

This change creates a `DenseMapInfo` trait specialization for the
SourceLocation class. The empty key, the tombstone key, and the hash
function are identical to `DenseMapInfo<unsigned>`, because we already
have hash maps that use raw the representation of `SourceLocation` as
a key.

The update of existing `DenseMap`s containing raw representation of
`SourceLocation`s will be done in a follow-up patch.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D89719

Files:
  clang/include/clang/Basic/SourceLocation.h
  clang/lib/Basic/SourceLocation.cpp


Index: clang/lib/Basic/SourceLocation.cpp
===================================================================
--- clang/lib/Basic/SourceLocation.cpp
+++ clang/lib/Basic/SourceLocation.cpp
@@ -14,6 +14,7 @@
 #include "clang/Basic/LLVM.h"
 #include "clang/Basic/PrettyStackTrace.h"
 #include "clang/Basic/SourceManager.h"
+#include "llvm/ADT/DenseMapInfo.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/MemoryBuffer.h"
@@ -40,6 +41,10 @@
 // SourceLocation
 //===----------------------------------------------------------------------===//
 
+unsigned SourceLocation::getHashValue() const {
+  return llvm::DenseMapInfo<unsigned>::getHashValue(ID);
+}
+
 void SourceLocation::print(raw_ostream &OS, const SourceManager &SM)const{
   if (!isValid()) {
     OS << "<invalid loc>";
Index: clang/include/clang/Basic/SourceLocation.h
===================================================================
--- clang/include/clang/Basic/SourceLocation.h
+++ clang/include/clang/Basic/SourceLocation.h
@@ -175,6 +175,7 @@
            End.isFileID();
   }
 
+  unsigned getHashValue() const;
   void print(raw_ostream &OS, const SourceManager &SM) const;
   std::string printToString(const SourceManager &SM) const;
   void dump(const SourceManager &SM) const;
@@ -479,6 +480,27 @@
     }
   };
 
+  /// Define DenseMapInfo so that SourceLocation's can be used as keys in
+  /// DenseMap and DenseSet. This trait class is eqivalent to
+  /// DenseMapInfo<unsigned> which uses SourceLocation::ID is used as a key.
+  template <> struct DenseMapInfo<clang::SourceLocation> {
+    static clang::SourceLocation getEmptyKey() {
+      return clang::SourceLocation::getFromRawEncoding(~0U);
+    }
+
+    static clang::SourceLocation getTombstoneKey() {
+      return clang::SourceLocation::getFromRawEncoding(~0U - 1);
+    }
+
+    static unsigned getHashValue(clang::SourceLocation Loc) {
+      return Loc.getHashValue();
+    }
+
+    static bool isEqual(clang::SourceLocation LHS, clang::SourceLocation RHS) {
+      return LHS == RHS;
+    }
+  };
+
   // Teach SmallPtrSet how to handle SourceLocation.
   template<>
   struct PointerLikeTypeTraits<clang::SourceLocation> {


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