[CUDA] Use FunctionDeclAndLoc for the Sema::LocsWithCUDACallDiags hashtable.

[jlebar]

Summary

NFC

[rnk]

lgtm

clang/include/clang/Sema/Sema.h

public:
 
   /// Diagnostics that are emitted only if we discover that the given function
   /// must be codegen'ed.  Because handling these correctly adds overhead to
   /// compilation, this is currently only enabled for CUDA compilations.
   llvm::DenseMap<CanonicalDeclPtr<FunctionDecl>,
                  std::vector<PartialDiagnosticAt>>
       CUDADeferredDiags;
 
-  /// FunctionDecls plus raw encodings of SourceLocations for which
-  /// CheckCUDACall has emitted a (maybe deferred) "bad call" diagnostic.  We
-  /// use this to avoid emitting the same deferred diag twice.
-  llvm::DenseSet<std::pair<CanonicalDeclPtr<FunctionDecl>, unsigned>>
-      LocsWithCUDACallDiags;
-
-  /// A pair of a canonical FunctionDecl and a SourceLocation.
+  /// A pair of a canonical FunctionDecl and a SourceLocation.  When used as the
+  /// key in a hashtable, both the FD and location are hashed.
   struct FunctionDeclAndLoc {
     CanonicalDeclPtr<FunctionDecl> FD;
     SourceLocation Loc;
   };
 
+  /// FunctionDecls and SourceLocations for which CheckCUDACall has emitted a
+  /// (maybe deferred) "bad call" diagnostic.  We use this to avoid emitting the
+  /// same deferred diag twice.
+  llvm::DenseSet<FunctionDeclAndLoc> LocsWithCUDACallDiags;
+
   /// An inverse call graph, mapping known-emitted functions to one of their
   /// known-emitted callers (plus the location of the call).
   ///
   /// Functions that we can tell a priori must be emitted aren't added to this
   /// map.
   llvm::DenseMap</* Callee = */ CanonicalDeclPtr<FunctionDecl>,
                  /* Caller = */ FunctionDeclAndLoc>
       CUDAKnownEmittedFns;

 struct LateParsedTemplate {
   CachedTokens Toks;
   /// \brief The template function declaration to be late parsed.
   Decl *D;
 };
 
 } // end namespace clang
 
+namespace llvm {
+// Hash a FunctionDeclAndLoc by looking at both its FunctionDecl and its
+// SourceLocation.
+template <> struct DenseMapInfo<clang::Sema::FunctionDeclAndLoc> {
+  using FunctionDeclAndLoc = clang::Sema::FunctionDeclAndLoc;
+  using FDBaseInfo = DenseMapInfo<clang::CanonicalDeclPtr<clang::FunctionDecl>>;
+
+  static FunctionDeclAndLoc getEmptyKey() {
+    return {FDBaseInfo::getEmptyKey(), clang::SourceLocation()};
+  }
+
+  static FunctionDeclAndLoc getTombstoneKey() {
+    return {FDBaseInfo::getTombstoneKey(), clang::SourceLocation()};
+  }
+
+  static unsigned getHashValue(const FunctionDeclAndLoc &FDL) {
+    return hash_combine(FDBaseInfo::getHashValue(FDL.FD),
+                        FDL.Loc.getRawEncoding());
+  }
+
+  static bool isEqual(const FunctionDeclAndLoc &LHS,
+                      const FunctionDeclAndLoc &RHS) {
+    return LHS.FD == RHS.FD && LHS.Loc == RHS.Loc;
+  }
+};
+} // namespace llvm
+
 #endif

clang/lib/Sema/SemaCUDA.cpp

bool Sema::CheckCUDACall(SourceLocation Loc, FunctionDecl *Callee) {
 
   if (DiagKind == CUDADiagBuilder::K_Nop)
     return true;
 
   // Avoid emitting this error twice for the same location.  Using a hashtable
   // like this is unfortunate, but because we must continue parsing as normal
   // after encountering a deferred error, it's otherwise very tricky for us to
   // ensure that we only emit this deferred error once.
-  if (!LocsWithCUDACallDiags.insert({Caller, Loc.getRawEncoding()}).second)
+  if (!LocsWithCUDACallDiags.insert({Caller, Loc}).second)
     return true;
 
   CUDADiagBuilder(DiagKind, Loc, diag::err_ref_bad_target, Caller, *this)
       << IdentifyCUDATarget(Callee) << Callee << IdentifyCUDATarget(Caller);
   CUDADiagBuilder(DiagKind, Callee->getLocation(), diag::note_previous_decl,
                   Caller, *this)
       << Callee;
   return DiagKind != CUDADiagBuilder::K_Immediate &&