1 files changed, 73 insertions, 15 deletions

diff --git a/include/llvm/ExecutionEngine/JITSymbol.h b/include/llvm/ExecutionEngine/JITSymbol.h
index f09e95fddb97..4172f240ba39 100644
--- a/include/llvm/ExecutionEngine/JITSymbol.h
+++ b/include/llvm/ExecutionEngine/JITSymbol.h
@@ -21,6 +21,8 @@
 #include <functional>
 #include <string>
 
+#include "llvm/Support/Error.h"
+
 namespace llvm {
 
 class GlobalValue;
@@ -41,10 +43,11 @@ public:
 
   enum FlagNames : UnderlyingType {
     None = 0,
-    Weak = 1U << 0,
-    Common = 1U << 1,
-    Absolute = 1U << 2,
-    Exported = 1U << 3
+    HasError = 1U << 0,
+    Weak = 1U << 1,
+    Common = 1U << 2,
+    Absolute = 1U << 3,
+    Exported = 1U << 4
   };
 
   /// @brief Default-construct a JITSymbolFlags instance.
@@ -53,6 +56,11 @@ public:
   /// @brief Construct a JITSymbolFlags instance from the given flags.
   JITSymbolFlags(FlagNames Flags) : Flags(Flags) {}
 
+  /// @brief Return true if there was an error retrieving this symbol.
+  bool hasError() const {
+    return (Flags & HasError) == HasError;
+  }
+
   /// @brief Returns true is the Weak flag is set.
   bool isWeak() const {
     return (Flags & Weak) == Weak;
@@ -113,11 +121,17 @@ private:
 /// @brief Represents a symbol in the JIT.
 class JITSymbol {
 public:
-  using GetAddressFtor = std::function<JITTargetAddress()>;
+  using GetAddressFtor = std::function<Expected<JITTargetAddress>()>;
+
+  /// @brief Create a 'null' symbol, used to represent a "symbol not found"
+  ///        result from a successful (non-erroneous) lookup.
+  JITSymbol(std::nullptr_t)
+      : CachedAddr(0) {}
 
-  /// @brief Create a 'null' symbol that represents failure to find a symbol
-  ///        definition.
-  JITSymbol(std::nullptr_t) {}
+  /// @brief Create a JITSymbol representing an error in the symbol lookup
+  ///        process (e.g. a network failure during a remote lookup).
+  JITSymbol(Error Err)
+    : Err(std::move(Err)), Flags(JITSymbolFlags::HasError) {}
 
   /// @brief Create a symbol for a definition with a known address.
   JITSymbol(JITTargetAddress Addr, JITSymbolFlags Flags)
@@ -137,18 +151,59 @@ public:
   /// user can materialize the definition at any time by calling the getAddress
   /// method.
   JITSymbol(GetAddressFtor GetAddress, JITSymbolFlags Flags)
-      : GetAddress(std::move(GetAddress)), Flags(Flags) {}
+      : GetAddress(std::move(GetAddress)), CachedAddr(0), Flags(Flags) {}
+
+  JITSymbol(const JITSymbol&) = delete;
+  JITSymbol& operator=(const JITSymbol&) = delete;
+
+  JITSymbol(JITSymbol &&Other)
+    : GetAddress(std::move(Other.GetAddress)), Flags(std::move(Other.Flags)) {
+    if (Flags.hasError())
+      Err = std::move(Other.Err);
+    else
+      CachedAddr = std::move(Other.CachedAddr);
+  }
+
+  JITSymbol& operator=(JITSymbol &&Other) {
+    GetAddress = std::move(Other.GetAddress);
+    Flags = std::move(Other.Flags);
+    if (Flags.hasError())
+      Err = std::move(Other.Err);
+    else
+      CachedAddr = std::move(Other.CachedAddr);
+    return *this;
+  }
+
+  ~JITSymbol() {
+    if (Flags.hasError())
+      Err.~Error();
+    else
+      CachedAddr.~JITTargetAddress();
+  }
 
   /// @brief Returns true if the symbol exists, false otherwise.
-  explicit operator bool() const { return CachedAddr || GetAddress; }
+  explicit operator bool() const {
+    return !Flags.hasError() && (CachedAddr || GetAddress);
+  }
+
+  /// @brief Move the error field value out of this JITSymbol.
+  Error takeError() {
+    if (Flags.hasError())
+      return std::move(Err);
+    return Error::success();
+  }
 
   /// @brief Get the address of the symbol in the target address space. Returns
   ///        '0' if the symbol does not exist.
-  JITTargetAddress getAddress() {
+  Expected<JITTargetAddress> getAddress() {
+    assert(!Flags.hasError() && "getAddress called on error value");
     if (GetAddress) {
-      CachedAddr = GetAddress();
-      assert(CachedAddr && "Symbol could not be materialized.");
-      GetAddress = nullptr;
+      if (auto CachedAddrOrErr = GetAddress()) {
+        GetAddress = nullptr;
+        CachedAddr = *CachedAddrOrErr;
+        assert(CachedAddr && "Symbol could not be materialized.");
+      } else
+        return CachedAddrOrErr.takeError();
     }
     return CachedAddr;
   }
@@ -157,7 +212,10 @@ public:
 
 private:
   GetAddressFtor GetAddress;
-  JITTargetAddress CachedAddr = 0;
+  union {
+    JITTargetAddress CachedAddr;
+    Error Err;
+  };
   JITSymbolFlags Flags;
 };