[ExecutionEngine] Use std::function rather than a function pointer for the

LazyFunctionCreator.

Patch by Pierre-Andre Saulais. Thanks Pierre!

llvm-svn: 241962

include/llvm/ExecutionEngine/ExecutionEngine.h

@@ -31,6 +31,7 @@
 #include <map>
 #include <string>
 #include <vector>
+#include <functional>
 
 namespace llvm {
 
@@ -89,6 +90,8 @@ public:
   uint64_t RemoveMapping(StringRef Name);
 };
 
+using FunctionCreator = std::function<void *(const std::string &)>;
+
 /// \brief Abstract interface for implementation execution of LLVM modules,
 /// designed to support both interpreter and just-in-time (JIT) compiler
 /// implementations.
@@ -147,7 +150,7 @@ protected:
   /// LazyFunctionCreator - If an unknown function is needed, this function
   /// pointer is invoked to create it.  If this returns null, the JIT will
   /// abort.
-  void *(*LazyFunctionCreator)(const std::string &);
+  FunctionCreator LazyFunctionCreator;
 
   /// getMangledName - Get mangled name.
   std::string getMangledName(const GlobalValue *GV);
@@ -470,8 +473,8 @@ public:
   /// InstallLazyFunctionCreator - If an unknown function is needed, the
   /// specified function pointer is invoked to create it.  If it returns null,
   /// the JIT will abort.
-  void InstallLazyFunctionCreator(void* (*P)(const std::string &)) {
-    LazyFunctionCreator = P;
+  void InstallLazyFunctionCreator(FunctionCreator C) {
+    LazyFunctionCreator = C;
   }
 
 protected:

unittests/ExecutionEngine/MCJIT/MCJITTest.cpp

@@ -199,4 +199,69 @@ TEST_F(MCJITTest, multiple_decl_lookups) {
   EXPECT_EQ(A, B) << "Repeat calls to getPointerToFunction fail.";
 }
 
+typedef void * (*FunctionHandlerPtr)(const std::string &str);
+
+TEST_F(MCJITTest, lazy_function_creator_pointer) {
+  SKIP_UNSUPPORTED_PLATFORM;
+  
+  Function *Foo = insertExternalReferenceToFunction<int32_t(void)>(M.get(),
+                                                                   "\1Foo");
+  Function *Parent = startFunction<int32_t(void)>(M.get(), "Parent");
+  CallInst *Call = Builder.CreateCall(Foo, {});
+  Builder.CreateRet(Call);
+  
+  createJIT(std::move(M));
+  
+  // Set up the lazy function creator that records the name of the last
+  // unresolved external function found in the module. Using a function pointer
+  // prevents us from capturing local variables, which is why this is static.
+  static std::string UnresolvedExternal;
+  FunctionHandlerPtr UnresolvedHandler = [] (const std::string &str) {
+    UnresolvedExternal = str;
+    return (void *)(uintptr_t)-1;
+  };
+  TheJIT->InstallLazyFunctionCreator(UnresolvedHandler);
+  
+  // JIT the module.
+  TheJIT->finalizeObject();
+  
+  // Verify that our handler was called.
+  EXPECT_EQ(UnresolvedExternal, "Foo");
+}
+
+TEST_F(MCJITTest, lazy_function_creator_lambda) {
+  SKIP_UNSUPPORTED_PLATFORM;
+  
+  Function *Foo1 = insertExternalReferenceToFunction<int32_t(void)>(M.get(),
+                                                                   "\1Foo1");
+  Function *Foo2 = insertExternalReferenceToFunction<int32_t(void)>(M.get(),
+                                                                   "\1Foo2");
+  Function *Parent = startFunction<int32_t(void)>(M.get(), "Parent");
+  CallInst *Call1 = Builder.CreateCall(Foo1, {});
+  CallInst *Call2 = Builder.CreateCall(Foo2, {});
+  Value *Result = Builder.CreateAdd(Call1, Call2);
+  Builder.CreateRet(Result);
+  
+  createJIT(std::move(M));
+  
+  // Set up the lazy function creator that records the name of unresolved
+  // external functions in the module.
+  std::vector<std::string> UnresolvedExternals;
+  auto UnresolvedHandler = [&UnresolvedExternals] (const std::string &str) {
+    llvm:dbgs() << "str is '" << str << "'\n";
+    UnresolvedExternals.push_back(str);
+    return (void *)(uintptr_t)-1;
+  };
+  TheJIT->InstallLazyFunctionCreator(UnresolvedHandler);
+  
+  // JIT the module.
+  TheJIT->finalizeObject();
+  
+  // Verify that our handler was called for each unresolved function.
+  auto I = UnresolvedExternals.begin(), E = UnresolvedExternals.end();
+  EXPECT_EQ(UnresolvedExternals.size(), 2);
+  EXPECT_FALSE(std::find(I, E, "Foo1") == E);
+  EXPECT_FALSE(std::find(I, E, "Foo2") == E);
+}
+
 }