[MCJIT] Make repeat calls to MCJIT::getPointerToFunction for declarations safe.

MCJIT::getPointerForFunction adds the resulting address to the global mapping.
This should be done via updateGlobalMapping rather than addGlobalMapping, since
the latter asserts if a mapping already exists.

MCJIT::getPointerToFunction is actually deprecated - hopefully we can remove it
(or more likely re-task it) entirely soon. In the mean time it should at least
work as advertised.

<rdar://problem/18727946>

llvm-svn: 220444

2 files changed, 21 insertions, 0 deletions

diff --git a/llvm/unittests/ExecutionEngine/MCJIT/MCJITTest.cpp b/llvm/unittests/ExecutionEngine/MCJIT/MCJITTest.cpp
index 15e0efdb971..64d8c2fca04 100644
--- a/llvm/unittests/ExecutionEngine/MCJIT/MCJITTest.cpp
+++ b/llvm/unittests/ExecutionEngine/MCJIT/MCJITTest.cpp
@@ -187,4 +187,16 @@ TEST_F(MCJITTest, multiple_functions) {
 
 #endif /*!defined(__arm__)*/
 
+TEST_F(MCJITTest, multiple_decl_lookups) {
+  SKIP_UNSUPPORTED_PLATFORM;
+
+  Function *Foo = insertExternalReferenceToFunction<void(void)>(M.get(), "_exit");
+  createJIT(std::move(M));
+  void *A = TheJIT->getPointerToFunction(Foo);
+  void *B = TheJIT->getPointerToFunction(Foo);
+
+  EXPECT_TRUE(A != 0) << "Failed lookup - test not correctly configured.";
+  EXPECT_EQ(A, B) << "Repeat calls to getPointerToFunction fail.";
+}
+
 }
diff --git a/llvm/unittests/ExecutionEngine/MCJIT/MCJITTestBase.h b/llvm/unittests/ExecutionEngine/MCJIT/MCJITTestBase.h
index bc44418003c..eea88bbe3f4 100644
--- a/llvm/unittests/ExecutionEngine/MCJIT/MCJITTestBase.h
+++ b/llvm/unittests/ExecutionEngine/MCJIT/MCJITTestBase.h
@@ -107,6 +107,15 @@ protected:
     return Result;
   }
 
+  // Inserts a declaration to a function defined elsewhere
+  template <typename FuncType>
+  Function *insertExternalReferenceToFunction(Module *M, StringRef Name) {
+    Function *Result = Function::Create(
+                         TypeBuilder<FuncType, false>::get(Context),
+                         GlobalValue::ExternalLinkage, Name, M);
+    return Result;
+  }
+
   // Inserts an declaration to a function defined elsewhere
   Function *insertExternalReferenceToFunction(Module *M, StringRef Name,
                                               FunctionType *FuncTy) {