Fix PR6360. It's easy for a stub's address to escape to user code, so we can't

just count references to it from JIT output to decide when to destroy it.  This
patch waits to destroy the JIT's memory of a stub until the Function it refers
to is destroyed.  External function stubs and GVIndirectSyms aren't destroyed
until the JIT itself is.

llvm-svn: 97737

1 files changed, 23 insertions, 0 deletions

diff --git a/llvm/unittests/ExecutionEngine/JIT/JITTest.cpp b/llvm/unittests/ExecutionEngine/JIT/JITTest.cpp
index 168bb3cb98d..b85f724353c 100644
--- a/llvm/unittests/ExecutionEngine/JIT/JITTest.cpp
+++ b/llvm/unittests/ExecutionEngine/JIT/JITTest.cpp
@@ -655,6 +655,29 @@ TEST_F(JITTest, NeedsExactSizeWithManyGlobals) {
   EXPECT_EQ(42, *********test());
 }
 
+TEST_F(JITTest, EscapedLazyStubStillCallable) {
+  TheJIT->DisableLazyCompilation(false);
+  LoadAssembly("define internal i32 @stubbed() { "
+               "  ret i32 42 "
+               "} "
+               " "
+               "define i32()* @get_stub() { "
+               "  ret i32()* @stubbed "
+               "} ");
+  typedef int32_t(*StubTy)();
+
+  // Call get_stub() to get the address of @stubbed without actually JITting it.
+  Function *get_stubIR = M->getFunction("get_stub");
+  StubTy (*get_stub)() = reinterpret_cast<StubTy(*)()>(
+    (intptr_t)TheJIT->getPointerToFunction(get_stubIR));
+  StubTy stubbed = get_stub();
+  // Now get_stubIR is the only reference to stubbed's stub.
+  get_stubIR->eraseFromParent();
+  // Now there are no references inside the JIT, but we've got a pointer outside
+  // it.  The stub should be callable and return the right value.
+  EXPECT_EQ(42, stubbed());
+}
+
 // Converts the LLVM assembly to bitcode and returns it in a std::string.  An
 // empty string indicates an error.
 std::string AssembleToBitcode(LLVMContext &Context, const char *Assembly) {