From 5cc966a6c1258e007d90dd0b92a8c146087de9a9 Mon Sep 17 00:00:00 2001
From: Jeffrey Yasskin <jyasskin@google.com>
Date: Sat, 12 Dec 2009 05:58:14 +0000
Subject: [PATCH] Fix available_externally linkage for globals.  It's probably
 still not supported by emitGlobals, but I don't have a test case for that.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91208 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/ExecutionEngine/JIT/JIT.cpp           |  2 +-
 unittests/ExecutionEngine/JIT/JITTest.cpp | 25 +++++++++++++++++++++++
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/lib/ExecutionEngine/JIT/JIT.cpp b/lib/ExecutionEngine/JIT/JIT.cpp
index 6d781c7e22c..3607f1fcb09 100644
--- a/lib/ExecutionEngine/JIT/JIT.cpp
+++ b/lib/ExecutionEngine/JIT/JIT.cpp
@@ -681,7 +681,7 @@ void *JIT::getOrEmitGlobalVariable(const GlobalVariable *GV) {
   if (Ptr) return Ptr;
 
   // If the global is external, just remember the address.
-  if (GV->isDeclaration()) {
+  if (GV->isDeclaration() || GV->hasAvailableExternallyLinkage()) {
 #if HAVE___DSO_HANDLE
     if (GV->getName() == "__dso_handle")
       return (void*)&__dso_handle;
diff --git a/unittests/ExecutionEngine/JIT/JITTest.cpp b/unittests/ExecutionEngine/JIT/JITTest.cpp
index 12c6b67d987..bbf34603872 100644
--- a/unittests/ExecutionEngine/JIT/JITTest.cpp
+++ b/unittests/ExecutionEngine/JIT/JITTest.cpp
@@ -534,6 +534,31 @@ TEST_F(JITTest, FunctionPointersOutliveTheirCreator) {
 #endif
 }
 
+}  // anonymous namespace
+// This variable is intentionally defined differently in the statically-compiled
+// program from the IR input to the JIT to assert that the JIT doesn't use its
+// definition.
+extern "C" int32_t JITTest_AvailableExternallyGlobal;
+int32_t JITTest_AvailableExternallyGlobal = 42;
+namespace {
+
+TEST_F(JITTest, AvailableExternallyGlobalIsntEmitted) {
+  TheJIT->DisableLazyCompilation(true);
+  LoadAssembly("@JITTest_AvailableExternallyGlobal = "
+               "  available_externally global i32 7 "
+               " "
+               "define i32 @loader() { "
+               "  %result = load i32* @JITTest_AvailableExternallyGlobal "
+               "  ret i32 %result "
+               "} ");
+  Function *loaderIR = M->getFunction("loader");
+
+  int32_t (*loader)() = reinterpret_cast<int32_t(*)()>(
+    (intptr_t)TheJIT->getPointerToFunction(loaderIR));
+  EXPECT_EQ(42, loader()) << "func should return 42 from the external global,"
+                          << " not 7 from the IR version.";
+}
+
 // This code is copied from JITEventListenerTest, but it only runs once for all
 // the tests in this directory.  Everything seems fine, but that's strange
 // behavior.