GlobalOpt: fix an issue where CXAAtExitFn points to a deleted function.

CXAAtExitFn was set outside a loop and before optimizations where functions
can be deleted. This patch will set CXAAtExitFn inside the loop and after
optimizations.

Seg fault when running LTO because of accesses to a deleted function.
rdar://problem/13838828


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@181838 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 9 insertions, 3 deletions

diff --git a/lib/Transforms/IPO/GlobalOpt.cpp b/lib/Transforms/IPO/GlobalOpt.cpp
index 0ef900e..4a9cb27 100644
--- a/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/lib/Transforms/IPO/GlobalOpt.cpp
@@ -3323,8 +3323,6 @@ bool GlobalOpt::runOnModule(Module &M) {
   // Try to find the llvm.globalctors list.
   GlobalVariable *GlobalCtors = FindGlobalCtors(M);
 
-  Function *CXAAtExitFn = FindCXAAtExit(M, TLI);
-
   bool LocalChange = true;
   while (LocalChange) {
     LocalChange = false;
@@ -3342,7 +3340,9 @@ bool GlobalOpt::runOnModule(Module &M) {
     // Resolve aliases, when possible.
     LocalChange |= OptimizeGlobalAliases(M);
 
-    // Try to remove trivial global destructors.
+    // Try to remove trivial global destructors if they are not removed
+    // already.
+    Function *CXAAtExitFn = FindCXAAtExit(M, TLI);
     if (CXAAtExitFn)
       LocalChange |= OptimizeEmptyGlobalCXXDtors(CXAAtExitFn);
 
diff --git a/test/Transforms/GlobalOpt/atexit.ll b/test/Transforms/GlobalOpt/atexit.ll
new file mode 100644
index 0000000..dbcd0d7
--- /dev/null
+++ b/test/Transforms/GlobalOpt/atexit.ll
@@ -0,0 +1,6 @@
+; RUN: opt < %s -globalopt -S | FileCheck %s
+
+; CHECK: ModuleID
+define internal hidden i32 @__cxa_atexit(void (i8*)* nocapture %func, i8* nocapture %arg, i8* nocapture %dso_handle) nounwind readnone optsize noimplicitfloat {
+  unreachable
+}