CGDecl: Skip static variable initializers in unreachable code

[MatzeB]

Summary

This fixes http://llvm.org/PR31054

I don't know whether that is the correct fix: Are we actually allowed to skip the destructor registration if the static variable is unreachable?

[rsmith]

Yes, this is correct; per [stmt.dcl]/5, the destructor only runs if the object was constructed.

cfe/trunk/lib/CodeGen/CGDecl.cpp

CodeGenFunction::AddInitializerToStaticVarDecl(const VarDecl &D,
                                                llvm::GlobalVariable *GV) {
   llvm::Constant *Init = CGM.EmitConstantInit(D, this);
 
   // If constant emission failed, then this should be a C++ static
   // initializer.
   if (!Init) {
     if (!getLangOpts().CPlusPlus)
       CGM.ErrorUnsupported(D.getInit(), "constant l-value expression");
-    else if (Builder.GetInsertBlock()) {
+    else if (HaveInsertPoint()) {
       // Since we have a static initializer, this global variable can't
       // be constant.
       GV->setConstant(false);
 
       EmitCXXGuardedInit(D, GV, /*PerformInit*/true);
     }
     return GV;
   }
if (GV->getType()->getElementType() != Init->getType()) {
 
     // Erase the old global, since it is no longer used.
     OldGV->eraseFromParent();
   }
 
   GV->setConstant(CGM.isTypeConstant(D.getType(), true));
   GV->setInitializer(Init);
 
-  if (hasNontrivialDestruction(D.getType())) {
+  if (hasNontrivialDestruction(D.getType()) && HaveInsertPoint()) {
     // We have a constant initializer, but a nontrivial destructor. We still
     // need to perform a guarded "initialization" in order to register the
     // destructor.
     EmitCXXGuardedInit(D, GV, /*PerformInit*/false);
   }
 
   return GV;
 }

cfe/trunk/test/CodeGenCXX/pr31054.cpp

+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm -o - %s | FileCheck %s
+
+struct A { ~A(); };
+void func() {
+  return;
+  static A k;
+}
+
+// Test that we did not crash, by checking whether function was created.
+// CHECK-LABEL: define void @_Z4funcv() #0 {
+// CHECK: ret void
+// CHECK: }