$OpenBSD: patch-lib_Target_X86_X86TargetMachine_cpp,v 1.8 2021/03/15 21:02:10 sthen Exp $

Add a clang pass that identifies potential ROP gadgets and replaces ROP
friendly instructions with safe alternatives. This initial commit fixes
3 instruction forms that will lower to include a c3 (return) byte.
Additional problematic instructions can be fixed incrementally using
this framework.

Index: lib/Target/X86/X86TargetMachine.cpp
--- lib/Target/X86/X86TargetMachine.cpp.orig
+++ lib/Target/X86/X86TargetMachine.cpp
@@ -525,6 +525,7 @@ void X86PassConfig::addPreEmitPass() {
   }
   addPass(createX86DiscriminateMemOpsPass());
   addPass(createX86InsertPrefetchPass());
+  addPass(createX86FixupGadgetsPass());
 }
 
 void X86PassConfig::addPreEmitPass2() {
