Index: Common/CMakeLists.txt
===================================================================
--- Common/CMakeLists.txt
+++ Common/CMakeLists.txt
@@ -22,11 +22,7 @@
   )
 
 # TODO add support for ARM (NT) and ARM64
-# TODO build these unconditionally as we cannot do cross-debugging or WoW
-if(CMAKE_SYSTEM_PROCESSOR MATCHES "x86_64|AMD64")
-  target_sources(lldbPluginProcessWindowsCommon PRIVATE
-    x64/RegisterContextWindows_x64.cpp)
-elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "i?86|X86")
-  target_sources(lldbPluginProcessWindowsCommon PRIVATE
-    x86/RegisterContextWindows_x86.cpp)
-endif()
+target_sources(lldbPluginProcessWindowsCommon PRIVATE
+  x64/RegisterContextWindows_x64.cpp)
+target_sources(lldbPluginProcessWindowsCommon PRIVATE
+  x86/RegisterContextWindows_x86.cpp)
Index: Common/x64/RegisterContextWindows_x64.h
===================================================================
--- Common/x64/RegisterContextWindows_x64.h
+++ Common/x64/RegisterContextWindows_x64.h
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+#if defined(__x86_64__) || defined(__amd64__) || defined(_M_X64) || defined(_M_AMD64)
+
 #ifndef liblldb_RegisterContextWindows_x64_H_
 #define liblldb_RegisterContextWindows_x64_H_
 
@@ -41,3 +43,5 @@
 }
 
 #endif // #ifndef liblldb_RegisterContextWindows_x64_H_
+
+#endif // defined(__x86_64__) || defined(__amd64__) || defined(_M_X64) || defined(_M_AMD64)
Index: Common/x64/RegisterContextWindows_x64.cpp
===================================================================
--- Common/x64/RegisterContextWindows_x64.cpp
+++ Common/x64/RegisterContextWindows_x64.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+#if defined(__x86_64__) || defined(__amd64__) || defined(_M_X64) || defined(_M_AMD64)
+
 #include "lldb/Host/windows/HostThreadWindows.h"
 #include "lldb/Host/windows/windows.h"
 #include "lldb/Utility/RegisterValue.h"
@@ -534,3 +536,5 @@
   return ::SetThreadContext(
       wthread.GetHostThread().GetNativeThread().GetSystemHandle(), &m_context);
 }
+
+#endif // defined(__x86_64__) || defined(__amd64__) || defined(_M_X64) || defined(_M_AMD64)
Index: Common/x86/RegisterContextWindows_x86.h
===================================================================
--- Common/x86/RegisterContextWindows_x86.h
+++ Common/x86/RegisterContextWindows_x86.h
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+#if defined(__i386__) || defined(_M_IX86)
+
 #ifndef liblldb_RegisterContextWindows_x86_H_
 #define liblldb_RegisterContextWindows_x86_H_
 
@@ -45,3 +47,5 @@
 }
 
 #endif // #ifndef liblldb_RegisterContextWindows_x86_H_
+
+#endif // defined(__i386__) || defined(_M_IX86)
Index: Common/x86/RegisterContextWindows_x86.cpp
===================================================================
--- Common/x86/RegisterContextWindows_x86.cpp
+++ Common/x86/RegisterContextWindows_x86.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+#if defined(__i386__) || defined(_M_IX86)
+
 #include "lldb/Host/windows/HostThreadWindows.h"
 #include "lldb/Host/windows/windows.h"
 #include "lldb/Utility/RegisterValue.h"
@@ -282,3 +284,5 @@
   reg_value.SetUInt32(value);
   return true;
 }
+
+#endif // defined(__i386__) || defined(_M_IX86)