Fix empty register set when trying to get size of register

GetSharedRegisterInfoVector is a function to get the singleton of total
register info. Also, PrivateGetRegisterCount assumes that we have already
filled the object in GetSharedRegisterInfoVector and panic when the object
is empty.
However, the actually function possess the register info
is GetRegisterInfo_i386. Originally, I plan to solve this by only
referencing object in GetSharedRegisterInfoVector. However,
RegisterInfos_x86_64.h requires the symbol with name g_register_infos in
current scope so that the header can append x86_64 registers after it.
As a result, I decide to copy the info to the object in
GetSharedRegisterInfoVector.

Also, reorder the header order and provide tests for debugging 32bit
binary on 64bit platform.

Author: aokblast

lldb/source/Host/freebsd/Host.cpp

@@ -18,8 +18,6 @@
 #include <dlfcn.h>
 #include <execinfo.h>
 
-#include "llvm/Object/ELF.h"
-
 #include "lldb/Host/FileSystem.h"
 #include "lldb/Host/Host.h"
 #include "lldb/Host/HostInfo.h"
@@ -32,6 +30,7 @@
 #include "lldb/Utility/Status.h"
 #include "lldb/Utility/StreamString.h"
 
+#include "llvm/Object/ELF.h"
 #include "llvm/TargetParser/Host.h"
 
 namespace lldb_private {

lldb/source/Plugins/Process/Utility/RegisterContextFreeBSD_x86_64.cpp

@@ -76,8 +76,7 @@ static std::vector<lldb_private::RegisterInfo> &GetSharedRegisterInfoVector() {
 
 static const RegisterInfo *
 GetRegisterInfo_i386(const lldb_private::ArchSpec &arch) {
-  static std::vector<lldb_private::RegisterInfo> g_register_infos(
-      GetSharedRegisterInfoVector());
+  static std::vector<lldb_private::RegisterInfo> g_register_infos;
 
   // Allocate RegisterInfo only once
   if (g_register_infos.empty()) {
@@ -93,6 +92,9 @@ GetRegisterInfo_i386(const lldb_private::ArchSpec &arch) {
 #define UPDATE_REGISTER_INFOS_I386_STRUCT_WITH_X86_64_OFFSETS
 #include "RegisterInfos_x86_64.h"
 #undef UPDATE_REGISTER_INFOS_I386_STRUCT_WITH_X86_64_OFFSETS
+    std::vector<lldb_private::RegisterInfo> &shared_regs =
+        GetSharedRegisterInfoVector();
+    shared_regs = g_register_infos;
   }
 
   return &g_register_infos[0];