Skip to content

Conversation

aokblast
Copy link
Contributor

@aokblast aokblast commented Oct 10, 2025

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. But 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 and provide a test for debugging 32bit binary on 64bit platform.

@aokblast
Copy link
Contributor Author

aokblast commented Oct 10, 2025

I fell asleep so I will write the test case tomorrow. I put it here to first let more people test it and to seek comments on my method.

@llvmbot
Copy link
Member

llvmbot commented Oct 10, 2025

@llvm/pr-subscribers-lldb

Author: None (aokblast)

Changes

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 a test for debugging 32bit binary on 64bit platform.


Full diff: https://github.com/llvm/llvm-project/pull/162890.diff

2 Files Affected:

  • (modified) lldb/source/Host/freebsd/Host.cpp (+1-2)
  • (modified) lldb/source/Plugins/Process/Utility/RegisterContextFreeBSD_x86_64.cpp (+4-2)
diff --git a/lldb/source/Host/freebsd/Host.cpp b/lldb/source/Host/freebsd/Host.cpp
index fa7efad466bad..dfdbfea0c3c0a 100644
--- a/lldb/source/Host/freebsd/Host.cpp
+++ b/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 {
diff --git a/lldb/source/Plugins/Process/Utility/RegisterContextFreeBSD_x86_64.cpp b/lldb/source/Plugins/Process/Utility/RegisterContextFreeBSD_x86_64.cpp
index e0f3971c6e272..b55a5c595d3ca 100644
--- a/lldb/source/Plugins/Process/Utility/RegisterContextFreeBSD_x86_64.cpp
+++ b/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];

@aokblast aokblast changed the title Fix empty register set when trying to get size of register [LLDB, FreeBSD, x86] Fix empty register set when trying to get size of register Oct 10, 2025
…f register info

The register set information is stored as a singleton in
GetRegisterInfo_i386. However, it is later use by other function which
assume it stores in GetSharedRegisterInfoVector. Therefore, we copy the
data to GetSharedRegisterInfoVector directly so that LLDB won't get
panic.

Also, reorder the header order and provide a test for debugging 32bit
binary on 64bit platform. This test is just a copy paste from
dummy-target.test but change the target as -m32.
@aokblast
Copy link
Contributor Author

@DavidSpickett Hello:
I think the error is because LLVM CI container does not ship 32bit library. Do you have any idea about this?

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Labels

Projects

None yet

Development

Successfully merging this pull request may close these issues.

2 participants