[Lldb-commits] [lldb] [lldb][windows] fix x86_64 arg register mapping for lldb-server (PR #197663)

[Charles Zablit via lldb-commits]

https://github.com/charles-zablit created https://github.com/llvm/llvm-project/pull/197663

The register info table used by `NativeRegisterContextWindows_x86_64` (which backs the lldb-server path on Windows) was using incorrect calling conventions mappings (Linux?).

Windows x64 uses a different convention. `RegisterContextWindows_x64.cpp` (used by the in-process
ProcessWindows plugin) already had the correct mapping.

This patch fixes 63 test failures when running `check-lldb` with `LLDB_USE_LLDB_SERVER=1`.

>From ce8afd8376b06dcc8f3fe307df46697e2c3dbcca Mon Sep 17 00:00:00 2001
From: Charles Zablit <c_zablit at apple.com>
Date: Thu, 14 May 2026 10:44:20 +0100
Subject: [PATCH] [lldb][Windows] Fix x86_64 arg register mapping for
 lldb-server

---
 .../Utility/RegisterContextWindows_x86_64.cpp        | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/lldb/source/Plugins/Process/Utility/RegisterContextWindows_x86_64.cpp b/lldb/source/Plugins/Process/Utility/RegisterContextWindows_x86_64.cpp
index bd483707ef88f..b5e255ead06df 100644
--- a/lldb/source/Plugins/Process/Utility/RegisterContextWindows_x86_64.cpp
+++ b/lldb/source/Plugins/Process/Utility/RegisterContextWindows_x86_64.cpp
@@ -90,14 +90,14 @@ static RegisterInfo g_register_infos_x86_64[] = {
 //  ===========================  ==================    ================      =========================   ====================
     DEFINE_GPR(rax,    nullptr,  dwarf_rax_x86_64,     dwarf_rax_x86_64,     LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM),
     DEFINE_GPR(rbx,    nullptr,  dwarf_rbx_x86_64,     dwarf_rbx_x86_64,     LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM),
-    DEFINE_GPR(rcx,    nullptr,  dwarf_rcx_x86_64,     dwarf_rcx_x86_64,     LLDB_REGNUM_GENERIC_ARG4,   LLDB_INVALID_REGNUM),
-    DEFINE_GPR(rdx,    nullptr,  dwarf_rdx_x86_64,     dwarf_rdx_x86_64,     LLDB_REGNUM_GENERIC_ARG3,   LLDB_INVALID_REGNUM),
-    DEFINE_GPR(rdi,    nullptr,  dwarf_rdi_x86_64,     dwarf_rdi_x86_64,     LLDB_REGNUM_GENERIC_ARG1,   LLDB_INVALID_REGNUM),
-    DEFINE_GPR(rsi,    nullptr,  dwarf_rsi_x86_64,     dwarf_rsi_x86_64,     LLDB_REGNUM_GENERIC_ARG2,   LLDB_INVALID_REGNUM),
+    DEFINE_GPR(rcx,    nullptr,  dwarf_rcx_x86_64,     dwarf_rcx_x86_64,     LLDB_REGNUM_GENERIC_ARG1,   LLDB_INVALID_REGNUM),
+    DEFINE_GPR(rdx,    nullptr,  dwarf_rdx_x86_64,     dwarf_rdx_x86_64,     LLDB_REGNUM_GENERIC_ARG2,   LLDB_INVALID_REGNUM),
+    DEFINE_GPR(rdi,    nullptr,  dwarf_rdi_x86_64,     dwarf_rdi_x86_64,     LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM),
+    DEFINE_GPR(rsi,    nullptr,  dwarf_rsi_x86_64,     dwarf_rsi_x86_64,     LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM),
     DEFINE_GPR(rbp,    nullptr,  dwarf_rbp_x86_64,     dwarf_rbp_x86_64,     LLDB_REGNUM_GENERIC_FP,     LLDB_INVALID_REGNUM),
     DEFINE_GPR(rsp,    nullptr,  dwarf_rsp_x86_64,     dwarf_rsp_x86_64,     LLDB_REGNUM_GENERIC_SP,     LLDB_INVALID_REGNUM),
-    DEFINE_GPR(r8,     nullptr,  dwarf_r8_x86_64,      dwarf_r8_x86_64,      LLDB_REGNUM_GENERIC_ARG5,   LLDB_INVALID_REGNUM),
-    DEFINE_GPR(r9,     nullptr,  dwarf_r9_x86_64,      dwarf_r9_x86_64,      LLDB_REGNUM_GENERIC_ARG6,   LLDB_INVALID_REGNUM),
+    DEFINE_GPR(r8,     nullptr,  dwarf_r8_x86_64,      dwarf_r8_x86_64,      LLDB_REGNUM_GENERIC_ARG3,   LLDB_INVALID_REGNUM),
+    DEFINE_GPR(r9,     nullptr,  dwarf_r9_x86_64,      dwarf_r9_x86_64,      LLDB_REGNUM_GENERIC_ARG4,   LLDB_INVALID_REGNUM),
     DEFINE_GPR(r10,    nullptr,  dwarf_r10_x86_64,     dwarf_r10_x86_64,     LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM),
     DEFINE_GPR(r11,    nullptr,  dwarf_r11_x86_64,     dwarf_r11_x86_64,     LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM),
     DEFINE_GPR(r12,    nullptr,  dwarf_r12_x86_64,     dwarf_r12_x86_64,     LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM),