[Lldb-commits] [lldb] c577c6c - [lldb] Test undefined return addresses in signal frames (#223046)

[via lldb-commits]

Author: Minsoo Choo
Date: 2026-09-13T18:29:21-04:00
New Revision: c577c6c3f88baddcb2f5368c5cf7f2ca6137b5be

URL: https://github.com/llvm/llvm-project/commit/c577c6c3f88baddcb2f5368c5cf7f2ca6137b5be
DIFF: https://github.com/llvm/llvm-project/commit/c577c6c3f88baddcb2f5368c5cf7f2ca6137b5be.diff

LOG: [lldb] Test undefined return addresses in signal frames (#223046)

Signal-frame CFI can explicitly mark its return-address register
undefined to represent a terminal synthetic context. This is useful for
contexts such as newly created FreeBSD kernel threads that do not have
an interrupted caller.

Verify that LLDB keeps the signal frame in the backtrace and terminates
the unwind without creating a caller.

Assisted-by: GPT

Added: 
    lldb/test/Shell/Unwind/Inputs/signal-frame-undefined-ra.s
    lldb/test/Shell/Unwind/signal-frame-undefined-ra.test

Modified: 
    

Removed: 
    


################################################################################
diff  --git a/lldb/test/Shell/Unwind/Inputs/signal-frame-undefined-ra.s b/lldb/test/Shell/Unwind/Inputs/signal-frame-undefined-ra.s
new file mode 100644
index 0000000000000..247584db9dd0a
--- /dev/null
+++ b/lldb/test/Shell/Unwind/Inputs/signal-frame-undefined-ra.s
@@ -0,0 +1,19 @@
+        .att_syntax
+        .text
+        .globl  asm_main
+asm_main:
+        .cfi_startproc
+        callq   terminal
+        xorl    %eax, %eax
+        retq
+        .cfi_endproc
+
+        .globl  terminal
+terminal:
+        .cfi_startproc
+        .cfi_signal_frame
+        .cfi_def_cfa %rsp, 8
+        .cfi_undefined %rip
+        int3
+        retq
+        .cfi_endproc

diff  --git a/lldb/test/Shell/Unwind/signal-frame-undefined-ra.test b/lldb/test/Shell/Unwind/signal-frame-undefined-ra.test
new file mode 100644
index 0000000000000..5b4ae97d01451
--- /dev/null
+++ b/lldb/test/Shell/Unwind/signal-frame-undefined-ra.test
@@ -0,0 +1,18 @@
+# Test that an undefined return address terminates a signal frame without
+# creating a caller.
+
+# UNSUPPORTED: system-windows
+# REQUIRES: target-x86_64, native
+
+# RUN: %clang_host %p/Inputs/call-asm.c %p/Inputs/signal-frame-undefined-ra.s -o %t
+# RUN: %lldb %t -s %s -o exit | FileCheck %s
+
+breakpoint set -n terminal
+# CHECK: Breakpoint 1: where = {{.*}}`terminal
+
+process launch
+# CHECK: stop reason = breakpoint 1.1
+
+thread backtrace -u
+# CHECK: frame #0: {{.*}}`terminal
+# CHECK-NOT: frame #1: