We're porting libcxx to Hexagon. Stepping the first line in wait.pass.cpp
will put lldb in a bad state - it thinks the target has resumed, but it
never sends a step or resume packet to the remote gdbserver. Sometimes it
will step part of the line, return control, then stepping again goes to the
bad state.
The system has 4 threads; only thread 3 is currently being used. The bad
state happens because ProcessGDBRemote::DoResume can't figure out how to
send a resume packet. During the thread plan it resumes all threads. Later
it goes to step thread 3, but it also wants to resume threads 1,2,4, but our
gdbserver doesn't support vCont, so it gives up. I don't think it should be
resuming threads 1,2,4.
How can I fix this?
The source file is wait.pass.cpp:
https://llvm.org/svn/llvm-project/libcxx/trunk/test/std/thread/thread.condit
ion/thread.condition.condvar/wait.pass.cpp
Disassembly of line 43:
42 {
-> 43 std::unique_locklk(mut);
44 std::thread t(f);
-> 0x10011c4 <+20>: { memw(r30+#-20) = r2 }
0x10011c8 <+24>: { immext(#18198784)
0x10011cc <+28>: r2 = ##18198784 }
0x10011d0 <+32>: { memw(r30+#-24) = r2 }
0x10011d4 <+36>: { r2 = memw(r30 + #-20) }
wait.pass.cpp.exe`main + 40 [inlined]
std::__1::unique_lock::unique_lock(std::__1::mutex&) at
wait.pass.cpp:43
0x10011d8 <+40>: { r3 = memw(r30 + #-24) }
wait.pass.cpp.exe`main + 44 [inlined]
std::__1::unique_lock::unique_lock(std::__1::mutex&) + 4 at
wait.pass.cpp:43
0x10011dc <+44>: { memw(r2+#0) = r3 }
wait.pass.cpp.exe`main + 48 [inlined]
std::__1::unique_lock::unique_lock(std::__1::mutex&) + 8 at
wait.pass.cpp:43
0x10011e0 <+48>: { memb(r2+#4)=#1 }
wait.pass.cpp.exe`main + 52 [inlined]
std::__1::unique_lock::unique_lock(std::__1::mutex&) + 12
at wait.pass.cpp:43
0x10011e4 <+52>: { r0 = memw(r2 + #0) }
0x10011e8 <+56>: { call 0x1001ab4 }; std::__1::mutex::lock at
mutex.cpp:31
The only change-of-flow is the call instruction at the end.
Select linetable info, from llvm-dwarfdump:
AddressLine Column File ISA Discriminator Flags
-- -- -- -- --- - -
0x010011c4 43 33 11 0 0 is_stmt
prologue_end
0x010011d8112 17 3 0 0 is_stmt
0x010011dc112 11 3 0 0
0x010011e0112 23 3 0 0
0x010011e4112 38 3 0 0
0x010011ec 44 17 11 0 0 is_stmt
File 11 is wait.pass.cpp; file 3 is __mutex_base, where the inlined
std::unique_lock is defined.
Step log:
(lldb) r
Process 1 launched: 'c:\lldb\test\cxx11\wait.pass.cpp.exe' (hexagon)
Process 1 stopped
* thread #3: tid = 0x0003, 0x010011c4 wait.pass.cpp.exe`main + 20 at
wait.pass.cpp:43, stop reason = breakpoint 1.1
frame #0: 0x010011c4 wait.pass.cpp.exe`main + 20 at wait.pass.cpp:43
40
41 int main()
42 {
-> 43 std::unique_locklk(mut);
44 std::thread t(f);
45 assert(test1 == 0);
46 while (test1 == 0) {
(lldb) thread list
Process 1 stopped
thread #1: tid = 0x0001, 0xff004f64
thread #2: tid = 0x0002, 0xff004f64
* thread #3: tid = 0x0003, 0x010011c4 wait.pass.cpp.exe`main + 20 at
wait.pass.cpp:43, stop reason = breakpoint 1.1
thread #4: tid = 0x0004, 0xff004f64
(lldb) log enable lldb step
(lldb) s
Finding branch index from address @ 0x010011c4
Instruction @0x010011C4 : 0xA79EE2FB
Packet start @0x010011C8
Instruction @0x010011C8 : 0x001156C4
Instruction @0x010011D0 : 0xA79EE2FA
Packet start @0x010011D4
Thread::PushPlan(0x04E678D0): "Stepping in through line
wait.pass.cpp:43.", tid = 0x0003.
Process::PrivateResume() m_stop_id = 2, public state: stopped private state:
stopped
Failed to create new thread notification breakpoint.
Thread::PushPlan(0x04E678D0): "Single stepping past breakpoint site
2 at 0x10011c4", tid = 0x0003.
lldb_private::ThreadPlan::WillResume Thread #1 (0x045DDE10): tid =
0x0001, pc = 0xff004f64, sp = 0xff00cb78, fp = 0xff002d10, plan = 'base
plan', state= suspended, stop others = 0
lldb_private::ThreadPlan::WillResume Thread #2 (0x04E660B0): tid =
0x0002, pc = 0xff004f64, sp = 0xff00cc70, fp = 0x, plan = 'base
plan', state= suspended, stop others = 0
lldb_private::ThreadPlan::WillResume Thread #3 (0x04E678D0): tid =
0x0003, pc = 0x010011c4, sp = 0x0525eca8, fp = 0x0525ecf8, plan = 'Step over
breakpoint trap', state = stepping, stop others = 1
lldb_private::ThreadPlan::WillResume Thread #4 (0x04E69080): tid =
0x0004, pc = 0xff004f64, sp = 0xff00ce60, fp = 0x, plan = 'base
plan', state= suspended, stop others = 0
Current Plan for thread 1(045DDE10) (0x0001, suspended): base plan
being asked whether we should report run.
Current Plan for th
