[PATCH 1/4] Fix calling convention of thread entry point

[PATCH 1/4] Fix calling convention of thread entry point

[Hannes Domani]

For i686 the CreateThread entry point function needs the WINAPI (stdcall)
calling convention:

../../gdb/windows-nat.c: In constructor 'windows_nat_target::windows_nat_target()':
../../gdb/windows-nat.c:450:56: error: invalid user-defined conversion from 'windows_nat_target::windows_nat_target()::<lambda(LPVOID)>' to 'LPTHREAD_START_ROUTINE' {aka 'long unsigned int (__attribute__((stdcall)) *)(void*)'} [-fpermissive]
  450 |   HANDLE bg_thread = CreateThread (nullptr, 64 * 1024, fn, this, 0, nullptr);
      |                                                        ^~
../../gdb/windows-nat.c:444:13: note: candidate is: 'constexpr windows_nat_target::windows_nat_target()::<lambda(LPVOID)>::operator DWORD (*)(LPVOID)() const' (near match)
  444 |   auto fn = [] (LPVOID self) -> DWORD
      |             ^
../../gdb/windows-nat.c:444:13: note:   no known conversion from 'DWORD (*)(LPVOID)' {aka 'long unsigned int (*)(void*)'} to 'LPTHREAD_START_ROUTINE' {aka 'long unsigned int (__attribute__((stdcall)) *)(void*)'}

Since it's not possible to change the calling convention of a lambda, I've
moved it to a separate function.
---
 gdb/windows-nat.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/gdb/windows-nat.c b/gdb/windows-nat.c
index 5d506507b6d..f61f6c1cb35 100644
--- a/gdb/windows-nat.c
+++ b/gdb/windows-nat.c
@@ -344,6 +344,9 @@ struct windows_nat_target final : public x86_nat_target<inf_child_target>
   BOOL windows_continue (DWORD continue_status, int id, int killed,
 			 bool last_call = false);
 
+  /* Helper function to start process_thread.  */
+  static DWORD WINAPI process_thread_starter (LPVOID self);
+
   /* This function implements the background thread that starts
      inferiors and waits for events.  */
   void process_thread ();
@@ -404,13 +407,8 @@ windows_nat_target::windows_nat_target ()
     m_response_event (CreateEvent (nullptr, false, false, nullptr)),
     m_wait_event (make_serial_event ())
 {
-  auto fn = [] (LPVOID self) -> DWORD
-    {
-      ((windows_nat_target *) self)->process_thread ();
-      return 0;
-    };
-
-  HANDLE bg_thread = CreateThread (nullptr, 64 * 1024, fn, this, 0, nullptr);
+  HANDLE bg_thread = CreateThread (nullptr, 64 * 1024,
+				   process_thread_starter, this, 0, nullptr);
   CloseHandle (bg_thread);
 }
 
@@ -453,6 +451,13 @@ wait_for_single (HANDLE handle, DWORD howlong)
     }
 }
 
+DWORD WINAPI
+windows_nat_target::process_thread_starter (LPVOID self)
+{
+  ((windows_nat_target *) self)->process_thread ();
+  return 0;
+}
+
 void
 windows_nat_target::process_thread ()
 {
-- 
2.35.1

[PATCH 2/4] Don't use auto for lambda parameter

[Hannes Domani]

Older gcc versions (here 4.9.2) can't handle auto for a lambda parameter:

../../gdb/windows-nat.c: In member function 'void windows_nat_target::delete_thread(ptid_t, DWORD, bool)':
../../gdb/windows-nat.c:629:12: error: use of 'auto' in lambda parameter declaration only available with -std=c++1y or -std=gnu++1y [-Werror]
        [=] (auto &th)
            ^
---
 gdb/windows-nat.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gdb/windows-nat.c b/gdb/windows-nat.c
index f61f6c1cb35..6da6757acaf 100644
--- a/gdb/windows-nat.c
+++ b/gdb/windows-nat.c
@@ -631,7 +631,7 @@ windows_nat_target::delete_thread (ptid_t ptid, DWORD exit_code,
 
   auto iter = std::find_if (windows_process.thread_list.begin (),
 			    windows_process.thread_list.end (),
-			    [=] (auto &th)
+			    [=] (std::unique_ptr<windows_thread_info> &th)
 			    {
 			      return th->tid == id;
 			    });
-- 
2.35.1

Re: [PATCH 2/4] Don't use auto for lambda parameter

[Tom Tromey]

>>>>> "Hannes" == Hannes Domani via Gdb-patches <gdb-patches@sourceware.org> writes:

Hannes> Older gcc versions (here 4.9.2) can't handle auto for a lambda parameter:

This is ok.  Thank you for the patch.

Tom

[PATCH 3/4] Actually set m_is_async to current async mode

[Hannes Domani]

Looks like this was missed in the async mode implementation.
---
 gdb/windows-nat.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/gdb/windows-nat.c b/gdb/windows-nat.c
index 6da6757acaf..e2d2176f138 100644
--- a/gdb/windows-nat.c
+++ b/gdb/windows-nat.c
@@ -427,6 +427,8 @@ windows_nat_target::async (bool enable)
 		      nullptr, "windows_nat_target");
   else
     delete_file_handler (async_wait_fd ());
+
+  m_is_async = enable;
 }
 
 /* A wrapper for WaitForSingleObject that issues a warning if
-- 
2.35.1

Re: [PATCH 3/4] Actually set m_is_async to current async mode

[Tom Tromey]

>>>>> "Hannes" == Hannes Domani via Gdb-patches <gdb-patches@sourceware.org> writes:

Hannes> Looks like this was missed in the async mode implementation.

Yikes, that's a bad oversight.  Sorry about this.

The patch is ok.

Tom

[PATCH 4/4] Remove no longer used jump label

[Hannes Domani]

---
 gdb/windows-nat.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/gdb/windows-nat.c b/gdb/windows-nat.c
index e2d2176f138..17422e15f80 100644
--- a/gdb/windows-nat.c
+++ b/gdb/windows-nat.c
@@ -1824,7 +1824,6 @@ windows_nat_target::get_windows_debug_event
 			       windows_process.desired_stop_thread_id, 0));
     }
 
-out:
   if (thread_id == 0)
     return null_ptid;
   return ptid_t (windows_process.current_event.dwProcessId, thread_id, 0);
-- 
2.35.1

Re: [PATCH 4/4] Remove no longer used jump label

[Tom Tromey]

>>>>> "Hannes" == Hannes Domani via Gdb-patches <gdb-patches@sourceware.org> writes:

Hannes> ---

It's good to have a bit of text in the commit message.

Anyway this patch is ok, could even be done under the 'obvious' rule.
Thank you.

Tom

Re: [PATCH 1/4] Fix calling convention of thread entry point

[Tom Tromey]

>>>>> "Hannes" == Hannes Domani via Gdb-patches <gdb-patches@sourceware.org> writes:

Hannes> For i686 the CreateThread entry point function needs the WINAPI (stdcall)
Hannes> calling convention:

Thanks, this is ok.

I don't know why, but I don't see this when building on a Windows
machine here.  However, I can reproduce it using the mingw cross
toolchain on Fedora.

Tom

Re: [PATCH 1/4] Fix calling convention of thread entry point

[Hannes Domani]

 Am Montag, 28. November 2022, 20:24:51 MEZ hat Tom Tromey <tom@tromey.com> Folgendes geschrieben:

> >>>>> "Hannes" == Hannes Domani via Gdb-patches <gdb-patches@sourceware.org> writes:
>
> Hannes> For i686 the CreateThread entry point function needs the WINAPI (stdcall)
> Hannes> calling convention:
>
> Thanks, this is ok.
>
> I don't know why, but I don't see this when building on a Windows
> machine here.  However, I can reproduce it using the mingw cross
> toolchain on Fedora.

Thanks, I've pushed these 4 patches.


Hannes