[lldb] [test] Make 2lwp_process_SIGSEGV test more portable

[mgorny]

Summary

Fix 2lwp_process_SIGSEGV NetBSD core test to terminate inside regular
function rather than libc call, in order to get reproducible backtrace
on different platforms.

[krytarowski]

lldb/packages/Python/lldbsuite/test/functionalities/postmortem/netbsd-core/2lwp_process_SIGSEGV.c

11–12

Just style, but I would use while (1) continue;

34

It's a style but I would replace sleep(1) with a global volatile int that is switched in bar and here we could wait with: while (!initialized) continue;

[mgorny]

Updated as requested by @krytarowski

lldb/packages/Python/lldbsuite/test/functionalities/postmortem/netbsd-core/2lwp_process_SIGSEGV.c

 #include <lwp.h>
 #include <stddef.h>
 #include <stdlib.h>
 #include <unistd.h>
 #include <signal.h>
 
+volatile int sem = 0;
+
 static void bar() {
   char F = 'b';
-  kill(getpid(), SIGSEGV); // Frame bar
+  sem = 1;
+  while (1) continue; // Frame bar
 }
 
 static void foo(void (*boomer)()) {
   char F = 'f';
   boomer(); // Frame foo
 }
 
 static void lwp_main(void *unused) {
   char F = 'l';
   foo(bar); // Frame lwp_main
 }
 
 int main(int argc, char **argv) {
   ucontext_t uc;
   lwpid_t lid;
   static const size_t ssize = 16 * 1024;
   void *stack;
 
   stack = malloc(ssize);
   _lwp_makecontext(&uc, lwp_main, NULL, NULL, stack, ssize);
   _lwp_create(&uc, 0, &lid);
+  while (sem != 1) continue;
+  kill(getpid(), SIGSEGV);
   _lwp_wait(lid, NULL);
 }

lldb/packages/Python/lldbsuite/test/functionalities/postmortem/netbsd-core/TestNetBSDCore.py

 
 class NetBSD2LWPProcessSigCoreTestCase(NetBSDCoreCommonTestCase):
     THREAD_COUNT = 2
 
     def check_stack(self, process, pid, filename):
         thread = process.GetSelectedThread()
         self.assertTrue(thread)
         self.assertEqual(thread.GetThreadID(), 2)
-        self.assertEqual(thread.GetThreadID(), 2)
         self.assertEqual(thread.GetStopReason(), lldb.eStopReasonSignal)
         self.assertEqual(thread.GetStopReasonDataCount(), 1)
         self.assertEqual(thread.GetStopReasonDataAtIndex(0), signal.SIGSEGV)
-        backtrace = ["_kill", "bar", "foo", "lwp_main"]
+        backtrace = ["bar", "foo", "lwp_main"]
         self.check_backtrace(thread, filename, backtrace)
 
         # thread 1 should have the same signal
         thread = process.GetThreadByID(1)
         self.assertEqual(thread.GetStopReason(), lldb.eStopReasonSignal)
         self.assertEqual(thread.GetStopReasonDataCount(), 1)
         self.assertEqual(thread.GetStopReasonDataAtIndex(0), signal.SIGSEGV)
 
-    @skipIf  # TODO: fails with non-netbsd libc
     @skipIfLLVMTargetMissing("X86")
     def test_amd64(self):
         """Test double-threaded amd64 core dump where process is signalled."""
-        self.do_test("2lwp_process_SIGSEGV.amd64", pid=141, region_count=24)
+        self.do_test("2lwp_process_SIGSEGV.amd64", pid=665, region_count=24)