Adding test-case for llvm.org/pr15936 (known failure with GCC 4.6/4.7)

- verify that backtraces for stacks that include functions which contain 
  illegal instructions are correct, and that variables in said functions can be
  printed.

llvm-svn: 181442

lldb/test/linux/builtin_trap/Makefile

@@ -0,0 +1,5 @@
+LEVEL = ../../make
+
+CXX_SOURCES := main.cpp
+
+include $(LEVEL)/Makefile.rules

lldb/test/linux/builtin_trap/TestBuiltinTrap.py

@@ -0,0 +1,70 @@
+"""
+Test lldb ability to unwind a stack with a function containing a call to the
+'__builtin_trap' intrinsic, which GCC (4.6) encodes to an illegal opcode.
+"""
+
+import os
+import unittest2
+import lldb
+from lldbtest import *
+import lldbutil
+
+class BuiltinTrapTestCase(TestBase):
+
+    mydir = os.path.join("linux", "builtin_trap")
+
+    @unittest2.skipUnless(sys.platform.startswith("darwin"), "requires Darwin")
+    @dsym_test
+    def test_with_dsym_and_run_command(self):
+        """Test that LLDB handles a function with __builtin_trap correctly."""
+        self.buildDsym()
+        self.builtin_trap_unwind()
+
+    @dwarf_test
+    @expectedFailureGcc # PR-15936: LLDB is omits a function that contains an
+                        #           illegal opcode from backtraces. This
+                        #           failure is GCC 4.6 specific.
+    def test_with_dwarf_and_run_command(self):
+        """Test that LLDB handles a function with __builtin_trap correctly."""
+        self.buildDwarf()
+        self.builtin_trap_unwind()
+
+    def setUp(self):
+        # Call super's setUp().
+        TestBase.setUp(self)
+        # Find the line number to break at.
+        self.line = line_number('main.cpp', '// Set break point at this line.')
+
+    def builtin_trap_unwind(self):
+        """Test that LLDB handles unwinding a frame that contains a function
+           with a __builtin_trap intrinsic.
+        """
+        self.runCmd("file a.out", CURRENT_EXECUTABLE_SET)
+
+        lldbutil.run_break_set_by_file_and_line (self, "main.cpp", self.line,
+                                                 num_expected_locations=1,
+                                                 loc_exact=True)
+
+        self.runCmd("run", RUN_SUCCEEDED)
+
+        # The stop reason of the thread should be breakpoint.
+        self.expect("thread list", STOPPED_DUE_TO_BREAKPOINT,
+            substrs = ['stopped',
+                       'stop reason = breakpoint'])
+
+        # print backtrace, expect both 'bar' and 'main' functions to be listed
+        self.expect('bt', substrs = ['bar', 'main'])
+
+        # go up one frame
+        self.runCmd("up", RUN_SUCCEEDED)
+
+        # evaluate a local
+        self.expect('p foo', substrs = ['= 5'])
+
+
+
+if __name__ == '__main__':
+    import atexit
+    lldb.SBDebugger.Initialize()
+    atexit.register(lambda: lldb.SBDebugger.Terminate())
+    unittest2.main()

lldb/test/linux/builtin_trap/main.cpp

@@ -0,0 +1,17 @@
+//===-- main.cpp ------------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+void bar(int const *foo) {
+  __builtin_trap(); // Set break point at this line.
+}
+
+int main() {
+  int foo = 5;
+  bar(&foo);
+}