[lldb] Fix TestDyldExecLinux with xml enabled

NativeProcessLinux is not able to properly read libraries-svr4 data when
running with ld.so as the "main" executable. Normally, this is not a big
problem, as it returns an error message, and lldb can fallback to manual
library loading.

Unfortunately, lldb-server also does not clear cached svr4 data on exec,
which means that it does *not* return an error when the application
execs from the "regular" to the "ld.so" mode. Instead it returns
incorrect data (it is missing the main executable) and causes
TestDyldExecLinux to fail (but only when building with xml support
enabled).

This patch makes ensures that cached process data is cleared on exec,
fixing the test. Since TestDyldExecLinux has shown to be sensitive to
the way we read library info, I fork it into two (with svr4 enabled and
disabled).

lldb/include/lldb/Host/common/NativeProcessProtocol.h

@@ -457,7 +457,7 @@ protected:
   ///
   /// Provide a mechanism for a delegate to clear out any exec-
   /// sensitive data.
-  void NotifyDidExec();
+  virtual void NotifyDidExec();
 
   NativeThreadProtocol *GetThreadByIDUnlocked(lldb::tid_t tid);
 

lldb/source/Host/common/NativeProcessProtocol.cpp

@@ -322,6 +322,8 @@ void NativeProcessProtocol::NotifyDidExec() {
   Log *log = GetLog(LLDBLog::Process);
   LLDB_LOG(log, "process {0} exec()ed", GetID());
 
+  m_software_breakpoints.clear();
+
   m_delegate.DidExec(this);
 }
 

lldb/source/Plugins/Process/POSIX/NativeProcessELF.cpp

@@ -180,4 +180,9 @@ NativeProcessELF::GetLoadedSVR4Libraries() {
   return library_list;
 }
 
+void NativeProcessELF::NotifyDidExec() {
+  NativeProcessProtocol::NotifyDidExec();
+  m_shared_library_info_addr.reset();
+}
+
 } // namespace lldb_private

lldb/source/Plugins/Process/POSIX/NativeProcessELF.h

@@ -45,6 +45,8 @@ protected:
   llvm::Expected<SVR4LibraryInfo>
   ReadSVR4LibraryInfo(lldb::addr_t link_map_addr);
 
+  void NotifyDidExec() override;
+
   std::unique_ptr<AuxVector> m_aux_vector;
   llvm::Optional<lldb::addr_t> m_shared_library_info_addr;
 };

lldb/test/API/functionalities/dyld-exec-linux/TestDyldExecLinux.py

@@ -12,11 +12,20 @@ from lldbsuite.test import lldbutil
 
 class TestLinux64ExecViaDynamicLoader(TestBase):
     mydir = TestBase.compute_mydir(__file__)
+    NO_DEBUG_INFO_TESTCASE = True
+
+    @skipIfXmlSupportMissing
+    @skipIf(oslist=no_match(['linux']))
+    def test_with_svr4(self):
+        self.runCmd("settings set plugin.process.gdb-remote.use-libraries-svr4 true")
+        self._test()
 
     @skipIf(oslist=no_match(['linux']))
-    @no_debug_info_test
-    @skipIf(oslist=["linux"], archs=["arm"])
-    def test(self):
+    def test_without_svr4(self):
+        self.runCmd("settings set plugin.process.gdb-remote.use-libraries-svr4 false")
+        self._test()
+
+    def _test(self):
         self.build()
 
         # Extracts path of the interpreter.