Lldb: Use qtHookData to retrieve Qt version

Adds caching of Qt version information.

In case that qVersion() can not be found, use qtHookData[2] to retrieve
the Qt Library version number.

In case that also fails, we now use self.fallbackQtVersion instead
of just returning 0x50200.

Previously debugging apps in the iOS Simulator would fail to correctly
detect the Qt Version, as qVersion might be optimized out, especially
for very simple applications.

Change-Id: I9183c1e9793bd899f296a231c693cd5bc146ab96
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

share/qtcreator/debugger/lldbbridge.py

@@ -719,7 +719,18 @@ class Dumper(DumperBase):
             pass
         return '0x%x' % address
 
-    def qtVersionAndNamespace(self):
+    def fetchInternalFunctions(self):
+        funcs = self.target.FindFunctions('QObject::customEvent')
+        if len(funcs):
+            symbol = funcs[0].GetSymbol()
+            self.qtCustomEventFunc = symbol.GetStartAddress().GetLoadAddress(self.target)
+
+        funcs = self.target.FindFunctions('QObject::property')
+        if len(funcs):
+            symbol = funcs[0].GetSymbol()
+            self.qtPropertyFunc = symbol.GetStartAddress().GetLoadAddress(self.target)
+
+    def fetchQtVersionAndNamespace(self):
         for func in self.target.FindFunctions('qVersion'):
             name = func.GetSymbol().GetName()
             if name.endswith('()'):
@@ -755,24 +766,41 @@ class Dumper(DumperBase):
             qtVersion = 0x10000 * int(major) + 0x100 * int(minor) + int(patch)
             self.qtVersion = lambda: qtVersion
 
-            funcs = self.target.FindFunctions('QObject::customEvent')
-            if len(funcs):
-                symbol = funcs[0].GetSymbol()
-                self.qtCustomEventFunc = symbol.GetStartAddress().GetLoadAddress(self.target)
-
-            funcs = self.target.FindFunctions('QObject::property')
-            if len(funcs):
-                symbol = funcs[0].GetSymbol()
-                self.qtPropertyFunc = symbol.GetStartAddress().GetLoadAddress(self.target)
             return (qtNamespace, qtVersion)
 
-        return ('', 0x50200)
+        try:
+            versionValue = self.target.EvaluateExpression('qtHookData[2]')
+            if versionValue.IsValid():
+                return ('', versionValue.unsigned)
+        except:
+            pass
+
+        return ('', self.fallbackQtVersion)
+
+    def qtVersionAndNamespace(self):
+        qtVersionAndNamespace = None
+        try:
+            qtVersionAndNamespace = self.fetchQtVersionAndNamespace()
+            DumperBase.warn("Detected Qt Version: 0x%0x (namespace='%s')" %
+                            (qtVersionAndNamespace[1], qtVersionAndNamespace[0] or "no namespace"))
+        except Exception as e:
+            DumperBase.warn('[lldb] Error detecting Qt version: %s' % e)
+
+        try:
+            self.fetchInternalFunctions()
+            DumperBase.warn('Found function QObject::property: 0x%0x' % self.qtPropertyFunc)
+            DumperBase.warn('Found function QObject::customEvent: 0x%0x' % self.qtCustomEventFunc)
+        except Exception as e:
+            DumperBase.warn('[lldb] Error fetching internal Qt functions: %s' % e)
+
+        # Cache version information by overriding this function.
+        self.qtVersionAndNamespace = lambda: qtVersionAndNamespace
+        return qtVersionAndNamespace
 
     def qtNamespace(self):
         return self.qtVersionAndNamespace()[0]
 
     def qtVersion(self):
-        self.qtVersionAndNamespace()
         return self.qtVersionAndNamespace()[1]
 
     def handleCommand(self, command):