V4: Set correct source locations for jumps out of conditionalsv5.9.0-beta1

We always want to place the jump on the last line of the conditionally
executed statement, unless we might never execute the last line.

In the latter case, that is if the inner statement is again a
conditional, we use some token of the outer condition. This works fine
with loops, as the loop condition is actually checked after each
iteration, and it's plausible to the user that we jump there.

With "if" statements, it's not so great. We cannot really explain why we
jump back to the "if" token after executing the conditional statement.
However, we have to add some source location to the jump instruction as
otherwise it uses the source location of the last statement that had
one, which is rather random.

Task-number: QTBUG-59204
Task-number: QTBUG-59774
Change-Id: I48e331ce1c1830f236e16b75c9201a2f490d2092
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

1 files changed, 48 insertions, 20 deletions

diff --git a/tests/auto/qml/debugger/qv4debugger/tst_qv4debugger.cpp b/tests/auto/qml/debugger/qv4debugger/tst_qv4debugger.cpp
index 6d0d884ed7..584bd10151 100644
--- a/tests/auto/qml/debugger/qv4debugger/tst_qv4debugger.cpp
+++ b/tests/auto/qml/debugger/qv4debugger/tst_qv4debugger.cpp
@@ -315,8 +315,8 @@ private slots:
     void stepToEndOfScript_data() { redundancy_data(); }
     void stepToEndOfScript();
 
-    void lastLineOfLoop_data();
-    void lastLineOfLoop();
+    void lastLineOfConditional_data();
+    void lastLineOfConditional();
 private:
     QV4Debugger *debugger() const
     {
@@ -801,32 +801,60 @@ void tst_qv4debugger::stepToEndOfScript()
     QCOMPARE(state.lineNumber, -4); // A return instruction without proper line number.
 }
 
-void tst_qv4debugger::lastLineOfLoop_data()
+void tst_qv4debugger::lastLineOfConditional_data()
 {
-    QTest::addColumn<QString>("loopHead");
-    QTest::addColumn<QString>("loopTail");
-
-    QTest::newRow("for")       << "for (var i = 0; i < 10; ++i) {\n"   << "}\n";
-    QTest::newRow("for..in")   << "for (var i in [0, 1, 2, 3, 4]) {\n" << "}\n";
-    QTest::newRow("while")     << "while (ret < 10) {\n"               << "}\n";
-    QTest::newRow("do..while") << "do {\n"                             << "} while (ret < 10);\n";
+    QTest::addColumn<QString>("head");
+    QTest::addColumn<QString>("tail");
+    QTest::addColumn<int>("breakPoint");
+    QTest::addColumn<int>("lastLine");
+
+    QTest::newRow("for {block}")       << "for (var i = 0; i < 10; ++i) {\n"   << "}" << 4 << 7;
+    QTest::newRow("for..in {block}")   << "for (var i in [0, 1, 2, 3, 4]) {\n" << "}" << 4 << 7;
+    QTest::newRow("while {block}")     << "while (ret < 10) {\n"               << "}" << 4 << 7;
+    QTest::newRow("do..while {block}") << "do {\n"           << "} while (ret < 10);" << 4 << 7;
+
+    QTest::newRow("if true {block}")       << "if (true) {\n"  << "}"
+                                           << 4 << 7;
+    QTest::newRow("if false {block}")      << "if (false) {\n" << "}"
+                                           << 2 << 8;
+    QTest::newRow("if true else {block}")  << "if (true) {\n"  << "} else {\n    ret += 8;\n}"
+                                           << 4 << 7;
+    QTest::newRow("if false else {block}") << "if (false) {\n" << "} else {\n    ret += 8;\n}"
+                                           << 8 << 9;
+
+    QTest::newRow("for statement")       << "for (var i = 0; i < 10; ++i)\n"   << "" << 4 << 2;
+    QTest::newRow("for..in statement")   << "for (var i in [0, 1, 2, 3, 4])\n" << "" << 4 << 2;
+    QTest::newRow("while statement")     << "while (ret < 10)\n"               << "" << 4 << 2;
+    QTest::newRow("do..while statement") << "do\n"            << "while (ret < 10);" << 4 << 7;
+
+    // For two nested if statements without blocks, we need to map the jump from the inner to the
+    // outer one on the outer "if". There is just no better place.
+    QTest::newRow("if true statement")       << "if (true)\n"  << ""                    << 4 << 2;
+    QTest::newRow("if false statement")      << "if (false)\n" << ""                    << 2 << 8;
+
+    // Also two nested ifs without blocks.
+    QTest::newRow("if true else statement")  << "if (true)\n"  << "else\n    ret += 8;" << 4 << 2;
+    QTest::newRow("if false else statement") << "if (false)\n" << "else\n    ret += 8;" << 8 << 9;
 }
 
-void tst_qv4debugger::lastLineOfLoop()
+void tst_qv4debugger::lastLineOfConditional()
 {
-    QFETCH(QString, loopHead);
-    QFETCH(QString, loopTail);
+    QFETCH(QString, head);
+    QFETCH(QString, tail);
+    QFETCH(int, breakPoint);
+    QFETCH(int, lastLine);
 
     QString script =
-            "var ret = 0;\n"
-            + loopHead +
+            "var ret = 2;\n"
+            + head +
             "    if (ret == 2)\n"
             "        ret += 4;\n" // breakpoint, then step over
-            "    else \n"
+            "    else\n"
             "        ret += 1;\n"
-            + loopTail;
+            + tail + "\n" +
+            "ret -= 5;";
 
-    debugger()->addBreakPoint("trueBranch", 4);
+    debugger()->addBreakPoint("trueBranch", breakPoint);
     m_debuggerAgent->m_resumeSpeed = QV4Debugger::StepOver;
     evaluateJavaScript(script, "trueBranch");
     QVERIFY(m_debuggerAgent->m_wasPaused);
@@ -834,10 +862,10 @@ void tst_qv4debugger::lastLineOfLoop()
     QVERIFY(m_debuggerAgent->m_statesWhenPaused.count() > 1);
     QV4Debugger::ExecutionState firstState = m_debuggerAgent->m_statesWhenPaused.first();
     QCOMPARE(firstState.fileName, QString("trueBranch"));
-    QCOMPARE(firstState.lineNumber, 4);
+    QCOMPARE(firstState.lineNumber, breakPoint);
     QV4Debugger::ExecutionState secondState = m_debuggerAgent->m_statesWhenPaused.at(1);
     QCOMPARE(secondState.fileName, QString("trueBranch"));
-    QCOMPARE(secondState.lineNumber, 7);
+    QCOMPARE(secondState.lineNumber, lastLine);
 }
 
 void tst_qv4debugger::redundancy_data()