Debugger[CDB]: Display more context in disassembly.

Emulate gdb's behaviour trying to disassemble the function.

Task-number: QTCREATORBUG-5205
Change-Id: I2f4dc9393e12324b0423734c5235758a25395fec
Reviewed-on: http://codereview.qt.nokia.com/1029
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@nokia.com>

src/plugins/debugger/cdb/cdbengine.cpp

@@ -478,6 +478,7 @@ void CdbEngine::init()
     m_extensionMessageBuffer.clear();
     m_pendingBreakpointMap.clear();
     m_customSpecialStopData.clear();
+    m_symbolAddressCache.clear();
 
     // Create local list of mappings in native separators
     m_sourcePathMappings.clear();
@@ -1532,16 +1533,149 @@ void CdbEngine::selectThread(int index)
     postBuiltinCommand(cmd, 0, &CdbEngine::dummyHandler, CommandListStack);
 }
 
+// Default address range for showing disassembly.
+enum { DisassemblerRange = 512 };
+
+/* Try to emulate gdb's behaviour: When passed an address, display
+ * the disassembled function. CDB's 'u' (disassemble) command takes a symbol,
+ * but does not display the whole function, only 10 lines per default.
+ * So, to ensure the agent's
+ * address is in that range, resolve the function symbol, cache it and
+ * request the disassembly for a range that contains the agent's address. */
+
 void CdbEngine::fetchDisassembler(DisassemblerAgent *agent)
 {
     QTC_ASSERT(m_accessible, return;)
+    const QString function = agent->location().functionName();
+    const QString module = agent->location().from();
+    const QVariant cookie = qVariantFromValue<DisassemblerAgent*>(agent);
+    if (function.isEmpty() || module.isEmpty()) {
+        // No function, display a default range.
+        postDisassemblerCommand(agent->address(), cookie);
+    } else {
+        postResolveSymbol(module, function, cookie);
+    }
+}
+
+void CdbEngine::postDisassemblerCommand(quint64 address, const QVariant &cookie)
+{
+    postDisassemblerCommand(address - DisassemblerRange / 2,
+                            address + DisassemblerRange / 2, cookie);
+}
+
+void CdbEngine::postDisassemblerCommand(quint64 address, quint64 endAddress,
+                                        const QVariant &cookie)
+{
     QByteArray cmd;
     ByteArrayInputStream str(cmd);
-    str <<  "u " << hex << hexPrefixOn << agent->address() << " L40";
+    str <<  "u " << hex <<hexPrefixOn << address << ' ' << endAddress;
-    const QVariant cookie = qVariantFromValue<DisassemblerAgent*>(agent);
     postBuiltinCommand(cmd, 0, &CdbEngine::handleDisassembler, 0, cookie);
 }
 
+void CdbEngine::postResolveSymbol(const QString &module, const QString &function,
+                                  const QVariant &cookie)
+{
+    const QString symbol = module + QLatin1Char('!') + function;
+    const QList<quint64> addresses = m_symbolAddressCache.values(symbol);
+    if (addresses.isEmpty()) {
+        QVariantList cookieList;
+        cookieList << QVariant(symbol) << cookie;
+        showMessage(QLatin1String("Resolving symbol: ") + symbol, LogMisc);
+        postBuiltinCommand(QByteArray("x ") + symbol.toLatin1(), 0,
+                           &CdbEngine::handleResolveSymbol, 0,
+                           QVariant(cookieList));
+    } else {
+        showMessage(QString::fromLatin1("Using cached addresses for %1.").
+                    arg(symbol), LogMisc);
+        handleResolveSymbol(addresses, cookie);
+    }
+}
+
+// Parse address from 'x' response.
+// "00000001`3f7ebe80 module!foo (void)"
+static inline quint64 resolvedAddress(const QByteArray &line)
+{
+    const int blankPos = line.indexOf(' ');
+    if (blankPos >= 0) {
+        QByteArray addressBA = line.left(blankPos);
+        if (addressBA.size() > 9 && addressBA.at(8) == '`')
+            addressBA.remove(8, 1);
+        bool ok;
+        const quint64 address = addressBA.toULongLong(&ok, 16);
+        if (ok)
+            return address;
+    }
+    return 0;
+}
+
+void CdbEngine::handleResolveSymbol(const CdbBuiltinCommandPtr &command)
+{
+    QTC_ASSERT(command->cookie.type() == QVariant::List, return; );
+    const QVariantList cookieList = command->cookie.toList();
+    const QString symbol = cookieList.front().toString();
+    // Insert all matches of (potentially) ambiguous symbols
+    if (const int size = command->reply.size()) {
+        for (int i = 0; i < size; i++) {
+            if (const quint64 address = resolvedAddress(command->reply.at(i))) {
+                m_symbolAddressCache.insert(symbol, address);
+                showMessage(QString::fromLatin1("Obtained 0x%1 for %2 (#%3)").
+                            arg(address, 0, 16).arg(symbol).arg(i + 1), LogMisc);
+            }
+        }
+    } else {
+        showMessage(QLatin1String("Symbol resolution failed: ")
+                    + QString::fromLatin1(command->joinedReply()),
+                    LogError);
+    }
+    handleResolveSymbol(m_symbolAddressCache.values(symbol), cookieList.back());
+}
+
+// Find the function address matching needle in a list of function
+// addresses obtained from the 'x' command. Check for the
+// mimimum POSITIVE offset (needle >= function address.)
+static inline quint64 findClosestFunctionAddress(const QList<quint64> &addresses,
+                                                 quint64 needle)
+{
+    const int size = addresses.size();
+    if (!size)
+        return 0;
+    if (size == 1)
+       return addresses.front();
+    int closestIndex = 0;
+    quint64 closestOffset = 0xFFFFFFFF;
+    for (int i = 0; i < size; i++) {
+        if (addresses.at(i) <= needle) {
+            const quint64 offset = needle - addresses.at(i);
+            if (offset < offset) {
+                closestOffset = offset;
+                closestIndex = i;
+            }
+        }
+    }
+    return addresses.at(closestIndex);
+}
+
+void CdbEngine::handleResolveSymbol(const QList<quint64> &addresses, const QVariant &cookie)
+{
+    // Disassembly mode: Determine suitable range containing the
+    // agent's address within the function to display.
+    if (qVariantCanConvert<DisassemblerAgent*>(cookie)) {
+        DisassemblerAgent *agent = cookie.value<DisassemblerAgent *>();
+        const quint64 agentAddress = agent->address();
+        const quint64 functionAddress
+                = findClosestFunctionAddress(addresses, agentAddress);
+        if (functionAddress > 0 && functionAddress <= agentAddress) {
+            quint64 endAddress = agentAddress + DisassemblerRange / 2;
+            if (const quint64 remainder = endAddress % 8)
+                endAddress += 8 - remainder;
+            postDisassemblerCommand(functionAddress, endAddress, cookie);
+        } else {
+            postDisassemblerCommand(agentAddress, cookie);
+        }
+        return;
+    }
+}
+
 // Parse: "00000000`77606060 cc              int     3"
 void CdbEngine::handleDisassembler(const CdbBuiltinCommandPtr &command)
 {

src/plugins/debugger/cdb/cdbengine.h

@@ -40,6 +40,7 @@
 #include <QtCore/QProcess>
 #include <QtCore/QVariantList>
 #include <QtCore/QMap>
+#include <QtCore/QMultiHash>
 #include <QtCore/QTime>
 #include <QtCore/QPair>
 #include <QtCore/QList>
@@ -211,8 +212,12 @@ private:
     void postWidgetAtCommand();
     void handleCustomSpecialStop(const QVariant &v);
     void postFetchMemory(const MemoryViewCookie &c);
+    inline void postDisassemblerCommand(quint64 address, const QVariant &cookie = QVariant());
+    void postDisassemblerCommand(quint64 address, quint64 endAddress,
+                                 const QVariant &cookie = QVariant());
+    void postResolveSymbol(const QString &module, const QString &function,
+                           const QVariant &cookie =  QVariant());
     void evaluateExpression(QByteArray exp, const QVariant &cookie = QVariant());
-
     // Builtin commands
     void dummyHandler(const CdbBuiltinCommandPtr &);
     void handleStackTrace(const CdbExtensionCommandPtr &);
@@ -220,7 +225,10 @@ private:
     void handleDisassembler(const CdbBuiltinCommandPtr &);
     void handleJumpToLineAddressResolution(const CdbBuiltinCommandPtr &);
     void handleExpression(const CdbExtensionCommandPtr &);
+    void handleResolveSymbol(const CdbBuiltinCommandPtr &command);
+    void handleResolveSymbol(const QList<quint64> &addresses, const QVariant &cookie);
     void jumpToAddress(quint64 address);
+
     // Extension commands
     void handleThreads(const CdbExtensionCommandPtr &);
     void handlePid(const CdbExtensionCommandPtr &reply);
@@ -270,6 +278,7 @@ private:
     int m_watchPointY;
     PendingBreakPointMap m_pendingBreakpointMap;
     QHash<QString, QString> m_fileNameModuleHash;
+    QMultiHash<QString, quint64> m_symbolAddressCache;
     bool m_ignoreCdbOutput;
     QVariantList m_customSpecialStopData;
     QList<SourcePathMapping> m_sourcePathMappings;

src/plugins/debugger/debuggerengine.cpp

@@ -97,6 +97,7 @@ Internal::Location::Location(const StackFrame &frame, bool marker)
     m_functionName = frame.function;
     m_hasDebugInfo = frame.isUsable();
     m_address = frame.address;
+    m_from = frame.from;
 }
 
 QDebug operator<<(QDebug d, DebuggerState state)

src/plugins/debugger/debuggerengine.h

@@ -100,6 +100,7 @@ public:
     Location(const StackFrame &frame, bool marker = true);
     QString fileName() const { return m_fileName; }
     QString functionName() const { return m_functionName; }
+    QString from() const { return m_from; }
     int lineNumber() const { return m_lineNumber; }
     void setNeedsRaise(bool on) { m_needsRaise = on; }
     void setNeedsMarker(bool on) { m_needsMarker = on; }
@@ -118,6 +119,7 @@ private:
     int m_lineNumber;
     QString m_fileName;
     QString m_functionName;
+    QString m_from;
     quint64 m_address;
 };