Debugger: Add support for two more floating point display formats

1. The `std::hexfloat` representation produced by `std::sstream`.
2. Breaking the number into a normalized value and a integral power of 2,
   as does the `std::frexp()` function.

M_PI looks like "0x1.921fb54442d18p+1" and "0.785398163397 * 2^2"
respectively.

Fixes: QTCREATORBUG-26793
Change-Id: Ib08ea9408f79201434eb75ec328b94ab933259a4
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/debugger/debuggerprotocol.h

@@ -316,7 +316,9 @@ enum DisplayFormat
     CharCodeIntegerFormat       = 28, // Frontend internal only
 
     CompactFloatFormat          = 26, // Frontend internal only
-    ScientificFloatFormat       = 27  // Frontend internal only
+    ScientificFloatFormat       = 27, // Frontend internal only
+    HexFloatFormat              = 29, // Frontend internal only
+    NormalizedTwoFloatFormat    = 30, // Frontend internal only
 };
 
 

src/plugins/debugger/watchdata.cpp

@@ -628,6 +628,19 @@ QString WatchItem::sourceExpression() const
     return QString("%1.%2").arg(p->sourceExpression(), name);
 }
 
+int WatchItem::guessSize() const
+{
+    if (size != 0)
+        return size;
+    if (type == "double")
+        return 8;
+    if (type == "float")
+        return 4;
+    if (type == "qfloat16")
+        return 2;
+    return 0;
+}
+
 } // namespace Internal
 } // namespace Debugger
 

src/plugins/debugger/watchdata.h

@@ -65,6 +65,7 @@ public:
 
     bool isValid()   const { return !iname.isEmpty(); }
     bool isVTablePointer() const;
+    int guessSize() const;
 
     void setError(const QString &);
     void setValue(const QString &);

src/plugins/debugger/watchhandler.cpp

@@ -63,6 +63,7 @@
 #include <QClipboard>
 #include <QDebug>
 #include <QFile>
+#include <QFloat16>
 #include <QItemDelegate>
 #include <QJsonArray>
 #include <QJsonObject>
@@ -80,7 +81,10 @@
 #include <QVBoxLayout>
 
 #include <algorithm>
+#include <cmath>
 #include <cstring>
+#include <sstream>
+
 #include <ctype.h>
 
 using namespace Core;
@@ -770,6 +774,32 @@ static QString formattedValue(const WatchItem *item)
         return QString::number(dd, 'g');
     }
 
+    if (format == HexFloatFormat) {
+        double dd = item->value.toDouble();
+        std::ostringstream ss;
+        ss << std::hexfloat;
+        switch (item->guessSize()) {
+            case 2: ss << qfloat16(dd); break;
+            case 4: ss << float(dd); break;
+            default: ss << dd; break;
+        }
+        return QString::fromStdString(ss.str());
+    }
+
+    if (format == NormalizedTwoFloatFormat) {
+        double dd = item->value.toDouble();
+        std::ostringstream ss;
+        int pow2_exp;
+        double norm = std::frexp(dd, &pow2_exp);
+        int numDecimalDigits = 12;
+        switch (item->guessSize()) {
+            case 2: numDecimalDigits = 4; break;
+            case 4: numDecimalDigits = 8; break;
+            default: break;
+        }
+        return QString::number(norm, 'f', numDecimalDigits) + " * 2^" + QString::number(pow2_exp);
+    }
+
     if (item->type == "va_list")
         return item->value;
 
@@ -992,6 +1022,8 @@ static DisplayFormats typeFormatList(const WatchItem *item)
     if (ok) {
         formats.append(CompactFloatFormat);
         formats.append(ScientificFloatFormat);
+        formats.append(HexFloatFormat);
+        formats.append(NormalizedTwoFloatFormat);
     }
 
     // Fixed artificial integral types.
@@ -2084,6 +2116,8 @@ QString WatchModel::nameForFormat(int format)
 
         case CompactFloatFormat: return tr("Compact Float");
         case ScientificFloatFormat: return tr("Scientific Float");
+        case HexFloatFormat: return tr("Hexadecimal Float");
+        case NormalizedTwoFloatFormat: return tr("Normalized, with Power-of-Two Exponent");
     }
 
     QTC_CHECK(false);