Deprecate QElapsedTimer::TickCounter

Also remove left-over code paths related to it.

[ChangeLog][QtCore] QElapsedTimer::TickCounter enum is now
deprecated. Qt does not use the Windows API behind this
enum already since Qt 5.9, so it's fair to assume that
any code path relying on the enum is dead code.

Change-Id: I308fe23658835034774e2015a8ee64659102de56
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 14 insertions, 27 deletions

diff --git a/src/corelib/kernel/qelapsedtimer_win.cpp b/src/corelib/kernel/qelapsedtimer_win.cpp
index deeeb05921..7d0528d5fd 100644
--- a/src/corelib/kernel/qelapsedtimer_win.cpp
+++ b/src/corelib/kernel/qelapsedtimer_win.cpp
@@ -44,7 +44,7 @@
 
 QT_BEGIN_NAMESPACE
 
-// Result of QueryPerformanceFrequency, 0 indicates that the high resolution timer is unavailable
+// Result of QueryPerformanceFrequency
 static quint64 counterFrequency = 0;
 
 static void resolveCounterFrequency()
@@ -55,26 +55,19 @@ static void resolveCounterFrequency()
 
     // Retrieve the number of high-resolution performance counter ticks per second
     LARGE_INTEGER frequency;
-    if (!QueryPerformanceFrequency(&frequency)) {
+    if (!QueryPerformanceFrequency(&frequency) || frequency.QuadPart == 0)
         qFatal("QueryPerformanceFrequency failed, even though Microsoft documentation promises it wouldn't.");
-        counterFrequency = 0;
-    } else {
-        counterFrequency = frequency.QuadPart;
-    }
+    counterFrequency = frequency.QuadPart;
 
     done = true;
 }
 
 static inline qint64 ticksToNanoseconds(qint64 ticks)
 {
-    if (counterFrequency > 0) {
-        // QueryPerformanceCounter uses an arbitrary frequency
-        qint64 seconds = ticks / counterFrequency;
-        qint64 nanoSeconds = (ticks - seconds * counterFrequency) * 1000000000 / counterFrequency;
-        return seconds * 1000000000 + nanoSeconds;
-    }
-    // GetTickCount(64) returns milliseconds
-    return ticks * 1000000;
+    // QueryPerformanceCounter uses an arbitrary frequency
+    qint64 seconds = ticks / counterFrequency;
+    qint64 nanoSeconds = (ticks - seconds * counterFrequency) * 1000000000 / counterFrequency;
+    return seconds * 1000000000 + nanoSeconds;
 }
 
 
@@ -82,18 +75,12 @@ static quint64 getTickCount()
 {
     resolveCounterFrequency();
 
-    // This avoids a division by zero and disables the high performance counter if it's not available
-    if (counterFrequency > 0) {
-        LARGE_INTEGER counter;
-
-        bool ok = QueryPerformanceCounter(&counter);
-        Q_ASSERT_X(ok, "QElapsedTimer::start()",
-                   "QueryPerformanceCounter failed, although QueryPerformanceFrequency succeeded.");
-        Q_UNUSED(ok);
-        return counter.QuadPart;
-    }
-
-    return GetTickCount64();
+    LARGE_INTEGER counter;
+    bool ok = QueryPerformanceCounter(&counter);
+    Q_ASSERT_X(ok, "QElapsedTimer::start()",
+               "QueryPerformanceCounter failed, although QueryPerformanceFrequency succeeded.");
+    Q_UNUSED(ok);
+    return counter.QuadPart;
 }
 
 quint64 qt_msectime()
@@ -105,7 +92,7 @@ QElapsedTimer::ClockType QElapsedTimer::clockType() noexcept
 {
     resolveCounterFrequency();
 
-    return counterFrequency > 0 ? PerformanceCounter : TickCounter;
+    return PerformanceCounter;
 }
 
 bool QElapsedTimer::isMonotonic() noexcept