bpo-31773: time.perf_counter() uses again double (GH-3964)

time.clock() and time.perf_counter() now use again C double
internally.

Remove also _PyTime_GetWinPerfCounterWithInfo(): use
_PyTime_GetPerfCounterDoubleWithInfo() instead on Windows.

2 files changed, 27 insertions, 21 deletions

diff --git a/Python/import.c b/Python/import.c
index d396b4de79..76aa912dc8 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -1669,10 +1669,10 @@ PyImport_ImportModuleLevelObject(PyObject *name, PyObject *globals,
     else {
         static int ximporttime = 0;
         static int import_level;
-        static _PyTime_t accumulated;
+        static double accumulated;
         _Py_IDENTIFIER(importtime);
 
-        _PyTime_t t1 = 0, accumulated_copy = accumulated;
+        double t1 = 0, accumulated_copy = accumulated;
 
         Py_XDECREF(mod);
 
@@ -1695,7 +1695,7 @@ PyImport_ImportModuleLevelObject(PyObject *name, PyObject *globals,
 
         if (ximporttime) {
             import_level++;
-            t1 = _PyTime_GetPerfCounter();
+            t1 = _PyTime_GetPerfCounterDouble();
             accumulated = 0;
         }
 
@@ -1711,12 +1711,12 @@ PyImport_ImportModuleLevelObject(PyObject *name, PyObject *globals,
                                            mod != NULL);
 
         if (ximporttime) {
-            _PyTime_t cum = _PyTime_GetPerfCounter() - t1;
+            double cum = _PyTime_GetPerfCounterDouble() - t1;
 
             import_level--;
             fprintf(stderr, "import time: %9ld | %10ld | %*s%s\n",
-                    (long)_PyTime_AsMicroseconds(cum - accumulated, _PyTime_ROUND_CEILING),
-                    (long)_PyTime_AsMicroseconds(cum, _PyTime_ROUND_CEILING),
+                    (long)ceil((cum - accumulated) * 1e6),
+                    (long)ceil(cum * 1e6),
                     import_level*2, "", PyUnicode_AsUTF8(abs_name));
 
             accumulated = accumulated_copy + cum;
diff --git a/Python/pytime.c b/Python/pytime.c
index dbf1dda4a0..7fd2a90f3b 100644
--- a/Python/pytime.c
+++ b/Python/pytime.c
@@ -801,8 +801,8 @@ _PyTime_GetMonotonicClockWithInfo(_PyTime_t *tp, _Py_clock_info_t *info)
 
 
 #ifdef MS_WINDOWS
-int
-_PyTime_GetWinPerfCounterWithInfo(_PyTime_t *t, _Py_clock_info_t *info)
+static int
+win_perf_counter(double *tp, _Py_clock_info_t *info)
 {
     static LONGLONG cpu_frequency = 0;
     static LONGLONG ctrStart;
@@ -829,28 +829,33 @@ _PyTime_GetWinPerfCounterWithInfo(_PyTime_t *t, _Py_clock_info_t *info)
     }
 
     diff = diff / (double)cpu_frequency;
-    return _PyTime_FromDouble(t, diff, _PyTime_ROUND_FLOOR, SEC_TO_NS);
+    *tp = diff;
+    return 0;
 }
 #endif
 
 
 int
-_PyTime_GetPerfCounterWithInfo(_PyTime_t *t, _Py_clock_info_t *info)
+_PyTime_GetPerfCounterDoubleWithInfo(double *d, _Py_clock_info_t *info)
 {
 #ifdef MS_WINDOWS
-    return _PyTime_GetWinPerfCounterWithInfo(t, info);
+    return win_perf_counter(d, info);
 #else
-    return _PyTime_GetMonotonicClockWithInfo(t, info);
+    _PyTime_t t;
+    if (_PyTime_GetMonotonicClockWithInfo(&t, info) < 0) {
+        return -1;
+    }
+    *d = _PyTime_AsSecondsDouble(t);
+    return 0;
 #endif
 }
 
 
-_PyTime_t
-_PyTime_GetPerfCounter(void)
+double
+_PyTime_GetPerfCounterDouble(void)
 {
-    _PyTime_t t;
-    if (_PyTime_GetPerfCounterWithInfo(&t, NULL) < 0) {
-        /* should not happen, _PyTime_Init() checked the clock at startup */
+    double t;
+    if (_PyTime_GetPerfCounterDoubleWithInfo(&t, NULL)) {
         Py_UNREACHABLE();
     }
     return t;
@@ -860,17 +865,18 @@ _PyTime_GetPerfCounter(void)
 int
 _PyTime_Init(void)
 {
-    /* check that the 3 most important clocks are working properly
-       to not have to check for exceptions at runtime. If a clock works once,
-       it cannot fail in next calls. */
+    /* check that time.time(), time.monotonic() and time.perf_counter() clocks
+       are working properly to not have to check for exceptions at runtime. If
+       a clock works once, it cannot fail in next calls. */
     _PyTime_t t;
+    double d;
     if (_PyTime_GetSystemClockWithInfo(&t, NULL) < 0) {
         return -1;
     }
     if (_PyTime_GetMonotonicClockWithInfo(&t, NULL) < 0) {
         return -1;
     }
-    if (_PyTime_GetPerfCounterWithInfo(&t, NULL) < 0) {
+    if (_PyTime_GetPerfCounterDoubleWithInfo(&d, NULL) < 0) {
         return -1;
     }
     return 0;