From b2accb9a49107983f1f6cbbcf6ff8a072f905253 Mon Sep 17 00:00:00 2001
From: David Mandelin <dmandelin@mozilla.com>
Date: Tue, 4 May 2010 18:06:30 -0700
Subject: [PATCH] Bug 563842: Make PRMJ_Now always high-resolution in Windows
 shell builds, r=brendan

---
 js/src/prmjtime.cpp | 8 ++++++--
 js/src/shell/js.cpp | 7 +++++++
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/js/src/prmjtime.cpp b/js/src/prmjtime.cpp
index 986f480a30be..b9ee16161b6b 100644
--- a/js/src/prmjtime.cpp
+++ b/js/src/prmjtime.cpp
@@ -407,6 +407,11 @@ def PRMJ_Now():
 
 */
 
+// We parameterize the delay count just so that shell builds can
+// set it to 0 in order to get high-resolution benchmarking.
+// 10 seems to be the number of calls to load with a blank homepage.
+int CALIBRATION_DELAY_COUNT = 10;
+
 JSInt64
 PRMJ_Now(void)
 {
@@ -424,8 +429,7 @@ PRMJ_Now(void)
        This does not appear to be needed on Vista as the timeBegin/timeEndPeriod
        calls seem to immediately take effect. */
     int thiscall = JS_ATOMIC_INCREMENT(&nCalls);
-    /* 10 seems to be the number of calls to load with a blank homepage */
-    if (thiscall <= 10) {
+    if (thiscall <= CALIBRATION_DELAY_COUNT) {
         LowResTime(&ft);
         return (FILETIME2INT64(ft)-win2un)/10L;
     }
diff --git a/js/src/shell/js.cpp b/js/src/shell/js.cpp
index 509283a5fdf6..5afeaca3e7d5 100644
--- a/js/src/shell/js.cpp
+++ b/js/src/shell/js.cpp
@@ -5010,6 +5010,13 @@ main(int argc, char **argv, char **envp)
     argc--;
     argv++;
 
+#ifdef XP_WIN
+    // Set the timer calibration delay count to 0 so we get high
+    // resolution right away, which we need for precise benchmarking.
+    extern int CALIBRATION_DELAY_COUNT;
+    CALIBRATION_DELAY_COUNT = 0;
+#endif
+
     rt = JS_NewRuntime(64L * 1024L * 1024L);
     if (!rt)
         return 1;