From 3222db0937aaf1ae5681bc124406ec37f550bc7c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thorbj=C3=B8rn=20Martsum?= <tmartsum@gmail.com>
Date: Thu, 10 Jan 2013 19:42:59 +0100
Subject: QVector - removeLast optimize

In case somebody uses QVector as a stack, it is not fair to have
takeLast, removeLast and pop_back to do way too much work.

This is still very slow compared to std::vector::pop_back
(mostly due implicit sharing), however it is more than a
factor faster than before.

Change-Id: I636872675e80c8ca0c8ebc94b04f587a2dcd6d8d
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
---
 tests/benchmarks/corelib/tools/qvector/main.cpp | 37 +++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

(limited to 'tests/benchmarks')

diff --git a/tests/benchmarks/corelib/tools/qvector/main.cpp b/tests/benchmarks/corelib/tools/qvector/main.cpp
index 1795f2dc6f..3c6defb572 100644
--- a/tests/benchmarks/corelib/tools/qvector/main.cpp
+++ b/tests/benchmarks/corelib/tools/qvector/main.cpp
@@ -206,6 +206,7 @@ private slots:
     void qvector_separator() { qWarning() << "QVector results: "; }
     void qvector_const_read_access();
     void qvector_mutable_read_access();
+    void qvector_pop_back();
     #ifdef TEST_RETURN
     void qvector_fill_and_return();
     #endif
@@ -214,6 +215,8 @@ private slots:
     void stdvector() { qWarning() << "std::vector results: "; }
     void stdvector_const_read_access();
     void stdvector_mutable_read_access();
+    void stdvector_pop_back();
+
     #ifdef TEST_RETURN
     void stdvector_fill_and_return();
     #endif
@@ -315,6 +318,24 @@ void tst_QVector::qrawvector_mutable_read_access()
     }
 }
 
+void tst_QVector::qvector_pop_back()
+{
+    const int c1 = 100000;
+    QVERIFY(N % c1 == 0);
+
+    QVector<int> v;
+    v.resize(N);
+
+    QBENCHMARK {
+        for (int i = 0; i < c1; ++i)
+            v.pop_back();
+        if (v.size() == 0)
+            v.resize(N);
+    }
+}
+
+
+
 #ifdef TEST_RETURN
 extern QVector<double> qrawvector_fill_and_return_helper();
 
@@ -356,6 +377,22 @@ void tst_QVector::stdvector_mutable_read_access()
     }
 }
 
+void tst_QVector::stdvector_pop_back()
+{
+    const int c1 = 100000;
+    QVERIFY(N % c1 == 0);
+
+    std::vector<int> v;
+    v.resize(N);
+
+    QBENCHMARK {
+        for (int i = 0; i < c1; ++i)
+            v.pop_back();
+        if (v.size() == 0)
+            v.resize(N);
+    }
+}
+
 #ifdef TEST_RETURN
 extern std::vector<double> stdvector_fill_and_return_helper();
 
-- 
cgit v1.2.3