tests: Add test program for C++ threads

Simple program that spawns threads equal to the number of CPU cores and
has some false sharing for testing coherence protocols.

Change-Id: I5be907fd6fea9a8b8e80b63785d186619be41354
Signed-off-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-on: https://gem5-review.googlesource.com/8901
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>

tests/test-progs/threads/src/Makefile

@@ -0,0 +1,3 @@
+
+../bin/x86/linux/threads: threads.cpp
+	g++ -o ../bin/x86/linux/threads threads.cpp -pthread -std=c++11

tests/test-progs/threads/src/threads.cpp

@@ -0,0 +1,120 @@
+/*
+ * Copyright (c) 2017 Jason Lowe-Power
+* All rights reserved.
+*
+* Redistribution and use in source and binary forms, with or without
+* modification, are permitted provided that the following conditions are
+* met: redistributions of source code must retain the above copyright
+* notice, this list of conditions and the following disclaimer;
+* redistributions in binary form must reproduce the above copyright
+* notice, this list of conditions and the following disclaimer in the
+* documentation and/or other materials provided with the distribution;
+* neither the name of the copyright holders nor the names of its
+* contributors may be used to endorse or promote products derived from
+* this software without specific prior written permission.
+*
+* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*
+* Authors: Jason Lowe-Power
+*/
+
+#include <iostream>
+#include <thread>
+
+using namespace std;
+
+/*
+ * c = a + b
+ */
+void array_add(int *a, int *b, int *c, int tid, int threads, int num_values)
+{
+    for (int i = tid; i < num_values; i += threads) {
+        c[i] = a[i] + b[i];
+    }
+}
+
+
+int main(int argc, char *argv[])
+{
+    unsigned num_values;
+    if (argc == 1) {
+        num_values = 100;
+    } else if (argc == 2) {
+        num_values = atoi(argv[1]);
+        if (num_values <= 0) {
+            cerr << "Usage: " << argv[0] << " [num_values]" << endl;
+            return 1;
+        }
+    } else {
+        cerr << "Usage: " << argv[0] << " [num_values]" << endl;
+        return 1;
+    }
+
+    unsigned cpus = thread::hardware_concurrency();
+
+    cout << "Running on " << cpus << " cores. ";
+    cout << "with " << num_values << " values" << endl;
+
+    int *a, *b, *c;
+    a = new int[num_values];
+    b = new int[num_values];
+    c = new int[num_values];
+
+    if (!(a && b && c)) {
+        cerr << "Allocation error!" << endl;
+        return 2;
+    }
+
+    for (int i = 0; i < num_values; i++) {
+        a[i] = i;
+        b[i] = num_values - i;
+        c[i] = 0;
+    }
+
+    thread **threads = new thread*[cpus];
+
+    // NOTE: -1 is required for this to work in SE mode.
+    for (int i = 0; i < cpus - 1; i++) {
+        threads[i] = new thread(array_add, a, b, c, i, cpus, num_values);
+    }
+    // Execute the last thread with this thread context to appease SE mode
+    array_add(a, b, c, cpus - 1, cpus, num_values);
+
+    cout << "Waiting for other threads to complete" << endl;
+
+    for (int i = 0; i < cpus - 1; i++) {
+        threads[i]->join();
+    }
+
+    delete[] threads;
+
+    cout << "Validating..." << flush;
+
+    int num_valid = 0;
+    for (int i = 0; i < num_values; i++) {
+        if (c[i] == num_values) {
+            num_valid++;
+        } else {
+            cerr << "c[" << i << "] is wrong.";
+            cerr << " Expected " << num_values;
+            cerr << " Got " << c[i] << "." << endl;
+        }
+    }
+
+    if (num_valid == num_values) {
+        cout << "Success!" << endl;
+        return 0;
+    } else {
+        return 2;
+    }
+}