gpu-compute: "<random>" -> "base/random.hh" in testers/gpu... (#140)

In "src/cpu/testers/gpu_ruby_test" a random number generator was used.
This was using the CPP "<random>" library. This patch changes it to the
gem5 random class (that declared in "base/random.hh").

In addition to this, undeterministic behavior has been removed. Via
"protocol_tester.cc" the RNG is either seeded with a seed specified by
the user, or goes with the gem5 default seed. This ensures reproducable
runs. Prior to this patch the RNG was seeded with `time(NULL)`. This
made finding faults difficult.

This, at least partially, addresses Issue #138

Change-Id: Ia8e9f7b87e91323f828e0b7f6c3906c0c5793b2c

src/cpu/testers/gpu_ruby_test/ProtocolTester.py

@@ -73,7 +73,7 @@ class ProtocolTester(ClockedObject):
     random_seed = Param.Int(
         0,
         "Random seed number. Default value (0) means \
-                                using runtime-specific value.",
+                                using base/random.hh without seed.",
     )
     log_file = Param.String("Log file's name")
     system = Param.System(Parent.any, "System we belong to")

src/cpu/testers/gpu_ruby_test/address_manager.cc

@@ -33,7 +33,6 @@
 
 #include <algorithm>
 #include <climits>
-#include <random>
 
 #include "base/intmath.hh"
 #include "base/logging.hh"
@@ -101,7 +100,8 @@ AddressManager::getAddress(Location loc)
 AddressManager::Location
 AddressManager::getAtomicLoc()
 {
-    Location ret_atomic_loc = random() % numAtomicLocs;
+    Location ret_atomic_loc = \
+        random_mt.random<unsigned long>() % numAtomicLocs;
     atomicStructs[ret_atomic_loc]->startLocSelection();
     return ret_atomic_loc;
 }
@@ -206,7 +206,9 @@ AddressManager::AtomicStruct::getLoadLoc()
         // we can pick any location btw
         // locArray [firstMark : arraySize-1]
         int range_size = arraySize - firstMark;
-        Location ret_loc = locArray[firstMark + random() % range_size];
+        Location ret_loc = locArray[
+                firstMark + random_mt.random<unsigned int>() % range_size
+        ];
 
         // update loadStoreMap
         LdStMap::iterator it = loadStoreMap.find(ret_loc);
@@ -238,7 +240,9 @@ AddressManager::AtomicStruct::getStoreLoc()
     } else {
         // we can pick any location btw [firstMark : secondMark-1]
         int range_size = secondMark - firstMark;
-        Location ret_loc = locArray[firstMark + random() % range_size];
+        Location ret_loc = locArray[
+            firstMark + random_mt.random<unsigned int>() % range_size
+        ];
 
         // update loadStoreMap
         LdStMap::iterator it = loadStoreMap.find(ret_loc);

src/cpu/testers/gpu_ruby_test/episode.cc

@@ -34,6 +34,7 @@
 #include <fstream>
 #include <unordered_set>
 
+#include "base/random.hh"
 #include "cpu/testers/gpu_ruby_test/protocol_tester.hh"
 #include "cpu/testers/gpu_ruby_test/tester_thread.hh"
 
@@ -100,7 +101,7 @@ Episode::initActions()
     int num_loads = numLoads;
     int num_stores = numStores;
     while ((num_loads + num_stores) > 0) {
-        switch (random() % 2) {
+        switch (random_mt.random<unsigned int>() % 2) {
             case 0: // Load
                 if (num_loads > 0) {
                     actions.push_back(new Action(Action::Type::LOAD,

src/cpu/testers/gpu_ruby_test/protocol_tester.cc

@@ -34,8 +34,8 @@
 #include <algorithm>
 #include <ctime>
 #include <fstream>
-#include <random>
 
+#include "base/random.hh"
 #include "cpu/testers/gpu_ruby_test/cpu_thread.hh"
 #include "cpu/testers/gpu_ruby_test/dma_thread.hh"
 #include "cpu/testers/gpu_ruby_test/gpu_wavefront.hh"
@@ -141,11 +141,20 @@ ProtocolTester::ProtocolTester(const Params &p)
 
     sentExitSignal = false;
 
-    // set random seed number
+    // set random seed number, if specified.
+    // Note: random_m5 will use a fixed key if random_seed is not set.
+    // This ensures a reproducable.
     if (p.random_seed != 0) {
-        srand(p.random_seed);
+        random_mt.init(p.random_seed);
     } else {
-        srand(time(NULL));
+        warn(
+            "If `random_seed == 0` (or `random_seed` is unset) "
+            "ProtocolTester does not seed the RNG. This will NOT result in "
+            "the RNG generating different results each run. In this case the "
+            "RNG is seeded by a default value. This differs from behavior in "
+            "previous versions of gem5. Setting `random_seed` to a non-zero "
+            "value is strongly recommended."
+        );
     }
 
     actionCount = 0;

src/cpu/testers/gpu_ruby_test/tester_thread.cc

@@ -33,6 +33,7 @@
 
 #include <fstream>
 
+#include "base/random.hh"
 #include "debug/ProtocolTest.hh"
 
 namespace gem5
@@ -144,7 +145,8 @@ TesterThread::attachTesterThreadToPorts(ProtocolTester *_tester,
 void
 TesterThread::issueNewEpisode()
 {
-    int num_reg_loads = random() % tester->getEpisodeLength();
+    int num_reg_loads = \
+        random_mt.random<unsigned int>() % tester->getEpisodeLength();
     int num_reg_stores = tester->getEpisodeLength() - num_reg_loads;
 
     // create a new episode