From 6af3a7df1f42fe2ff1cb32ed5d373ce39691281f Mon Sep 17 00:00:00 2001
From: Giacomo Travaglini <giacomo.travaglini@arm.com>
Date: Mon, 5 Feb 2018 17:08:43 +0000
Subject: [PATCH] sim: Remove _numContexts member in System class

A System object has a _numContexts member variable which represent the
number of ThreadContext registered in the System.  Since this has to
match the size of the ThreadContext vector, this patch removes the
manually cached size. This was usually used as a for-loop index, whereas
we want to enforce the use of range-based loops whenever possible.

Change-Id: I1ba317c0393bcc9c1aeebbb1fc22d7b2bc2cf90c
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/8062
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Brandon Potter <Brandon.Potter@amd.com>
---
 src/arch/arm/kvm/gic.cc      |  8 ++++----
 src/arch/arm/linux/system.cc |  3 +--
 src/sim/system.cc            | 17 +++++++++--------
 src/sim/system.hh            |  7 +------
 4 files changed, 15 insertions(+), 20 deletions(-)

diff --git a/src/arch/arm/kvm/gic.cc b/src/arch/arm/kvm/gic.cc
index 887fa8d697..d2423a6ec9 100644
--- a/src/arch/arm/kvm/gic.cc
+++ b/src/arch/arm/kvm/gic.cc
@@ -305,7 +305,7 @@ void
 MuxingKvmGic::copyBankedDistRange(BaseGicRegisters* from, BaseGicRegisters* to,
                                   Addr daddr, size_t size)
 {
-    for (int ctx = 0; ctx < system._numContexts; ++ctx)
+    for (int ctx = 0; ctx < system.numContexts(); ++ctx)
         for (auto a = daddr; a < daddr + size; a += 4)
             copyDistRegister(from, to, ctx, a);
 }
@@ -314,7 +314,7 @@ void
 MuxingKvmGic::clearBankedDistRange(BaseGicRegisters* to,
                                    Addr daddr, size_t size)
 {
-    for (int ctx = 0; ctx < system._numContexts; ++ctx)
+    for (int ctx = 0; ctx < system.numContexts(); ++ctx)
         for (auto a = daddr; a < daddr + size; a += 4)
             to->writeDistributor(ctx, a, 0xFFFFFFFF);
 }
@@ -345,7 +345,7 @@ MuxingKvmGic::copyGicState(BaseGicRegisters* from, BaseGicRegisters* to)
     // Copy CPU Interface Control Register (CTLR),
     //      Interrupt Priority Mask Register (PMR), and
     //      Binary Point Register (BPR)
-    for (int ctx = 0; ctx < system._numContexts; ++ctx) {
+    for (int ctx = 0; ctx < system.numContexts(); ++ctx) {
         copyCpuRegister(from, to, ctx, GICC_CTLR);
         copyCpuRegister(from, to, ctx, GICC_PMR);
         copyCpuRegister(from, to, ctx, GICC_BPR);
@@ -423,7 +423,7 @@ MuxingKvmGic::fromKvmToPl390()
     // have been shifted by three bits due to its having been emulated by
     // a VGIC with only 5 PMR bits in its VMCR register.  Presently the
     // Linux kernel does not repair this inaccuracy, so we correct it here.
-    for (int cpu = 0; cpu < system._numContexts; ++cpu) {
+    for (int cpu = 0; cpu < system.numContexts(); ++cpu) {
        cpuPriority[cpu] <<= 3;
        assert((cpuPriority[cpu] & ~0xff) == 0);
     }
diff --git a/src/arch/arm/linux/system.cc b/src/arch/arm/linux/system.cc
index 7f06475125..094e4d7a72 100644
--- a/src/arch/arm/linux/system.cc
+++ b/src/arch/arm/linux/system.cc
@@ -250,8 +250,7 @@ LinuxArmSystem::startup()
         std::string task_filename = "tasks.txt";
         taskFile = simout.create(name() + "." + task_filename);
 
-        for (int i = 0; i < _numContexts; i++) {
-            ThreadContext *tc = threadContexts[i];
+        for (const auto tc : threadContexts) {
             uint32_t pid = tc->getCpuPtr()->getPid();
             if (pid != BaseCPU::invldPid) {
                 mapPid(tc, pid);
diff --git a/src/sim/system.cc b/src/sim/system.cc
index ed01e0e64c..38eed1c2ab 100644
--- a/src/sim/system.cc
+++ b/src/sim/system.cc
@@ -47,6 +47,8 @@
 
 #include "sim/system.hh"
 
+#include <algorithm>
+
 #include "arch/remote_gdb.hh"
 #include "arch/utility.hh"
 #include "base/loader/object_file.hh"
@@ -87,7 +89,6 @@ int System::numSystemsRunning = 0;
 
 System::System(Params *p)
     : MemObject(p), _systemPort("system_port", this),
-      _numContexts(0),
       multiThread(p->multi_thread),
       pagePtr(0),
       init_param(p->init_param),
@@ -256,7 +257,6 @@ System::registerThreadContext(ThreadContext *tc, ContextID assigned)
              "Cannot have two CPUs with the same id (%d)\n", id);
 
     threadContexts[id] = tc;
-    _numContexts++;
 
 #if THE_ISA != NULL_ISA
     int port = getRemoteGDBPort();
@@ -287,12 +287,13 @@ System::registerThreadContext(ThreadContext *tc, ContextID assigned)
 int
 System::numRunningContexts()
 {
-    int running = 0;
-    for (int i = 0; i < _numContexts; ++i) {
-        if (threadContexts[i]->status() != ThreadContext::Halted)
-            ++running;
-    }
-    return running;
+    return std::count_if(
+        threadContexts.cbegin(),
+        threadContexts.cend(),
+        [] (ThreadContext* tc) {
+            return tc->status() != ThreadContext::Halted;
+        }
+    );
 }
 
 void
diff --git a/src/sim/system.hh b/src/sim/system.hh
index 5b0c178729..a72f2a762a 100644
--- a/src/sim/system.hh
+++ b/src/sim/system.hh
@@ -196,7 +196,6 @@ class System : public MemObject
 #endif
 
     std::vector<ThreadContext *> threadContexts;
-    int _numContexts;
     const bool multiThread;
 
     ThreadContext *getThreadContext(ContextID tid)
@@ -204,11 +203,7 @@ class System : public MemObject
         return threadContexts[tid];
     }
 
-    int numContexts()
-    {
-        assert(_numContexts == (int)threadContexts.size());
-        return _numContexts;
-    }
+    unsigned numContexts() const { return threadContexts.size(); }
 
     /** Return number of running (non-halted) thread contexts in
      * system.  These threads could be Active or Suspended. */