Subzero: Print memory usage info when dumping.

Adds "-verbose mem" to enable printing the amount of CfgLocalAllocator memory allocated, each time Cfg::dump() is called.

"-verbose mem,status" is a good way to get summary info.

BUG= none
R=kschimpf@google.com

Review URL: https://codereview.chromium.org/1743043002 .
diff --git a/src/IceCfg.cpp b/src/IceCfg.cpp
index 480893a..5c51ae6 100644
--- a/src/IceCfg.cpp
+++ b/src/IceCfg.cpp
@@ -203,8 +203,10 @@
       FunctionTimer.reset(new TimerMarker(
           getContext()->getTimerID(GlobalContext::TSK_Funcs, Name),
           getContext(), GlobalContext::TSK_Funcs));
-    if (isVerbose(IceV_Status))
-      getContext()->getStrDump() << ">>>Translating " << Name << "\n";
+    if (isVerbose(IceV_Status)) {
+      getContext()->getStrDump() << ">>>Translating "
+                                 << getFunctionNameAndSize() << "\n";
+    }
   }
   TimerMarker T(TimerStack::TT_translate, this);
 
@@ -1084,6 +1086,12 @@
   Ostream &Str = Ctx->getStrDump();
   if (!Message.empty())
     Str << "================ " << Message << " ================\n";
+  if (isVerbose(IceV_Mem)) {
+    constexpr size_t OneMB = 1024 * 1024;
+    Str << "Memory size = "
+        << (CfgLocalAllocator<int>().current()->getTotalMemory() / OneMB)
+        << " MB\n";
+  }
   setCurrentNode(getEntryNode());
   // Print function name+args
   if (isVerbose(IceV_Instructions)) {