Subzero: Use CFG-local arena allocation for relevant containers.

src/IceCfg.cpp

 //===- subzero/src/IceCfg.cpp - Control flow graph implementation ---------===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file implements the Cfg class, including constant pool
 // management.
 //
 //===----------------------------------------------------------------------===//
 
 #include "IceCfg.h"
 #include "IceCfgNode.h"
 #include "IceClFlags.h"
 #include "IceDefs.h"
 #include "IceInst.h"
 #include "IceLiveness.h"
 #include "IceOperand.h"
 #include "IceTargetLowering.h"
 
 namespace Ice {
 
+thread_local const Cfg *Cfg::CurrentCfg = NULL;
+
+ArenaAllocator *getCurrentCfgAllocator() {
+  return Cfg::getCurrentCfgAllocator();
+}
+
 Cfg::Cfg(GlobalContext *Ctx)
     : Ctx(Ctx), FunctionName(""), ReturnType(IceType_void),
       IsInternalLinkage(false), HasError(false), FocusedTiming(false),
       ErrorMessage(""), Entry(NULL), NextInstNumber(Inst::NumberInitial),
-      Live(nullptr),
+      Allocator(new ArenaAllocator()), Live(nullptr),
       Target(TargetLowering::createLowering(Ctx->getTargetArch(), this)),
       VMetadata(new VariablesMetadata(this)),
       TargetAssembler(
           TargetLowering::createAssembler(Ctx->getTargetArch(), this)),
       CurrentNode(NULL) {
   assert(!Ctx->isIRGenerationDisabled() &&
          "Attempt to build cfg when IR generation disabled");
 }
 
-Cfg::~Cfg() {}
+Cfg::~Cfg() {
+  // TODO(stichnot,kschimpf): Set CurrentCfg=NULL in the dtor for
+  // safety.  This can't be done currently because the translator
+  // manages the Cfg by creating a new Cfg (which sets CurrentCfg to
+  // the new value), then deleting the old Cfg (which would then reset
+  // CurrentCfg to NULL).
+}
 
 void Cfg::setError(const IceString &Message) {
   HasError = true;
   ErrorMessage = Message;
   Ctx->getStrDump() << "ICE translation error: " << ErrorMessage << "\n";
 }
 
 CfgNode *Cfg::makeNode() {
   SizeT LabelIndex = Nodes.size();
   CfgNode *Node = CfgNode::create(this, LabelIndex);
@@ skipping 458 matching lines @@
     }
   }
   // Print each basic block
   for (CfgNode *Node : Nodes)
     Node->dump(this);
   if (getContext()->isVerbose(IceV_Instructions))
     Str << "}\n";
 }
 
 } // end of namespace Ice