Subzero: Improve malloc/free behavior.

src/IceCfg.h

@@ -164,7 +164,7 @@ private:
   // order to use a "Recycler" to preserve memory. If we keep all allocation
   // requests from the Cfg exposed via methods, we can always switch the
   // implementation over at a later point.
-  llvm::BumpPtrAllocator Allocator;
+  llvm::BumpPtrAllocatorImpl<llvm::MallocAllocator, 1024 * 1024> Allocator;
 
   GlobalContext *Ctx;
   IceString FunctionName;

src/IceGlobalContext.h

@@ -202,7 +202,7 @@ private:
   Ostream *StrDump; // Stream for dumping / diagnostics
   Ostream *StrEmit; // Stream for code emission
 
-  llvm::BumpPtrAllocator Allocator;
+  llvm::BumpPtrAllocatorImpl<llvm::MallocAllocator, 1024 * 1024> Allocator;
   VerboseMask VMask;
   std::unique_ptr<class ConstantPool> ConstPool;
   Intrinsics IntrinsicsInfo;

src/IceInst.cpp

@@ -250,6 +250,7 @@ InstBr::InstBr(Cfg *Func, CfgNode *Target)
 
 NodeList InstBr::getTerminatorEdges() const {
   NodeList OutEdges;
+  OutEdges.reserve(TargetTrue ? 2 : 1);
   OutEdges.push_back(TargetFalse);
   if (TargetTrue)
     OutEdges.push_back(TargetTrue);
@@ -409,6 +410,7 @@ void InstSwitch::addBranch(SizeT CaseIndex, uint64_t Value, CfgNode *Label) {
 
 NodeList InstSwitch::getTerminatorEdges() const {
   NodeList OutEdges;
+  OutEdges.reserve(NumCases + 1);
   OutEdges.push_back(LabelDefault);
   for (SizeT I = 0; I < NumCases; ++I) {
     OutEdges.push_back(Labels[I]);