Enable Local CSE by default

src/IceDefs.h

 //===- subzero/src/IceDefs.h - Common Subzero declarations ------*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 290 matching lines @@
   /// live-out variables for each block. Identifies and deletes dead
   /// instructions (primarily stores).
   Liveness_Basic,
 
   /// In addition to Liveness_Basic, also calculate the complete live range for
   /// each variable in a form suitable for interference calculation and register
   /// allocation.
   Liveness_Intervals
 };
 
+enum class LCSEOptions {

[Jim Stichnoth, 2016/07/29 14:49:02]

Bikeshed: For consistency with these other enums, I would use "enum" instead of
"enum class", and then pick a "unique" short prefix for the enum values.  E.g.:

enum LcseOptions {
  LCSE_Disabled,
  LCSE_EnabledSSA,
  LCSE_EnabledNoSSA
};

I agree though that "enum class" is a cleaner way to deal with the global
namespace pollution.  This is probably a legacy of pre-C++11 code.

[manasijm, 2016/08/01 17:39:24]

Done.

+  Disabled,
+  EnabledSSA,  // Default Mode, assumes SSA.
+  EnabledNoSSA // Does not assume SSA, to be enabled if CSE is done later.
+};
+
 enum RegAllocKind {
   RAK_Unknown,
   RAK_Global,       /// full, global register allocation
   RAK_SecondChance, /// second-chance bin-packing after full regalloc attempt
   RAK_Phi,          /// infinite-weight Variables with active spilling/filling
   RAK_InfOnly       /// allocation only for infinite-weight Variables
 };
 
 enum VerboseItem {
   IceV_None = 0,
@@ skipping 113 matching lines @@
   RPE_PooledConstantReordering,
   RPE_RegAllocRandomization,
   RPE_num
 };
 
 using RelocOffsetArray = llvm::SmallVector<class RelocOffset *, 4>;
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICEDEFS_H