Enable Local CSE by default

src/IceClFlags.def

 //===- subzero/src/IceClFlags.def - Cl Flags for translation ----*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 122 matching lines @@
   X(DumpStrings, bool, dev_opt_flag,                                           \
     "dump-strings",                                                            \
     cl::desc("Dump string pools during compilation"),                          \
     cl::init(false))                                                           \
                                                                                \
   X(EnableBlockProfile, bool, dev_opt_flag, "enable-block-profile",            \
     cl::desc("Instrument basic blocks, and output profiling "                  \
              "information to stdout at the end of program execution."),        \
     cl::init(false))                                                           \
                                                                                \
-  X(EnableExperimental, bool, dev_opt_flag, "enable-experimental",             \
-    cl::desc("Enable Optimizations not yet part of O2"),                       \
+  X(LocalCSE, bool, dev_opt_flag, "lcse",                                      \

[John, 2016/07/28 14:21:50]

nit: instead of two bool flags (lcse, lcse-no-ssa), I would suggest using a
single, enum flag (e.g., -target). I would name the flag cse, and the values,
{no, yes, yes-no-assume-cse)

+    cl::desc("Local Common Subexpression elimination"),                        \
+    cl::init(true))                                                            \
+                                                                               \
+  X(LocalCSENoSSA, bool, dev_opt_flag, "lcse-no-ssa",                          \
+    cl::desc("Do not assume SSA for lcse"),                                    \
     cl::init(false))                                                           \
                                                                                \
   X(EnablePhiEdgeSplit, bool, dev_opt_flag, "phi-edge-split",                  \
     cl::desc("Enable edge splitting for Phi lowering"), cl::init(true))        \
                                                                                \
   X(EnableShortCircuit, bool, dev_opt_flag, "enable-sc",                       \
     cl::desc("Split Nodes for short circuit evaluation"), cl::init(false))     \
                                                                                \
   X(ExcludedRegisters, std::string, dev_list_flag, "reg-exclude",              \
     cl::CommaSeparated, cl::desc("Don't use specified registers"))             \
@@ skipping 22 matching lines @@
   X(KeepDeletedInsts, bool, dev_opt_flag, "keep-deleted-insts",                \
     cl::desc("Retain deleted instructions in the Cfg"),                        \
     cl::init(Ice::BuildDefs::dump()))                                          \
                                                                                \
   X(LLVMVerboseErrors, bool, dev_opt_flag, "verbose-llvm-parse-errors",        \
     cl::desc("Print out more descriptive PNaCl bitcode parse errors when "     \
              "building LLVM IR first"),                                        \
     cl::init(false))                                                           \
                                                                                \
    X(LocalCseMaxIterations, int, dev_opt_flag, "lcse-max-iters",               \
-    cl::desc("Number of times local-cse is run on a block"), cl::init(2))      \
+    cl::desc("Number of times local-cse is run on a block"), cl::init(1))      \
                                                                                \
   X(LoopInvariantCodeMotion, bool, dev_opt_flag, "licm",                       \
     cl::desc("Hoist loop invariant arithmetic operations"), cl::init(false))   \
                                                                                \
   X(LogFilename, std::string, dev_opt_flag, "log",                             \
     cl::desc("Set log filename"), cl::init("-"), cl::value_desc("filename"))   \
                                                                                \
   X(MaxNopsPerInstruction, int, dev_opt_flag, "max-nops-per-instruction",      \
     cl::desc("Max number of nops to insert per instruction"), cl::init(1))     \
                                                                                \
@@ skipping 169 matching lines @@
                                                                                \
   X(WasmBoundsCheck, bool, dev_opt_flag, "wasm-bounds-check",                  \
     cl::desc("Add bounds checking code in WASM frontend"),                     \
     cl::init(true))
 
 //#define X(Name, Type, ClType, ...)
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICECLFLAGS_DEF