Add constant blinding/pooling option for X8632 code translation

src/IceOperand.cpp

 //===- subzero/src/IceOperand.cpp - High-level operand 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 Operand class and its target-independent
@@ skipping 473 matching lines @@
 Ostream &operator<<(Ostream &Str, const RegWeight &W) {
   if (!ALLOW_DUMP)
     return Str;
   if (W.getWeight() == RegWeight::Inf)
     Str << "Inf";
   else
     Str << W.getWeight();
   return Str;
 }
 
+// =========== Immediate Radomization and Pooling routines ==============

[Jim Stichnoth, 2015/06/12 23:48:17]

Randomization

[qining, 2015/06/17 04:28:53]

Done.

+// Immediate randomization and pooling threshold, we should not
+// randomize or pool small constants e.g. 2,4 etc.
+const uint32_t X86_INT_IMMEDIATE_RANDOMIZATION_THRESHOLD = 0xffff;
+
+// Specialization of the template member function for ConstantInteger32
+template <>
+bool ConstantInteger32::shouldBeRandomizedOrPooled(const GlobalContext *Ctx) {
+  if (Ctx->getFlags().shouldNotRandomizeOrPoolImmediates() == true)
+    return false;
+  bool typeCorrect = getType() == IceType_i32;

[Jim Stichnoth, 2015/06/12 23:48:17]

Can you just do this?
  if (getType() != IceType_i32)
    return false;

[qining, 2015/06/17 04:28:53]

Done. I've also add IceType_i8, IceType_i16 as valid type for randomization and
pooling.

+  bool largerThanThreshold =
+      X86_INT_IMMEDIATE_RANDOMIZATION_THRESHOLD / 2 + Value >=

[Jim Stichnoth, 2015/06/12 23:48:17]

Could you add a comment explaining that this checks whether the signed
representation of Value is between -threshold/2 and +threshold/2?

(I had to dig into the arcane rules of C++ automatic signed/unsigned conversion
to convince myself of this.)

[qining, 2015/06/17 04:28:53]

Done.

+      X86_INT_IMMEDIATE_RANDOMIZATION_THRESHOLD;
+  return typeCorrect && largerThanThreshold;
+}
+
 } // end of namespace Ice