Add constant blinding/pooling option for X8632 code translation

src/IceOperand.cpp

Index: src/IceOperand.cpp
diff --git a/src/IceOperand.cpp b/src/IceOperand.cpp
index 2d2c8cf2c3276fbf3ce89d28d116a74cdca3f54b..e053b9a6ee5f8f5b7f2f2c8aa46b638cca11b3d9 100644
--- a/src/IceOperand.cpp
+++ b/src/IceOperand.cpp
@@ -92,11 +92,11 @@ bool LiveRange::overlapsInst(InstNumberT OtherBegin, bool UseTrimmed) const {
     }
   }
 #if 0
-  // An equivalent but less inefficient implementation:
-  LiveRange Temp;
-  Temp.addSegment(OtherBegin, OtherBegin + 1);
-  bool Validation = overlaps(Temp);
-  assert(Result == Validation);
+		// An equivalent but less inefficient implementation:
+		LiveRange Temp;
+		Temp.addSegment(OtherBegin, OtherBegin + 1);
+		bool Validation = overlaps(Temp);
+		assert(Result == Validation);
 #endif

[JF, 2015/06/17 11:29:18]

`#if 0` and tabs are sad. Could you make this a comment, if it's useful to keep?

[qining, 2015/06/17 18:20:36]

Sorry for the unnecessary tabs. I will remove them. But I'm not so sure the
purpose of this '#if 0' here.

[Jim Stichnoth, 2015/06/19 16:51:02]

Let's keep the #if code.  This was meant to give a much clearer documentation of
the semantics, and validate that the more complex optimized implementation gives
the same result.  But it's expensive enough that I never want it on except in
emergencies.

   return Result;
 }
@@ -491,4 +491,26 @@ Ostream &operator<<(Ostream &Str, const RegWeight &W) {
   return Str;
 }
 
+// =========== Immediate Randomization and Pooling routines ==============
+// Immediates 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 = 0x1;

[qining, 2015/06/17 04:28:55]

The THRESHOLD is set to 0x1.

[JF, 2015/06/17 11:29:18]

This isn't use by other files? It's currently exported to them, and could cause
ODR (unlikely given the name). It should be static per LLVM's coding convention
(C++ usually prefers anonymous namespace, but not LLVM).

[qining, 2015/06/17 18:20:36]

Yes, you are right, I should confine this to a smaller scope. It can be either a
static constant or a local constant in the shouldBeRandomizeOrPooled() method
below.

+
+// Specialization of the template member function for ConstantInteger32
+template <>
+bool ConstantInteger32::shouldBeRandomizedOrPooled(const GlobalContext *Ctx) {
+  if (Ctx->getFlags().getRandomizeAndPoolImmediatesOption() == RPI_None)
+    return false;
+  if (getType() != IceType_i32 && getType() != IceType_i16 &&
+      getType() != IceType_i8)

[qining, 2015/06/17 04:28:55]

Consider i8, 16 constant integers.

+    return false;
+  // if(getType() != IceType_i32)  return false;
+  // The Following checks if the signed representation of Value is between
+  // -THRESHOLD/2 and +THRESHOLD/2
+  bool largerThanThreshold =
+      X86_INT_IMMEDIATE_RANDOMIZATION_THRESHOLD / 2 + Value >=
+      X86_INT_IMMEDIATE_RANDOMIZATION_THRESHOLD;
+  return largerThanThreshold;
+}
+
 } // end of namespace Ice