Selectively invert ICMP operands for better address optimization

src/IceInst.h

Index: src/IceInst.h
diff --git a/src/IceInst.h b/src/IceInst.h
index 029fcc59079c01a76f76b9567d8477ac70331945..dc240596f5ab80aa759729245477d8f62d990003 100644
--- a/src/IceInst.h
+++ b/src/IceInst.h
@@ -538,7 +538,7 @@ class InstIcmp : public InstHighLevel {
 
 public:
   enum ICond {
-#define X(tag, str) tag,
+#define X(tag, inverse, str) tag,
     ICEINSTICMP_TABLE
 #undef X
         _num
@@ -550,6 +550,7 @@ public:
         InstIcmp(Func, Condition, Dest, Source1, Source2);
   }
   ICond getCondition() const { return Condition; }
+  void invertConditionAndSwapOperands();

[Jim Stichnoth, 2016/07/10 13:25:32]

Per my comment in IceInst.def, I would rename this something like
reverseConditionAndOperands().  (If you use "reverse", I think you can omit
"swap" since it seems redundant.)

[manasijm, 2016/07/11 22:27:04]

Done.

   bool isMemoryWrite() const override { return false; }
   void dump(const Cfg *Func) const override;
   static bool classof(const Inst *Instr) { return Instr->getKind() == Icmp; }
@@ -558,7 +559,7 @@ private:
   InstIcmp(Cfg *Func, ICond Condition, Variable *Dest, Operand *Source1,
            Operand *Source2);
 
-  const ICond Condition;
+  ICond Condition;
 };
 
 /// InsertElement instruction.