Selectively invert ICMP operands for better address optimization

src/IceInst.cpp

Index: src/IceInst.cpp
diff --git a/src/IceInst.cpp b/src/IceInst.cpp
index f9cfdddf60c13b41771fd4a9fa80dd6d46edd2db..e869a77f903180eef7b9d330d9eb8dbf1e18dc3a 100644
--- a/src/IceInst.cpp
+++ b/src/IceInst.cpp
@@ -1085,6 +1085,43 @@ void InstTarget::dump(const Cfg *Func) const {
 InstBreakpoint::InstBreakpoint(Cfg *Func)
     : InstHighLevel(Func, Inst::Breakpoint, 0, nullptr) {}
 
+void InstIcmp::invert() {
+  switch (Condition) {
+  case Eq:

[Jim Stichnoth, 2016/07/08 11:45:46]

I think this would be cleaner if you encode the invert values in the
ICEINSTICMP_TABLE x-macro table.

You could probably add it to InstIcmpAttributes[].

[manasijm, 2016/07/08 18:11:40]

Done.

+    break;
+  case Ne:
+    break;
+  case Sge:
+    Condition = Sle;
+    break;
+  case Sgt:
+    Condition = Slt;
+    break;
+  case Sle:
+    Condition = Sge;
+    break;
+  case Slt:
+    Condition = Sgt;
+    break;
+  case Uge:
+    Condition = Ule;
+    break;
+  case Ugt:
+    Condition = Ult;
+    break;
+  case Ule:
+    Condition = Uge;
+    break;
+  case Ult:
+    Condition = Ugt;
+    break;
+  default:
+    return;
+  }
+  auto *TempOp = getSrc(0);
+  replaceSource(0, getSrc(1));
+  replaceSource(1, TempOp);
+}
 bool checkForRedundantAssign(const Variable *Dest, const Operand *Source) {
   const auto *SrcVar = llvm::dyn_cast<const Variable>(Source);
   if (!SrcVar)