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..2e449973b7b3eef8bb283eba6748035db7c5dcbe 100644
--- a/src/IceInst.cpp
+++ b/src/IceInst.cpp
@@ -65,9 +65,10 @@ const struct InstFcmpAttributes_ {
 // Using non-anonymous struct so that array_lengthof works.
 const struct InstIcmpAttributes_ {
   const char *DisplayString;
+  InstIcmp::ICond Inverse;
 } InstIcmpAttributes[] = {
-#define X(tag, str)                                                            \
-  { str }                                                                      \
+#define X(tag, inverse, str)                                                   \
+  { str, inverse }                                                             \
   ,
     ICEINSTICMP_TABLE
 #undef X
@@ -1085,6 +1086,12 @@ void InstTarget::dump(const Cfg *Func) const {
 InstBreakpoint::InstBreakpoint(Cfg *Func)
     : InstHighLevel(Func, Inst::Breakpoint, 0, nullptr) {}
 
+void InstIcmp::invertConditionAndSwapOperands() {
+  Condition = InstIcmpAttributes[Condition].Inverse;
+  auto *TempOp = getSrc(0);

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

Since Srcs[] is a protected field that you have access to, how about just:

  std::swap(Srcs[0], Srcs[1]);

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

Done.

+  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)