Okay

Author: AZero13

llvm/lib/Target/ARM/ARMISelLowering.cpp

@@ -4839,23 +4839,26 @@ static bool isFloatingPointZero(SDValue Op) {
   return false;
 }
 
-// TODO: This is copied from AArch64TargetLowering.cpp, which only has
-// ands, subs, and adds affecting flags. In ARM, we have more than that, so this
-// should be expanded to cover all the cases where we can adjust the condition
-// code to zero.
 static bool shouldBeAdjustedToZero(SDValue LHS, APInt C, ISD::CondCode &CC) {
-  // Special case where we can use pl or mi instead of lt or ge.
-  // Any instruction that sets flags can be optimized to use mi or pl
-  // this way.
+  // TODO: Can we know ahead of time if we can use a MOVS?
+  switch (LHS.getOpcode()) {
+  case ISD::AND:
+  case ISD::OR:
+  case ISD::XOR:
+  case ISD::ADD:
+  case ISD::SUB:
+  case ISD::MUL:
+    // In ARM, almost every instruction has a variant that sets flags.
+    break;
+  default:
+    return false;
+  }
+
   if (C.isAllOnes() && (CC == ISD::SETLE || CC == ISD::SETGT)) {
     CC = (CC == ISD::SETLE) ? ISD::SETLT : ISD::SETGE;
     return true;
   }
 
-  // TODO: Cover all cases where a comparison with 0 would be profitable...
-  if (LHS.getOpcode() != ISD::AND)
-    return false;
-
   if (C.isOne() && (CC == ISD::SETLT || CC == ISD::SETGE)) {
     CC = (CC == ISD::SETLT) ? ISD::SETLE : ISD::SETGT;
     return true;