[TargetLowering] Fix what look like copy/paste mistakes in compare with infinity handling SimplifySetCC.

[craig.topper]

Summary

I expect that the isCondCodeLegal checks should match that CC of
the node that we're going to create.

[spatel]

Looks like a good fix, but I think it would be better to use switch/case on these to reduce the duplication. Something like (make sure this matches the existing logic):

bool IsNegInf = CFP->getValueAPF().isNegative();
ISD::CondCode NewCond;
switch (Cond) {
// X == -Inf --> X <= -Inf or X == Inf --> X >= Inf
case ISD::SETOEQ: NewCond = IsNegInf ? ISD::SETOLE : ISD::SETOGE; break;
case ISD::SETUEQ: NewCond = IsNegInf ? ISD::SETULE : ISD::SETUGE; break;
// X != -Inf --> X > -Inf or X != Inf --> X < Inf
case ISD::SETONE: NewCond = IsNegInf ? ISD::SETOGT : ISD::SETOLT; break;
case ISD::SETUNE: NewCond = IsNegInf ? ISD::SETUGT : ISD::SETULT; break;
default: NewCond = ISD::SETCC_INVALID; break;
}
if (NewCond != ISD::SETCC_INVALID &&
    isCondCodeLegal(NewCond, N0.getSimpleValueType()))
  return DAG.getSetCC(dl, VT, N0, N1, NewCond);

[craig.topper]

Rewrite using a switch

[spatel]

LGTM

[RKSimon]

Committed in rGadc69729ec85aea0a32e7bdf24e91e8f6178a38b

llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp

if (!isa<ConstantFPSDNode>(N0) && isa<ConstantFPSDNode>(N1)) {
 
     // If the condition is not legal, see if we can find an equivalent one
     // which is legal.
     if (!isCondCodeLegal(Cond, N0.getSimpleValueType())) {
       // If the comparison was an awkward floating-point == or != and one of
       // the comparison operands is infinity or negative infinity, convert the
       // condition to a less-awkward <= or >=.
       if (CFP->getValueAPF().isInfinity()) {
-        if (CFP->getValueAPF().isNegative()) {
-          if (Cond == ISD::SETOEQ &&
-              isCondCodeLegal(ISD::SETOLE, N0.getSimpleValueType()))
-            return DAG.getSetCC(dl, VT, N0, N1, ISD::SETOLE);
-          if (Cond == ISD::SETUEQ &&
-              isCondCodeLegal(ISD::SETOLE, N0.getSimpleValueType()))
-            return DAG.getSetCC(dl, VT, N0, N1, ISD::SETULE);
-          if (Cond == ISD::SETUNE &&
-              isCondCodeLegal(ISD::SETUGT, N0.getSimpleValueType()))
-            return DAG.getSetCC(dl, VT, N0, N1, ISD::SETUGT);
-          if (Cond == ISD::SETONE &&
-              isCondCodeLegal(ISD::SETUGT, N0.getSimpleValueType()))
-            return DAG.getSetCC(dl, VT, N0, N1, ISD::SETOGT);
-        } else {
-          if (Cond == ISD::SETOEQ &&
-              isCondCodeLegal(ISD::SETOGE, N0.getSimpleValueType()))
-            return DAG.getSetCC(dl, VT, N0, N1, ISD::SETOGE);
-          if (Cond == ISD::SETUEQ &&
-              isCondCodeLegal(ISD::SETOGE, N0.getSimpleValueType()))
-            return DAG.getSetCC(dl, VT, N0, N1, ISD::SETUGE);
-          if (Cond == ISD::SETUNE &&
-              isCondCodeLegal(ISD::SETULT, N0.getSimpleValueType()))
-            return DAG.getSetCC(dl, VT, N0, N1, ISD::SETULT);
-          if (Cond == ISD::SETONE &&
-              isCondCodeLegal(ISD::SETULT, N0.getSimpleValueType()))
-            return DAG.getSetCC(dl, VT, N0, N1, ISD::SETOLT);
+        bool IsNegInf = CFP->getValueAPF().isNegative();
+        ISD::CondCode NewCond = ISD::SETCC_INVALID;
+        switch (Cond) {
+        case ISD::SETOEQ: NewCond = IsNegInf ? ISD::SETOLE : ISD::SETOGE; break;
+        case ISD::SETUEQ: NewCond = IsNegInf ? ISD::SETULE : ISD::SETUGE; break;
+        case ISD::SETUNE: NewCond = IsNegInf ? ISD::SETUGT : ISD::SETULT; break;
+        case ISD::SETONE: NewCond = IsNegInf ? ISD::SETOGT : ISD::SETOLT; break;
         }
+        if (NewCond != ISD::SETCC_INVALID &&
+            isCondCodeLegal(NewCond, N0.getSimpleValueType()))
+          return DAG.getSetCC(dl, VT, N0, N1, NewCond);
       }
     }
   }
 
   if (N0 == N1) {
     // The sext(setcc()) => setcc() optimization relies on the appropriate
     // constant being emitted.
     assert(!N0.getValueType().isInteger() &&