CannotBeOrderedLessThanZero: add some missing cases

[escha]

Summary

Per the title.

[arsenm]

Needs tests

[escha]

Added test cases and fixed a small error.

[spatel]

test/Transforms/InstSimplify/floating-point-compare.ll

72–80 ↗

(On Diff #44388)

This test already works via ThreadCmpOverSelect(). Is there some other way to expose this case?

[escha]

Fixed a test case to no longer fall victim to an unrelated optimization.

[spatel]

LGTM.

lib/Analysis/ValueTracking.cpp

   case Instruction::FRem:
     return CannotBeOrderedLessThanZero(I->getOperand(0), Depth+1) &&
            CannotBeOrderedLessThanZero(I->getOperand(1), Depth+1);
+  case Instruction::Select:
+    return CannotBeOrderedLessThanZero(I->getOperand(1), Depth+1) &&
+           CannotBeOrderedLessThanZero(I->getOperand(2), Depth+1);
   case Instruction::FPExt:
   case Instruction::FPTrunc:
+  case Instruction::UIToFP:
     // Widening/narrowing never change sign.
     return CannotBeOrderedLessThanZero(I->getOperand(0), Depth+1);
   case Instruction::Call: 
     if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) 
       switch (II->getIntrinsicID()) {
       default: break;
+      case Intrinsic::maxnum:
+        return CannotBeOrderedLessThanZero(I->getOperand(0), Depth+1) ||
+               CannotBeOrderedLessThanZero(I->getOperand(1), Depth+1);
+      case Intrinsic::minnum:
+        return CannotBeOrderedLessThanZero(I->getOperand(0), Depth+1) &&
+               CannotBeOrderedLessThanZero(I->getOperand(1), Depth+1);
       case Intrinsic::exp:
       case Intrinsic::exp2:
       case Intrinsic::fabs: