ValueTracking: Teach isKnownNeverInfinity about sqrt

[kpn]

I believe this is correct. I'm looking at n3054 Annex F and it says that sqrt(+inf) returns +inf. But since you are checking that the input cannot be inf it follows that the output cannot be inf.

LGTM

[arsenm]

9a214756517ffb1bee0308942d6a037ab6012a57

llvm/lib/Analysis/ValueTracking.cpp

if (auto *Inst = dyn_cast<Instruction>(V)) {
     }
     default:
       break;
     }
 
     if (const auto *II = dyn_cast<IntrinsicInst>(V)) {
       switch (II->getIntrinsicID()) {
       case Intrinsic::fabs:
+      case Intrinsic::sqrt:
       case Intrinsic::canonicalize:
       case Intrinsic::copysign:
       case Intrinsic::arithmetic_fence:
       case Intrinsic::floor:
       case Intrinsic::ceil:
       case Intrinsic::trunc:
       case Intrinsic::rint:
       case Intrinsic::nearbyint:

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

;
   %cmp = fcmp une double %op, 0x7ff0000000000000
   ret i1 %cmp
 }
 
 declare double @llvm.maximum.f64(double, double)
 
 define i1 @isKnownNeverInfinity_sqrt(double %x) {
 ; CHECK-LABEL: @isKnownNeverInfinity_sqrt(
-; CHECK-NEXT:    [[A:%.*]] = fadd ninf double [[X:%.*]], 1.000000e+00
-; CHECK-NEXT:    [[E:%.*]] = call double @llvm.sqrt.f64(double [[A]])
-; CHECK-NEXT:    [[R:%.*]] = fcmp une double [[E]], 0x7FF0000000000000
-; CHECK-NEXT:    ret i1 [[R]]
+; CHECK-NEXT:    ret i1 true
 ;
   %a = fadd ninf double %x, 1.0
   %e = call double @llvm.sqrt.f64(double %a)
   %r = fcmp une double %e, 0x7ff0000000000000
   ret i1 %r
 }
 
 define i1 @isNotKnownNeverInfinity_sqrt(double %x) {