[NFC][ValueTracking] Remove calls to computeKnownBits for non-intrinsic CallInsts in isKnownNonZeroFromOperator

[0xdc03]

Summary

For non-intrinsic CallInsts, computeKnownBits only handles range
metadata and checking getReturnedArgOperand(). Both of these are now
handled in isKnownNonZero, so there is no need to fall through to
a call to computeKnownBits anymore.

[0xdc03]

llvm/lib/Analysis/ValueTracking.cpp

2734

I suppose this can also be

} else if (const Value *RV = cast<CallBase>(I)->getReturnedArgOperand();
           RV && isKnownNonZero(RV, Depth, Q))
    return true;

[nikic]

LG

llvm/lib/Analysis/ValueTracking.cpp

static bool isKnownNonZeroFromOperator(const Operator *I,
   case Instruction::Call:
   case Instruction::Invoke:
     if (I->getType()->isPointerTy()) {
       const auto *Call = cast<CallBase>(I);
       if (Call->isReturnNonNull())
         return true;
       if (const auto *RP = getArgumentAliasingToReturnedPointer(Call, true))
         return isKnownNonZero(RP, Depth, Q);
+    } else if (const Value *RV = cast<CallBase>(I)->getReturnedArgOperand()) {
+      if (isKnownNonZero(RV, Depth, Q))
+        return true;
     }
 
     if (auto *II = dyn_cast<IntrinsicInst>(I)) {
       switch (II->getIntrinsicID()) {
       case Intrinsic::sshl_sat:
       case Intrinsic::ushl_sat:
       case Intrinsic::abs:
       case Intrinsic::bitreverse:
if (auto *II = dyn_cast<IntrinsicInst>(I)) {
         if (II->getArgOperand(0) == II->getArgOperand(1))
           return isKnownNonZero(II->getArgOperand(0), DemandedElts, Depth, Q);
         break;
       case Intrinsic::vscale:
         return true;
       default:
         break;
       }
-    }
       break;
     }
 
+    return false;
+  }
+
   KnownBits Known(BitWidth);
   computeKnownBits(I, DemandedElts, Known, Depth, Q);
   return Known.One != 0;
 }
 
 /// Return true if the given value is known to be non-zero when defined. For
 /// vectors, return true if every demanded element is known to be non-zero when
 /// defined. For pointers, if the context instruction and dominator tree are