[ValueTracking] Split isNonZero(mul) logic to a helper; NFC

Author: goldsteinn

llvm/lib/Analysis/ValueTracking.cpp

@@ -2463,6 +2463,34 @@ static bool isNonZeroSub(const APInt &DemandedElts, unsigned Depth,
   return ::isKnownNonEqual(X, Y, Depth, Q);
 }
 
+static bool isNonZeroMul(const APInt &DemandedElts, unsigned Depth,
+                         const SimplifyQuery &Q, unsigned BitWidth, Value *X,
+                         Value *Y, bool NSW, bool NUW) {
+  // If X and Y are non-zero then so is X * Y as long as the multiplication
+  // does not overflow.
+  if (NSW || NUW)
+    return isKnownNonZero(X, DemandedElts, Depth, Q) &&
+           isKnownNonZero(Y, DemandedElts, Depth, Q);
+
+  // If either X or Y is odd, then if the other is non-zero the result can't
+  // be zero.
+  KnownBits XKnown = computeKnownBits(X, DemandedElts, Depth, Q);
+  if (XKnown.One[0])
+    return isKnownNonZero(Y, DemandedElts, Depth, Q);
+
+  KnownBits YKnown = computeKnownBits(Y, DemandedElts, Depth, Q);
+  if (YKnown.One[0])
+    return XKnown.isNonZero() || isKnownNonZero(X, DemandedElts, Depth, Q);
+
+  // If there exists any subset of X (sX) and subset of Y (sY) s.t sX * sY is
+  // non-zero, then X * Y is non-zero. We can find sX and sY by just taking
+  // the lowest known One of X and Y. If they are non-zero, the result
+  // must be non-zero. We can check if LSB(X) * LSB(Y) != 0 by doing
+  // X.CountLeadingZeros + Y.CountLeadingZeros < BitWidth.
+  return (XKnown.countMaxTrailingZeros() + YKnown.countMaxTrailingZeros()) <
+         BitWidth;
+}
+
 static bool isNonZeroShift(const Operator *I, const APInt &DemandedElts,
                            unsigned Depth, const SimplifyQuery &Q,
                            const KnownBits &KnownVal) {
@@ -2658,33 +2686,10 @@ static bool isKnownNonZeroFromOperator(const Operator *I,
                         Q.IIQ.hasNoUnsignedWrap(BO));
   }
   case Instruction::Mul: {
-    // If X and Y are non-zero then so is X * Y as long as the multiplication
-    // does not overflow.
     const OverflowingBinaryOperator *BO = cast<OverflowingBinaryOperator>(I);
-    if (Q.IIQ.hasNoSignedWrap(BO) || Q.IIQ.hasNoUnsignedWrap(BO))
-      return isKnownNonZero(I->getOperand(0), DemandedElts, Depth, Q) &&
-             isKnownNonZero(I->getOperand(1), DemandedElts, Depth, Q);
-
-    // If either X or Y is odd, then if the other is non-zero the result can't
-    // be zero.
-    KnownBits XKnown =
-        computeKnownBits(I->getOperand(0), DemandedElts, Depth, Q);
-    if (XKnown.One[0])
-      return isKnownNonZero(I->getOperand(1), DemandedElts, Depth, Q);
-
-    KnownBits YKnown =
-        computeKnownBits(I->getOperand(1), DemandedElts, Depth, Q);
-    if (YKnown.One[0])
-      return XKnown.isNonZero() ||
-             isKnownNonZero(I->getOperand(0), DemandedElts, Depth, Q);
-
-    // If there exists any subset of X (sX) and subset of Y (sY) s.t sX * sY is
-    // non-zero, then X * Y is non-zero. We can find sX and sY by just taking
-    // the lowest known One of X and Y. If they are non-zero, the result
-    // must be non-zero. We can check if LSB(X) * LSB(Y) != 0 by doing
-    // X.CountLeadingZeros + Y.CountLeadingZeros < BitWidth.
-    return (XKnown.countMaxTrailingZeros() + YKnown.countMaxTrailingZeros()) <
-           BitWidth;
+    return isNonZeroMul(DemandedElts, Depth, Q, BitWidth, I->getOperand(0),
+                        I->getOperand(1), Q.IIQ.hasNoSignedWrap(BO),
+                        Q.IIQ.hasNoUnsignedWrap(BO));
   }
   case Instruction::Select: {
     // (C ? X : Y) != 0 if X != 0 and Y != 0.