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[ValueTracking] Remove handling for BitWidth being 0 in ComputeSignBit and isKnownNonZero.

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I don't believe its possible to have non-zero values here since DataLayout became required. The APInt constructor inside of the KnownBits object will assert if this ever happens.

llvm-svn: 302089
This commit is contained in:
Craig Topper 2017-05-03 22:25:19 +00:00
parent 3ae9fc9012
commit 621facfb33
1 changed files with 5 additions and 12 deletions
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17
lib/Analysis/ValueTracking.cpp
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@ -59,8 +59,8 @@ static cl::opt<bool>
DontImproveNonNegativePhiBits("dont-improve-non-negative-phi-bits",
cl::Hidden, cl::init(true));
/// Returns the bitwidth of the given scalar or pointer type (if unknown returns
/// 0). For vector types, returns the element type's bitwidth.
/// Returns the bitwidth of the given scalar or pointer type. For vector types,
/// returns the element type's bitwidth.
static unsigned getBitWidth(Type *Ty, const DataLayout &DL) {
if (unsigned BitWidth = Ty->getScalarSizeInBits())
return BitWidth;
@ -1586,13 +1586,7 @@ void computeKnownBits(const Value *V, KnownBits &Known, unsigned Depth,
/// Convenience wrapper around computeKnownBits.
void ComputeSignBit(const Value *V, bool &KnownZero, bool &KnownOne,
unsigned Depth, const Query &Q) {
unsigned BitWidth = getBitWidth(V->getType(), Q.DL);
if (!BitWidth) {
KnownZero = false;
KnownOne = false;
return;
}
KnownBits Bits(BitWidth);
KnownBits Bits(getBitWidth(V->getType(), Q.DL));
computeKnownBits(V, Bits, Depth, Q);
KnownOne = Bits.isNegative();
KnownZero = Bits.isNonNegative();
@ -1843,7 +1837,7 @@ bool isKnownNonZero(const Value *V, unsigned Depth, const Query &Q) {
// shl X, Y != 0 if X is odd. Note that the value of the shift is undefined
// if the lowest bit is shifted off the end.
if (BitWidth && match(V, m_Shl(m_Value(X), m_Value(Y)))) {
if (match(V, m_Shl(m_Value(X), m_Value(Y)))) {
// shl nuw can't remove any non-zero bits.
const OverflowingBinaryOperator *BO = cast<OverflowingBinaryOperator>(V);
if (BO->hasNoUnsignedWrap())
@ -1902,7 +1896,7 @@ bool isKnownNonZero(const Value *V, unsigned Depth, const Query &Q) {
// If X and Y are both negative (as signed values) then their sum is not
// zero unless both X and Y equal INT_MIN.
if (BitWidth && XKnownNegative && YKnownNegative) {
if (XKnownNegative && YKnownNegative) {
KnownBits Known(BitWidth);
APInt Mask = APInt::getSignedMaxValue(BitWidth);
// The sign bit of X is set. If some other bit is set then X is not equal
@ -1967,7 +1961,6 @@ bool isKnownNonZero(const Value *V, unsigned Depth, const Query &Q) {
return true;
}
if (!BitWidth) return false;
KnownBits Known(BitWidth);
computeKnownBits(V, Known, Depth, Q);
return Known.One != 0;