/* Assumed in hexadecimal significand parsing, and conversion to
hexadecimal strings. */
-#define COMPILE_TIME_ASSERT(cond) extern int CTAssert[(cond) ? 1 : -1]
-COMPILE_TIME_ASSERT(integerPartWidth % 4 == 0);
+static_assert(integerPartWidth % 4 == 0, "Part width must be divisible by 4!");
namespace llvm {
{
StringRef::iterator p = begin;
*dot = end;
- while (*p == '0' && p != end)
+ while (p != end && *p == '0')
p++;
- if (*p == '.') {
+ if (p != end && *p == '.') {
*dot = p++;
assert(end - begin != 1 && "Significand has no digits");
- while (*p == '0' && p != end)
+ while (p != end && *p == '0')
p++;
}
else if (digitValue < 8 && digitValue > 0)
return lfLessThanHalf;
- /* Otherwise we need to find the first non-zero digit. */
- while (*p == '0')
+ // Otherwise we need to find the first non-zero digit.
+ while (p != end && (*p == '0' || *p == '.'))
p++;
assert(p != end && "Invalid trailing hexadecimal fraction!");
return *this;
}
+APFloat &
+APFloat::operator=(APFloat &&rhs) {
+ freeSignificand();
+
+ semantics = rhs.semantics;
+ significand = rhs.significand;
+ exponent = rhs.exponent;
+ category = rhs.category;
+ sign = rhs.sign;
+
+ rhs.semantics = &Bogus;
+ return *this;
+}
+
bool
APFloat::isDenormal() const {
return isFiniteNonZero() && (exponent == semantics->minExponent) &&
APFloat::APFloat(const fltSemantics &ourSemantics, integerPart value) {
initialize(&ourSemantics);
sign = 0;
+ category = fcNormal;
zeroSignificand();
exponent = ourSemantics.precision - 1;
significandParts()[0] = value;
initialize(&ourSemantics);
}
-APFloat::APFloat(const fltSemantics &ourSemantics,
- fltCategory ourCategory, bool negative) {
- initialize(&ourSemantics);
- category = ourCategory;
- sign = negative;
- if (isFiniteNonZero())
- category = fcZero;
- else if (ourCategory == fcNaN)
- makeNaN();
-}
-
APFloat::APFloat(const fltSemantics &ourSemantics, StringRef text) {
initialize(&ourSemantics);
convertFromString(text, rmNearestTiesToEven);
assign(rhs);
}
+APFloat::APFloat(APFloat &&rhs) : semantics(&Bogus) {
+ *this = std::move(rhs);
+}
+
APFloat::~APFloat()
{
freeSignificand();
void
APFloat::zeroSignificand()
{
- category = fcNormal;
APInt::tcSet(significandParts(), 0, partCount());
}
assert(semantics == rhs.semantics);
precision = semantics->precision;
- newPartsCount = partCountForBits(precision * 2);
+
+ // Allocate space for twice as many bits as the original significand, plus one
+ // extra bit for the addition to overflow into.
+ newPartsCount = partCountForBits(precision * 2 + 1);
if (newPartsCount > 4)
fullSignificand = new integerPart[newPartsCount];
// *this = a23 . a22 ... a0 * 2^e1
// rhs = b23 . b22 ... b0 * 2^e2
// the result of multiplication is:
- // *this = c47 c46 . c45 ... c0 * 2^(e1+e2)
- // Note that there are two significant bits at the left-hand side of the
- // radix point. Move the radix point toward left by one bit, and adjust
- // exponent accordingly.
- exponent += 1;
-
- if (addend) {
+ // *this = c48 c47 c46 . c45 ... c0 * 2^(e1+e2)
+ // Note that there are three significant bits at the left-hand side of the
+ // radix point: two for the multiplication, and an overflow bit for the
+ // addition (that will always be zero at this point). Move the radix point
+ // toward left by two bits, and adjust exponent accordingly.
+ exponent += 2;
+
+ if (addend && addend->isNonZero()) {
// The intermediate result of the multiplication has "2 * precision"
// signicant bit; adjust the addend to be consistent with mul result.
//
opStatus status;
unsigned int extendedPrecision;
- /* Normalize our MSB. */
- extendedPrecision = 2 * precision;
- if (omsb != extendedPrecision) {
+ // Normalize our MSB to one below the top bit to allow for overflow.
+ extendedPrecision = 2 * precision + 1;
+ if (omsb != extendedPrecision - 1) {
assert(extendedPrecision > omsb);
APInt::tcShiftLeft(fullSignificand, newPartsCount,
- extendedPrecision - omsb);
- exponent -= extendedPrecision - omsb;
+ (extendedPrecision - 1) - omsb);
+ exponent -= (extendedPrecision - 1) - omsb;
}
/* Create new semantics. */
status = extendedAddend.convert(extendedSemantics, rmTowardZero, &ignored);
assert(status == opOK);
(void)status;
+
+ // Shift the significand of the addend right by one bit. This guarantees
+ // that the high bit of the significand is zero (same as fullSignificand),
+ // so the addition will overflow (if it does overflow at all) into the top bit.
+ lost_fraction = extendedAddend.shiftSignificandRight(1);
+ assert(lost_fraction == lfExactlyZero &&
+ "Lost precision while shifting addend for fused-multiply-add.");
+
lost_fraction = addOrSubtractSignificand(extendedAddend, false);
/* Restore our state. */
// having "precision" significant-bits. First, move the radix point from
// poision "2*precision - 1" to "precision - 1". The exponent need to be
// adjusted by "2*precision - 1" - "precision - 1" = "precision".
- exponent -= precision;
+ exponent -= precision + 1;
// In case MSB resides at the left-hand side of radix point, shift the
// mantissa right by some amount to make sure the MSB reside right before
{
switch (PackCategoriesIntoKey(category, rhs.category)) {
default:
- llvm_unreachable(0);
+ llvm_unreachable(nullptr);
case PackCategoriesIntoKey(fcNaN, fcZero):
case PackCategoriesIntoKey(fcNaN, fcNormal):
case PackCategoriesIntoKey(fcZero, fcNaN):
case PackCategoriesIntoKey(fcNormal, fcNaN):
case PackCategoriesIntoKey(fcInfinity, fcNaN):
+ // We need to be sure to flip the sign here for subtraction because we
+ // don't have a separate negate operation so -NaN becomes 0 - NaN here.
+ sign = rhs.sign ^ subtract;
category = fcNaN;
copySignificand(rhs);
return opOK;
{
switch (PackCategoriesIntoKey(category, rhs.category)) {
default:
- llvm_unreachable(0);
+ llvm_unreachable(nullptr);
case PackCategoriesIntoKey(fcNaN, fcZero):
case PackCategoriesIntoKey(fcNaN, fcNormal):
case PackCategoriesIntoKey(fcNaN, fcInfinity):
case PackCategoriesIntoKey(fcNaN, fcNaN):
+ sign = false;
return opOK;
case PackCategoriesIntoKey(fcZero, fcNaN):
case PackCategoriesIntoKey(fcNormal, fcNaN):
case PackCategoriesIntoKey(fcInfinity, fcNaN):
+ sign = false;
category = fcNaN;
copySignificand(rhs);
return opOK;
{
switch (PackCategoriesIntoKey(category, rhs.category)) {
default:
- llvm_unreachable(0);
+ llvm_unreachable(nullptr);
+ case PackCategoriesIntoKey(fcZero, fcNaN):
+ case PackCategoriesIntoKey(fcNormal, fcNaN):
+ case PackCategoriesIntoKey(fcInfinity, fcNaN):
+ category = fcNaN;
+ copySignificand(rhs);
case PackCategoriesIntoKey(fcNaN, fcZero):
case PackCategoriesIntoKey(fcNaN, fcNormal):
case PackCategoriesIntoKey(fcNaN, fcInfinity):
case PackCategoriesIntoKey(fcNaN, fcNaN):
+ sign = false;
case PackCategoriesIntoKey(fcInfinity, fcZero):
case PackCategoriesIntoKey(fcInfinity, fcNormal):
case PackCategoriesIntoKey(fcZero, fcInfinity):
case PackCategoriesIntoKey(fcZero, fcNormal):
return opOK;
- case PackCategoriesIntoKey(fcZero, fcNaN):
- case PackCategoriesIntoKey(fcNormal, fcNaN):
- case PackCategoriesIntoKey(fcInfinity, fcNaN):
- category = fcNaN;
- copySignificand(rhs);
- return opOK;
-
case PackCategoriesIntoKey(fcNormal, fcInfinity):
category = fcZero;
return opOK;
{
switch (PackCategoriesIntoKey(category, rhs.category)) {
default:
- llvm_unreachable(0);
+ llvm_unreachable(nullptr);
case PackCategoriesIntoKey(fcNaN, fcZero):
case PackCategoriesIntoKey(fcNaN, fcNormal):
case PackCategoriesIntoKey(fcZero, fcNaN):
case PackCategoriesIntoKey(fcNormal, fcNaN):
case PackCategoriesIntoKey(fcInfinity, fcNaN):
+ sign = false;
category = fcNaN;
copySignificand(rhs);
return opOK;
fs = multiplySpecials(rhs);
if (isFiniteNonZero()) {
- lostFraction lost_fraction = multiplySignificand(rhs, 0);
+ lostFraction lost_fraction = multiplySignificand(rhs, nullptr);
fs = normalize(rounding_mode, lost_fraction);
if (lost_fraction != lfExactlyZero)
fs = (opStatus) (fs | opInexact);
extended-precision calculation. */
if (isFiniteNonZero() &&
multiplicand.isFiniteNonZero() &&
- addend.isFiniteNonZero()) {
+ addend.isFinite()) {
lostFraction lost_fraction;
lost_fraction = multiplySignificand(multiplicand, &addend);
/* If two numbers add (exactly) to zero, IEEE 754 decrees it is a
positive zero unless rounding to minus infinity, except that
adding two like-signed zeroes gives that zero. */
- if (category == fcZero && sign != addend.sign)
+ if (category == fcZero && !(fs & opUnderflow) && sign != addend.sign)
sign = (rounding_mode == rmTowardNegative);
} else {
fs = multiplySpecials(multiplicand);
switch (PackCategoriesIntoKey(category, rhs.category)) {
default:
- llvm_unreachable(0);
+ llvm_unreachable(nullptr);
case PackCategoriesIntoKey(fcNaN, fcZero):
case PackCategoriesIntoKey(fcNaN, fcNormal):
X86SpecialNan = true;
}
+ // If this is a truncation of a denormal number, and the target semantics
+ // has larger exponent range than the source semantics (this can happen
+ // when truncating from PowerPC double-double to double format), the
+ // right shift could lose result mantissa bits. Adjust exponent instead
+ // of performing excessive shift.
+ if (shift < 0 && isFiniteNonZero()) {
+ int exponentChange = significandMSB() + 1 - fromSemantics.precision;
+ if (exponent + exponentChange < toSemantics.minExponent)
+ exponentChange = toSemantics.minExponent - exponent;
+ if (exponentChange < shift)
+ exponentChange = shift;
+ if (exponentChange < 0) {
+ shift -= exponentChange;
+ exponent += exponentChange;
+ }
+ }
+
// If this is a truncation, perform the shift before we narrow the storage.
if (shift < 0 && (isFiniteNonZero() || category==fcNaN))
lostFraction = shiftRight(significandParts(), oldPartCount, -shift);
APFloat::convertFromHexadecimalString(StringRef s, roundingMode rounding_mode)
{
lostFraction lost_fraction = lfExactlyZero;
- integerPart *significand;
- unsigned int bitPos, partsCount;
- StringRef::iterator dot, firstSignificantDigit;
+ category = fcNormal;
zeroSignificand();
exponent = 0;
- category = fcNormal;
- significand = significandParts();
- partsCount = partCount();
- bitPos = partsCount * integerPartWidth;
+ integerPart *significand = significandParts();
+ unsigned partsCount = partCount();
+ unsigned bitPos = partsCount * integerPartWidth;
+ bool computedTrailingFraction = false;
- /* Skip leading zeroes and any (hexa)decimal point. */
+ // Skip leading zeroes and any (hexa)decimal point.
StringRef::iterator begin = s.begin();
StringRef::iterator end = s.end();
+ StringRef::iterator dot;
StringRef::iterator p = skipLeadingZeroesAndAnyDot(begin, end, &dot);
- firstSignificantDigit = p;
+ StringRef::iterator firstSignificantDigit = p;
- for (; p != end;) {
+ while (p != end) {
integerPart hex_value;
if (*p == '.') {
assert(dot == end && "String contains multiple dots");
dot = p++;
- if (p == end) {
- break;
- }
+ continue;
}
hex_value = hexDigitValue(*p);
- if (hex_value == -1U) {
+ if (hex_value == -1U)
break;
- }
p++;
- if (p == end) {
- break;
- } else {
- /* Store the number whilst 4-bit nibbles remain. */
- if (bitPos) {
- bitPos -= 4;
- hex_value <<= bitPos % integerPartWidth;
- significand[bitPos / integerPartWidth] |= hex_value;
- } else {
- lost_fraction = trailingHexadecimalFraction(p, end, hex_value);
- while (p != end && hexDigitValue(*p) != -1U)
- p++;
- break;
- }
+ // Store the number while we have space.
+ if (bitPos) {
+ bitPos -= 4;
+ hex_value <<= bitPos % integerPartWidth;
+ significand[bitPos / integerPartWidth] |= hex_value;
+ } else if (!computedTrailingFraction) {
+ lost_fraction = trailingHexadecimalFraction(p, end, hex_value);
+ computedTrailingFraction = true;
}
}
excessPrecision = calcSemantics.precision - semantics->precision;
truncatedBits = excessPrecision;
- APFloat decSig(calcSemantics, fcZero, sign);
- APFloat pow5(calcSemantics, fcZero, false);
+ APFloat decSig = APFloat::getZero(calcSemantics, sign);
+ APFloat pow5(calcSemantics);
sigStatus = decSig.convertFromUnsignedParts(decSigParts, sigPartCount,
rmNearestTiesToEven);
if (exp >= 0) {
/* multiplySignificand leaves the precision-th bit set to 1. */
- calcLostFraction = decSig.multiplySignificand(pow5, NULL);
+ calcLostFraction = decSig.multiplySignificand(pow5, nullptr);
powHUerr = powStatus != opOK;
} else {
calcLostFraction = decSig.divideSignificand(pow5);
42039/12655 < L < 28738/8651 [ numerator <= 65536 ]
*/
- if (decDigitValue(*D.firstSigDigit) >= 10U) {
+ // Test if we have a zero number allowing for strings with no null terminators
+ // and zero decimals with non-zero exponents.
+ //
+ // We computed firstSigDigit by ignoring all zeros and dots. Thus if
+ // D->firstSigDigit equals str.end(), every digit must be a zero and there can
+ // be at most one dot. On the other hand, if we have a zero with a non-zero
+ // exponent, then we know that D.firstSigDigit will be non-numeric.
+ if (D.firstSigDigit == str.end() || decDigitValue(*D.firstSigDigit) >= 10U) {
category = fcZero;
fs = opOK;
(D.normalizedExponent + 1) * 28738 <=
8651 * (semantics->minExponent - (int) semantics->precision)) {
/* Underflow to zero and round. */
+ category = fcNormal;
zeroSignificand();
fs = normalize(rounding_mode, lfLessThanHalf);
if (Sem == &PPCDoubleDouble)
return initFromPPCDoubleDoubleAPInt(api);
- llvm_unreachable(0);
+ llvm_unreachable(nullptr);
}
APFloat
// internal consistency.
const unsigned NumUnusedHighBits =
PartCount*integerPartWidth - semantics->precision;
- significand[PartCount - 1] = ~integerPart(0) >> NumUnusedHighBits;
+ significand[PartCount - 1] = (NumUnusedHighBits < integerPartWidth)
+ ? (~integerPart(0) >> NumUnusedHighBits)
+ : 0;
}
/// Make this number the smallest magnitude denormal number in the given
}
APFloat APFloat::getSmallestNormalized(const fltSemantics &Sem, bool Negative) {
- APFloat Val(Sem, fcNormal, Negative);
+ APFloat Val(Sem, uninitialized);
// We want (in interchange format):
// sign = {Negative}
// exponent = 0..0
// significand = 10..0
- Val.exponent = Sem.minExponent;
+ Val.category = fcNormal;
Val.zeroSignificand();
+ Val.sign = Negative;
+ Val.exponent = Sem.minExponent;
Val.significandParts()[partCountForBits(Sem.precision)-1] |=
(((integerPart) 1) << ((Sem.precision - 1) % integerPartWidth));
// Set FormatPrecision if zero. We want to do this before we
// truncate trailing zeros, as those are part of the precision.
if (!FormatPrecision) {
- // It's an interesting question whether to use the nominal
- // precision or the active precision here for denormals.
+ // We use enough digits so the number can be round-tripped back to an
+ // APFloat. The formula comes from "How to Print Floating-Point Numbers
+ // Accurately" by Steele and White.
+ // FIXME: Using a formula based purely on the precision is conservative;
+ // we can print fewer digits depending on the actual value being printed.
- // FormatPrecision = ceil(significandBits / lg_2(10))
- FormatPrecision = (semantics->precision * 59 + 195) / 196;
+ // FormatPrecision = 2 + floor(significandBits / lg_2(10))
+ FormatPrecision = 2 + semantics->precision * 59 / 196;
}
// Ignore trailing binary zeros.
// change the payload.
if (isSignaling()) {
result = opInvalidOp;
- // For consistency, propogate the sign of the sNaN to the qNaN.
- makeNaN(false, isNegative(), 0);
+ // For consistency, propagate the sign of the sNaN to the qNaN.
+ makeNaN(false, isNegative(), nullptr);
}
break;
case fcZero:
// Decrement the significand.
//
// We always do this since:
- // 1. If we are dealing with a non binade decrement, by definition we
+ // 1. If we are dealing with a non-binade decrement, by definition we
// just decrement the significand.
// 2. If we are dealing with a normal -> normal binade decrement, since
// we have an explicit integral bit the fact that all bits but the
exponent = semantics->minExponent-1;
APInt::tcSet(significandParts(), 0, partCount());
}
+
+APFloat llvm::scalbn(APFloat X, int Exp) {
+ if (X.isInfinity() || X.isZero() || X.isNaN())
+ return std::move(X);
+
+ auto MaxExp = X.getSemantics().maxExponent;
+ auto MinExp = X.getSemantics().minExponent;
+ if (Exp > (MaxExp - X.exponent))
+ // Overflow saturates to infinity.
+ return APFloat::getInf(X.getSemantics(), X.isNegative());
+ if (Exp < (MinExp - X.exponent))
+ // Underflow saturates to zero.
+ return APFloat::getZero(X.getSemantics(), X.isNegative());
+
+ X.exponent += Exp;
+ return std::move(X);
+}
projects / oota-llvm.git / blobdiff