X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FSupport%2FAPFloat.cpp;h=802233c10999fe0b3409077912ed76248240c397;hb=6cedb064926bf70195d9808ae0a821b8d5214929;hp=ae4a101febab4ab02a828e2031f2b412969bfb79;hpb=b57770387ab262a0a23e77f094f599b6c955ba14;p=oota-llvm.git diff --git a/lib/Support/APFloat.cpp b/lib/Support/APFloat.cpp index ae4a101feba..802233c1099 100644 --- a/lib/Support/APFloat.cpp +++ b/lib/Support/APFloat.cpp @@ -319,8 +319,8 @@ trailingHexadecimalFraction(StringRef::iterator p, StringRef::iterator end, 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!"); @@ -778,6 +778,7 @@ APFloat::bitwiseIsEqual(const APFloat &rhs) const { APFloat::APFloat(const fltSemantics &ourSemantics, integerPart value) { initialize(&ourSemantics); sign = 0; + category = fcNormal; zeroSignificand(); exponent = ourSemantics.precision - 1; significandParts()[0] = value; @@ -845,7 +846,6 @@ APFloat::significandParts() void APFloat::zeroSignificand() { - category = fcNormal; APInt::tcSet(significandParts(), 0, partCount()); } @@ -1354,6 +1354,7 @@ APFloat::addOrSubtractSpecials(const APFloat &rhs, bool subtract) case PackCategoriesIntoKey(fcZero, fcNaN): case PackCategoriesIntoKey(fcNormal, fcNaN): case PackCategoriesIntoKey(fcInfinity, fcNaN): + sign = false; category = fcNaN; copySignificand(rhs); return opOK; @@ -1472,11 +1473,13 @@ APFloat::multiplySpecials(const APFloat &rhs) 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; @@ -1510,23 +1513,22 @@ APFloat::divideSpecials(const APFloat &rhs) default: llvm_unreachable(0); + 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; @@ -1564,6 +1566,7 @@ APFloat::modSpecials(const APFloat &rhs) case PackCategoriesIntoKey(fcZero, fcNaN): case PackCategoriesIntoKey(fcNormal, fcNaN): case PackCategoriesIntoKey(fcInfinity, fcNaN): + sign = false; category = fcNaN; copySignificand(rhs); return opOK; @@ -1956,6 +1959,23 @@ APFloat::convert(const fltSemantics &toSemantics, 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); @@ -2283,56 +2303,46 @@ APFloat::opStatus 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; } } @@ -2488,7 +2498,7 @@ APFloat::convertFromDecimalString(StringRef str, roundingMode rounding_mode) // 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 (decDigitValue(*D.firstSigDigit) >= 10U || D.firstSigDigit == str.end()) { + if (D.firstSigDigit == str.end() || decDigitValue(*D.firstSigDigit) >= 10U) { category = fcZero; fs = opOK; @@ -2505,6 +2515,7 @@ APFloat::convertFromDecimalString(StringRef str, roundingMode rounding_mode) (D.normalizedExponent + 1) * 28738 <= 8651 * (semantics->minExponent - (int) semantics->precision)) { /* Underflow to zero and round. */ + category = fcNormal; zeroSignificand(); fs = normalize(rounding_mode, lfLessThanHalf); @@ -3391,6 +3402,7 @@ APFloat APFloat::getSmallestNormalized(const fltSemantics &Sem, bool Negative) { // exponent = 0..0 // significand = 10..0 + Val.category = fcNormal; Val.zeroSignificand(); Val.sign = Negative; Val.exponent = Sem.minExponent; @@ -3534,11 +3546,14 @@ void APFloat::toString(SmallVectorImpl &Str, // 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. @@ -3801,7 +3816,7 @@ APFloat::opStatus APFloat::next(bool nextDown) { // 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