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Fix long double<->shorter FP type conversions

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of zero, infinity, and NaNs.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@42298 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dale Johannesen 2007-09-25 17:25:00 +00:00
parent c3b0b5ca1d
commit 902ff94aff
1 changed files with 29 additions and 12 deletions
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41
lib/Support/APFloat.cpp
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@ -1329,26 +1329,30 @@ APFloat::convert(const fltSemantics &toSemantics,
/* Handle storage complications. If our new form is wider,
re-allocate our bit pattern into wider storage. If it is
narrower, we ignore the excess parts, but if narrowing to a
single part we need to free the old storage. */
single part we need to free the old storage.
Be careful not to reference significandParts for zeroes
and infinities, since it aborts. */
if (newPartCount > oldPartCount) {
integerPart *newParts;
newParts = new integerPart[newPartCount];
APInt::tcSet(newParts, 0, newPartCount);
APInt::tcAssign(newParts, significandParts(), oldPartCount);
if (category==fcNormal || category==fcNaN)
APInt::tcAssign(newParts, significandParts(), oldPartCount);
freeSignificand();
significand.parts = newParts;
} else if (newPartCount < oldPartCount) {
/* Capture any lost fraction through truncation of parts so we get
correct rounding whilst normalizing. */
lostFraction = lostFractionThroughTruncation
(significandParts(), oldPartCount, toSemantics.precision);
if (newPartCount == 1)
{
integerPart newPart = significandParts()[0];
freeSignificand();
significand.part = newPart;
}
if (category==fcNormal)
lostFraction = lostFractionThroughTruncation
(significandParts(), oldPartCount, toSemantics.precision);
if (newPartCount == 1) {
integerPart newPart = 0;
if (category==fcNormal || category==fcNaN)
newPart = significandParts()[0];
freeSignificand();
significand.part = newPart;
}
}
if(category == fcNormal) {
@ -1356,6 +1360,19 @@ APFloat::convert(const fltSemantics &toSemantics,
exponent += toSemantics.precision - semantics->precision;
semantics = &toSemantics;
fs = normalize(rounding_mode, lostFraction);
} else if (category == fcNaN) {
int shift = toSemantics.precision - semantics->precision;
// No normalization here, just truncate
if (shift>0)
APInt::tcShiftLeft(significandParts(), newPartCount, shift);
else if (shift < 0)
APInt::tcShiftRight(significandParts(), newPartCount, -shift);
// gcc forces the Quiet bit on, which means (float)(double)(float_sNan)
// does not give you back the same bits. This is dubious, and we
// don't currently do it. You're really supposed to get
// an invalid operation signal at runtime, but nobody does that.
semantics = &toSemantics;
fs = opOK;
} else {
semantics = &toSemantics;
fs = opOK;
@ -1818,7 +1835,7 @@ APFloat::initFromFloatAPInt(const APInt & api) {
} else if (myexponent==0xff && mysignificand==0) {
// exponent, significand meaningless
category = fcInfinity;
} else if (myexponent==0xff && (mysignificand & 0x400000)) {
} else if (myexponent==0xff && mysignificand!=0) {
// sign, exponent, significand meaningless
category = fcNaN;
*significandParts() = mysignificand;