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[APFloat] Make all arithmetic operations with NaN produce positive NaNs.

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IEEE-754R 1.4 Exclusions states that IEEE-754R does not specify the
interpretation of the sign of NaNs. In order to remove an irrelevant
variable that most floating point implementations do not use,
standardize add, sub, mul, div, mod so that operating anything with
NaN always yields a positive NaN.

In a later commit I am going to update the APIs for creating NaNs so
that one can not even create a negative NaN.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187314 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Michael Gottesman
2013-07-27 21:49:25 +00:00
parent 060d34b1cf
commit ca4d2e60ea
2 changed files with 49 additions and 96 deletions
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23
lib/Support/APFloat.cpp
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@@ -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;
@@ -1510,21 +1513,20 @@ APFloat::divideSpecials(const APFloat &rhs)
default:
llvm_unreachable(0);
case PackCategoriesIntoKey(fcNaN, fcZero):
case PackCategoriesIntoKey(fcNaN, fcNormal):
case PackCategoriesIntoKey(fcNaN, fcInfinity):
case PackCategoriesIntoKey(fcNaN, fcNaN):
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);
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(fcNormal, fcInfinity):
@@ -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;