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| author | Stephen Canon <scanon@apple.com> | 2014-06-08 16:53:31 +0000 |
|---|---|---|
| committer | Stephen Canon <scanon@apple.com> | 2014-06-08 16:53:31 +0000 |
| commit | bef256f49b77b17503b23699466d9bfc2f02d65f (patch) | |
| tree | 97f574bcfe3cd4b3f4bfcdcb2b576f2dc7721550 /lib/Support | |
| parent | c50f986b4d8ecbf3437c67e987e26e268ef5f06a (diff) | |
| download | llvm-bef256f49b77b17503b23699466d9bfc2f02d65f.tar.gz llvm-bef256f49b77b17503b23699466d9bfc2f02d65f.tar.bz2 llvm-bef256f49b77b17503b23699466d9bfc2f02d65f.tar.xz | |
APFloat: x - NaN needs to flip the signbit of NaN when x is a number.
Because we don't have a separate negate( ) function, 0 - NaN does double-duty as the IEEE-754 negate( ) operation, which (unlike most FP ops) *does* attach semantic meaning to the signbit of NaN.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210428 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Support')
| -rw-r--r-- | lib/Support/APFloat.cpp | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/lib/Support/APFloat.cpp b/lib/Support/APFloat.cpp index f9fe09541d..7989e30afa 100644 --- a/lib/Support/APFloat.cpp +++ b/lib/Support/APFloat.cpp @@ -1372,7 +1372,9 @@ APFloat::addOrSubtractSpecials(const APFloat &rhs, bool subtract) case PackCategoriesIntoKey(fcZero, fcNaN): case PackCategoriesIntoKey(fcNormal, fcNaN): case PackCategoriesIntoKey(fcInfinity, fcNaN): - sign = false; + // 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; |