[flang-commits] [PATCH] D131099: [flang] Handle subnormals while folding SCALE, SET_EXPONENT, & FRACTION
Peter Klausler via Phabricator via flang-commits
flang-commits at lists.llvm.org
Sun Aug 7 16:12:30 PDT 2022
This revision was automatically updated to reflect the committed changes.
Closed by commit rG1d1f5a5251f7: [flang] Handle subnormals while folding SCALE, SET_EXPONENT, & FRACTION (authored by klausler).
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D131099/new/
https://reviews.llvm.org/D131099
Files:
flang/include/flang/Evaluate/real.h
flang/lib/Evaluate/real.cpp
flang/test/Evaluate/folding07.f90
Index: flang/test/Evaluate/folding07.f90
===================================================================
--- flang/test/Evaluate/folding07.f90
+++ flang/test/Evaluate/folding07.f90
@@ -280,5 +280,6 @@
logical, parameter :: test_set_exponent_0 = set_exponent(1., 0) == 0.5
logical, parameter :: test_set_exponent_1 = set_exponent(1., 1) == 1.
logical, parameter :: test_set_exponent_2 = set_exponent(1., 2) == 2.
+ logical, parameter :: test_set_exponent_min = set_exponent(1., -149) == 1.40129846432481707092372958328991613128026194187651577175706828388979108268586060148663818836212158203125e-45_4
end module
Index: flang/lib/Evaluate/real.cpp
===================================================================
--- flang/lib/Evaluate/real.cpp
+++ flang/lib/Evaluate/real.cpp
@@ -765,9 +765,7 @@
} else if (IsZero()) {
return *this;
} else {
- Real result;
- result.Normalize(IsNegative(), expo + exponentBias - 1, GetFraction());
- return result;
+ return SCALE(Integer<32>(expo - UnbiasedExponent() - 1)).value;
}
}
Index: flang/include/flang/Evaluate/real.h
===================================================================
--- flang/include/flang/Evaluate/real.h
+++ flang/include/flang/Evaluate/real.h
@@ -177,17 +177,21 @@
template <typename INT>
ValueWithRealFlags<Real> SCALE(const INT &by,
Rounding rounding = TargetCharacteristics::defaultRounding) const {
- auto expo{exponentBias + by.ToInt64()};
+ // Normalize a fraction with just its LSB set and then multiply.
+ // (Set the LSB, not the MSB, in case the scale factor needs to
+ // be subnormal.)
+ auto adjust{exponentBias + binaryPrecision - 1};
+ auto expo{adjust + by.ToInt64()};
if (IsZero()) {
expo = exponentBias; // ignore by, don't overflow
} else if (by > INT{maxExponent}) {
- expo = maxExponent;
- } else if (by < INT{-exponentBias}) {
+ expo = maxExponent + binaryPrecision - 1;
+ } else if (by < INT{-adjust}) {
expo = -1;
}
Real twoPow;
RealFlags flags{
- twoPow.Normalize(false, static_cast<int>(expo), Fraction::MASKL(1))};
+ twoPow.Normalize(false, static_cast<int>(expo), Fraction::MASKR(1))};
ValueWithRealFlags<Real> result{Multiply(twoPow, rounding)};
result.flags |= flags;
return result;
-------------- next part --------------
A non-text attachment was scrubbed...
Name: D131099.450676.patch
Type: text/x-patch
Size: 2342 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/flang-commits/attachments/20220807/55c14878/attachment-0001.bin>
More information about the flang-commits
mailing list