diff options
| -rw-r--r-- | lib/Support/APFloat.cpp | 12 | ||||
| -rw-r--r-- | unittests/ADT/APFloatTest.cpp | 30 |
2 files changed, 42 insertions, 0 deletions
diff --git a/lib/Support/APFloat.cpp b/lib/Support/APFloat.cpp index 5ea75a6..84021de 100644 --- a/lib/Support/APFloat.cpp +++ b/lib/Support/APFloat.cpp @@ -1774,19 +1774,31 @@ APFloat::opStatus APFloat::roundToIntegral(roundingMode rounding_mode) { // precision of our format, and then subtract it back off again. The choice // of rounding modes for the addition/subtraction determines the rounding mode // for our integral rounding as well. + // NOTE: When the input value is negative, we do subtractation followed by + // addition instead. APInt IntegerConstant(NextPowerOf2(semanticsPrecision(*semantics)), 1); IntegerConstant <<= semanticsPrecision(*semantics)-1; APFloat MagicConstant(*semantics); fs = MagicConstant.convertFromAPInt(IntegerConstant, false, rmNearestTiesToEven); + MagicConstant.copySign(*this); + if (fs != opOK) return fs; + // Preserve the input sign so that we can handle 0.0/-0.0 cases correctly. + bool inputSign = isNegative(); + fs = add(MagicConstant, rounding_mode); if (fs != opOK && fs != opInexact) return fs; fs = subtract(MagicConstant, rounding_mode); + + // Restore the input sign. + if (inputSign != isNegative()) + changeSign(); + return fs; } diff --git a/unittests/ADT/APFloatTest.cpp b/unittests/ADT/APFloatTest.cpp index cc207f7..caa288a 100644 --- a/unittests/ADT/APFloatTest.cpp +++ b/unittests/ADT/APFloatTest.cpp @@ -648,6 +648,36 @@ TEST(APFloatTest, exactInverse) { EXPECT_FALSE(APFloat(1.40129846e-45f).getExactInverse(0)); } +TEST(APFloatTest, roundToIntegral) { + APFloat T(-0.5), S(3.14), P(0.0); + + P = T; + P.roundToIntegral(APFloat::rmTowardZero); + EXPECT_EQ(-0.0, P.convertToDouble()); + P = T; + P.roundToIntegral(APFloat::rmTowardNegative); + EXPECT_EQ(-1.0, P.convertToDouble()); + P = T; + P.roundToIntegral(APFloat::rmTowardPositive); + EXPECT_EQ(-0.0, P.convertToDouble()); + P = T; + P.roundToIntegral(APFloat::rmNearestTiesToEven); + EXPECT_EQ(-0.0, P.convertToDouble()); + + P = S; + P.roundToIntegral(APFloat::rmTowardZero); + EXPECT_EQ(3.0, P.convertToDouble()); + P = S; + P.roundToIntegral(APFloat::rmTowardNegative); + EXPECT_EQ(3.0, P.convertToDouble()); + P = S; + P.roundToIntegral(APFloat::rmTowardPositive); + EXPECT_EQ(4.0, P.convertToDouble()); + P = S; + P.roundToIntegral(APFloat::rmNearestTiesToEven); + EXPECT_EQ(3.0, P.convertToDouble()); +} + TEST(APFloatTest, getLargest) { EXPECT_EQ(3.402823466e+38f, APFloat::getLargest(APFloat::IEEEsingle).convertToFloat()); EXPECT_EQ(1.7976931348623158e+308, APFloat::getLargest(APFloat::IEEEdouble).convertToDouble()); |