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APFloat::roundToIntegral: Special values don't keep the exponent value up to date, don't rely on it. 

Add a couple of unit tests for special floats. Fixes 13929, found by MemorySanitizer.

llvm-svn: 164698
This commit is contained in:
Benjamin Kramer 2012-09-26 14:06:58 +00:00
parent cd3a11f725
commit c38fab2013
2 changed files with 18 additions and 1 deletions
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2
llvm/lib/Support/APFloat.cpp
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@ -1775,7 +1775,7 @@ APFloat::opStatus APFloat::roundToIntegral(roundingMode rounding_mode) {
// If the exponent is large enough, we know that this value is already
// integral, and the arithmetic below would potentially cause it to saturate
// to +/-Inf. Bail out early instead.
if (exponent+1 >= (int)semanticsPrecision(*semantics))
if (category == fcNormal && exponent+1 >= (int)semanticsPrecision(*semantics))
return opOK;
// The algorithm here is quite simple: we add 2^(p-1), where p is the

17
llvm/unittests/ADT/APFloatTest.cpp
View File

@ -689,6 +689,23 @@ TEST(APFloatTest, roundToIntegral) {
P = R;
P.roundToIntegral(APFloat::rmNearestTiesToEven);
EXPECT_EQ(R.convertToDouble(), P.convertToDouble());
P = APFloat::getZero(APFloat::IEEEdouble);
P.roundToIntegral(APFloat::rmTowardZero);
EXPECT_EQ(0.0, P.convertToDouble());
P = APFloat::getZero(APFloat::IEEEdouble, true);
P.roundToIntegral(APFloat::rmTowardZero);
EXPECT_EQ(-0.0, P.convertToDouble());
P = APFloat::getNaN(APFloat::IEEEdouble);
P.roundToIntegral(APFloat::rmTowardZero);
EXPECT_TRUE(IsNAN(P.convertToDouble()));
P = APFloat::getInf(APFloat::IEEEdouble);
P.roundToIntegral(APFloat::rmTowardZero);
EXPECT_TRUE(IsInf(P.convertToDouble()) && P.convertToDouble() > 0.0);
P = APFloat::getInf(APFloat::IEEEdouble, true);
P.roundToIntegral(APFloat::rmTowardZero);
EXPECT_TRUE(IsInf(P.convertToDouble()) && P.convertToDouble() < 0.0);
}
TEST(APFloatTest, getLargest) {