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APFloat: Fix ilogb for denormals 

llvm-svn: 263370
This commit is contained in:
Matt Arsenault 2016-03-13 05:12:32 +00:00
parent afa31cf4cc
commit 69fdf9b2e4
3 changed files with 35 additions and 12 deletions
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11
llvm/include/llvm/ADT/APFloat.h
View File

@ -511,16 +511,7 @@ public:
/// 0 -> \c IEK_Zero
/// Inf -> \c IEK_Inf
///
friend int ilogb(const APFloat &Arg) {
if (Arg.isNaN())
return IEK_NaN;
if (Arg.isZero())
return IEK_Zero;
if (Arg.isInfinity())
return IEK_Inf;
return Arg.exponent;
}
friend int ilogb(const APFloat &Arg);
/// \brief Returns: X * 2^Exp for integral exponents.
friend APFloat scalbn(APFloat X, int Exp, roundingMode);

18
llvm/lib/Support/APFloat.cpp
View File

@ -3945,6 +3945,24 @@ APFloat::makeZero(bool Negative) {
APInt::tcSet(significandParts(), 0, partCount());
}
int llvm::ilogb(const APFloat &Arg) {
if (Arg.isNaN())
return APFloat::IEK_NaN;
if (Arg.isZero())
return APFloat::IEK_Zero;
if (Arg.isInfinity())
return APFloat::IEK_Inf;
if (!Arg.isDenormal())
return Arg.exponent;
APFloat Normalized(Arg);
int SignificandBits = Arg.getSemantics().precision - 1;
Normalized.exponent += SignificandBits;
Normalized.normalize(APFloat::rmNearestTiesToEven, lfExactlyZero);
return Normalized.exponent - SignificandBits;
}
APFloat llvm::scalbn(APFloat X, int Exp, APFloat::roundingMode RoundingMode) {
auto MaxExp = X.getSemantics().maxExponent;
auto MinExp = X.getSemantics().minExponent;

18
llvm/unittests/ADT/APFloatTest.cpp
View File

@ -2821,6 +2821,19 @@ TEST(APFloatTest, abs) {
}
TEST(APFloatTest, ilogb) {
EXPECT_EQ(-1074, ilogb(APFloat::getSmallest(APFloat::IEEEdouble, false)));
EXPECT_EQ(-1074, ilogb(APFloat::getSmallest(APFloat::IEEEdouble, true)));
EXPECT_EQ(-1023, ilogb(APFloat(APFloat::IEEEdouble, "0x1.ffffffffffffep-1024")));
EXPECT_EQ(-1023, ilogb(APFloat(APFloat::IEEEdouble, "0x1.ffffffffffffep-1023")));
EXPECT_EQ(-1023, ilogb(APFloat(APFloat::IEEEdouble, "-0x1.ffffffffffffep-1023")));
EXPECT_EQ(-51, ilogb(APFloat(APFloat::IEEEdouble, "0x1p-51")));
EXPECT_EQ(-1023, ilogb(APFloat(APFloat::IEEEdouble, "0x1.c60f120d9f87cp-1023")));
EXPECT_EQ(-2, ilogb(APFloat(APFloat::IEEEdouble, "0x0.ffffp-1")));
EXPECT_EQ(-1023, ilogb(APFloat(APFloat::IEEEdouble, "0x1.fffep-1023")));
EXPECT_EQ(1023, ilogb(APFloat::getLargest(APFloat::IEEEdouble, false)));
EXPECT_EQ(1023, ilogb(APFloat::getLargest(APFloat::IEEEdouble, true)));
EXPECT_EQ(0, ilogb(APFloat(APFloat::IEEEsingle, "0x1p+0")));
EXPECT_EQ(0, ilogb(APFloat(APFloat::IEEEsingle, "-0x1p+0")));
EXPECT_EQ(42, ilogb(APFloat(APFloat::IEEEsingle, "0x1p+42")));
@ -2841,8 +2854,9 @@ TEST(APFloatTest, ilogb) {
EXPECT_EQ(127, ilogb(APFloat::getLargest(APFloat::IEEEsingle, false)));
EXPECT_EQ(127, ilogb(APFloat::getLargest(APFloat::IEEEsingle, true)));
EXPECT_EQ(-126, ilogb(APFloat::getSmallest(APFloat::IEEEsingle, false)));
EXPECT_EQ(-126, ilogb(APFloat::getSmallest(APFloat::IEEEsingle, true)));
EXPECT_EQ(-149, ilogb(APFloat::getSmallest(APFloat::IEEEsingle, false)));
EXPECT_EQ(-149, ilogb(APFloat::getSmallest(APFloat::IEEEsingle, true)));
EXPECT_EQ(-126,
ilogb(APFloat::getSmallestNormalized(APFloat::IEEEsingle, false)));
EXPECT_EQ(-126,