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[APFloat] Add PPCDoubleDouble multiplication

Reviewers: echristo, hfinkel, kbarton, iteratee

Subscribers: mehdi_amini, llvm-commits

Differential Revision: https://reviews.llvm.org/D28382

llvm-svn: 292860
This commit is contained in:
Tim Shen 2017-01-24 00:19:45 +00:00
parent 419f66e8c9
commit 28ce2d2c0f
2 changed files with 253 additions and 37 deletions

View File

@ -3895,6 +3895,7 @@ DoubleAPFloat &DoubleAPFloat::operator=(const DoubleAPFloat &RHS) {
return *this;
}
// Implement addition, subtraction, multiplication and division based on:
// "Software for Doubled-Precision Floating-Point Computations",
// by Seppo Linnainmaa, ACM TOMS vol 7 no 3, September 1981, pages 272-283.
APFloat::opStatus DoubleAPFloat::addImpl(const APFloat &a, const APFloat &aa,
@ -4037,12 +4038,88 @@ APFloat::opStatus DoubleAPFloat::subtract(const DoubleAPFloat &RHS,
APFloat::opStatus DoubleAPFloat::multiply(const DoubleAPFloat &RHS,
APFloat::roundingMode RM) {
assert(Semantics == &semPPCDoubleDouble && "Unexpected Semantics");
APFloat Tmp(semPPCDoubleDoubleLegacy, bitcastToAPInt());
auto Ret =
Tmp.multiply(APFloat(semPPCDoubleDoubleLegacy, RHS.bitcastToAPInt()), RM);
*this = DoubleAPFloat(semPPCDoubleDouble, Tmp.bitcastToAPInt());
return Ret;
const auto &LHS = *this;
auto &Out = *this;
/* Interesting observation: For special categories, finding the lowest
common ancestor of the following layered graph gives the correct
return category:
NaN
/ \
Zero Inf
\ /
Normal
e.g. NaN * NaN = NaN
Zero * Inf = NaN
Normal * Zero = Zero
Normal * Inf = Inf
*/
if (LHS.getCategory() == fcNaN) {
Out = LHS;
return opOK;
}
if (RHS.getCategory() == fcNaN) {
Out = RHS;
return opOK;
}
if ((LHS.getCategory() == fcZero && RHS.getCategory() == fcInfinity) ||
(LHS.getCategory() == fcInfinity && RHS.getCategory() == fcZero)) {
Out.makeNaN(false, false, nullptr);
return opOK;
}
if (LHS.getCategory() == fcZero || LHS.getCategory() == fcInfinity) {
Out = LHS;
return opOK;
}
if (RHS.getCategory() == fcZero || RHS.getCategory() == fcInfinity) {
Out = RHS;
return opOK;
}
assert(LHS.getCategory() == fcNormal && RHS.getCategory() == fcNormal &&
"Special cases not handled exhaustively");
int Status = opOK;
APFloat A = Floats[0], B = Floats[1], C = RHS.Floats[0], D = RHS.Floats[1];
// t = a * c
APFloat T = A;
Status |= T.multiply(C, RM);
if (!T.isFiniteNonZero()) {
Floats[0] = T;
Floats[1].makeZero(false);
return (opStatus)Status;
}
// tau = fmsub(a, c, t), that is -fmadd(-a, c, t).
APFloat Tau = A;
T.changeSign();
Status |= Tau.fusedMultiplyAdd(C, T, RM);
T.changeSign();
{
// v = a * d
APFloat V = A;
Status |= V.multiply(D, RM);
// w = b * c
APFloat W = B;
Status |= W.multiply(C, RM);
Status |= V.add(W, RM);
// tau += v + w
Status |= Tau.add(V, RM);
}
// u = t + tau
APFloat U = T;
Status |= U.add(Tau, RM);
Floats[0] = U;
if (!U.isFinite()) {
Floats[1].makeZero(false);
} else {
// Floats[1] = (t - u) + tau
Status |= T.subtract(U, RM);
Status |= T.add(Tau, RM);
Floats[1] = T;
}
return (opStatus)Status;
}
APFloat::opStatus DoubleAPFloat::divide(const DoubleAPFloat &RHS,

View File

@ -3203,14 +3203,26 @@ TEST(APFloatTest, PPCDoubleDoubleAddSpecial) {
APFloat::roundingMode RM;
std::tie(Op1[0], Op1[1], Op2[0], Op2[1], Expected, RM) = Tp;
APFloat A1(APFloat::PPCDoubleDouble(), APInt(128, 2, Op1));
APFloat A2(APFloat::PPCDoubleDouble(), APInt(128, 2, Op2));
A1.add(A2, RM);
{
APFloat A1(APFloat::PPCDoubleDouble(), APInt(128, 2, Op1));
APFloat A2(APFloat::PPCDoubleDouble(), APInt(128, 2, Op2));
A1.add(A2, RM);
EXPECT_EQ(Expected, A1.getCategory())
<< formatv("({0:x} + {1:x}) + ({2:x} + {3:x})", Op1[0], Op1[1], Op2[0],
Op2[1])
.str();
EXPECT_EQ(Expected, A1.getCategory())
<< formatv("({0:x} + {1:x}) + ({2:x} + {3:x})", Op1[0], Op1[1],
Op2[0], Op2[1])
.str();
}
{
APFloat A1(APFloat::PPCDoubleDouble(), APInt(128, 2, Op1));
APFloat A2(APFloat::PPCDoubleDouble(), APInt(128, 2, Op2));
A2.add(A1, RM);
EXPECT_EQ(Expected, A2.getCategory())
<< formatv("({0:x} + {1:x}) + ({2:x} + {3:x})", Op2[0], Op2[1],
Op1[0], Op1[1])
.str();
}
}
}
@ -3255,18 +3267,34 @@ TEST(APFloatTest, PPCDoubleDoubleAdd) {
APFloat::roundingMode RM;
std::tie(Op1[0], Op1[1], Op2[0], Op2[1], Expected[0], Expected[1], RM) = Tp;
APFloat A1(APFloat::PPCDoubleDouble(), APInt(128, 2, Op1));
APFloat A2(APFloat::PPCDoubleDouble(), APInt(128, 2, Op2));
A1.add(A2, RM);
{
APFloat A1(APFloat::PPCDoubleDouble(), APInt(128, 2, Op1));
APFloat A2(APFloat::PPCDoubleDouble(), APInt(128, 2, Op2));
A1.add(A2, RM);
EXPECT_EQ(Expected[0], A1.bitcastToAPInt().getRawData()[0])
<< formatv("({0:x} + {1:x}) + ({2:x} + {3:x})", Op1[0], Op1[1], Op2[0],
Op2[1])
.str();
EXPECT_EQ(Expected[1], A1.bitcastToAPInt().getRawData()[1])
<< formatv("({0:x} + {1:x}) + ({2:x} + {3:x})", Op1[0], Op1[1], Op2[0],
Op2[1])
.str();
EXPECT_EQ(Expected[0], A1.bitcastToAPInt().getRawData()[0])
<< formatv("({0:x} + {1:x}) + ({2:x} + {3:x})", Op1[0], Op1[1],
Op2[0], Op2[1])
.str();
EXPECT_EQ(Expected[1], A1.bitcastToAPInt().getRawData()[1])
<< formatv("({0:x} + {1:x}) + ({2:x} + {3:x})", Op1[0], Op1[1],
Op2[0], Op2[1])
.str();
}
{
APFloat A1(APFloat::PPCDoubleDouble(), APInt(128, 2, Op1));
APFloat A2(APFloat::PPCDoubleDouble(), APInt(128, 2, Op2));
A2.add(A1, RM);
EXPECT_EQ(Expected[0], A2.bitcastToAPInt().getRawData()[0])
<< formatv("({0:x} + {1:x}) + ({2:x} + {3:x})", Op2[0], Op2[1],
Op1[0], Op1[1])
.str();
EXPECT_EQ(Expected[1], A2.bitcastToAPInt().getRawData()[1])
<< formatv("({0:x} + {1:x}) + ({2:x} + {3:x})", Op2[0], Op2[1],
Op1[0], Op1[1])
.str();
}
}
}
@ -3304,16 +3332,111 @@ TEST(APFloatTest, PPCDoubleDoubleSubtract) {
}
}
TEST(APFloatTest, PPCDoubleDoubleMultiplySpecial) {
using DataType = std::tuple<uint64_t, uint64_t, uint64_t, uint64_t,
APFloat::fltCategory, APFloat::roundingMode>;
DataType Data[] = {
// fcNaN * fcNaN = fcNaN
std::make_tuple(0x7ff8000000000000ull, 0, 0x7ff8000000000000ull, 0,
APFloat::fcNaN, APFloat::rmNearestTiesToEven),
// fcNaN * fcZero = fcNaN
std::make_tuple(0x7ff8000000000000ull, 0, 0, 0, APFloat::fcNaN,
APFloat::rmNearestTiesToEven),
// fcNaN * fcInfinity = fcNaN
std::make_tuple(0x7ff8000000000000ull, 0, 0x7ff0000000000000ull, 0,
APFloat::fcNaN, APFloat::rmNearestTiesToEven),
// fcNaN * fcNormal = fcNaN
std::make_tuple(0x7ff8000000000000ull, 0, 0x3ff0000000000000ull, 0,
APFloat::fcNaN, APFloat::rmNearestTiesToEven),
// fcInfinity * fcInfinity = fcInfinity
std::make_tuple(0x7ff0000000000000ull, 0, 0x7ff0000000000000ull, 0,
APFloat::fcInfinity, APFloat::rmNearestTiesToEven),
// fcInfinity * fcZero = fcNaN
std::make_tuple(0x7ff0000000000000ull, 0, 0, 0, APFloat::fcNaN,
APFloat::rmNearestTiesToEven),
// fcInfinity * fcNormal = fcInfinity
std::make_tuple(0x7ff0000000000000ull, 0, 0x3ff0000000000000ull, 0,
APFloat::fcInfinity, APFloat::rmNearestTiesToEven),
// fcZero * fcZero = fcZero
std::make_tuple(0, 0, 0, 0, APFloat::fcZero,
APFloat::rmNearestTiesToEven),
// fcZero * fcNormal = fcZero
std::make_tuple(0, 0, 0x3ff0000000000000ull, 0, APFloat::fcZero,
APFloat::rmNearestTiesToEven),
};
for (auto Tp : Data) {
uint64_t Op1[2], Op2[2];
APFloat::fltCategory Expected;
APFloat::roundingMode RM;
std::tie(Op1[0], Op1[1], Op2[0], Op2[1], Expected, RM) = Tp;
{
APFloat A1(APFloat::PPCDoubleDouble(), APInt(128, 2, Op1));
APFloat A2(APFloat::PPCDoubleDouble(), APInt(128, 2, Op2));
A1.multiply(A2, RM);
EXPECT_EQ(Expected, A1.getCategory())
<< formatv("({0:x} + {1:x}) * ({2:x} + {3:x})", Op1[0], Op1[1],
Op2[0], Op2[1])
.str();
}
{
APFloat A1(APFloat::PPCDoubleDouble(), APInt(128, 2, Op1));
APFloat A2(APFloat::PPCDoubleDouble(), APInt(128, 2, Op2));
A2.multiply(A1, RM);
EXPECT_EQ(Expected, A2.getCategory())
<< formatv("({0:x} + {1:x}) * ({2:x} + {3:x})", Op2[0], Op2[1],
Op1[0], Op1[1])
.str();
}
}
}
TEST(APFloatTest, PPCDoubleDoubleMultiply) {
using DataType = std::tuple<uint64_t, uint64_t, uint64_t, uint64_t, uint64_t,
uint64_t, APFloat::roundingMode>;
// TODO: Only a sanity check for now. Add more edge cases when the
// double-double algorithm is implemented.
DataType Data[] = {
// 1/3 * 3 = 1.0
std::make_tuple(0x3fd5555555555555ull, 0x3c75555555555556ull,
0x4008000000000000ull, 0, 0x3ff0000000000000ull, 0,
APFloat::rmNearestTiesToEven),
// (1 + epsilon) * (1 + 0) = fcZero
std::make_tuple(0x3ff0000000000000ull, 0x0000000000000001ull,
0x3ff0000000000000ull, 0, 0x3ff0000000000000ull,
0x0000000000000001ull, APFloat::rmNearestTiesToEven),
// (1 + epsilon) * (1 + epsilon) = 1 + 2 * epsilon
std::make_tuple(0x3ff0000000000000ull, 0x0000000000000001ull,
0x3ff0000000000000ull, 0x0000000000000001ull,
0x3ff0000000000000ull, 0x0000000000000002ull,
APFloat::rmNearestTiesToEven),
// -(1 + epsilon) * (1 + epsilon) = -1
std::make_tuple(0xbff0000000000000ull, 0x0000000000000001ull,
0x3ff0000000000000ull, 0x0000000000000001ull,
0xbff0000000000000ull, 0, APFloat::rmNearestTiesToEven),
// (0.5 + 0) * (1 + 2 * epsilon) = 0.5 + epsilon
std::make_tuple(0x3fe0000000000000ull, 0, 0x3ff0000000000000ull,
0x0000000000000002ull, 0x3fe0000000000000ull,
0x0000000000000001ull, APFloat::rmNearestTiesToEven),
// (0.5 + 0) * (1 + epsilon) = 0.5
std::make_tuple(0x3fe0000000000000ull, 0, 0x3ff0000000000000ull,
0x0000000000000001ull, 0x3fe0000000000000ull, 0,
APFloat::rmNearestTiesToEven),
// __LDBL_MAX__ * (1 + 1 << 106) = inf
std::make_tuple(0x7fefffffffffffffull, 0x7c8ffffffffffffeull,
0x3ff0000000000000ull, 0x3950000000000000ull,
0x7ff0000000000000ull, 0, APFloat::rmNearestTiesToEven),
// __LDBL_MAX__ * (1 + 1 << 107) > __LDBL_MAX__, but not inf, yes =_=|||
std::make_tuple(0x7fefffffffffffffull, 0x7c8ffffffffffffeull,
0x3ff0000000000000ull, 0x3940000000000000ull,
0x7fefffffffffffffull, 0x7c8fffffffffffffull,
APFloat::rmNearestTiesToEven),
// __LDBL_MAX__ * (1 + 1 << 108) = __LDBL_MAX__
std::make_tuple(0x7fefffffffffffffull, 0x7c8ffffffffffffeull,
0x3ff0000000000000ull, 0x3930000000000000ull,
0x7fefffffffffffffull, 0x7c8ffffffffffffeull,
APFloat::rmNearestTiesToEven),
};
for (auto Tp : Data) {
@ -3321,18 +3444,34 @@ TEST(APFloatTest, PPCDoubleDoubleMultiply) {
APFloat::roundingMode RM;
std::tie(Op1[0], Op1[1], Op2[0], Op2[1], Expected[0], Expected[1], RM) = Tp;
APFloat A1(APFloat::PPCDoubleDouble(), APInt(128, 2, Op1));
APFloat A2(APFloat::PPCDoubleDouble(), APInt(128, 2, Op2));
A1.multiply(A2, RM);
{
APFloat A1(APFloat::PPCDoubleDouble(), APInt(128, 2, Op1));
APFloat A2(APFloat::PPCDoubleDouble(), APInt(128, 2, Op2));
A1.multiply(A2, RM);
EXPECT_EQ(Expected[0], A1.bitcastToAPInt().getRawData()[0])
<< formatv("({0:x} + {1:x}) * ({2:x} + {3:x})", Op1[0], Op1[1], Op2[0],
Op2[1])
.str();
EXPECT_EQ(Expected[1], A1.bitcastToAPInt().getRawData()[1])
<< formatv("({0:x} + {1:x}) * ({2:x} + {3:x})", Op1[0], Op1[1], Op2[0],
Op2[1])
.str();
EXPECT_EQ(Expected[0], A1.bitcastToAPInt().getRawData()[0])
<< formatv("({0:x} + {1:x}) * ({2:x} + {3:x})", Op1[0], Op1[1],
Op2[0], Op2[1])
.str();
EXPECT_EQ(Expected[1], A1.bitcastToAPInt().getRawData()[1])
<< formatv("({0:x} + {1:x}) * ({2:x} + {3:x})", Op1[0], Op1[1],
Op2[0], Op2[1])
.str();
}
{
APFloat A1(APFloat::PPCDoubleDouble(), APInt(128, 2, Op1));
APFloat A2(APFloat::PPCDoubleDouble(), APInt(128, 2, Op2));
A2.multiply(A1, RM);
EXPECT_EQ(Expected[0], A2.bitcastToAPInt().getRawData()[0])
<< formatv("({0:x} + {1:x}) * ({2:x} + {3:x})", Op2[0], Op2[1],
Op1[0], Op1[1])
.str();
EXPECT_EQ(Expected[1], A2.bitcastToAPInt().getRawData()[1])
<< formatv("({0:x} + {1:x}) * ({2:x} + {3:x})", Op2[0], Op2[1],
Op1[0], Op1[1])
.str();
}
}
}