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| author | Brian Kessler <brian.m.kessler@gmail.com> | 2020-03-13 23:24:38 -0600 |
|---|---|---|
| committer | Robert Griesemer <gri@golang.org> | 2020-03-25 04:06:34 +0000 |
| commit | 6b6414cab49fcc035e1f20bafdb723077e7d36bb (patch) | |
| tree | c1c99f9731668aa9fe1dd98beaaed1ea68b7743c /src/math | |
| parent | 97585092f590072209110bce336f57506984c02b (diff) | |
| download | go-6b6414cab49fcc035e1f20bafdb723077e7d36bb.tar.gz go-6b6414cab49fcc035e1f20bafdb723077e7d36bb.zip | |
math: correct Atan2(±y,+∞) = ±0 on s390x
The s390x assembly implementation was previously only handling this
case correctly for x = -Pi. Update the special case handling for
any y.
Fixes #35446
Change-Id: I355575e9ec8c7ce8bd9db10d74f42a22f39a2f38
Reviewed-on: https://go-review.googlesource.com/c/go/+/223420
Run-TryBot: Brian Kessler <brian.m.kessler@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Munday <mike.munday@ibm.com>
Reviewed-by: Robert Griesemer <gri@golang.org>
Diffstat (limited to 'src/math')
| -rw-r--r-- | src/math/all_test.go | 4 | ||||
| -rw-r--r-- | src/math/atan2_s390x.s | 11 |
2 files changed, 11 insertions, 4 deletions
diff --git a/src/math/all_test.go b/src/math/all_test.go index 1ac9d71a25..3aae0373c7 100644 --- a/src/math/all_test.go +++ b/src/math/all_test.go @@ -827,6 +827,8 @@ var vfatan2SC = [][2]float64{ {+Pi, Inf(-1)}, {+Pi, 0}, {+Pi, Inf(1)}, + {1.0, Inf(1)}, + {-1.0, Inf(1)}, {+Pi, NaN()}, {Inf(1), Inf(-1)}, {Inf(1), -Pi}, @@ -864,6 +866,8 @@ var atan2SC = []float64{ Pi, // atan2(+Pi, -Inf) Pi / 2, // atan2(+Pi, +0) 0, // atan2(+Pi, +Inf) + 0, // atan2(+1, +Inf) + Copysign(0, -1), // atan2(-1, +Inf) NaN(), // atan2(+Pi, NaN) 3 * Pi / 4, // atan2(+Inf, -Inf) Pi / 2, // atan2(+Inf, -Pi) diff --git a/src/math/atan2_s390x.s b/src/math/atan2_s390x.s index 6b9af252e2..587b89e9b5 100644 --- a/src/math/atan2_s390x.s +++ b/src/math/atan2_s390x.s @@ -134,9 +134,9 @@ yIsPosInf: MOVD $NegInf, R3 CMPUBEQ R3, R1, negInfPosInf - //special case Atan2(-Pi, +Inf) = Pi - MOVD $NegPi, R3 - CMPUBEQ R3, R1, negPiPosInf + //special case Atan2(x, +Inf) = Copysign(0, x) + CMPBLT R1, $0, returnNegZero + BR returnPosZero Normal: FMOVD x+0(FP), F0 @@ -288,7 +288,10 @@ negInfPosInf: MOVD $NegPiDiv4, R1 MOVD R1, ret+16(FP) RET -negPiPosInf: +returnNegZero: MOVD $NegZero, R1 MOVD R1, ret+16(FP) RET +returnPosZero: + MOVD $0, ret+16(FP) + RET |