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-rw-r--r--src/math/all_test.go7
-rw-r--r--src/math/fma.go5
2 files changed, 12 insertions, 0 deletions
diff --git a/src/math/all_test.go b/src/math/all_test.go
index 886267bc17..96a398e9c6 100644
--- a/src/math/all_test.go
+++ b/src/math/all_test.go
@@ -2059,6 +2059,9 @@ var fmaC = []struct{ x, y, z, want float64 }{
// Special
{0, 0, 0, 0},
+ {Copysign(0, -1), 0, 0, 0},
+ {0, 0, Copysign(0, -1), 0},
+ {Copysign(0, -1), 0, Copysign(0, -1), Copysign(0, -1)},
{-1.1754226043408471e-38, NaN(), Inf(0), NaN()},
{0, 0, 2.22507385643494e-308, 2.22507385643494e-308},
{-8.65697792e+09, NaN(), -7.516192799999999e+09, NaN()},
@@ -2077,6 +2080,10 @@ var fmaC = []struct{ x, y, z, want float64 }{
{4.612811918325842e+18, 1.4901161193847641e-08, 2.6077032311277997e-08, 6.873625395187494e+10},
{-9.094947033611148e-13, 4.450691014249257e-308, 2.086006742350485e-308, 2.086006742346437e-308},
{-7.751454006381804e-05, 5.588653777189071e-308, -2.2207280111272877e-308, -2.2211612130544025e-308},
+
+ // Issue #61130
+ {-1, 1, 1, 0},
+ {1, 1, -1, 0},
}
var sqrt32 = []float32{
diff --git a/src/math/fma.go b/src/math/fma.go
index ca0bf99f21..ba03fbe8a9 100644
--- a/src/math/fma.go
+++ b/src/math/fma.go
@@ -132,6 +132,11 @@ func FMA(x, y, z float64) float64 {
ps, pe, pm1, pm2, zs, ze, zm1, zm2 = zs, ze, zm1, zm2, ps, pe, pm1, pm2
}
+ // Special case: if p == -z the result is always +0 since neither operand is zero.
+ if ps != zs && pe == ze && pm1 == zm1 && pm2 == zm2 {
+ return 0
+ }
+
// Align significands
zm1, zm2 = shrcompress(zm1, zm2, uint(pe-ze))