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Correct sign handling in fma32 when one of x, y is NaN

--- a/lib/math/fpmath-fma-impl.myr

+++ b/lib/math/fpmath-fma-impl.myr

@@ -9,10 +9,24 @@

 const exp_mask64 : uint64 = 0x7ff << 52

 pkglocal const fma32 = {x : flt32, y : flt32, z : flt32

+	var xn, yn

+	(xn, _, _) = std.flt32explode(x)

+	(yn, _, _) = std.flt32explode(y)

 	var xd : flt64 = flt64fromflt32(x)

 	var yd : flt64 = flt64fromflt32(y)

 	var zd : flt64 = flt64fromflt32(z)

 	var prod : flt64 = xd * yd

+	var pn, pe, ps

+	(pn, pe, ps) = std.flt64explode(prod)

+	if pe == -1023

+		pe = -1022

+	;;

+	if pn != (xn != yn)

+		/* In case of NaNs, sign might not have been preserved */

+		pn = (xn != yn)

+		prod = std.flt64assem(pn, pe, ps)

+	;;

+

 	var r : flt64 = prod + zd

 	var zn, ze, zs

@@ -19,11 +33,6 @@

 	(zn, ze, zs) = std.flt32explode(z)

 	if ze == -127

 		ze = -126

-	;;

-	var pn, pe, ps

-	(pn, pe, ps) = std.flt64explode(prod)

-	if pe == -1023

-		pe = -1022

 	;;

 	var beyond : int64 = 0

--- a/lib/math/test/fpmath-fma-impl.myr

+++ b/lib/math/test/fpmath-fma-impl.myr

@@ -33,6 +33,8 @@

 		(0x7689f580, 0x91418000, 0xaa2822ae, 0xc8508e21),

 		(0xbd813cc0, 0x421f0000, 0x9f098e17, 0xc0208977),

 		(0x3745461a, 0x4db9b736, 0xb6d7deff, 0x458f1cd8),

+		(0xa3ccfd37, 0x7f800000, 0xed328e70, 0xff800000),

+		(0xa3790205, 0x5033a3e6, 0xa001fd11, 0xb42ebbd5),

 	][:]

 	for (x, y, z, r) : inputs