math: fix x86 asin, atan, exp, log1p to raise underflow

[musl] / src / math / i386 / log1p.s

diff --git a/src/math/i386/log1p.s b/src/math/i386/log1p.s
index 9971e53..6b6929c 100644 (file)
--- a/src/math/i386/log1p.s
+++ b/src/math/i386/log1p.s
@@ -7,9 +7,18 @@ log1p:
        fldl 4(%esp)
        cmp $0x3fd28f00,%eax
        ja 1f
+       cmp $0x00100000,%eax
+       jb 2f
        fyl2xp1
        ret
 1:     fld1
        faddp
        fyl2x
        ret
+               # subnormal x, return x with underflow
+2:     fnstsw %ax
+       and $16,%ax
+       jnz 1f
+       fsts 4(%esp)
+       fstp %st(1)
+1:     ret