From 31c5fb80b9eae86f801be4f46025bc6532a554c5 Mon Sep 17 00:00:00 2001
From: Szabolcs Nagy <nsz@port70.net>
Date: Thu, 15 Aug 2013 10:56:57 +0000
Subject: math: fix x86 asin, atan, exp, log1p to raise underflow

underflow is raised by an inexact subnormal float store,
since subnormal operations are slow, check the underflow
flag and skip the store if it's already raised
---
 src/math/i386/atanf.s | 12 ++++++++++++
 1 file changed, 12 insertions(+)

(limited to 'src/math/i386/atanf.s')

diff --git a/src/math/i386/atanf.s b/src/math/i386/atanf.s
index 3cd40233..8caddefa 100644
--- a/src/math/i386/atanf.s
+++ b/src/math/i386/atanf.s
@@ -2,6 +2,18 @@
 .type atanf,@function
 atanf:
 	flds 4(%esp)
+	mov 4(%esp),%eax
+	add %eax,%eax
+	cmp $0x01000000,%eax
+	jb 1f
 	fld1
 	fpatan
 	ret
+		# subnormal x, return x with underflow
+1:	fnstsw %ax
+	and $16,%ax
+	jnz 2f
+	fld %st(0)
+	fmul %st(1)
+	fstps 4(%esp)
+2:	ret
-- 
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