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-rw-r--r--sysdeps/libm-i387/s_log1p.S54
1 files changed, 46 insertions, 8 deletions
diff --git a/sysdeps/libm-i387/s_log1p.S b/sysdeps/libm-i387/s_log1p.S
index ce8665d3a5..10e8a36369 100644
--- a/sysdeps/libm-i387/s_log1p.S
+++ b/sysdeps/libm-i387/s_log1p.S
@@ -7,18 +7,56 @@
 
 RCSID("$NetBSD: s_log1p.S,v 1.7 1995/05/09 00:10:58 jtc Exp $")
 
+#ifdef __ELF__
+	.section .rodata
+#else
+	.text
+#endif
+	.align ALIGNARG(4)
+	/* The fyl2xp1 can only be used for values in
+		-1 + sqrt(2) / 2 <= x <= 1 - sqrt(2) / 2
+	   0.29 is a safe value.
+	*/
+limit:	.double 0.29
+one:	.double 1.0
+
 /*
- * Since the fyl2xp1 instruction has such a limited range:
- *	-(1 - (sqrt(2) / 2)) <= x <= sqrt(2) - 1
- * it's not worth trying to use it.
+ * Use the fyl2xp1 function when the argument is in the range -0.29 to 0.29,
+ * otherwise fyl2x with the needed extra computation.
  */
-
+	.text
 ENTRY(__log1p)
 	fldln2
-	fldl 4(%esp)
-	fld1
-	faddp
+
+	fldl	4(%esp)
+
+#ifdef	PIC
+	call	1f
+1:	popl	%edx
+	addl	$_GLOBAL_OFFSET_TABLE_+[.-1b], %edx
+#endif
+
+	fld	%st
+	fabs
+#ifdef PIC
+	fcompl	limit@GOTOFF(%edx)
+#else
+	fcompl	limit
+#endif
+	fnstsw
+	sahf
+	jc	2f
+
+#ifdef PIC
+	faddl	one@GOTOFF(%edx)
+#else
+	faddl	one
+#endif
 	fyl2x
 	ret
-PSEUDO_END (__log1p)
+
+2:	fyl2xp1
+	ret
+
+END (__log1p)
 weak_alias (__log1p, log1p)