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-rw-r--r--sysdeps/x86_64/fpu/e_log2l.S8
1 files changed, 7 insertions, 1 deletions
diff --git a/sysdeps/x86_64/fpu/e_log2l.S b/sysdeps/x86_64/fpu/e_log2l.S
index c12906d456..a063255ddd 100644
--- a/sysdeps/x86_64/fpu/e_log2l.S
+++ b/sysdeps/x86_64/fpu/e_log2l.S
@@ -78,7 +78,13 @@ ENTRY(__log2l_finite)
fnstsw // x-1 : x : 1
andb $0x45, %ah
jz 2b
- fstp %st(1) // x-1 : 1
+ fxam
+ fnstsw
+ andb $0x45, %ah
+ cmpb $0x40, %ah
+ jne 6f
+ fabs // log2(1) is +0 in all rounding modes.
+6: fstp %st(1) // x-1 : 1
fyl2xp1 // log(x)
ret
END (__log2l_finite)