From: Szabolcs Nagy <nsz@port70.net>
Date: Thu, 5 Sep 2013 12:23:44 +0000 (+0000)
Subject: math: fix expm1l on x86_64 (avoid underflow for large negative x)
X-Git-Tag: v0.9.14~26
X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=02343946215a7ae03634c6490abcc69da68df589;p=oweals%2Fmusl.git

math: fix expm1l on x86_64 (avoid underflow for large negative x)

copy the fix from i386: return -1 instead of exp2l(x)-1 when x <= -65
---

diff --git a/src/math/x86_64/ceill.s b/src/math/x86_64/ceill.s
index bc29f15c..f5cfa3b3 100644
--- a/src/math/x86_64/ceill.s
+++ b/src/math/x86_64/ceill.s
@@ -1 +1 @@
-# see floor.s
+# see floorl.s
diff --git a/src/math/x86_64/exp2l.s b/src/math/x86_64/exp2l.s
index e7145881..0d6cd563 100644
--- a/src/math/x86_64/exp2l.s
+++ b/src/math/x86_64/exp2l.s
@@ -4,8 +4,18 @@ expm1l:
 	fldt 8(%rsp)
 	fldl2e
 	fmulp
+	movl $0xc2820000,-4(%rsp)
+	flds -4(%rsp)
+	fucomp %st(1)
+	fnstsw %ax
+	sahf
 	fld1
-	fld %st(1)
+	jb 1f
+		# x*log2e <= -65, return -1 without underflow
+	fstp %st(1)
+	fchs
+	ret
+1:	fld %st(1)
 	fabs
 	fucom %st(1)
 	fnstsw %ax
diff --git a/src/math/x86_64/truncl.s b/src/math/x86_64/truncl.s
index bc29f15c..f5cfa3b3 100644
--- a/src/math/x86_64/truncl.s
+++ b/src/math/x86_64/truncl.s
@@ -1 +1 @@
-# see floor.s
+# see floorl.s