From e1418cfe3e313f0646f374c0ab4e86a29069deef Mon Sep 17 00:00:00 2001
From: Peter Avalos <pavalos@dragonflybsd.org>
Date: Sun, 17 Jun 2007 02:27:53 +0000
Subject: [PATCH] make an intermediate float variable "volatile" on i386 to
 work around a gcc optimization problem: subsequent add/subs were done inside
 FPU registers, with "double" precision, without rounding to "float" in
 between

Obtained-from:  NetBSD
---
 lib/libm/src/lrintf.c  | 12 ++++++++----
 lib/libm/src/s_rintf.c | 10 +++++++---
 2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/lib/libm/src/lrintf.c b/lib/libm/src/lrintf.c
index e65b880d76..3ad9fee418 100644
--- a/lib/libm/src/lrintf.c
+++ b/lib/libm/src/lrintf.c
@@ -23,8 +23,8 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- * $NetBSD: lrintf.c,v 1.3 2004/10/13 15:18:32 drochner Exp $
- * $DragonFly: src/lib/libm/src/lrintf.c,v 1.1 2005/07/26 21:15:20 joerg Exp $
+ * $NetBSD: lrintf.c,v 1.4 2006/08/01 20:14:35 drochner Exp $
+ * $DragonFly: src/lib/libm/src/lrintf.c,v 1.2 2007/06/17 02:27:53 pavalos Exp $
  */
 
 #include <math.h>
@@ -53,6 +53,10 @@ LRINTNAME(float x)
 	u_int32_t i0;
 	int e, s, shift;
 	RESTYPE res;
+#ifdef __i386__ /* XXX gcc4 will omit the rounding otherwise */
+	volatile
+#endif
+		float w;
 
 	GET_FLOAT_WORD(i0, x);
 	e = i0 >> SNG_FRACBITS;
@@ -69,8 +73,8 @@ LRINTNAME(float x)
 	/* >= 2^23 is already an exact integer */
 	if (e < SNG_FRACBITS) {
 		/* round, using current direction */
-		x += TWO23[s];
-		x -= TWO23[s];
+		w = TWO23[s] + x;
+		x = w - TWO23[s];
 	}
 
 	GET_FLOAT_WORD(i0, x);
diff --git a/lib/libm/src/s_rintf.c b/lib/libm/src/s_rintf.c
index 9ec603b0ab..0790312fad 100644
--- a/lib/libm/src/s_rintf.c
+++ b/lib/libm/src/s_rintf.c
@@ -12,8 +12,8 @@
  * is preserved.
  * ====================================================
  *
- * $NetBSD: s_rintf.c,v 1.7 2002/05/26 22:01:58 wiz Exp $
- * $DragonFly: src/lib/libm/src/s_rintf.c,v 1.1 2005/07/26 21:15:20 joerg Exp $
+ * $NetBSD: s_rintf.c,v 1.8 2006/08/01 20:14:35 drochner Exp $
+ * $DragonFly: src/lib/libm/src/s_rintf.c,v 1.2 2007/06/17 02:27:53 pavalos Exp $
  */
 
 #include <math.h>
@@ -30,7 +30,11 @@ rintf(float x)
 {
 	int32_t i0,j0,sx;
 	u_int32_t i,i1;
-	float w,t;
+#ifdef __i386__ /* XXX gcc4 will omit the rounding otherwise */
+	volatile
+#endif
+		float w;
+	float t;
 	GET_FLOAT_WORD(i0,x);
 	sx = (i0>>31)&1;
 	j0 = ((i0>>23)&0xff)-0x7f;
-- 
2.41.0