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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
This commit is contained in:
drochner 2006-08-01 20:14:35 +00:00
parent b6116cb922
commit d81b3ce220
2 changed files with 13 additions and 5 deletions
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10
lib/libm/src/lrintf.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: lrintf.c,v 1.3 2004/10/13 15:18:32 drochner Exp $ */
/* $NetBSD: lrintf.c,v 1.4 2006/08/01 20:14:35 drochner Exp $ */
/*-
* Copyright (c) 2004
@ -52,6 +52,10 @@ 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;
@ -68,8 +72,8 @@ 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);

8
lib/libm/src/s_rintf.c
View File

@ -15,7 +15,7 @@
#include <sys/cdefs.h>
#if defined(LIBM_SCCS) && !defined(lint)
__RCSID("$NetBSD: s_rintf.c,v 1.7 2002/05/26 22:01:58 wiz Exp $");
__RCSID("$NetBSD: s_rintf.c,v 1.8 2006/08/01 20:14:35 drochner Exp $");
#endif
#include "math.h"
@ -32,7 +32,11 @@ 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;