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Date: Tue, 14 Oct 2014 15:09:45 +0800
From: "bobodog" <8192542@...com>
To: "musl" <musl@...ts.openwall.com>
Subject: RE：[BUG][math]build musl with optimizing flags, some math functions are broken.
Further confirmation, the problem is -ffast-math flag, just remove this flag, all tests passed, please fix this bug, the openbsd's msun math library, have not any problem with this flags.
may be say to Szabolcs Nagy<nsz@...t70.net>, his work is comming, found big bug ^_^
------------------
____________________________
蒋建军
深圳市九鼎创展科技有限公司
地址：深圳市宝安区西乡街道宝源路宝安互联网产业基地A区7栋301
邮编：518101
手机：18665386306
电邮：8192542@...com
网站：http://www.9tripod.com
论坛：http://xboot.org
------------------ 原始邮件 ------------------
发件人: "8192542";<8192542@...com>;
发送时间: 2014年10月14日(星期二) 下午2:43
收件人: "musl"<musl@...ts.openwall.com>;
主题: [BUG][math]build musl with optimizing flags, some math functions are broken.
HI, ALL:
Here is the detail steps, and will show bugs.
1) enter the musl's source code
cd /home/jjj/test/musl/
2) pull the newest codes
git pull origin master
3) export some toolchains, (Sourcery CodeBench Lite arm-2013.05-23-arm-none-eabi-i686-pc-linux-gnu.tar.bz2)
export PATH=$PATH:/home/jjj/software/eclipse-kepler-for-arm-gtk-linux-x86_64/compiler/arm-2013.05/bin/
4) configure musl to arm target
CC=arm-none-eabi-gcc CFLAGS="-mcpu=cortex-a8 -mtune=cortex-a8 -march=armv7-a -mfpu=neon -ftree-vectorize -ffast-math -mfloat-abi=softfp" ./configure --target=arm --prefix=/home/jjj/test/musl/usr/local/musl/
5) compiler musl and install
make
make install
6) export REALGCC to arm linux toolchains
export REALGCC=arm-none-eabi-gcc
7) write test cases and save to test.c
#include <stdio.h>
#include <math.h>
int main(int argc, char ** argv)
{
double n = 0.0;
int i;
for(i = 0; i < 20; i++)
{
n = n - 0.125;
printf("ceil(%f) = %f, floor(%f) = %f, round(%f) = %f\n", n, ceil(n), n, floor(n), n, round(n));
}
return 0;
}
8) compile test cases
./tools/musl-gcc test.c -o test -static
9) file test, will showing: test: ELF 32-bit LSB executable, ARM, version 1 (SYSV), statically linked, not stripped
file test
10) running test case using qemu-arm
qemu-arm test
11) result...
ceil(-0.125000) = 0.000000, floor(-0.125000) = -1.000000, round(-0.125000) = 0.000000
ceil(-0.250000) = 0.000000, floor(-0.250000) = -1.000000, round(-0.250000) = 0.000000
ceil(-0.375000) = 0.000000, floor(-0.375000) = -1.000000, round(-0.375000) = 0.000000
ceil(-0.500000) = 0.000000, floor(-0.500000) = -1.000000, round(-0.500000) = -0.500000
ceil(-0.625000) = 0.000000, floor(-0.625000) = -1.000000, round(-0.625000) = -0.625000
ceil(-0.750000) = 0.000000, floor(-0.750000) = -1.000000, round(-0.750000) = -0.750000
ceil(-0.875000) = 0.000000, floor(-0.875000) = -1.000000, round(-0.875000) = -0.875000
ceil(-1.000000) = -1.000000, floor(-1.000000) = -1.000000, round(-1.000000) = -1.000000
ceil(-1.125000) = -1.125000, floor(-1.125000) = -1.125000, round(-1.125000) = -1.125000
ceil(-1.250000) = -1.250000, floor(-1.250000) = -1.250000, round(-1.250000) = -1.250000
ceil(-1.375000) = -1.375000, floor(-1.375000) = -1.375000, round(-1.375000) = -1.375000
ceil(-1.500000) = -1.500000, floor(-1.500000) = -1.500000, round(-1.500000) = -1.500000
ceil(-1.625000) = -1.625000, floor(-1.625000) = -1.625000, round(-1.625000) = -1.625000
ceil(-1.750000) = -1.750000, floor(-1.750000) = -1.750000, round(-1.750000) = -1.750000
ceil(-1.875000) = -1.875000, floor(-1.875000) = -1.875000, round(-1.875000) = -1.875000
ceil(-2.000000) = -2.000000, floor(-2.000000) = -2.000000, round(-2.000000) = -2.000000
ceil(-2.125000) = -2.125000, floor(-2.125000) = -2.125000, round(-2.125000) = -2.125000
ceil(-2.250000) = -2.250000, floor(-2.250000) = -2.250000, round(-2.250000) = -2.250000
ceil(-2.375000) = -2.375000, floor(-2.375000) = -2.375000, round(-2.375000) = -2.375000
ceil(-2.500000) = -2.500000, floor(-2.500000) = -2.500000, round(-2.500000) = -2.500000
please some body to fix these bugs, optimizing flags is very important for embedded platform,
____________________________
蒋建军
深圳市九鼎创展科技有限公司
地址：深圳市宝安区西乡街道宝源路宝安互联网产业基地A区7栋301
邮编：518101
手机：18665386306
电邮：8192542@...com
网站：http://www.9tripod.com
论坛：http://xboot.org
------------------ 原始邮件 ------------------
发件人: "8192542";<8192542@...com>;
发送时间: 2014年10月14日(星期二) 下午2:26
收件人: "musl"<musl@...ts.openwall.com>;
主题: RE：[musl ] [math] I Found math library's bug in ceil, floor, round functions, Using arm toolchains
HI, ALL
I found basic math functions bug, include ceil ,floor, round ... when using arm toolchains.
Here is the patch file, just for ceil.c :
diff --git a/src/math/ceil.c b/src/math/ceil.c
index 22dc224..8634145 100644
--- a/src/math/ceil.c
+++ b/src/math/ceil.c
@@ -4,15 +4,16 @@ double ceil(double x)
{
union {double f; uint64_t i;} u = {x};
int e = u.i >> 52 & 0x7ff;
+ uint64_t n = 0x1p52;
double_t y;
if (e >= 0x3ff+52 || x == 0)
return x;
/* y = int(x) - x, where int(x) is an integer neighbor of x */
if (u.i >> 63)
- y = (double)(x - 0x1p52) + 0x1p52 - x;
+ y = (double)(x - n) + n - x;
else
- y = (double)(x + 0x1p52) - 0x1p52 - x;
+ y = (double)(x + n) - n - x;
/* special case because of non-nearest rounding modes */
if (e <= 0x3ff-1) {
FORCE_EVAL(y);
To solve this problem, must define a variate: uint64_t n = 0x1p52;
using n to instead of 0x1p52, then all result are correctly.
The compile flags:
MCFLAGS := -mcpu=cortex-a8 -mtune=cortex-a8 -march=armv7-a -mfpu=neon -ftree-vectorize -ffast-math -mfloat-abi=softfp
I belive, when using this flags, the bug will happen. any one tell me how to solve it. we need optimizing flags to compile musl libc.
Thanks Rich Felker's help!
------------------
____________________________
蒋建军
深圳市九鼎创展科技有限公司
地址：深圳市宝安区西乡街道宝源路宝安互联网产业基地A区7栋301
邮编：518101
手机：18665386306
电邮：8192542@...com
网站：http://www.9tripod.com
论坛：http://xboot.org
------------------ 原始邮件 ------------------
发件人: "8192542";<8192542@...com>;
发送时间: 2014年10月14日(星期二) 中午12:11
收件人: "musl"<musl@...ts.openwall.com>;
抄送: "musl"<musl@...ts.openwall.com>;
主题: 回复： [musl] 回复： [musl ] [math] The math library have some bugforceil,floor,round functioin, in arm mode
1) enter the musl's source code
cd /home/jjj/test/musl/
2) pull the newest codes
git pull origin master
3) export some toolchains
export PATH=$PATH:/home/jjj/9tripod/android_exynos4412_ics_rtm_v10/prebuilt/linux-x86/toolchain/arm-2009q3/bin/
4) configure musl to arm target
CC=arm-none-linux-gnueabi-gcc ./configure --target=arm --prefix=/home/jjj/test/musl/usr/local/musl/
5) compiler musl and install
make
make install
6) export REALGCC to arm linux toolchains
export REALGCC=arm-none-linux-gnueabi-gcc
7) write test cases and save to test.c
#include <stdio.h>
#include <math.h>
int main(int argc, char ** argv)
{
double n = 0.0;
int i;
for(i = 0; i < 20; i++)
{
n = n - 0.125;
printf("ceil(%f) = %f, floor(%f) = %f, round(%f) = %f\n", n, ceil(n), n, floor(n), n, round(n));
}
return 0;
}
8) compile test cases
./tools/musl-gcc test.c -o test -static
9) file test, will showing: test: ELF 32-bit LSB executable, ARM, version 1 (SYSV), statically linked, not stripped
file test
10) running test case using qemu-arm
qemu-arm test
11) result...
ceil(-0.125000) = -0.000000, floor(-0.125000) = -1.000000, round(-0.125000) = -0.000000
ceil(-0.250000) = -0.000000, floor(-0.250000) = -1.000000, round(-0.250000) = -0.000000
ceil(-0.375000) = -0.000000, floor(-0.375000) = -1.000000, round(-0.375000) = -0.000000
ceil(-0.500000) = -0.000000, floor(-0.500000) = -1.000000, round(-0.500000) = -1.000000
ceil(-0.625000) = -0.000000, floor(-0.625000) = -1.000000, round(-0.625000) = -1.000000
ceil(-0.750000) = -0.000000, floor(-0.750000) = -1.000000, round(-0.750000) = -1.000000
ceil(-0.875000) = -0.000000, floor(-0.875000) = -1.000000, round(-0.875000) = -1.000000
ceil(-1.000000) = -1.000000, floor(-1.000000) = -1.000000, round(-1.000000) = -1.000000
ceil(-1.125000) = -1.000000, floor(-1.125000) = -2.000000, round(-1.125000) = -1.000000
ceil(-1.250000) = -1.000000, floor(-1.250000) = -2.000000, round(-1.250000) = -1.000000
ceil(-1.375000) = -1.000000, floor(-1.375000) = -2.000000, round(-1.375000) = -1.000000
ceil(-1.500000) = -1.000000, floor(-1.500000) = -2.000000, round(-1.500000) = -2.000000
ceil(-1.625000) = -1.000000, floor(-1.625000) = -2.000000, round(-1.625000) = -2.000000
ceil(-1.750000) = -1.000000, floor(-1.750000) = -2.000000, round(-1.750000) = -2.000000
ceil(-1.875000) = -1.000000, floor(-1.875000) = -2.000000, round(-1.875000) = -2.000000
ceil(-2.000000) = -2.000000, floor(-2.000000) = -2.000000, round(-2.000000) = -2.000000
ceil(-2.125000) = -2.000000, floor(-2.125000) = -3.000000, round(-2.125000) = -2.000000
ceil(-2.250000) = -2.000000, floor(-2.250000) = -3.000000, round(-2.250000) = -2.000000
ceil(-2.375000) = -2.000000, floor(-2.375000) = -3.000000, round(-2.375000) = -2.000000
ceil(-2.500000) = -2.000000, floor(-2.500000) = -3.000000, round(-2.500000) = -3.000000
Using qemu-arm, the result is correct. we will test in real hardware and review result, and find bug somewhere
------------------
____________________________
蒋建军
深圳市九鼎创展科技有限公司
地址：深圳市宝安区西乡街道宝源路宝安互联网产业基地A区7栋301
邮编：518101
手机：18665386306
电邮：8192542@...com
网站：http://www.9tripod.com
论坛：http://xboot.org
------------------ 原始邮件 ------------------
发件人: "Rich Felker";<dalias@...c.org>;
发送时间: 2014年10月14日(星期二) 中午11:03
收件人: "bobodog"<8192542@...com>;
抄送: "musl"<musl@...ts.openwall.com>;
主题: Re: [musl] 回复： [musl ] [math] The math library have some bugforceil,floor,round functioin, in arm mode
On Tue, Oct 14, 2014 at 10:51:58AM +0800, bobodog wrote:
> Test it in qemu-system-arm, with soft fp, realview-pb-a8 platform
>
> we porting musl to our project, and just write test functions to
> test cases, i don't kown, how to test musl in origin test cases.
Can you show a complete test program with correct prototypes for
printf, ceil, floor, and round that exhibits the problem for you?
Rich
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