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Date: Wed, 22 Apr 2020 13:56:46 +0000
From: leijitang <leijitang@...wei.com>
To: "musl@...ts.openwall.com" <musl@...ts.openwall.com>
CC: "zhangwentao (M)" <zhangwentao234@...wei.com>, "wanghao (H)"
<wanghao293@...wei.com>, "Huangqiang (H)" <h.huangqiang@...wei.com>
Subject: Unexpected exceptions in math functions
Hi all,
Recently we update musl in our project from 1.1.2 to version 1.2.0. But there are some errors about math functions when running
the opensource test cases for musl, which are passed in musl 1.1.2. These errors are about exp2(), pow() and powf().
Logs are listed below.
According to the commit message, the underflow exception is signaled if the result is in the subnormal range even if
the result is exact (e.g. exp2(-1023.0)). But we got INEXACT exception at the same time, which is not as expected.
Is this a problem?
Otherwise, there is a overflow exception in powf(0x1.fffffep+127,0x1p+0) with FE_UPWARD rounding mode(log is also behind. As
0x1.fffffep+127 is the largest number that float can represent, there should not be INEXACT|OVERFLOW exceptions.
If these are problems affirmed, is there any patch to fix this?
/ $ ./exp2.exe
src/math/special/exp2.h:12: bad fp exception: RN exp2(-0x1.ff8p+9)=0x1p-1023, want 0 got INEXACT|UNDERFLOW
src/math/special/exp2.h:18: bad fp exception: RN exp2(-0x1.ff8p+9)=0x1p-1023, want 0 got INEXACT|UNDERFLOW
src/math/special/exp2.h:20: bad fp exception: RN exp2(-0x1p+10)=0x1p-1024, want 0 got INEXACT|UNDERFLOW
src/math/special/exp2.h:21: bad fp exception: RN exp2(-0x1.004p+10)=0x1p-1025, want 0 got INEXACT|UNDERFLOW
src/math/special/exp2.h:22: bad fp exception: RN exp2(-0x1.0c8p+10)=0x1p-1074, want 0 got INEXACT|UNDERFLOW
/ $ ./pow.exe
src/math/crlibm/pow.h:13: bad fp exception: RN pow(0x1p+1,-0x1.0c8p+10)=0x1p-1074, want 0 got INEXACT|UNDERFLOW
src/math/ucb/pow.h:72: bad fp exception: RN pow(0x1p-1074,0x1p+0)=0x1p-1074, want 0 got INEXACT|UNDERFLOW
src/math/ucb/pow.h:73: bad fp exception: RN pow(0x1p-1042,0x1p+0)=0x1p-1042, want 0 got INEXACT|UNDERFLOW
src/math/ucb/pow.h:75: bad fp exception: RN pow(-0x1p-1074,0x1p+0)=-0x1p-1074, want 0 got INEXACT|UNDERFLOW
src/math/ucb/pow.h:76: bad fp exception: RN pow(-0x1p-1042,0x1p+0)=-0x1p-1042, want 0 got INEXACT|UNDERFLOW
src/math/ucb/pow.h:284: bad fp exception: RN pow(0x1p-1073,0x1p+0)=0x1p-1073, want 0 got INEXACT|UNDERFLOW
src/math/ucb/pow.h:300: bad fp exception: RN pow(0x1p-1024,0x1p+0)=0x1p-1024, want 0 got INEXACT|UNDERFLOW
src/math/ucb/pow.h:304: bad fp exception: RN pow(0x1p-1023,0x1p+0)=0x1p-1023, want 0 got INEXACT|UNDERFLOW
src/math/ucb/pow.h:310: bad fp exception: RN pow(0x1.ffffffffffffcp-1023,0x1p+0)=0x1.ffffffffffffcp-1023, want 0 got INEXACT|UNDERFLOW
src/math/ucb/pow.h:313: bad fp exception: RN pow(0x1.ffffffffffffep-1023,0x1p+0)=0x1.ffffffffffffep-1023, want 0 got INEXACT|UNDERFLOW
src/math/ucb/pow.h:338: bad fp exception: RN pow(0x1p-537,0x1p+1)=0x1p-1074, want 0 got INEXACT|UNDERFLOW
src/math/ucb/pow.h:437: bad fp exception: RN pow(0x1p+1,-0x1.0c8p+10)=0x1p-1074, want 0 got INEXACT|UNDERFLOW
src/math/ucb/pow.h:498: bad fp exception: RN pow(0x1p+350,-0x1.8p+1)=0x1p-1050, want 0 got INEXACT|UNDERFLOW
src/math/ucb/pow.h:499: bad fp exception: RN pow(0x1p+700,-0x1.8p+0)=0x1p-1050, want 0 got INEXACT|UNDERFLOW
src/math/ucb/pow.h:516: bad fp exception: RN pow(0x1p+1023,-0x1p+0)=0x1p-1023, want 0 got INEXACT|UNDERFLOW
src/math/ucb/pow.h:544: bad fp exception: RN pow(-0x1p-1073,0x1p+0)=-0x1p-1073, want 0 got INEXACT|UNDERFLOW
src/math/ucb/pow.h:548: bad fp exception: RN pow(-0x1p-1024,0x1p+0)=-0x1p-1024, want 0 got INEXACT|UNDERFLOW
src/math/ucb/pow.h:551: bad fp exception: RN pow(-0x1p-1023,0x1p+0)=-0x1p-1023, want 0 got INEXACT|UNDERFLOW
src/math/ucb/pow.h:557: bad fp exception: RN pow(-0x1.ffffffffffffcp-1023,0x1p+0)=-0x1.ffffffffffffcp-1023, want 0 got INEXACT|UNDERFLOW
src/math/ucb/pow.h:560: bad fp exception: RN pow(-0x1.ffffffffffffep-1023,0x1p+0)=-0x1.ffffffffffffep-1023, want 0 got INEXACT|UNDERFLOW
src/math/ucb/pow.h:581: bad fp exception: RN pow(-0x1p-537,0x1p+1)=0x1p-1074, want 0 got INEXACT|UNDERFLOW
src/math/ucb/pow.h:655: bad fp exception: RN pow(-0x1p+1,-0x1.0c8p+10)=0x1p-1074, want 0 got INEXACT|UNDERFLOW
src/math/ucb/pow.h:695: bad fp exception: RN pow(-0x1p+350,-0x1.8p+1)=-0x1p-1050, want 0 got INEXACT|UNDERFLOW
src/math/ucb/pow.h:708: bad fp exception: RN pow(-0x1p+1023,-0x1p+0)=-0x1p-1023, want 0 got INEXACT|UNDERFLOW
/ $ ./powf.exe
src/math/ucb/powf.h:103: bad fp exception: RU powf(0x1.fffffep+127,0x1p+0)=0x1.fffffep+127, want 0 got INEXACT|OVERFLOW
src/math/ucb/powf.h:530: bad fp exception: RN powf(0x1.fffff8p-127,0x1p+0)=0x1.fffff8p-127, want 0 got INEXACT|UNDERFLOW
src/math/ucb/powf.h:533: bad fp exception: RN powf(0x1.fffffcp-127,0x1p+0)=0x1.fffffcp-127, want 0 got INEXACT|UNDERFLOW
src/math/ucb/powf.h:719: bad fp exception: RN powf(-0x1.fffff8p-127,0x1p+0)=-0x1.fffff8p-127, want 0 got INEXACT|UNDERFLOW
src/math/ucb/powf.h:722: bad fp exception: RN powf(-0x1.fffffcp-127,0x1p+0)=-0x1.fffffcp-127, want 0 got INEXACT|UNDERFLOW
Regards
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