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[Bug math/18875] New: Excess precision leads incorrect libm
- From: "hjl.tools at gmail dot com" <sourceware-bugzilla at sourceware dot org>
- To: glibc-bugs at sourceware dot org
- Date: Wed, 26 Aug 2015 12:50:42 +0000
- Subject: [Bug math/18875] New: Excess precision leads incorrect libm
- Auto-submitted: auto-generated
https://sourceware.org/bugzilla/show_bug.cgi?id=18875
Bug ID: 18875
Summary: Excess precision leads incorrect libm
Product: glibc
Version: unspecified
Status: NEW
Severity: normal
Priority: P2
Component: math
Assignee: unassigned at sourceware dot org
Reporter: hjl.tools at gmail dot com
Target Milestone: ---
Target: x86
sysdeps/ieee754/flt-32/w_expf.c has
if (__builtin_expect (!isfinite (z) || z == 0, 0)
On x86 with excess precision, we got
(gdb) info float
=>R7: Valid 0x3d30e0d9b4d78a806800 +6.369668676344082156e-217
R6: Empty 0x40029000000000000000
and z (+6.369668676344082156e-217) == 0 became false. This
leads to
Failure: exp (-0x1.f1cf36p+8): errno set to 0, expected 34 (ERANGE)
Failure: exp_downward (-0x1.f1cf36p+8): errno set to 0, expected 34 (ERANGE)
Failure: exp_towardzero (-0x1.f1cf36p+8): errno set to 0, expected 34 (ERANGE)
in math/test-float.out. This may also be the cause for
Failure: exp10 (-0x1.31p+8): errno set to 0, expected 34 (ERANGE)
Failure: exp10 (-0x1.343792p+12): errno set to 0, expected 34 (ERANGE)
Failure: exp10 (-0x1.343794p+12): errno set to 0, expected 34 (ERANGE)
Failure: exp10 (-0x1.344p+12): errno set to 0, expected 34 (ERANGE)
Failure: exp10_downward (-0x1.31p+8): errno set to 0, expected 34 (ERANGE)
Failure: exp10_downward (-0x1.343792p+12): errno set to 0, expected 34 (ERANGE)
Failure: exp10_downward (-0x1.343794p+12): errno set to 0, expected 34 (ERANGE)
Failure: exp10_downward (-0x1.344p+12): errno set to 0, expected 34 (ERANGE)
Failure: exp10_towardzero (-0x1.31p+8): errno set to 0, expected 34 (ERANGE)
Failure: exp10_towardzero (-0x1.343792p+12): errno set to 0, expected 34
(ERANGE)
Failure: exp10_towardzero (-0x1.343794p+12): errno set to 0, expected 34
(ERANGE)
Failure: exp10_towardzero (-0x1.344p+12): errno set to 0, expected 34 (ERANGE)
Failure: exp2 (-0x1.3045fep+8): errno set to 0, expected 34 (ERANGE)
Failure: exp2 (-0x3.fb8p+8): errno set to 0, expected 34 (ERANGE)
Failure: exp2 (-0x3.fc8p+8): errno set to 0, expected 34 (ERANGE)
Failure: exp2 (-0x3.fd8p+8): errno set to 0, expected 34 (ERANGE)
Failure: exp2 (-0x4.01p+12): errno set to 0, expected 34 (ERANGE)
Failure: exp2 (-0x4.32p+8): errno set to 0, expected 34 (ERANGE)
Failure: exp2_downward (-0x1.3045fep+8): errno set to 0, expected 34 (ERANGE)
Failure: exp2_downward (-0x3.fb8p+8): errno set to 0, expected 34 (ERANGE)
Failure: exp2_downward (-0x3.fc8p+8): errno set to 0, expected 34 (ERANGE)
Failure: exp2_downward (-0x3.fd8p+8): errno set to 0, expected 34 (ERANGE)
Failure: exp2_downward (-0x4.01p+12): errno set to 0, expected 34 (ERANGE)
Failure: exp2_downward (-0x4.32p+8): errno set to 0, expected 34 (ERANGE)
Failure: exp2_towardzero (-0x1.3045fep+8): errno set to 0, expected 34 (ERANGE)
Failure: exp2_towardzero (-0x3.fb8p+8): errno set to 0, expected 34 (ERANGE)
Failure: exp2_towardzero (-0x3.fc8p+8): errno set to 0, expected 34 (ERANGE)
Failure: exp2_towardzero (-0x3.fd8p+8): errno set to 0, expected 34 (ERANGE)
Failure: exp2_towardzero (-0x4.01p+12): errno set to 0, expected 34 (ERANGE)
Failure: exp2_towardzero (-0x4.32p+8): errno set to 0, expected 34 (ERANGE)
Failure: pow10 (-0x1.31p+8): errno set to 0, expected 34 (ERANGE)
Failure: pow10 (-0x1.343792p+12): errno set to 0, expected 34 (ERANGE)
Failure: pow10 (-0x1.343794p+12): errno set to 0, expected 34 (ERANGE)
Failure: pow10 (-0x1.344p+12): errno set to 0, expected 34 (ERANGE)
Failure: pow10_downward (-0x1.31p+8): errno set to 0, expected 34 (ERANGE)
Failure: pow10_downward (-0x1.343792p+12): errno set to 0, expected 34 (ERANGE)
Failure: pow10_downward (-0x1.343794p+12): errno set to 0, expected 34 (ERANGE)
Failure: pow10_downward (-0x1.344p+12): errno set to 0, expected 34 (ERANGE)
Failure: pow10_towardzero (-0x1.31p+8): errno set to 0, expected 34 (ERANGE)
Failure: pow10_towardzero (-0x1.343792p+12): errno set to 0, expected 34
(ERANGE)
Failure: pow10_towardzero (-0x1.343794p+12): errno set to 0, expected 34
(ERANGE)
Failure: pow10_towardzero (-0x1.344p+12): errno set to 0, expected 34 (ERANGE)
in math/test-float.out on i686.
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