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* [Bug math/16576] New: PowerPC: glibc attempts to use fsqrt instruction on processors that do not implement it
@ 2014-02-13 15:43 adrian at humboldt dot co.uk
2014-02-13 17:32 ` [Bug math/16576] " joseph at codesourcery dot com
` (5 more replies)
0 siblings, 6 replies; 7+ messages in thread
From: adrian at humboldt dot co.uk @ 2014-02-13 15:43 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=16576
Bug ID: 16576
Summary: PowerPC: glibc attempts to use fsqrt instruction on
processors that do not implement it
Product: glibc
Version: unspecified
Status: NEW
Severity: normal
Priority: P2
Component: math
Assignee: unassigned at sourceware dot org
Reporter: adrian at humboldt dot co.uk
In sysdeps/powerpc/fpu/math_private.h, __CPU_HAS_FSQRT is set true on all 64
bit PowerPC processors. Recent 64-bit PowerPC processors (e5500 core) from
Freescale do not implement this instruction, causing any application using
sqrt() to fail.
28 # if __WORDSIZE == 64 || defined _ARCH_PWR4
29 # define __CPU_HAS_FSQRT 1
30 # else
31 # define __CPU_HAS_FSQRT ((GLRO(dl_hwcap) & PPC_FEATURE_64) != 0)
32 # endif
There is a patch for this in OpenEmbedded, but it provides a compile time fix
which is less useful for Linux distributions. A runtime probe for the existence
of the fsqrt instruction would be of wider use.
http://lists.openembedded.org/pipermail/openembedded-core/2012-September/068696.html
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* [Bug math/16576] [powerpc] glibc attempts to use fsqrt instruction on processors that do not implement it
2014-02-13 15:43 [Bug math/16576] New: PowerPC: glibc attempts to use fsqrt instruction on processors that do not implement it adrian at humboldt dot co.uk
2014-02-13 17:32 ` [Bug math/16576] " joseph at codesourcery dot com
@ 2014-02-13 17:32 ` jsm28 at gcc dot gnu.org
2014-02-13 19:59 ` adrian at humboldt dot co.uk
` (3 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: jsm28 at gcc dot gnu.org @ 2014-02-13 17:32 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=16576
Joseph Myers <jsm28 at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Host| |powerpc*-*-*
Summary|PowerPC: glibc attempts to |[powerpc] glibc attempts to
|use fsqrt instruction on |use fsqrt instruction on
|processors that do not |processors that do not
|implement it |implement it
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* [Bug math/16576] PowerPC: glibc attempts to use fsqrt instruction on processors that do not implement it
2014-02-13 15:43 [Bug math/16576] New: PowerPC: glibc attempts to use fsqrt instruction on processors that do not implement it adrian at humboldt dot co.uk
@ 2014-02-13 17:32 ` joseph at codesourcery dot com
2014-02-13 17:32 ` [Bug math/16576] [powerpc] " jsm28 at gcc dot gnu.org
` (4 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: joseph at codesourcery dot com @ 2014-02-13 17:32 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=16576
--- Comment #1 from joseph at codesourcery dot com <joseph at codesourcery dot com> ---
The correct compile-time test is _ARCH_PPCSQ (that's based on the same
condition GCC uses to decide whether to generate fsqrt instructions
itself). Not __WORDSIZE == 64, not _ARCH_PWR4.
Has Freescale (or anyone else) added an HWCAP / HWCAP2 bit to the kernel
to indicate whether fsqrt is available at runtime? That's what's needed
for any correct runtime probe (as opposed to the present incorrect probe
based on PPC_FEATURE_64).
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* [Bug math/16576] [powerpc] glibc attempts to use fsqrt instruction on processors that do not implement it
2014-02-13 15:43 [Bug math/16576] New: PowerPC: glibc attempts to use fsqrt instruction on processors that do not implement it adrian at humboldt dot co.uk
2014-02-13 17:32 ` [Bug math/16576] " joseph at codesourcery dot com
2014-02-13 17:32 ` [Bug math/16576] [powerpc] " jsm28 at gcc dot gnu.org
@ 2014-02-13 19:59 ` adrian at humboldt dot co.uk
2014-06-13 8:37 ` fweimer at redhat dot com
` (2 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: adrian at humboldt dot co.uk @ 2014-02-13 19:59 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=16576
--- Comment #2 from Adrian Cox <adrian at humboldt dot co.uk> ---
Unfortunately there is no HWCAP bit for the presence (or absence) of fsqrt.
The best I can find in the kernel source is that fsqrt is available if
PPC_FEATURE_64 is set and PPC_FEATURE_BOOKE is not set.
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* [Bug math/16576] [powerpc] glibc attempts to use fsqrt instruction on processors that do not implement it
2014-02-13 15:43 [Bug math/16576] New: PowerPC: glibc attempts to use fsqrt instruction on processors that do not implement it adrian at humboldt dot co.uk
` (2 preceding siblings ...)
2014-02-13 19:59 ` adrian at humboldt dot co.uk
@ 2014-06-13 8:37 ` fweimer at redhat dot com
2015-01-28 11:04 ` azanella at linux dot vnet.ibm.com
2015-01-28 11:04 ` azanella at linux dot vnet.ibm.com
5 siblings, 0 replies; 7+ messages in thread
From: fweimer at redhat dot com @ 2014-06-13 8:37 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=16576
Florian Weimer <fweimer at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Flags| |security-
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* [Bug math/16576] [powerpc] glibc attempts to use fsqrt instruction on processors that do not implement it
2014-02-13 15:43 [Bug math/16576] New: PowerPC: glibc attempts to use fsqrt instruction on processors that do not implement it adrian at humboldt dot co.uk
` (4 preceding siblings ...)
2015-01-28 11:04 ` azanella at linux dot vnet.ibm.com
@ 2015-01-28 11:04 ` azanella at linux dot vnet.ibm.com
5 siblings, 0 replies; 7+ messages in thread
From: azanella at linux dot vnet.ibm.com @ 2015-01-28 11:04 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=16576
Adhemerval Zanella Netto <azanella at linux dot vnet.ibm.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |azanella at linux dot vnet.ibm.com
--- Comment #3 from Adhemerval Zanella Netto <azanella at linux dot vnet.ibm.com> ---
Fixed upstream by 08cee2a464f614a6d4275b5af6c52481f1aa16e6.
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* [Bug math/16576] [powerpc] glibc attempts to use fsqrt instruction on processors that do not implement it
2014-02-13 15:43 [Bug math/16576] New: PowerPC: glibc attempts to use fsqrt instruction on processors that do not implement it adrian at humboldt dot co.uk
` (3 preceding siblings ...)
2014-06-13 8:37 ` fweimer at redhat dot com
@ 2015-01-28 11:04 ` azanella at linux dot vnet.ibm.com
2015-01-28 11:04 ` azanella at linux dot vnet.ibm.com
5 siblings, 0 replies; 7+ messages in thread
From: azanella at linux dot vnet.ibm.com @ 2015-01-28 11:04 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=16576
Adhemerval Zanella Netto <azanella at linux dot vnet.ibm.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution|--- |FIXED
--- Comment #4 from Adhemerval Zanella Netto <azanella at linux dot vnet.ibm.com> ---
Fixed upstream by 08cee2a464f614a6d4275b5af6c52481f1aa16e6.
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2014-02-13 15:43 [Bug math/16576] New: PowerPC: glibc attempts to use fsqrt instruction on processors that do not implement it adrian at humboldt dot co.uk
2014-02-13 17:32 ` [Bug math/16576] " joseph at codesourcery dot com
2014-02-13 17:32 ` [Bug math/16576] [powerpc] " jsm28 at gcc dot gnu.org
2014-02-13 19:59 ` adrian at humboldt dot co.uk
2014-06-13 8:37 ` fweimer at redhat dot com
2015-01-28 11:04 ` azanella at linux dot vnet.ibm.com
2015-01-28 11:04 ` azanella at linux dot vnet.ibm.com
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