GCC 4.8 enables -ftree-loop-distribute-patterns at -O3 by default and
this optimization may transform loops into memset/memmove calls. Without
proper handling this may generate unexpected PLT calls on GLIBC.
This patch fixes by create memset/memmove alias to internal GLIBC
__GI_memset/__GI_memmove symbols.
The most common use case of math functions is with default rounding
mode, i.e. rounding to nearest. Setting and restoring rounding mode
is an unnecessary overhead for this, so I've added support for a
context, which does the set/restore only if the FP status needs a
change. The code is written such that only x86 uses these. Other
architectures should be unaffected by it, but would definitely benefit
if the set/restore has as much overhead relative to the rest of the
code, as the x86 bits do.
Here's a summary of the performance improvement due to these
improvements; I've only mentioned functions that use the set/restore
and have benchmark inputs for x86_64:
Begin porting string performance tests to benchtests
This is the initial support for string function performance tests,
along with copying tests for memcpy and memcpy-ifunc as proof of
concept. The string function benchmarks perform operations at
different alignments and for different sizes and compare performance
between plain operations and the optimized string operations. Due to
this their output is incompatible with the function benchmarks where
we're interested in fastest time, throughput, etc.
In future, the correctness checks in the benchmark tests can be
removed. Same goes for the performance measurements in the
string/test-*.
__clock_gettime and other __clock_* functions could result in an extra
PLT reference within libc.so if it actually gets used. None of the
code currently uses them, which is why this probably went unnoticed.
Carlos O'Donell [Mon, 10 Jun 2013 16:05:11 +0000 (12:05 -0400)]
x86*: Return syscall error for lll_futex_wake.
It is very very possible that the futex syscall returns an
error and that the caller of lll_futex_wake may want to
look at that error and propagate the failure.
This patch allows a caller to see the syscall error.
There are no users of the syscall error at present, but
future cleanups are now be able to check for the error.
Avoid overwriting earlier flags in CPPFLAGS-nonlib in benchtests
When setting BENCH_DURATION in CPPFLAGS-nonlib, append to the variable
instead of assigning to it, to avoid overwriting earlier set flags,
notably the -DNOT_IN_libc=1 flag.
Carlos O'Donell [Mon, 3 Jun 2013 18:49:48 +0000 (14:49 -0400)]
BZ #15536: Fix ulp for 128-bit IBM long double.
In 128-bit IBM long double the precision of the type
decreases as you approach subnormal numbers, equaling
that of a double for subnormal numbers. Therefore
adjust the computation in ulp to use 2^(MIN_EXP - MANT_DIG)
which is correct for FP_SUBNORMAL for all types.
Avoid crashing in LD_DEBUG when program name is unavailable
Resolves: #15465
The program name may be unavailable if the user application tampers
with argc and argv[]. Some parts of the dynamic linker caters for
this while others don't, so this patch consolidates the check and
fallback into a single macro and updates all users.
Carlos O'Donell [Fri, 24 May 2013 18:03:14 +0000 (14:03 -0400)]
Correctly compute ulp near zero.
The current value used for ulp near zero is wrong,
and this commit fixes it such that ulp(0) is the smallest
subnormal value nearest to zero, which makes the most
sense for testing values near zero. Note that this is not
what Java does; they use the nearest normal value, which
is less accurate than what we want for glibc. Note that
there is no correct implementation of ulp since there
is no strict mathmatical definition that is accepted by
all groups using IEEE 754.
Previously with the large ulp values near zero there
were tests that previously passed, but were in fact
billions of ulp away from the precise answer. With this
commit we now need to disable one of the cpow tests which
is revealed to be inaccurate (bug 14473).
---
2013-05-24 Carlos O'Donell <carlos@redhat.com>
* math/libm-test.inc (MAX_EXP): Define.
(ULPDIFF): Define.
(ulp): New function.
(check_float_internal): Use ULPDIFF.
(cpow_test): Disable failing test.
(check_ulp): Test ulp() implemetnation.
(main): Call check_ulp before starting tests.
Chris Metcalf [Fri, 24 May 2013 18:02:31 +0000 (14:02 -0400)]
tile: improve detection for missing -mcmodel=large support
The existing test avoided passing -mcmodel=large if the compiler didn't
support it. However, we need to test not just the compiler support, but
also the toolchain (as and ld) support, so make the test more complete.
In addition, we have to avoid using the hwN_plt() assembly operators if
that support is missing, so guard the uses with #ifdef NO_PLT_PCREL.
This allows us to properly build glibc with the current community
binutils, which doesn't yet have the PC-relative PLT operator support.
The -mcmodel=large support is in gcc 4.8, but the toolchain support
won't be present in the community until binutils 2.24.
Ondrej Bilka [Fri, 24 May 2013 06:34:10 +0000 (08:34 +0200)]
Initialize wide struct info.
Fixes 15381.
Using wide character function is on byte oriented memstream is undefined
behaviour. This behaviour was masked by not initializing wide struct
info. We now initialize it to cause a predictable crash.
Carlos O'Donell [Wed, 22 May 2013 18:50:26 +0000 (14:50 -0400)]
Fix _nl_find_msg malloc failure case, and callers.
This patch fixes two issues, and perhaps should be two distinct commits,
but I present it here as one for the sake of completeness.
Commit 006dd86111c44572dbd3b26e9c63dd0f834d7762 fails to check malloc's
return in intl/dcigettext.c (_nl_find_msg):
~~~
freemem_size = INITIAL_BLOCK_SIZE;
newmem = (transmem_block_t *) malloc (freemem_size);
...
newmem->next = transmem_list;
transmem_list = newmem;
~~~
If malloc fails then newmem is NULL then newmem->next results in a
fault.
The fix is easy enough, check for newmem != NULL, and fall through to
the error condition below which returns (char *) -1 e.g. resource error.
The problem is that returning (char *) -1 will break all sorts of other
code, so while what we did is correct, the real failure case fix is
slightly broader.
There are 4 other places where _nl_find_msg is called, one is OK, the
other three are fixed to handle -1 error return value.
No regressions on x86-64 or x86.
However, no regressions isn't really a useful metric for this code.
The change was tested as documented here:
http://sourceware.org/glibc/wiki/Testing/WhiteBox
using SystemTap for fault injection to simulate malloc failure.
---
2013-05-03 Carlos O'Donell <carlos at redhat.com>
[BZ #15441]
* intl/dcigettext.c (DCIGETTEXT): Skip translating if _nl_find_msg
returns -1.
(_nl_find_msg): Return -1 if recursive call returned -1. If newmem is
null return -1.
* intl/loadmsgcat.c (_nl_load_domain): If _nl_find_msg returns -1 abort
loading the domain.
Dmitry V. Levin [Thu, 16 May 2013 21:55:09 +0000 (21:55 +0000)]
Test getaddrinfo return value
This helps testing for regression of BZ#15339. Creation of network
isolated environments is a privileged operation and therefore is not
included to the test.
Set EAI_SYSTEM only when h_errno is NETDB_INTERNAL
Fixes BZ #15339.
NSS_STATUS_UNAVAIL may mean that a necessary input resource is not
available. This could occur in a number of cases including when the
network is down, system runs out of file descriptors, etc. The
correct differentiator in such a case is the h_errno, which gives the
nature of failure. In case of failures other than a simple 'not
found', we set h_errno as NETDB_INTERNAL and let errno be the
identifier for the exact error.
Ondrej Bilka [Mon, 20 May 2013 06:26:00 +0000 (08:26 +0200)]
Faster memset on x64
This implementation speed up memset in several ways. First is avoiding
expensive computed jump. Second is using fact that arguments of memset
are most of time aligned to 8 bytes.
Benchmark results on:
kam.mff.cuni.cz/~ondra/benchmark_string/memset_profile_result27_04_13.tar.bz2
Ondrej Bilka [Mon, 20 May 2013 06:20:00 +0000 (08:20 +0200)]
Faster memcpy on x64.
We add new memcpy version that uses unaligned loads which are fast
on modern processors. This allows second improvement which is avoiding
computed jump which is relatively expensive operation.
Tests available here:
http://kam.mff.cuni.cz/~ondra/memcpy_profile_result27_04_13.tar.bz2
The compiler would optimize the benchmark function call out of the
loop and call it only once, resulting in blazingly fast times for some
benchmarks (notably atan, sin and cos). Mark the inputs as volatile
so that the code is forced to read again from the input for each
iteration.
git://sourceware.org / glibc.git / log