This line:
mask = mask | mask >> 8 | mask >> 16 | mask >> 24;
only works when mask has 0s in the lower 24 bits, so add
mask &= 0xff000000;
before.
Reported by Todd Rinaldo on the #cairo IRC channel.
The tls_name_key variable is passed to tls_name_get(), and the first
time this happens it isn't initialized. tls_name_get() then passes it
on to tls_name_alloc() which passes it on to pthread_setspecific()
leading to undefined behavior.
None of this is actually necessary at all because there is only one
such variable per thread local variable, so it doesn't need to passed
as a parameter at all.
All of this was pointed out by Tor Lillqvist on the cairo mailing
list.
This line:
mask = mask | mask >> 8 | mask >> 16 | mask >> 24;
only works when mask has 0s in the lower 24 bits, so add
mask &= 0xff000000;
before.
Reported by Todd Rinaldo on the #cairo IRC channel.
The tls_name_key variable is passed to tls_name_get(), and the first
time this happens it isn't initialized. tls_name_get() then passes it
on to tls_name_alloc() which passes it on to pthread_setspecific()
leading to undefined behavior.
None of this is actually necessary at all because there is only one
such variable per thread local variable, so it doesn't need to passed
as a parameter at all.
All of this was pointed out by Tor Lillqvist on the cairo mailing
list.
The problem was reported as bug 25534 against pixman in
freedesktop.org bugzila. Link to a patch for binutils:
http://sourceware.org/ml/binutils/2008-03/msg00260.html
For pixman the impact is a build failure when using
binutils 2.18. Versions 2.19 and higer are fine. Still
some distros may be using older versions of binutils and
this is causing problems.
This patch workarounds the problem by replacing a problematic
"vmov a, b" instruction with equivalent "vorr a, b, b". Actually
they even map to the same instruction opcode in the generated
code, so the resulting binary is identical with and without patch.
This can be used to override the architecture recorded in the EABI object
attribute section. We set a minimum arch to 'armv4'. Binutils documentation
recommends to use this directive with the code performing runtime detection
of CPU features.
Additionally NEON/VFP EABI attributes are suppressed. And the instruction
set to use is explicitly set to '.arm'.
Configure test for NEON support is also updated to include a bunch of
these new directives (if any of these is unsupported by the assembler,
it is better to fail configure test than to fail library build).
All these changes are required to fix SIGILL problem on armv4t, reported in
http://lists.freedesktop.org/archives/pixman/2010-March/000123.html
