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
Avoid a division-by-zero exception if the first number returned by
rand() is a multiple of 500, causing us to create a zero width pixmap,
and then attempt to use get_rand(0) when generating a random stride...
Fixes https://bugs.freedesktop.org/attachment.cgi?id=34162
This is a macroized version of SRC/OVER repeat normal/unneeded nearest
neighbour scaling instantiated for some common 8888 and 565 formats.
Based on work by Siarhei Siamashka
FAST_PATH_SAMPLES_COVER_CLIP:
This is set of the source sample grid, unrepeated but transformed
completely completely covers the clip destination. If this is set
you can use a simple scaled that doesn't have to care about the repeat
mode.
FAST_PATH_16BIT_SAFE:
This signifies two things:
1) The size of the src/mask fits in a 16.16 fixed point, so something like:
max_vx = src_image->bits.width << 16;
Is allowed and is guaranteed to not overflow max_vx
2) When stepping the source space we're guaranteed to never overflow
a 16.16 bit fix point variable, even if we step one extra step
in the destination space. This means that a loop doing:
x = vx >> 16;
vx += unit_x; d = src_row[x];
will never overflow vx causing x to be negative.
And additionally, if you track vx like above and apply NORMAL repeat
after the vx addition with something like:
while (vx >= max_vx) vx -= max_vx;
This will never overflow the vx even on the final increment that
takes vx one past the end of where we will read, which makes the
repeat loop safe.
