This project provides a convenient way to install the BlocksRuntime library from the compiler-rt project (see http://compiler-rt.llvm.org/).
Several systems (Linux, FreeBSD, MacPorts, etc.) provide the clang compiler
either preinstalled or as an available package which has Blocks support
-fblocks compiler option is used).
Unfortunately, those installer packages do not provide the Blocks runtime library.
On the other hand, the compiler-rt library can be downloaded and does contain the Blocks runtime support if properly enabled in the cmake build file.
By default, however, the compiler-rt library also builds a compiler runtime support library which is undesirable.
This project contains only the BlocksRuntime files (in the
subdirectory) along with tests (in the
BlocksRuntime/tests subdirectory) and
README.txt from the top-level
compiler-rt project (which have been placed in the
subdirectory). Note that in 2014-02 the compiler-rt project moved the
BlocksRuntime sources from the
BlocksRuntime directory to the
lib/BlocksRuntime directory and moved the tests from the
directory to the
test/BlocksRuntime directory. The files themselves, however,
remain unchanged and are still the same as they were in 2010-08.
This runtime can also be used with the
gcc-apple-4.2 compiler built using the
MacPorts.org apple-gcc42 package on Mac OS X.
The compiler-rt project (and hence the BlocksRuntime since it's a part of that
project) has a very liberal dual-license of either the UIUC or MIT license.
The MIT license is fully GPL compatible (and pretty much compatible with just
about everything), so there should be no problems linking the
libBlocksRuntime.a library with your executable. (Note that on the FSF's site
http://www.gnu.org/licenses/license-list.html, you find the MIT license under
the 'X11 License' section.) See the
LICENSE.TXT file in the
subdirectory for all the details.
Since there are only two files to build, a makefile didn't seem warranted. A
config.h file has been created to make the build work. Build the
libBlocksRuntime.a library by running:
gcc compiler will be used by default, but you can do
for example to use the
clang compiler instead. Note that neither
cmake are needed (but
ranlib will be used but they can also be
changed with the
RANLIB environment variables similarly to the way
the compiler can be changed).
IMPORTANT Mac OS X Note: If you are building this library on Mac OS X
(presumably to use with a
gcc-apple-4.2 built with MacPorts or
otherwise obtained), you probably want a fat library with multiple architectures
in it. You can do that with the
CFLAGS variable like so:
CFLAGS='-O2 -arch x86_64 -arch ppc64 -arch i386 -arch ppc' ./buildlib
buildlib-osx script will attempt to make an intelligent guess about
building an OS X library and then run
buildlib. If you're using Mac OS X you
can do this to build a FAT OS X library:
buildlib-osx) script takes a single optional
argument. If given it will attempt to also build a shared library instead
of just a static one in case you have a policy situation where use of a static
library has been forbidden.
Skip this step at your peril! It's really quite painless. You see it's
possible that the underlying blocks ABI between the blocks runtime files
provided in this project and the blocks ABI used by your version of the clang
compiler to implement the
-fblocks option have diverged in an incompatible
way. If this has happened, at least some of the tests should fail in
spectacular ways (i.e. bus faults). For that reason skipping this step is not
You must have the clang compiler with
-fblocks support installed for this step
(if you don't have a clang compiler with
-fblocks support available, why
bother installing the Blocks runtime in the first place?)
Run the tests like so:
checktests expects the
clang compiler to be available in the
PATH and named
clang. If you are using
gcc-apple-4.2 or your
named something different (such as
clang-mp-3.0) run the
tests like this instead (replacing
clang-mp-3.0 with your compiler's name):
Problems are indicated with a line that starts
not ok. You will see a few
of these. The ones that are marked with
# TODO are expected to fail for the
reason shown. The
copy-block-literal-rdar6439600.c expected failure is a real
failure. No it's not a bug in the Blocks runtime library, it's actually a bug
in the compiler. You may want to examine the
source file to make sure you fully grok the failure so you can avoid getting
burned by it in your code. There may be a fix in the clang project by now (but
as of the clang 3.2 release it still seems to fail), however it may be a while
until it rolls downhill to your clang package.
If you are using
CC=gcc-apple-4.2, you will probably get two additional expect
failure compiler bugs in the
josh.C tests. These extra failures
are not failures in the blocks runtime itself, just
gcc not accepting some
source files that
clang accepts. You can still use the
library just fine.
Note that if you have an earlier version of
clang (anything before version 2.8
clang -v) then
clang++ (C++ support) is either incomplete or missing and
the few C++ tests (
.C extension) will be automatically skipped (if
is missing) or possibly fail in odd ways (if
clang++ is present but older than
Note that the
./checktests output is TAP (Test Anything Protocol) compliant
and can therefore be run with Perl's prove utility like so:
prove -v checktests
Optionally first setting
CC like so:
CC=gcc-apple-4.2 prove -v checktests
-v option for more succinct output.
ARM Hard Float Bug
When running on a system that uses the ARM hard float ABI (e.g. RaspberryPi), the clang compiler has a bug. When passing float arguments to a vararg function they must also be passed on the stack, not just in hardware floating point registers. The clang compiler does this correctly for normal vararg functions, but fails to do this for block vararg functions.
If you really need this, a workaround is to call a normal vararg function that
takes a block and
... arguments. It can then package up the
va_list and then call the block it was passed as an argument passing
the block the
va_list. This works fine and avoids the
clang bug even
though it's fugly.
checktests script marks this test (
variadic.c) as expect fail when
running the tests on an ARM hard float ABI system if it's able to detect that
the ARM hard float ABI is in use.
clang -fblocks failure
If clang is not using the integrated assembler (option
-integrated-as) then it
will incorrectly pass options such as
-fblocks down to the assembler which
will probably not like it. One example of an error caused by this bug is:
gcc: error: unrecognized command line option '-fblocks'
In this case clang is not using the integrated assembler (which is not supported
on all platforms) and passes the
-fblocks option down to the gcc assembler
which does not like that option at all.
The following references talk about this:
The ugly workaround for this problem is to compile the sources using both the
-fblocks options to produce a
.s file which can then be compiled
into whatever is desired without needing to use the
checktests detects this situation it will emit a line similar to this:
WARNING: -S required for -fblocks with clang
If this is the case, then rules to compile
.s and then compile
.o (or whatever) will be needed instead of the usual compile
.o (or whatever).
Note that this workaround is required to use
-fblocks with the version of
clang included with cygwin.
Assuming that you have built the library (with
./buildlib) and are satisfied
it works (
./checktests) then it can be installed with:
The default installation
/usr/local, but can be changed to
/myprefix like so:
sudo env prefix=/myprefix ./installlib
The include file (
Block.h) is installed into
$prefix/include and the library
$prefix/lib by default. (Those can also be
changed by setting and exporting
libdir in the same way
prefix can be changed.)
If you want to see what will be installed without actually installing use:
DESTDIR is supported by the
installlib script if that's needed.
DESTDIR before running
installlib the same way
prefix can be set.
Note that if the shared library exists it will also be installed. Add a single
-static option to install only one or the other.
After you have installed the Blocks runtime header and library, you can check
to make sure everything's working by building the
sample.c file. The
instructions are at the top of the file (use
head sample.c to see them) or
just do this (replace
clang with the name of the compiler you're using):
clang -o sample -fblocks sample.c -lBlocksRuntime && ./sample
If the above line outputs
Hello world 2 then your Blocks runtime support is
correctly installed and fully usable. Have fun!
Note that if you have the problem described above in the section named "clang -fblocks failure", then you'll need to do this instead:
clang -S -o sample.s -fblocks sample.c && \ clang -o sample sample.s -lBlocksRuntime && ./sample
Note that it's possible to use the Blocks runtime without installing it into
the system directories. You simply need to add an appropriate
-I option to
Block.h header when you compile your source(s). And a
-L option to
libBlocksRuntime.a library when you link your executable. Since
libBlocksRuntime.a is a static library no special system support will be
needed to run the resulting executable.
unistd.h header from older versions of
glibc has an incompatibility with
-fblocks option. See http://mackyle.github.io/blocksruntime/#glibc for
This problem was corrected with commit 84ae135d3282dc362bed0a5c9a575319ef336884
(http://repo.or.cz/w/glibc.git/commit/84ae135d) on 2013-11-21 and first
glibc-2.19 released on 2014-02-07. Since
ldd is part of
you can check to see what version of
glibc you have with:
You can find information on the Blocks language extension at these URLs