Between May and June 2016, I worked with ocamlyices2, an OCaml package that binds to the Yices C++ library. Both projects (as well as many Linux projects) are built using the "Autotools" suite.
The Autotools suite includes tools like autoconf, automake and libtool. These tools generate a bunch of shell scripts and Makefiles using shell scripts and the M4 macro language. The user of your projects ends up two simple commands to build your project:
./configure
make
Why did I bother with this? As part of my PhD, I worked on a tool, touist, which uses SMT solvers like Yices. The
touist
CLI was written in OCaml (a popular language among academics, including my supervisor), which meant I had to go through hoops to interoperate with C/C++ solvers like Yices.
My first challenge with ocamlyices2 was the fact that I needed a statically-linked libyices.a
. And since Yices depends on GMP, I had to dive deep into Yices2's configure.ac
and find a way to select the static version of GMP.
But building a static library libyices.a
was not enough. I was to build in PIC mode (position-independant code, enabled with -fPIC
in gcc). The position-independant code is required when you want to embed a static library into a dynamically-linked library. That's due to the fact that OCaml requires both the .so
and .a
versions of the "stub" library (a stub library is a C library that wraps another C library using OCaml C primitives). And naturally, Yices' build system had not been written to support building a static PIC libyices.a
.
I remember these days as an epic struggle against old build systems. This experience taught me everything about autoconf
, Makefiles, position-independant code, gcc
, ldd
and libtool
. And in this post, I want to share these discoveries and how I progressed into contributing to the ocamlyices2 project.
Here is a diagram showing the dependencies between libraries. Ocamlyices2 depends on Yices and Yices depends on GMP.
build: dune
touist lang: ocaml
| output: touist binary (statically linked)
|
|
|depends on
|
|
|
v
ocamlyices2 build: autoconf + make
| lang: ocaml + C
| output: libyices2_stubs.a
|
|depends on
|
|
|
v build: autoconf + hacky make
yices lang: C++
| output: libyices.a (with PIC enabled)
|
|
|depends on
|
|
|
v build: autoconf + automake + libtool
gmp lang: C, assembly
output: libgmp.a (with PIC enabled)
The most important thing about this diagram is that since we need a PIC-enabled static library libyices.a
in order to build the "binding libraries": the shared library yices2.cmxs
and the static library libyices2_stubs.a
.
And in order to get this PIC-enabled libyices.a
, I needed to make sure that the GMP library picked by the Yices ./configure
would be static and PIC-enabled.
In early 2016, the Yices build system was limited to building a shared library with no support for cross-compilation (a requirement to build on Windows) and no support for enforcing PIC in libgmp.a
and libyices.a
.
Yices2 & autoconf: an attempt at fixing a limited build system
I remember the warmth that we had in May 2016. My daughter had turned three and we were still living in a tiny appartment since I was technically still a student.
My first patch to the ocamlyices2 project took over a month of intense work. The stake was immense: I aimed at revamping the whole Yices2 build system. The original build system didn't allow developers to statically build libyices.a
. More generally, it was a pain to work with: most configuration was happening at ./configure
time, but a ton of things had still to be passed at make time (e.g., make VAR=value
).
This change (25f5eb15) brought a ton of features. But the most important ones were:
-
Better
./configure && make
experience. Instead of having some parts of the build configuration being passed as Makefile variables, I moved everything to nice flags that you would pass to./configure
. -
Proper PIC support. Sometimes, Yices'
./configure
would pick up alibgmp.a
that would not be "PIC". So I wrote a new M4 macro,CSL_CHECK_STATIC_GMP_HAS_PIC
, that would do the PIC check using libtool. For example, the developer would be able to ask for a static library with PIC support:
./configure --with-pic --enable-static --disable-shared --with-pic-gmp=$PWD/with-pic/libgmp.a
-
Static
libyices.a
. The original build system did not -
Using
libtool
. Instead of hand-crafted targets for building the static & dynamic libraries,libtool
allowed me to build both with very little effort (at the cost of slightly longer build times). I remember trying to fiddle with the Makefile to be able to get PIC/non-PIC as well as dynamic/static.o
units. Usinglibtool
made it so easier to build simultanously the static and dynamic versions oflibyices
(libyices.a
andlibyices.so
). - Cross-compilation. I wanted to be able to release binaries for Windows users, which meant that I needed to cross-compile from a Cygwin environment to a Win32 executable.
I also fixed weird bugs like a failure on Alpine 3.5 due to a race condition in ltmain.sh
. Yes, you heard well! A race condition in a build system!
Not sure, but 25f5eb15 might be my biggest commit ever:
Author: Maël Valais <mael.valais@gmail.com>
Date: Fri May 5 10:31:37 2017 +0200
Commit: 25f5eb15
libyices: build system: moved all config from Makefile to ./configure
What I tried to fix:
* Impossible to produces static archive libyices.a for the mingw32 host.
* So much configuration done in Makefile instead of ./configure.
* The 'make build OPTION= MODE=' is kind of unexpected and not really standard.
* As an end-user builder, it is hard to guess that my system-installed libgmp.a
is not PIC. The build system should help me with that.
* CFLAGS and CPPFLAGS cannot be overritten by the end-user builder at 'make'
time. See 'Preset Output Variables' in the autoconf manual.
* `smt2_commands.c`, `smt2_parser.c` and `smt2_term_stack.c` are all including
`smt2_commands.h`, and in `smt2_commands.h` there is a definition of a type,
so there is a clash of symbols at link time. Solution 1: use 'extern' in .h
and definition in .c. Solution 2: typedef the enum.
* The build system should be fully parallel-proof. Note that 'make -j' is a
thread bomb; prefer using 'make -j4' if you have 4 processors.
* Why removing libyices.a when using 'dist'? (rm -f $(distdir)/lib/libyices.a)
libyices.a should be distributed to the end-users along with the shared lib.
* Why does libgmp.a contain more than libgmp.so? I guess it is because some
function are needed by the tests and the tests are never dynamically linked
to the shared libyices.so... For example, the test `test_type_matching` calls
a function 'delete_pstore' that is not exported. This means we cannot use the
created libyices.so! We must instead use the object files directly.
Features of the new build system:
* It is now possible to select what you want to build using --enable-static
and --enable-shared. By default, both are built. You can speed up the build
by disabling one of the modes, for example --disable-shared.
* Running ./configure will tell you if the libgmp.a found/given with
--with-static-gmp or --with-pic-gmp is PIC or not.
* Libtool now handles all shared library naming with version number and symbolic
links. on linux, .so, on mac os .dylib, on windows .a, .dll.a and .dll...
* It is now possible to choose if you want PIC-only code in the static
library libyices.a using --with-pic.
* The ./configure now configures and the Makefile makes; moved all the
configuration steps that were done in the Makefile.
* It is not required anymore to pass OPTION when using make. OPTION is now
handled by passing for example --host=i686-w64-mingw32 when running
./configure, instead of 'make OPTION=mingw32',
* It is not required anymore to pass MODE in make. MODE is now handled by
the argument --with-mode=release (for example) when running ./configure.
* Removed the confusing mess of build/<host>/... and configs/make.<host>.
Build objects are simply put in build/.
* Merged the many Makefiles that were sharing a lot of code in common.
* Standardized the 'make' target and experience:
- make build for building binaries and library (no need for OPTION or MODE)
- make dist (non-standard) for showing the results of the build as it would
be distributed
- make distclean for removing any files created by ./configure
- make lib if you only want the library
- make install and uninstall for installing/uninstalling (DESTDIR supported)
* On Windows, we can now build a static library libyices.a.
* On Windows, shared and static libraries can be built at once. The static
version of libyices.a can be renamed using --with-static-name.
* DESTDIR works as expected: it will reproduce the hierarchy using the prefix
when running 'make install DESTDIR=/path'
* A nice summary of the configuration is now printed when running ./configure.
It allows to check if libgmp.a is PIC or not, and helps to have a clear
view of what is going to happen.
* Moved version number of Yices in configure.ac
* If the user wants to use --with-pic-gmp but his libgmp.a is not PIC, give him
an indication of what command to run to build the with-PIC libgmp.a.
* Moved the gmaketest into configure; warn the user if 'make' is not gnu make.
* Parallel build is now fully supported (make -j)
* when using --with-static-gmp (and other similar flags), try to find gmp.h
in . and ../include automatically, and fall back with the system-wide gmp.h
* check for gmp.h even when no --with-static-gmp-include-dir is given
* moved all csl_* functions into autoconf/m4/csl_check_libs.m4 so that they
can be reused somewhere else
* compute dependencies only if not in release mode and at compile time
instead of ahead of time. This saves time during compilation, because deps
are not necessary if the .c or .h files are not changed (i.e., if the builder
is the end-user). If the builder is a developer, then he will set
--with-mode={debug,profile...} and this will trigger the deps to be computed.
* 'make test' compiles and runs all tests in tests/unit
* 'make test_api12' will compile and run the test tests/unit/test_api12.c
* removed version_*.c file as it is rebuilt at make time
* gperf is now only necessary when changing the tokens.txt or keywords.txt files,
the end-user builder does not have to have gperf installed.
Side notes:
* CPPFLAGS, CFLAGS, LDFLAGS and any other makefile variable can be overwritten
using 'make LDFLAGS=...' (was already the case with the previous version of the
build system)
Known issues:
* on Mac OS X, linking executables agains non-PIC libgmp.a will throw the
following warning:
ld: warning: PIE disabled. Absolute addressing (perhaps -mdynamic-no-pic)
not allowed in code signed PIE, but used in ___gmpn_mul_1 from libgmp.a(mul_1.o).
To fix this warning, don't compile with -mdynamic-no-pic or link with -Wl,-no_pie
Todo:
* produce libyices.def on Windows
* make sure the test on libgmp-10.dll is future-proof (remove the '-10')
* fix the 'echo summary'
* I did not test the checks made configure.ac on mcsat and libpoly; we should
do the same tests as done on libgmp.a (for checking that it is PIC) and
add a helping message at the end of configure.ac.
* For the tests, I read that two kind of tests were compiled:
- 'tests' where the tests are linked to the non-PIC libgmp.a and static libgmp.a
- 'tests-static' where the tests are linked to the PIC libgmp.a and shared
GMP library.
I changed the second one: it links to the shared version of libyices and shared
version of GMP. But building the with-PIC libyices.a would be really easy
(and it is still possible using the flag --with-pic).
* 'make dist' is not a staging area (for now) for 'make install'. They both
install from built objects.
* it is not possible to compile the tests against the shared library
because many symbols which are used in the tests are not exported ('export'
in the C code). They exist if we do 'nm' but they are just not usable.
* pstore issue:
The visibility is T (visible) in static mode and t (hidden) in shared mode. This
is because 'abstract_values.c' has not been 'exported' (=added in `yices_api.c`).
Here is an example of the difference (functions from )
```
# nm build/lib/libyices.a | grep pstore
0000000000000090 T _delete_pstore
0000000000000000 T _init_pstore
# nm build/lib/.libs/libyices.2.dylib | grep pstore
0000000000037e10 t _delete_pstore
0000000000037d80 t _init_pstore
```
I tweaked the ltmain.sh to be able to pass different CPPFLAGS for the compilation
of static and shared objects by the `%.o: %.c` rule. CPPFLAGS must be different
because of Windows dlls: `-DNOYICES_DLL -D__GMP_LIBGMP_DLL=0` for example.
I added two variables LT_STATIC_CFLAGS and LT_SHARED_CFLAGS. They allow me
to pass CFLAGS to libtool for .c -> .o targets. It allows me to pass things
like -DYICES_STATIC, -DNOYICES_DLL and -D_LIBGMP_DLL.
```
diff
diff --git a/ext/yices/autoconf/ltmain.sh b/ext/yices/autoconf/ltmain.sh
index bf5d83b..7b7dd3a 100644
--- a/ext/yices/autoconf/ltmain.sh
+++ b/ext/yices/autoconf/ltmain.sh
@@ -3500,10 +3500,10 @@ compiler."
fbsd_hideous_sh_bug=$base_compile
if test no != "$pic_mode"; then
- command="$base_compile $qsrcfile $pic_flag"
+ command="$base_compile $LT_SHARED_CFLAGS $qsrcfile $pic_flag"
else
# Don't build PIC code
- command="$base_compile $qsrcfile"
+ command="$base_compile $LT_SHARED_CFLAGS $qsrcfile"
fi
func_mkdir_p "$xdir$objdir"
@@ -3552,9 +3552,9 @@ compiler."
if test yes = "$build_old_libs"; then
if test yes != "$pic_mode"; then
# Don't build PIC code
- command="$base_compile $qsrcfile$pie_flag"
+ command="$base_compile $LT_STATIC_CFLAGS $qsrcfile$pie_flag"
else
- command="$base_compile $qsrcfile $pic_flag"
+ command="$base_compile $LT_STATIC_CFLAGS $qsrcfile $pic_flag"
fi
if test yes = "$compiler_c_o"; then
func_append command " -o $obj"
```
`
What a massive commit message, right?!
Oviously, I still needed to use all the new features that I had just addeed to the Yices ./configure
. So I proposed a second patch (ccb5a563) with changes to the ocamlyices2's own ./configure
; that took the form of new flags so that I would be able to build a static libyices.a
by specifying the static version of the GMP library libgmp.a
.
I also used the new cross-compilation capability of the Yices ./configure
so that it would be possible to build ocamlyices2 on Windows. The compilation would rely on the POSIX-compliant Cygwin suite and cross-compile to a native Win32 executable using MinGW32 (which a port of GCC).
`eml
Author: Maël Valais mael.valais@gmail.com
Date: Fri May 5 16:18:46 2017 +0200
Commit: ccb5a563
ocamlyices2: only build the static stub using static libgmp.a.
The library libgmp.a will be searched in system dirs or you can use the flag
--with-static-gmp= when running ./configure for setting your own libgmp.a. If
no libgmp.a is found, the shared library is used. You can force the use of
shared gmp library with --with-shared-gmp.
If --with-shared-gmp is not given, the libgmp.a that has been found
will be included in the list of installed files. The reason is because
if we want to build a shared-gmp-free binary, zarith will sometimes pick the
shared library (with -lgmp) over the static lbirary libgmp.a.
Including libgmp.a in the distribution of ocamlyices2 is a convenience for
creating gmp-shared-free binaries.
Why do we prefer using a static version of libgmp.a?
===================================================
This is because we build a non-PIC static version of libyices.a. If
we wanted to build both static and shared stubs, we should either
- build a PIC libyices.a but it would conflict with the non-PIC one
- build a shared library libyices.so.
For now, I chose to just skip the shared stubs (dllyices2_stubs.so).
Also:
* turn on -fPIC (in configure.ac) only if non-static gmp
* added a way to link statically to libgmp.a (--with-static-gmp)
* use -package instead of -I/lib for compiling *.c in ocamlc
This option uses the change I made to the build system of libyices.
Why? Because I want the possibility of producing binaries that do
not need any dll alongside.
Guess the host system and pass it to libyices ./configure
=========================================================
It is now possible to use ./configure for mingw32 cross-compilation.
`
A month past and I soon realized that GMP was not embedded at all in libyices.a
. I could see the symbols as undefined (U
) when running nm libyices.a
. It took me a while to figure this out... back to tweaking the fragile Yices ./configure
!
Along the way, I also realized how different Linux distributions are. Arch Linux is notably lacking support for partial linking (ld -r
). Which meant I had to add a flag for this specific purpose in commit 38200b0a:
`eml
Author: Maël Valais mael.valais@gmail.com
Date: Fri Jun 16 21:18:37 2017 +0200
Commit: 38200b0a
libyices: added option --without-gmp-embedded
This option will disable the partial linking that allows to embed
GMP into libyices.a (only with --enable-static).
For example, on Arch linux, the partial linking command
ld -r -lgmp *.o -o libyices.o
would fail even if libgmp.so is correclty installed. It seems that 'ld -r'
would only work with a static libgmp.a (but the arch linux repo only installs
the shared gmp library).
Why this `ld -r`? This command is the only way I found to compile a
static libyices.a from either a shared or a static libgmp and produce
a gmp-depend-free libyices.a.
Two solutions:
1. Drop the necessity for building a libyices.a free of gmp dependency.
In this case, I could remove the `ld -r`.
It would then create a libyices.a that depends on libgmp.a/so.
2. Separate the gmp-dependency-free libyices.a from the normal
gmp-dependent libyices.a. For example, I could use the option
`--without-gmp-embedded`
So I went with solution (2).
This option disables the embedding of GMP inside libyices.a. This
'embedding' is made using partial linking (ld -r) which seems to
be failing on Arch Linux when using the shared GMP library.
`
Although I had already added a check (CSL_CHECK_STATIC_GMP_HAS_PIC
in 25f5eb15) to make sure that the user-provided libgmp was PIC when using --with-pic
, I realized that it was trickier that what I thought in 55c8e92a...
`eml
Author: Maël Valais mael.valais@gmail.com
Date: Sat Jun 17 14:09:12 2017 +0200
Commit: 55c8e92a
libyices: with --enable-static and --with-pic, enforce PIC libgmp.a
One problem I came across was that most of the time, when I was doing
./configure --enable-static --with-pic
the produced libyices.a would still contain non-PIC libgmp.a, although
being itself PIC. In this commit, I enforce that if --with-pic is given,
then:
1) either --with-pic-gmp has been given, in this case we use that for
creating the PIC libyices.a;
2) or --with-pic-gmp has not been given and thus we try to simply use the
shared gmp through -lgmp.
Reminder: we also check that the system libgmp.a or the libgmp.a given with
--with-static-gmp is PIC. If it is the case, the PIC libgmp.a will be used
for --with-pic.
`
Now, I also had to fix ocamlyices2's ./configure
since ld -r
(partial linking) was not supported on Arch Linux (see [PR's CI failure](pull request](https://github.com/ocaml/opam-repository/pull/9086). I remember waiting for hours for the CI to run on all imaginable systems: Debian, Ubuntu, Suse, Arch Linux, Alpine, CentOS, Fedora, macOS and Windows...
Commits df7c89a1 and 70dc5de5) fix the partial linking issue on Arch Linux:
`eml
Author: Maël Valais mael.valais@gmail.com
Date: Sat Jun 17 16:52:59 2017 +0200
Commit: df7c89a1
ocamlyices2: added --with-libyices and --with-libyices-include-dir
These options allow to give your own libyices.a and the include directory
where the libyices headers are.
Author: Maël Valais mael.valais@gmail.com
Date: Sat Jun 17 17:01:58 2017 +0200
Commit: 70dc5de5
ocamlyices2: use --without-gmp-embedded by default
After giving it some thoughts, the need for having a self-contained libyices.a
(which would only need -lyices, no -lgmp needed) in ocamlyices2 is pointless
as 'zarith' will still need '-lgmp' anyway.
The Makefile will still put libgmp.a and libyices.a inside src/ so that
the static version of gmp is used (with -L.) instead of the shared version.
Rationale: disabling the partial linking fixes the build on Arch Linux, which
(I re-tested on a docker image) cannot accept partial linking with -lgmp when
only libgmp.so is available. Here is the failing command:
ld -r *.o -lgmp -o libyices.o
`
Final result of the Yices2 build system
The experience with the re-written ./configure
(here) is very different from the original one. When the user wants to compile the library with PIC, they get a warning if one of the dependencies is not PIC. There is a much finer control over what the user wants: dynamic vs. static, PIC vs. non-PIC. But also more control over dependencies like GMP, since the user must be able to pass a static or dynamic version of libgmp.
The ./configure
that you can see here gained many features like --with-shared-gmp
or --with-pic
.
sh
configure' configures Yices 2.5.2 to adapt to many kinds of systems.
% ./configure --help
Usage: ./configure [OPTION]... [VAR=VALUE]...
System types:
--build=BUILD configure for building on BUILD [guessed]
--host=HOST cross-compile to build programs to run on HOST [BUILD]
Optional Features:
--enable-shared[=PKGS] build shared libraries [default=yes]
--enable-static[=PKGS] build static libraries [default=yes]
--disable-libtool-lock avoid locking (might break parallel builds)
--enable-mcsat Enable support for MCSAT. This requires the libpoly
library.
Optional Packages:
--with-pic[=PKGS] try to use only PIC/non-PIC objects [default=use
both]
--with-static-gmp=
Full path to a static GMP library (e.g., libgmp.a)
--with-static-gmp-include-dir=
Directory of include file "gmp.h" compatible with
static GMP library
--with-pic-gmp= Full path to a relocatable GMP library (e.g.,
libgmp.a)
--with-pic-gmp-include-dir=
Directory of include file "gmp.h" compatible with
relocatable GMP library
--with-static-libpoly=
Full path to libpoly.a
--with-static-libpoly-include-dir=
Path to include files compatible with libpoly.a
(e.g., /usr/local/include)
--with-pic-libpoly=
Full path to a relocatable libpoly.a
--with-pic-libpoly-include-dir=
Path to include files compatible with the
relocatable libpoly.a
--with-shared-gmp By default, a static version of the GMP library will
be searched. This option forces the use of the
shared version. This applies for both shared and
static libraries.
--without-gmp-embedded (Only when --enable-static) By default, the static
library libyices.a created will be partially linked
(ld -r) so that the GMP library is not needed
afterwards (i.e., only -lyices is needed). If you
want to disable the partial linking (and thus -lgmp
and -lyices will be needed), you can use this flag.
--with-mode=MODE The mode used during compilation/distribution. It
can be one of release, debug, devel, profile, gcov,
valgrind, purify, quantify or gperftools. (default:
release)
--with-static-name=name (Windows only) when building simultanously shared
and static libraries, allows you to give a different
name for the static version of libyices.a.
`
I also added a ton of diagnostic information that appears at the end of ./configure
. That's very useful when you want to make sure that ./configure
has picked up the right version of libgmp
:
`plain
configure: Summary of the configuration:
EXEEXT:
SED: /usr/bin/sed
LN_S: ln -s
MKDIR_P: /usr/local/opt/coreutils/libexec/gnubin/mkdir -p
CC: gcc
LD: /Library/Developer/CommandLineTools/usr/bin/ld
AR: ar
RANLIB: ranlib
STRIP: strip
GPERF: gperf
NO_STACK_PROTECTOR: -fno-stack-protector
STATIC_GMP: /usr/local/lib/libgmp.a
STATIC_GMP_INCLUDE_DIR:
PIC_GMP: /usr/local/lib/libgmp.a
PIC_GMP_INCLUDE_DIR:
ENABLE_MCSAT: no
STATIC_LIBPOLY:
STATIC_LIBPOLY_INCLUDE_DIR:
PIC_LIBPOLY:
PIC_LIBPOLY_INCLUDE_DIR:
Version: Yices 2.5.2
Host type: x86_64-apple-darwin19.4.0
Install prefix: /Users/mvalais/code/ocamlyices2/ext/yices
Build mode: release
For both static and shared library:
CPPFLAGS: -DMACOSX -DNDEBUG
CFLAGS: -fvisibility=hidden -Wall -Wredundant-decls -O3 -fomit-frame-pointer -fno-stack-protector
LDFLAGS:
For static library libyices.a:
Enable: yes
STATIC_CPPFLAGS: -DYICES_STATIC
STATIC_LIBS:
Libgmp.a found: yes
Libgmp.a path: /usr/local/lib/libgmp.a
Libgmp.a is pic: yes (non-PIC is faster for the static library)
PIC mode for libyices.a: default
Use shared gmp instead of libgmp.a: no
Embed gmp in libyices.a: yes
For shared library:
Enable: yes
SHARED_CPPFLAGS:
SHARED_LIBS:
Libgmp.a with PIC found: yes
Libgmp.a path: /usr/local/lib/libgmp.a
Use shared gmp instead of libgmp.a: no
`
A final word about the Makefile
: since all the build configuration is handled by ./configure
, you don't have to pass any variables at make
time anymore, which really helps when you need to make
multiple times in a row and don't want to type the variables every single time.
Inpecting static and dynamic libraries
Here are two tips that I learned along the way. First, I very often need to know what libraries an executable is depending on:
`sh
macOS
% otool -L /bin/ls
/bin/ls:
/usr/lib/libutil.dylib (compatibility version 1.0.0, current version 1.0.0)
/usr/lib/libncurses.5.4.dylib (compatibility version 5.4.0, current version 5.4.0)
/usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1281.100.1)
Linux (Alpine Linux 3.9)
ldd /bin/ls
/lib/ld-musl-x86_64.so.1 (0x7fc9b2c84000)
libc.musl-x86_64.so.1 => /lib/ld-musl-x86_64.so.1 (0x7fc9b2c84000)
`
I also had to dig into the symbols of libraries in order to make sure that static libraries contained all the needed symbols:
sh
% nm ext/libyices_pic_no_gmp/lib/libyices.a
ext/libyices_pic_no_gmp/lib/libyices.a(libyices.o):
00000000000ef6c0 t _convert_rba_tree
0000000000049a20 t _convert_simple_value
00000000000c2f70 t _convert_term_to_bit
00000000000d97e0 t _convert_term_to_conditional
0000000000049700 t _convert_term_to_val
0000000000049b30 t _convert_val
00000000000028b0 T _yices_or
0000000000002fa0 T _yices_or2
0000000000002ca0 T _yices_or3
0000000000003480 T _yices_pair
000000000002ad30 t _yices_parse
0000000000006420 T _yices_parse_bvbin
00000000000064b0 T _yices_parse_bvhex
0000000000004200 T _yices_parse_float
0000000000004180 T _yices_parse_rational
000000000000b150 T _yices_parse_term
000000000000b090 T _yices_parse_type
U _memcpy
U _memset
U _memset_pattern16
U ___error
0000000000145280 S ___gmp_0
000000000017dcf0 D ___gmp_allocate_func
00000000001099e0 T ___gmp_assert_fail
0000000000109980 T ___gmp_assert_header
0000000000145460 S ___gmp_binvert_limb_table
000000000014527c S ___gmp_bits_per_limb
0000000000109a60 T ___gmp_default_allocate
0000000000109ae0 T ___gmp_default_free
0000000000109a90 T ___gmp_default_reallocate
0000000000145290 S ___gmp_digit_value_tab
The letter before the symbol is the "symbol type" (from man nm
):
Each symbol name is preceded by its value (blanks if undefined). This value is followed by one of the following characters, representing the symbol type:
- U = undefined,
- T (text section symbol),
- D (data section symbol),
- S (symbol in a section other than those above).
If the symbol is local (non-external), the symbol's type is instead represented by the corresponding lowercase letter. A lower case u in a dynamic shared library indicates a undefined reference to a private external in another module in the same library.
For example, the symbol _yices_parse_float
is an external symbol, meaning that this symbol isn't static to libyices.a
. On the other side, _convert_simple_value
is statically defined (t
).
Contributing the new Yices build system to upstream
On 16 June 2016, I sent an email to Bruno Dutertre, one of the developers at SRI (the company behind the Yices SMT solver). I proposed all these changes with links to the various patches on GitHub. Unfortunately, it didn't work out, and the reason might be that the whole patch was enormous and very hard to review.
Hi Maël,
Thanks for the message and for your efforts. We'll look into your updates.
We know that the Yices build system is unconventional because most of the work is done in the Makefiles rather that in the configure script. There are historical reason for this (and it should be able to build PIC libraries without problems).
By the way, Yices is now open-source (GPL) on github: https://github.com/SRI-CSL/yices2. Take a look when you have time,
Thanks again,
Bruno
I wish we had a unit-test framework for autoconf
. The autoconf
ecosystem generates very fragile scripts and the only way to test them is to run them with all possible flag combinations, which is pretty much impossible.
- Update 31 May 2020: added the ascii "dependency" diagram to give a better sense of what the challenge was.
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