I’m trying to call into a bulky C++ library from OCaml, and I’m having trouble with ocamlopt, which sitently fails with error code 2.
I’m doing the whole dance with putting up a C interface, and I can get it to work in general, but as soon as I reference this library, build breaks.
Is there some way to know what exactly is failing? I tried the -verbose flag, but it just prints the commandline arguments (which are quite long).
Would you have any tips as to how to investigate a silent failure like this?
TL;DR; check that you have enough memory and/or disk space.
Something like this could happen when ocamlopt is either killed by a signal or runs out the memory (or both), check the dmesg output, look for OOM messages from the kernel, also use htop to get the idea on the memory footprint.
Also, since this happens when you're trying to link with the C++ library, it is most likey that it is the ld process which is failing (again, most likely with OOM), as ocamlopt uses the system linker.
In case anyone else runs into this again: the problem was that there were too many -ccopt and -cclib arguments getting passed in by the build driver. When I started including a C++ library with lots of other dependencies, we seemed to have reached the breaking point.
The solution was to change the build driver's OCaml compiler and linker rules to write all the compiler and linker args into files so they could all be passed in as a single -ccopt #<compiler.args> or -cclib #<linker.args> argument. Both gcc and ld support the #file command line option.
GitHub issue: ocamlopt lets the compiler/linker silently fail if too many -ccopt or -cclib arguments are passed in
Related
I am trying to compile a code with crayftn.
I get an error message
/opt/cray/pe/cce/10.0.1/binutils/x86_64/x86_64-pc-linux-gnu/bin/ld: failed to convert GOTPCREL relocation; relink with --no-relax
So it wants the flag --no-relax? OK, I can do that. So I re-link with that flag, and then it tells me
ftn -O3 --no-relax -dynamic -h pic -h omp -o stream_cray stream_mpi.o mysecond.o
ftn-2115 crayftn: ERROR in command line
"-no-relax" is an invalid command-line option.
So it asks for "--no-relax", but then it doesn't understand it. Anyone know of a way out of this conundrum? Or another way of solving the root problem in the first place?
I found this link:
https://bb.cgd.ucar.edu/cesm/threads/failed-to-convert-gotpcrel-relocation-relink-with-no-relax.4494/
PROBLEM:
Hi, I get the following error message for CLM5.0 compilation with
Intel compilers, during the final cesm bld ..ld: failed to convert GOTPCREL relocation; relink with --no-relax
SOLUTION:
Hi, Seems like found a solution to fix the compilation ...Adding of
"-Wl,--no-relax" in LDFLAGS does not solve this problem, but
"-mcmodel medium" in FFLAGS fixes this issue, after searching for
"Relocation truncated to fit" in google search engine, it comes up
with this link which was helpful to solve the issue
"https://software.intel.com/en-us/forums/intel-fortran-compiler-for-linux-and-mac-os-x/topic/268394"
Best Regards,Prabhakar
See also:
https://community.intel.com/t5/Intel-Fortran-Compiler/relocation-truncated-to-fit/td-p/1146616
This looks like mixing compilers and libraries from different systems
mixed up, either 32bit vs. 64bit or installations for ifort and
mpiifort based on different glibc or something similar.
I'm still curious about your "development environment":
Q: Have you been able to successfully compile, link and run ANY
program with your crayftn? Q: What version of crayftn? 10.0.1? Q: What
platform? Where is x86_64-pc-linux coming from? Just curious...
Problem
llc is giving me the following error:
LLVM ERROR: unsupported relocation on symbol
Detailed compilation flow
I am implementing an LLVM frontend for a middle-level IR (MIR) of a compiler, and after I convert various methods to many bitcode files, I link them (llvm-link), optimize them (opt), convert them to machine code (llc), make them a shared library (clang for it's linker wrapper), and dynamically load them.
llc step fails for some of the methods that I am compiling!
Step 1: llvm-link: Merge many bitcode files
I may have many functions calling each other, so I llvm-link the different bitcode files that might interact with each other. This step has no issues. Example:
llvm-link function1.bc function2.bc -o lnk.bc
Step 2: opt: Run optimization passes
For now I am using the following:
opt -O3 lnk.bc -o opt.bc
This step proceeds with no issues, but that's the one that CAUSES the problem!
Also, it's necessary because in the future I will need this step to pass extra passes, e.g. loop-unroll
Step 3: llc: Generate machine code (PIC)
I am using the following command:
llc -march=thumb -arm-reserve-r9 -mcpu=cortex-a9 -filetype=obj -relocation-model pic opt.bc -o obj.o
I have kept the arch specific flags I've set just in case they contribute to the issue. I am using Position Independent Code because on next step I will be building a shared object.
This command fails with the error I've written on top of this answer.
Step 4: clang: Generate Shared Object
For the cases that Step 3 fails, this step isn't reached.
If llc succeeds, this step will succeed too!
Additional information
Configuration
The following run on an llvm3.6, which runs on an arm device.
Things I've noticed
If I omit -O3 (or any other level) with the opt step, then llc would work.
If I don't, and instead I omit them from llc, llc would still fail. Which makes me think that opt -O<level> is causing the issue.
If I use llc directly it will work, but I won't be able to run specific passes that opt allows me, so this is not a option for me.
I've faced this issue ONLY with 2 functions that I've compiled so far (from their original MIR), which use loops. The others produce working code!
If I don't use pic model at llc, it can generate obj.o, but then I'll have problems creating an .so from it!
Questions
Why is this happening??!!
Why opt has -relocation-model option? Isn't that supposed to be just an llc thing? I've tried setting this both at opt and llc to pic, but still fails.
I am using clang because it has a wrapper to a linker to get the the .so. Is there a way to do this step with an LLVM tool instead?
First of all, do not use neither llc nor opt. These are developer-side tools that should be never used in any production environment. Instead of this, implement your own proper optimization and codegeneration runtime via LLVM libraries.
As for this particular bug - the thumb codegenerator might contain some bugs. Please reduce the problem and report it. Or don't use Thumb mode at all :)
I'm developing on an ARM9E processor running Linux. Sometimes my application crashes with the following message :
[ 142.410000] Alignment trap: rtspserverd (996) PC=0x4034f61c
Instr=0xe591300c Address=0x0000000d FSR 0x001
How can I translate the PC address to actual source code? In other words, how can I make sense out of this message?
With objdump. Dump your executable, then search for 4034f61c:.
The -x, --disassemble, and -l options are particularly useful.
You can turn on listings in the compiler and tell the linker to produce a map file. The map file will give you the meaning of the absolute addresses up to the function where the problem occurs, while the listing will help you pinpoint the exact location of the exception within the function.
For example in gcc you can do
gcc -Wa,-a,-ad -c foo.c > foo.lst
to produce a listing in the file foo.lst.
-Wa, sends the following options to the assembler (gas).
-a tells gas to produce a listing on standard output.
-ad tells gas to omit debug directives, which would otherwise add a lot of clutter.
The option for the GNU linker to produce a map file is -M or --print-map. If you link with gcc you need to pass the option to the linker with an option starting with -Wl,, for example -Wl,-M.
Alternatively you could also run your application in the debugger (e.g. gdb) and look at the stack dump after the crash with the bt command.
I'm debugging a nasty problem where #includeing a file(not anything I wrote, for the record) causes a crash in my program. This means, I have working and broken, with only one C(++) include statement changed. Some of the libraries I'm using don't have debugging information.
What I would like to do is get GDB to output every line of C++ executed for the program run, and x86 instructions where not available to a textfile in such a format that I can diff the two outputs and hopefully figure out what went wrong.
Is this easily possible in GDB?
You can check the difference between the pre-processed output in each version. For example:
gcc -dD -E a.cc -o a.pre
gcc -dD -E b.cc -o b.pre
diff -u a.pre b.pre
You can experiment with different "-d" settings to make that more verbose/concise. Maybe something in the difference of listings will be obvious. It's usually something like a struct which changes size depending on include files.
Failing that, if you really want to mess with per-instruction or line traces, you could probably use valgrind and see where the paths diverge, but I think you may be in for a world of pain. In fact you'll probably find valgrind finds your bug and then 100 you didn't know about :) I expect the problem is just a struct or other data size difference, and you won't need to bother.
You could get gdb to automate line tracing. It would be quite painful. Basically you'd need to script it to run "n" (next line) repeatedly until a crash, then check the logs. If you can script "b main", then "run", then infinite "n" that would do it. There's probably a built-in command to do it but I'm not aware of it.
I don't think GDB can do this; maybe a profile will help, though? Are you compiling with gcc? Look at the -p and -pf commands, I think those might be useful.
The disassemble command at the gdb prompt will disassemble the current function you are stopped in, but I don't think outputting the entire execution path is feasible.
What library are you including? If it is open source, you can recompile it with debugging symbols enabled. Also, if you're using Linux, most distributions have -dbg versions of packages for common libraries.
I'm trying to profile a C++ application, that I did not write, to get a sense for where the major computation points are. I'm not a C++ expert and even less so C++ debugging/profiling expert. I believe I am running into a (common?) problem with dynamic libraries.
I compile link to Google CPU Profiler using (OS X, G++):
env LIBS=-lprofiler ./configure
make
make install
I then run profile the installed application (jags) with:
env CPUPROFILE=./jags.prof /usr/local/bin/jags regression.cmd
pprof /usr/local/bin/jags jags.prof
Unfortunately, I get the error:
pprof /usr/local/bin/jags jags.prof Can't exec "objdump":
No such file or directory at /usr/local/bin/pprof line 2833.
objdump /System/Library/Frameworks/Accelerate.framework/Versions/A/
Frameworks/vecLib.framework/Versions/A/libLAPACK.dylib: No such file or directory
The program dynamically links to libLAPACK.dylib. So prof does not seem to understand it (?). I thought about trying to statically link, but the documents associated with the program say that it is impossible to statically link in LAPACK or BLAS (two required libraries).
Is there a way to have the profiler ignore libLAPACK? I'm okay if it doesn't sample within libLAPACK. Or how might I get profiling to work?
This error was caused by jags being a shell script, that subsequently called profilable code.
pprof /usr/local/bin/REAL_EXEC jags.prof
fixes the problem.
I don't see a clean way to do it, but maybe there's a hacky workaround -- what happens if you hack the pprof perl script (or better a copy thereof;-), line 2834, so that instead of calling error it emits the message and then does return undef;?
If you're profiling on OSX, the Shark tool is really great as well. It's very simple to use, and has worked out of the box for me when I've tried it.