[cfe-dev] computed goto/labels as values in interpreters

[Carsten Mattner]

On Tue, Sep 18, 2012 at 3:01 PM, Rafael Espíndola
<rafael.espindola at gmail.com> wrote:
>> I can try picking likely files and confirm they're such.
>> That wouldn't mean it's the only files. Would that help?
>> Is it important to compare compile and link steps?
>> If it is I'd have to see how I can measure it without messing
>> around too much.
>
> It should help yes. Even if there are multiple problems, fixing one
> makes it easy to isolate others. I would suggest starting with the
> file clang takes the longest to compile relative to gcc.
>
> Cheers,
> Rafael

With no MAKEFLAGS set and in the trees configured and already built
as described in my earlier email:

$ cd otp/gcc
$ export ERL_TOP=$PWD
$ export PATH=$ERL_TOP/bin:$PATH
$ cd erts
$ touch emulator/beam/beam_emu.c
$ /usr/bin/time make
11.09user 0.83system 0:18.99elapsed 62%CPU (0avgtext+0avgdata 63448maxresident)k
89712inputs+37832outputs (124major+265927minor)pagefaults 0swaps
$ cd ../lib/wx
$ touch c_src/*.c* c_src/gen/*.c* && /usr/bin/time make
113.29user 6.28system 2:00.54elapsed 99%CPU (0avgtext+0avgdata
623272maxresident)k
0inputs+38112outputs (0major+1684363minor)pagefaults 0swaps

# new shell
$ cd otp/clang
$ export ERL_TOP=$PWD
$ export PATH=$ERL_TOP/bin:$PATH
# even though it's all set to clang and clang++ from the ./configure step,
# let's make sure the we have the same environment configured
$ export CC=clang
$ export CXX=clang++
$ cd erts
$ touch emulator/beam/beam_emu.c
$ /usr/bin/time make
270.64user 0.96system 4:42.57elapsed 96%CPU (0avgtext+0avgdata
164248maxresident)k
118008inputs+26656outputs (298major+284692minor)pagefaults 0swaps
$ cd ../lib/wx
$ touch c_src/*.c* c_src/gen/*.c* && /usr/bin/time make
# c_src/gen/wxe_funcs.cpp is generated code and seems to infinite loop
on compile
# killed the make process after about 32mins of trying to build wxe_funcs.cpp
^Cmake[1]: *** [i686-pc-linux-gnu/wxe_funcs.o] Interrupt
make: *** [opt] Interrupt
Command terminated by signal 2
8.65user 0.56system 33:25.77elapsed 0%CPU (0avgtext+0avgdata 63860maxresident)k
48inputs+4104outputs (0major+177432minor)pagefaults 0swaps

excerpt from top for the offending clang invocation before killing:
PR  NI  VIRT  RES  SHR S  %CPU %MEM    TIME+  COMMAND
20   0  339m 314m  21m R  99.8 15.8  32:44.97 clang