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[[!meta title="Enable Google Go programming (GCC: gccgo)"]]
[[!tag open_issue_gcc]]
Make the [Google Go programming language](http://golang.org/) available on
GNU/Hurd in its [[GCC]] *gccgo* implementation, and enable Hurd-specific
features.
There is a [[!FF_project 263]][[!tag bounty]] on this task.
---
# Part I
First, make the language functional, have its test suite pass without errors.
## Original [[community/GSoC]] Task Description
[[!inline pages=community/gsoc/project_ideas/gccgo feeds=no]]
## `tschwinge/t/hurd/go`
There is now a `tschwinge/t/hurd/go` branch in GCC's Git repository, where the
Hurd port for Go is being polished.
## `getcontext`/`makecontext`/`setcontext`/`swapcontext` usage analysis
In context of [[glibc/t/tls-threadvar]]. Looking at GCC trunk commit
f6568ea476aa52a6e23c6db43b3e240cde55783a (2013-04-26).
The check in `libgo/configure.ac` *whether setcontext clobbers TLS variables*
is invalid on GNU Hurd.
The `*context` functions are used in `libgo/runtime/go-signal.c` and
`libgo/runtime/proc.c`.
`__splitstack_getcontext`, `__splitstack_setcontext`,
`__splitstack_makecontext`, `__splitstack_resetcontext`,
`__splitstack_block_signals_context` are to be provided by libgcc. However, in
said libgo runtime files, they're used only `#ifdef USING_SPLIT_STACK`.
[[I|tschwinge]] would assume that before we can enable split stacks, first
[[open_issues/glibc/t/tls-threadvar]] needs to be fixed.
In `libgo/runtime/proc.c`:`runtime_gogo`, `setcontext` is used to *switch
context to a different goroutine*. TODO.
In `libgo/runtime/proc.c`:`runtime_mcall`, which *save[s] context and call[s]
fn passing g as a parameter*, `getcontext` and `setcontext` are used; this is
only called from `libgo/runtime/proc.c`:`runtime_gosched`. TODO.
In `libgo/runtime/proc.c`:`runtime_tracebackothers`, `getcontext` is used to
*switch context to the goroutine*. TODO.
In `libgo/runtime/proc.c`:`runtime_mstart`, which is *called to start an M*,
`getcontext` is used. TODO.
In `libgo/runtime/proc.c`:`runtime_entersyscall`, which is called when *the
goroutine g is about to enter a system call*, `getcontext` is used to *save the
registers in the g structure so that any pointers held in registers will be
seen by the garbage collector*. Should be fine.
In `libgo/runtime/proc.c`:`__go_go`, `getcontext` and `makecontext` are used.
TODO.
In `libgo/runtime/thread.c`:`runtime_minit`, which is *[c]alled to initialize a
new m (including the bootstrap m)*, `ss.ss_sp` is set to a new stack retrieved
via `libgo/runtime/proc.c:runtime_malg`, which *allocate[s] a new g, with a
stack [...]*, and then `sigaltstack` is called. TODO.
libgo/runtime/go-signal.c: /* We are now running on the stack registered via sigaltstack.
libgo/runtime/go-signal.c: and sigaltstack when the program starts.) */
libgo/runtime/proc.c: vnewg->context.uc_stack.ss_sp = vsp;
libgo/runtime/proc.c: vnewg->context.uc_stack.ss_sp += vspsize;
libgo/runtime/proc.c: vnewg->context.uc_stack.ss_size = vspsize;
Also, in `libgo/runtime/proc.c`:`runtime_newm`, `pthread_attr_setstacksize` is
used, which we also can't support yet, for the same reason.
## 2013-07-15, Fotis
**gccgo manages to get compiled and pass a fair amount of its tests, however its library is failing all but one of its tests.**
Following are the results of the passing suite between the libgo tests run on linux (x86) and the Hurd:
### the Hurd:
Test Run By root on Fri Jul 12 17:56:44 UTC 2013
Native configuration is i686-unknown-gnu0.3
=== libgo tests ===
Schedule of variations:
unix
...
=== libgo Summary ===
# of expected passes 1
# of unexpected failures 130
/root/gcc_new/gccbuild/./gcc/gccgo version 4.9.0 20130606 (experimental) (GCC)
### Linux results:
Test Run By fotis on Τρι 02 Ιούλ 2013 09:20:20 μμ EEST
Native configuration is i686-pc-linux-gnu
=== libgo tests ===
Schedule of variations:
unix
...
=== libgo Summary ===
# of expected passes 131
/home/fotis/Software/gcc_build/./gcc/gccgo version 4.9.0 20130702 (experimental) (GCC)
## SIGCHLD busy-loops
[[I|tschwinge]] have no recollection anymore what this is about...
(gdb) thread apply all bt
Thread 3 (Thread 19802.3):
#0 0x01daab5c in swtch_pri () at /usr/src/eglibc-2.17/build-tree/hurd-i386-libc/mach/swtch_pri.S:2
#1 0x01dac544 in __spin_lock_solid (lock=0x1fb700c) at spin-solid.c:26
#2 0x01dc1e07 in __spin_lock (__lock=<optimized out>) at ../mach/lock-intern.h:54
#3 _hurd_sigstate_lock (ss=ss@entry=0x2b008) at hurdsig.c:172
#4 0x01deaefb in __sigprocmask (how=how@entry=2, set=set@entry=0x209ffc9c, oset=oset@entry=0x0) at ../sysdeps/mach/hurd/sigprocmask.c:43
#5 0x01deeaff in abort () at abort.c:67
#6 0x01dec7c3 in __sigreturn (scp=0x209ffd00) at ../sysdeps/mach/hurd/i386/sigreturn.c:74
#7 0x01dc6ac6 in trampoline () from /lib/i386-gnu/libc.so.0.3
#8 0x209ffd00 in ?? ()
Backtrace stopped: previous frame inner to this frame (corrupt stack?)
Thread 2 (Thread 19802.2):
#0 0x01daaafc in mach_msg_trap () at /usr/src/eglibc-2.17/build-tree/hurd-i386-libc/mach/mach_msg_trap.S:2
#1 0x01dab3be in __mach_msg (msg=msg@entry=0x23fdef0, option=option@entry=3, send_size=32, rcv_size=rcv_size@entry=4096, rcv_name=rcv_name@entry=100, timeout=timeout@entry=0, notify=notify@entry=0) at msg.c:110
#2 0x01dabaeb in __mach_msg_server_timeout (demux=demux@entry=0x1dbc9f0 <msgport_server>, max_size=max_size@entry=4096, rcv_name=rcv_name@entry=100, option=option@entry=0, timeout=timeout@entry=0) at msgserver.c:150
#3 0x01dabbbb in __mach_msg_server (demux=demux@entry=0x1dbc9f0 <msgport_server>, max_size=4096, rcv_name=100) at msgserver.c:195
#4 0x01dbcaed in _hurd_msgport_receive () at msgportdemux.c:67
#5 0x01f54ab4 in entry_point (start_routine=0x1dbca80 <_hurd_msgport_receive>, arg=0x0) at ./pthread/pt-create.c:57
#6 0x00000000 in ?? ()
Thread 1 (Thread 19802.1):
#0 0x01daab5c in swtch_pri () at /usr/src/eglibc-2.17/build-tree/hurd-i386-libc/mach/swtch_pri.S:2
#1 0x01dac544 in __spin_lock_solid (lock=0x1fb700c) at spin-solid.c:26
#2 0x01dc1e07 in __spin_lock (__lock=<optimized out>) at ../mach/lock-intern.h:54
#3 _hurd_sigstate_lock (ss=ss@entry=0x1fb7808) at hurdsig.c:172
#4 0x01deaefb in __sigprocmask (how=1, set=0x0, oset=0x2004dc78) at ../sysdeps/mach/hurd/sigprocmask.c:43
#5 0x01dfe027 in getcontext () at ../sysdeps/mach/hurd/i386/getcontext.S:66
#6 0x012d4208 in runtime_mcall (pfn=0x12d4eb0 <schedule>) at ../../../go/libgo/runtime/proc.c:420
#7 0x012d48aa in runtime_gosched () at ../../../go/libgo/runtime/proc.c:1371
#8 0x012d4acf in syscall.Exitsyscall () at ../../../go/libgo/runtime/proc.c:1494
#9 0x012d1cc1 in runtime_MHeap_Scavenger (dummy=0x0) at ../../../go/libgo/runtime/mheap.c:453
#10 0x012d4946 in kickoff () at ../../../go/libgo/runtime/proc.c:370
#11 0x01dfe0ed in makecontext () at ../sysdeps/mach/hurd/i386/makecontext.S:95
#12 0x00000000 in ?? ()
(Perhaps in the mean time had received a SIGALARM or whatever DejaGnu sends
after timeout, if at all?)
-# of expected passes 1714
-# of unexpected failures 575
+# of expected passes 5067
+# of unexpected failures 12
# of expected failures 1
-# of untested testcases 13
+# of untested testcases 7
## TODO
+go_net_cgo_file = go/net/cgo_linux.go
+go_net_sock_file = go/net/sock_gnu.go
copied from libgo/go/net/sock_bsd.go
+go_net_sockopt_file = go/net/sockopt_bsd.go
+go_net_sockoptip_file = go/net/sockoptip_bsd.go go/net/sockoptip_posix.go
+go_os_sys_file = go/os/sys_uname.go
+go_os_stat_file = go/os/stat_atim.go
+archive_tar_atim_file = go/archive/tar/stat_atim.go
+syscall_exec_file = go/syscall/exec_unix.go
+syscall_exec_os_file = go/syscall/exec_gnu.go
copied from libgo/go/syscall/exec_bsd.go
+syscall_libcall_file = go/syscall/libcall_gnu.go
copied from libgo/go/syscall/libcall_posix.go
updated
? go_net_poll_file
? go_net_fd_os_file
libgo/runtime/proc.c | 10 +-
libgo/runtime/thread.c | 7 +
(some?) code moved elsewhere (runtime_m()->gsignal = runtime_malg(...))
New libgo/go/reflect/makefunc_386.S and libgo/go/reflect/makefunc_amd64.S
contain Linux thingy. Review x86 one anyway. Also:
libgo/go/reflect/makefuncgo_386.go.
--- ./libgo/go/syscall/libcall_posix.go
+++ ./libgo/go/syscall/libcall_posix.go
-const nfdbits = int(unsafe.Sizeof(fds_bits_type) * 8)
+const nfdbits = int(unsafe.Sizeof(fds_bits_type(0)) * 8)
Have then not anymore reviewed *Go* changes in GCC -- have to restart this from
scratch.
---
# Part II
Next, Hurd-specific features can be added. Add an interface to the
language/environment for being able to do [[RPC]] calls, in order to program
[[hurd/translator]]s natively in the Google Go programming language.
## Original [[community/GSoC]] Task Description
[[!inline pages=community/gsoc/project_ideas/language_bindings feeds=no]]