On Tue, Aug 9, 2022 at 2:02 PM Martin Liška <mli...@suse.cz> wrote:
>
> Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
>
> Ready to be installed?
> Thanks,
> Martin
>
> PR lto/106328
>
> gcc/ChangeLog:
>
> * jobserver.h (struct jobserver_info): Add pipefd.
> (jobserver_info::connect): New.
> (jobserver_info::disconnect): Likewise.
> (jobserver_info::get_token): Likewise.
> (jobserver_info::return_token): Likewise.
>
> gcc/lto/ChangeLog:
>
> * lto.cc (wait_for_child): Decrement nruns once a process
> finishes.
> (stream_out_partitions): Use job server if active.
> (do_whole_program_analysis): Likewise.
> ---
> gcc/jobserver.h | 54 ++++++++++++++++++++++++++++++++++++++++++++++++
> gcc/lto/lto.cc | 55 +++++++++++++++++++++++++++++++++++++------------
> 2 files changed, 96 insertions(+), 13 deletions(-)
>
> diff --git a/gcc/jobserver.h b/gcc/jobserver.h
> index 856e326ddfc..2a7dc9f4113 100644
> --- a/gcc/jobserver.h
> +++ b/gcc/jobserver.h
> @@ -31,6 +31,18 @@ struct jobserver_info
> /* Default constructor. */
> jobserver_info ();
>
> + /* Connect to the server. */
> + void connect ();
> +
> + /* Disconnect from the server. */
> + void disconnect ();
> +
> + /* Get token from the server. */
> + bool get_token ();
> +
> + /* Return token to the server. */
> + void return_token ();
> +
> /* Error message if there is a problem. */
> string error_msg = "";
> /* Skipped MAKEFLAGS where --jobserver-auth is skipped. */
> @@ -41,6 +53,8 @@ struct jobserver_info
> int wfd = -1;
> /* Named pipe path. */
> string pipe_path = "";
> + /* Pipe file descriptor. */
> + int pipefd = -1;
> /* Return true if jobserver is active. */
> bool is_active = false;
> };
> @@ -97,4 +111,44 @@ jobserver_info::jobserver_info ()
> error_msg = "jobserver is not available: " + error_msg;
> }
>
> +void
> +jobserver_info::connect ()
> +{
> + if (!pipe_path.empty ())
> + pipefd = open (pipe_path.c_str (), O_RDWR);
> +}
> +
> +void
> +jobserver_info::disconnect ()
If it's not a template and the methods not inline won't we get multiple
definition errors when this include file is included in multiple places
from an executable? opts-common.cc might be a good place to
stuff it, and opts.h to declare (if it were not for std::string, so possibly
jobserver.h is good enough, or opts-jobserver.h?)
> +{
> + if (!pipe_path.empty ())
> + {
> + gcc_assert (close (pipefd) == 0);
> + pipefd = -1;
> + }
> +}
> +
> +bool
> +jobserver_info::get_token ()
> +{
> + int fd = pipe_path.empty () ? rfd : pipefd;
> + char c;
> + unsigned n = read (fd, &c, 1);
> + if (n != 1)
> + {
> + gcc_assert (errno == EAGAIN);
> + return false;
> + }
> + else
> + return true;
> +}
> +
> +void
> +jobserver_info::return_token ()
> +{
> + int fd = pipe_path.empty () ? wfd : pipefd;
> + char c = 'G';
> + gcc_assert (write (fd, &c, 1) == 1);
> +}
> +
> #endif /* GCC_JOBSERVER_H */
> diff --git a/gcc/lto/lto.cc b/gcc/lto/lto.cc
> index 31b0c1862f7..56266195ead 100644
> --- a/gcc/lto/lto.cc
> +++ b/gcc/lto/lto.cc
> @@ -54,11 +54,17 @@ along with GCC; see the file COPYING3. If not see
> #include "attribs.h"
> #include "builtins.h"
> #include "lto-common.h"
> -
> +#include "jobserver.h"
>
> /* Number of parallel tasks to run, -1 if we want to use GNU Make jobserver.
> */
> static int lto_parallelism;
>
> +/* Number of active WPA streaming processes. */
> +static int nruns = 0;
> +
> +/* GNU make's jobserver info. */
> +static jobserver_info *jinfo = NULL;
> +
> /* Return true when NODE has a clone that is analyzed (i.e. we need
> to load its body even if the node itself is not needed). */
>
> @@ -205,6 +211,12 @@ wait_for_child ()
> "streaming subprocess was killed by signal");
> }
> while (!WIFEXITED (status) && !WIFSIGNALED (status));
> +
> + --nruns;
> +
> + /* Return token to the jobserver if active. */
> + if (jinfo != NULL && jinfo->is_active)
> + jinfo->return_token ();
> }
> #endif
>
> @@ -228,25 +240,35 @@ stream_out_partitions (char *temp_filename, int blen,
> int min, int max,
> bool ARG_UNUSED (last))
> {
> #ifdef HAVE_WORKING_FORK
> - static int nruns;
> -
> if (lto_parallelism <= 1)
> {
> stream_out_partitions_1 (temp_filename, blen, min, max);
> return;
> }
>
> - /* Do not run more than LTO_PARALLELISM streamings
> - FIXME: we ignore limits on jobserver. */
> if (lto_parallelism > 0 && nruns >= lto_parallelism)
> - {
> - wait_for_child ();
> - nruns --;
> - }
> + wait_for_child ();
> +
> /* If this is not the last parallel partition, execute new
> streaming process. */
> if (!last)
> {
> + if (jinfo != NULL && jinfo->is_active)
> + while (true)
> + {
> + if (jinfo->get_token ())
> + break;
> + if (nruns > 0)
> + wait_for_child ();
> + else
> + {
> + /* There are no free tokens, lets do the job outselves. */
> + stream_out_partitions_1 (temp_filename, blen, min, max);
> + asm_nodes_output = true;
> + return;
> + }
> + }
> +
> pid_t cpid = fork ();
>
> if (!cpid)
> @@ -264,10 +286,12 @@ stream_out_partitions (char *temp_filename, int blen,
> int min, int max,
> /* Last partition; stream it and wait for all children to die. */
> else
> {
> - int i;
> stream_out_partitions_1 (temp_filename, blen, min, max);
> - for (i = 0; i < nruns; i++)
> + while (nruns > 0)
> wait_for_child ();
> +
> + if (jinfo != NULL && jinfo->is_active)
> + jinfo->disconnect ();
> }
> asm_nodes_output = true;
> #else
> @@ -460,9 +484,14 @@ do_whole_program_analysis (void)
>
> lto_parallelism = 1;
>
> - /* TODO: jobserver communication is not supported, yet. */
> if (!strcmp (flag_wpa, "jobserver"))
> - lto_parallelism = param_max_lto_streaming_parallelism;
> + {
> + jinfo = new jobserver_info ();
> + if (jinfo->is_active)
> + jinfo->connect ();
> +
> + lto_parallelism = param_max_lto_streaming_parallelism;
> + }
> else
> {
> lto_parallelism = atoi (flag_wpa);
> --
> 2.37.1
>
