From 63010af19ff11e77aee0846e7b795cc4df897f4a Mon Sep 17 00:00:00 2001
From: Helmut Eller <eller.helmut@gmail.com>
Date: Fri, 16 Aug 2024 08:21:25 +0200
Subject: [PATCH 1/4] Introduce a struct igc_params

* src/igc.h (struct igc_params): New.
(init_igc): Take igc_params as argument.
* src/emacs.c (parse_igc_params, parse_igc_param): New.
(main): Parse igc_params before init_igc.
(usage_message, standard_args): Include --igc-param.
* src/igc.c (make_arena): Use igc_params to configure pause_time.
(init_igc, make_igc): Pass igc_params along.
---
 src/emacs.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 src/igc.c   | 14 +++++++++-----
 src/igc.h   | 11 ++++++++++-
 3 files changed, 74 insertions(+), 7 deletions(-)

diff --git a/src/emacs.c b/src/emacs.c
index 88b96ca7761..ced3f723919 100644
--- a/src/emacs.c
+++ b/src/emacs.c
@@ -291,6 +291,11 @@ #define MAIN_PROGRAM
 --fingerprint               output fingerprint and exit\n\
 ",
 #endif
+#if HAVE_MPS
+    "\
+--igc-param PARAM=VALUE     set IGC paramater PARAM to VALUE\n\
+"
+#endif
 #if SECCOMP_USABLE
     "\
 --seccomp=FILE              read Seccomp BPF filter from FILE\n\
@@ -730,6 +735,42 @@ argmatch (char **argv, int argc, const char *sstr, const char *lstr,
     }
 }
 
+#ifdef HAVE_MPS
+static void
+parse_igc_param (const char *val, struct igc_params *params)
+{
+  int n = 0;
+  if ((sscanf (val, "pause_time=%lf%n", &params->pause_time.seconds, &n) == 1)
+      && val[n] == '\0' && params->pause_time.seconds >= 0)
+    {
+      params->pause_time.dflt = false;
+      return;
+    }
+  fprintf (stderr, "Invalid igc_param: %s\n", val);
+  exit (1);
+}
+
+static struct igc_params
+parse_igc_params (int argc, char **argv)
+{
+  struct igc_params params = {
+    .pause_time = { .dflt = true },
+    .gen_params = { .dflt = true },
+  };
+  for (int skip = 0; skip != argc;)
+    {
+      char *val = NULL;
+      if (argmatch (argv, argc, "-igc-param", "--igc-param", 11, &val, &skip))
+	parse_igc_param (val, &params);
+      else if (argmatch (argv, argc, "--", NULL, 0, NULL, &skip))
+	break;
+      else
+	skip++;
+    }
+  return params;
+}
+#endif
+
 #if !defined HAVE_ANDROID || defined ANDROID_STUBIFY
 
 /* Find a name (absolute or relative) of the Emacs executable whose
@@ -1421,7 +1462,8 @@ main (int argc, char **argv)
   init_signals ();
 
 #ifdef HAVE_MPS
-  init_igc ();
+  const struct igc_params params = parse_igc_params (argc, argv);
+  init_igc (&params);
 #endif
 
   /* This is needed early because load_pdump can call 'float-time' (via
@@ -2051,6 +2093,15 @@ main (int argc, char **argv)
   init_module_assertions (module_assertions);
 #endif
 
+#ifdef HAVE_MPS
+  {
+    char *arg;
+    while (argmatch (argv, argc, "-igc-param", "--igc-param", 11,
+		     &arg, &skip_args))
+      ;
+  }
+#endif
+
 #ifdef HAVE_NS
   if (!noninteractive)
     {
@@ -2681,6 +2732,9 @@ main (int argc, char **argv)
   { "-no-build-details", "--no-build-details", 63, 0 },
 #ifdef HAVE_MODULES
   { "-module-assertions", "--module-assertions", 62, 0 },
+#endif
+#ifdef HAVE_MPS
+  {"-igc-param", "--igc-param", 61, 1 },
 #endif
   /* -d must come last before the options handled in startup.el.  */
   { "-d", "--display", 60, 1 },
diff --git a/src/igc.c b/src/igc.c
index f069a2becc9..c294eae747e 100644
--- a/src/igc.c
+++ b/src/igc.c
@@ -4448,12 +4448,16 @@ DEFUN ("igc--set-commit-limit", Figc__set_commit_limit,
   return Qnil;
 }
 
+static_assert (sizeof (struct igc_gen_param) == sizeof (mps_gen_param_s));
+
 static void
-make_arena (struct igc *gc)
+make_arena (struct igc *gc, const struct igc_params *params)
 {
   mps_res_t res;
   MPS_ARGS_BEGIN (args)
   {
+    if (!params->pause_time.dflt)
+      MPS_ARGS_ADD (args, MPS_KEY_PAUSE_TIME, params->pause_time.seconds);
     res = mps_arena_create_k (&gc->arena, mps_arena_class_vm (), args);
   }
   MPS_ARGS_END (args);
@@ -4534,10 +4538,10 @@ make_pool_amcz (struct igc *gc, mps_fmt_t fmt)
 }
 
 static struct igc *
-make_igc (void)
+make_igc (const struct igc_params *params)
 {
   struct igc *gc = xzalloc (sizeof *gc);
-  make_arena (gc);
+  make_arena (gc, params);
 
   /* We cannot let the GC run until at least all staticpros haven been
      processed. Otherwise we might allocate objects that are not
@@ -4967,11 +4971,11 @@ DEFUN ("igc--remove-extra-dependency", Figc__remove_extra_dependency,
  ***********************************************************************/
 
 void
-init_igc (void)
+init_igc (const struct igc_params *params)
 {
   /* Returns previous handler.  */
   (void) mps_lib_assert_fail_install (igc_assert_fail);
-  global_igc = make_igc ();
+  global_igc = make_igc (params);
   add_main_thread ();
   set_state (IGC_STATE_USABLE_PARKED);
 }
diff --git a/src/igc.h b/src/igc.h
index 00e37b6c952..586db8ce77f 100644
--- a/src/igc.h
+++ b/src/igc.h
@@ -60,8 +60,17 @@ #define EMACS_IGC_H
 
 #ifdef HAVE_MPS
 
+struct igc_params
+{
+  struct
+  {
+    bool dflt;
+    double seconds; /* in seconds; valid values in [0..INF] */
+  } pause_time;
+};
+
 void igc_break (void);
-void init_igc (void);
+void init_igc (const struct igc_params *);
 void syms_of_igc (void);
 void *igc_thread_add (struct thread_state *ts);
 void igc_thread_remove (void **info);
-- 
2.39.2