[Guile-commits] GNU Guile branch, boehm-demers-weiser-gc, updated. release_1-9-2-147-ge3eb628

[Ludovic Courtès]

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- Log -----------------------------------------------------------------
commit e3eb628d889b8cb9821a274e41b72f9751b6ee0a
Author: Ludovic Courtès <address@hidden>
Date:   Thu Aug 20 01:56:47 2009 +0200

    Implement precise marking of the VM stack.
    
    Suggested by Andy Wingo.
    
    * libguile/vm.c (VM_ENABLE_PRECISE_STACK_GC_SCAN): New macro.
      (vm_stack_gc_kind): New variable.
      (make_vm)[VM_ENABLE_PRECISE_STACK_GC_SCAN]: Use `GC_generic_malloc ()'
      to allocate the stack.
      (vm_stack_mark): New function.
      (scm_bootstrap_vm)[VM_ENABLE_PRECISE_STACK_GC_SCAN]: Initialize
      `vm_stack_gc_kind'.

commit 75d315e1fbb0da6af8c48d17fd5b2a7a759fe849
Author: Ludovic Courtès <address@hidden>
Date:   Thu Aug 20 01:20:58 2009 +0200

    Fix bogus computation of `vm->stack_limit'.
    
    * libguile/vm.c (make_vm): Remove bogus "- 3" when computing
      `stack_size'.
    
    * libguile/vm-engine.h (CHECK_OVERFLOW): Change accordingly.

commit 1f7de769402cf8a9ad54b5283dc96d60e86fb5bb
Author: Ludovic Courtès <address@hidden>
Date:   Thu Aug 20 01:16:38 2009 +0200

    Simplify the creation of the SMOB GC "kind".
    
    * libguile/smob.c (smob_freelist): Remove.
      (scm_smob_prehistory): Adjust accordingly.

commit aec3d99bcd1dd4020e56c426909dc570d0109d91
Author: Ludovic Courtès <address@hidden>
Date:   Thu Aug 20 01:14:14 2009 +0200

    Include "scmconfig.h" in <libguile/boehm-gc.h>.
    
    * libguile/boehm-gc.h: Use "scmconfig.h".  Check for
      `SCM_USE_PTHREAD_THREADS', not `SCM_I_GSC_USE_PTHREAD_THREADS'.

-----------------------------------------------------------------------

Summary of changes:
 libguile/boehm-gc.h  |    6 ++--
 libguile/smob.c      |    9 ++----
 libguile/vm-engine.h |    2 +-
 libguile/vm.c        |   77 +++++++++++++++++++++++++++++++++++++++++++++++++-
 4 files changed, 83 insertions(+), 11 deletions(-)

diff --git a/libguile/boehm-gc.h b/libguile/boehm-gc.h
index 708f17b..b3a8514 100644
--- a/libguile/boehm-gc.h
+++ b/libguile/boehm-gc.h
@@ -1,7 +1,7 @@
 #ifndef SCM_BOEHM_GC_H
 #define SCM_BOEHM_GC_H
 
-/* Copyright (C) 2006, 2008 Free Software Foundation, Inc.
+/* Copyright (C) 2006, 2008, 2009 Free Software Foundation, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -20,9 +20,9 @@
 
 /* Correct header inclusion.  */
 
-#include "libguile/gen-scmconfig.h"
+#include "libguile/scmconfig.h"
 
-#ifdef SCM_I_GSC_USE_PTHREAD_THREADS
+#ifdef SCM_USE_PTHREAD_THREADS
 
 /* When pthreads are used, let `libgc' know about it and redirect allocation
    calls such as `GC_MALLOC ()' to (contention-free, faster) thread-local
diff --git a/libguile/smob.c b/libguile/smob.c
index 0598bae..b2c083c 100644
--- a/libguile/smob.c
+++ b/libguile/smob.c
@@ -496,10 +496,8 @@ free_print (SCM exp, SCM port, scm_print_state *pstate 
SCM_UNUSED)
 /* Marking SMOBs using user-supplied mark procedures.  */
 
 
-/* The freelist and GC kind used for SMOB types that provide a custom mark
-   procedure.  */
-static void **smob_freelist = NULL;
-static int    smob_gc_kind = 0;
+/* The GC kind used for SMOB types that provide a custom mark procedure.  */
+static int smob_gc_kind;
 
 
 /* The generic SMOB mark procedure that gets called for SMOBs allocated with
@@ -636,8 +634,7 @@ scm_smob_prehistory ()
   long i;
   scm_t_bits tc;
 
-  smob_freelist = GC_new_free_list ();
-  smob_gc_kind = GC_new_kind ((void **)smob_freelist,
+  smob_gc_kind = GC_new_kind (GC_new_free_list (),
                              GC_MAKE_PROC (GC_new_proc (smob_mark), 0),
                              0,
                              /* Clear new objects.  As of version 7.1, libgc
diff --git a/libguile/vm-engine.h b/libguile/vm-engine.h
index 240969c..b819b90 100644
--- a/libguile/vm-engine.h
+++ b/libguile/vm-engine.h
@@ -252,7 +252,7 @@
 #endif
 
 #define CHECK_OVERFLOW()                       \
-  if (sp > stack_limit)                                \
+  if (sp >= stack_limit)                       \
     goto vm_error_stack_overflow
 
 #define CHECK_UNDERFLOW()                       \
diff --git a/libguile/vm.c b/libguile/vm.c
index df1ad88..2920924 100644
--- a/libguile/vm.c
+++ b/libguile/vm.c
@@ -23,6 +23,11 @@
 #include <stdlib.h>
 #include <alloca.h>
 #include <string.h>
+#include <assert.h>
+
+#include "libguile/boehm-gc.h"
+#include <gc/gc_mark.h>
+
 #include "_scm.h"
 #include "vm-bootstrap.h"
 #include "frames.h"
@@ -56,6 +61,13 @@
 #define VM_ENABLE_ASSERTIONS
 #endif
 
+/* When defined, arrange so that the GC doesn't scan the VM stack beyond its
+   current SP.  This should help avoid excess data retention.  See
+   
http://thread.gmane.org/gmane.comp.programming.garbage-collection.boehmgc/3001
+   for a discussion.  */
+#define VM_ENABLE_PRECISE_STACK_GC_SCAN
+
+
 
 /*
  * VM Continuation
@@ -281,6 +293,13 @@ static const scm_t_vm_engine vm_engines[] =
 
 scm_t_bits scm_tc16_vm;
 
+#ifdef VM_ENABLE_PRECISE_STACK_GC_SCAN
+
+/* The GC "kind" for the VM stack.  */
+static int vm_stack_gc_kind;
+
+#endif
+
 static SCM
 make_vm (void)
 #define FUNC_NAME "make_vm"
@@ -293,12 +312,25 @@ make_vm (void)
   struct scm_vm *vp = scm_gc_malloc (sizeof (struct scm_vm), "vm");
 
   vp->stack_size  = VM_DEFAULT_STACK_SIZE;
+
+#ifdef VM_ENABLE_PRECISE_STACK_GC_SCAN
+  vp->stack_base = GC_generic_malloc (vp->stack_size * sizeof (SCM),
+                                     vm_stack_gc_kind);
+
+  /* Keep a pointer to VP so that `vm_stack_mark ()' can know what the stack
+     top is.  */
+  *vp->stack_base = PTR2SCM (vp);
+  vp->stack_base++;
+  vp->stack_size--;
+#else
   vp->stack_base  = scm_gc_malloc (vp->stack_size * sizeof (SCM),
                                   "stack-base");
+#endif
+
 #ifdef VM_ENABLE_STACK_NULLING
   memset (vp->stack_base, 0, vp->stack_size * sizeof (SCM));
 #endif
-  vp->stack_limit = vp->stack_base + vp->stack_size - 3;
+  vp->stack_limit = vp->stack_base + vp->stack_size;
   vp->ip         = NULL;
   vp->sp         = vp->stack_base - 1;
   vp->fp         = NULL;
@@ -313,6 +345,41 @@ make_vm (void)
 }
 #undef FUNC_NAME
 
+#ifdef VM_ENABLE_PRECISE_STACK_GC_SCAN
+
+/* Mark the VM stack region between its base and its current top.  */
+static struct GC_ms_entry *
+vm_stack_mark (GC_word *addr, struct GC_ms_entry *mark_stack_ptr,
+              struct GC_ms_entry *mark_stack_limit, GC_word env)
+{
+  GC_word *word;
+  const struct scm_vm *vm;
+
+  /* The first word of the VM stack should contain a pointer to the
+     corresponding VM.  */
+  vm = * ((struct scm_vm **) addr);
+
+  if (vm->stack_base == NULL)
+    /* ADDR must be a pointer to a free-list element, which we must ignore
+       (see warning in <gc/gc_mark.h>).  */
+    return mark_stack_ptr;
+
+  /* Sanity checks.  */
+  assert ((SCM *) addr == vm->stack_base - 1);
+  assert (vm->sp >= (SCM *) addr);
+  assert (vm->stack_limit - vm->stack_base == vm->stack_size);
+
+  for (word = (GC_word *) vm->stack_base; word <= (GC_word *) vm->sp; word++)
+    mark_stack_ptr = GC_MARK_AND_PUSH ((* (GC_word **) word),
+                                      mark_stack_ptr, mark_stack_limit,
+                                      NULL);
+
+  return mark_stack_ptr;
+}
+
+#endif /* VM_ENABLE_PRECISE_STACK_GC_SCAN */
+
+
 SCM
 scm_c_vm_run (SCM vm, SCM program, SCM *argv, int nargs)
 {
@@ -595,6 +662,14 @@ scm_bootstrap_vm (void)
                             (scm_t_extension_init_func)scm_init_vm, NULL);
 
   strappage = 1;
+
+#ifdef VM_ENABLE_PRECISE_STACK_GC_SCAN
+  vm_stack_gc_kind =
+    GC_new_kind (GC_new_free_list (),
+                GC_MAKE_PROC (GC_new_proc (vm_stack_mark), 0),
+                0, 1);
+
+#endif
 }
 
 void


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