wingo pushed a commit to branch wip-whippet
in repository guile.
commit 2bfc66554e9c5fe6616048e5f5d87a8c2306ef1c
Author: Andy Wingo <wi...@pobox.com>
AuthorDate: Thu May 15 09:25:03 2025 +0200
Remove BDW alloc lock API in vm.c
* libguile/vm.c (vm_expand_stack_inner):
(vm_expand_stack):
(reinstate_continuation_x):
(compose_continuation): Use gc_inhibit_preemption /
gc_reallow_preemption.
---
libguile/vm.c | 125 ++++++++++++++++------------------------------------------
1 file changed, 33 insertions(+), 92 deletions(-)
diff --git a/libguile/vm.c b/libguile/vm.c
index a042e9535..acdc0ad8f 100644
--- a/libguile/vm.c
+++ b/libguile/vm.c
@@ -777,29 +777,17 @@ scm_i_vm_free_stack (struct scm_vm *vp)
memset (vp, 0, sizeof (*vp));
}
-struct vm_expand_stack_data
+static union scm_vm_stack_element *
+vm_expand_stack_inner (struct scm_vm *vp, size_t needed_size,
+ union scm_vm_stack_element *new_sp)
{
- struct scm_vm *vp;
- size_t stack_size;
- union scm_vm_stack_element *new_sp;
-};
-
-static void *
-vm_expand_stack_inner (void *data_ptr)
-{
- struct vm_expand_stack_data *data = data_ptr;
-
- struct scm_vm *vp = data->vp;
- union scm_vm_stack_element *old_top, *new_bottom;
- size_t new_size;
- ptrdiff_t reloc;
-
- old_top = vp->stack_top;
- new_size = vp->stack_size;
- while (new_size < data->stack_size)
+ union scm_vm_stack_element *old_top = vp->stack_top;
+ size_t new_size = vp->stack_size;
+ while (new_size < needed_size)
new_size *= 2;
- new_bottom = expand_stack (vp->stack_bottom, vp->stack_size, new_size);
+ union scm_vm_stack_element *new_bottom =
+ expand_stack (vp->stack_bottom, vp->stack_size, new_size);
if (!new_bottom)
return NULL;
@@ -807,13 +795,12 @@ vm_expand_stack_inner (void *data_ptr)
vp->stack_size = new_size;
vp->stack_top = vp->stack_bottom + new_size;
vp->stack_limit = vp->stack_bottom;
- reloc = vp->stack_top - old_top;
+ ptrdiff_t reloc = vp->stack_top - old_top;
if (vp->fp)
vp->fp += reloc;
- data->new_sp += reloc;
- return new_bottom;
+ return new_sp + reloc;
}
static ptrdiff_t
@@ -873,17 +860,13 @@ vm_expand_stack (struct scm_vm *vp, union
scm_vm_stack_element *new_sp)
if (stack_size > vp->stack_size)
{
- struct vm_expand_stack_data data;
+ gc_inhibit_preemption (SCM_I_CURRENT_THREAD->mutator);
+ new_sp = vm_expand_stack_inner (vp, stack_size, new_sp);
+ gc_reallow_preemption (SCM_I_CURRENT_THREAD->mutator);
- data.vp = vp;
- data.stack_size = stack_size;
- data.new_sp = new_sp;
-
- if (!GC_call_with_alloc_lock (vm_expand_stack_inner, &data))
+ if (!new_sp)
/* Throw an unwind-only exception. */
scm_report_stack_overflow ();
-
- new_sp = data.new_sp;
}
vp->sp = new_sp;
@@ -1082,34 +1065,6 @@ push_interrupt_frame (scm_thread *thread, uint8_t *mra)
thread->vm.fp = new_fp;
}
-struct return_to_continuation_data
-{
- struct scm_vm_cont *cp;
- struct scm_vm *vp;
-};
-
-/* Called with the GC lock to prevent the stack marker from traversing a
- stack in an inconsistent state. */
-static void *
-vm_return_to_continuation_inner (void *data_ptr)
-{
- struct return_to_continuation_data *data = data_ptr;
- struct scm_vm *vp = data->vp;
- struct scm_vm_cont *cp = data->cp;
-
- /* We know that there is enough space for the continuation, because we
- captured it in the past. However there may have been an expansion
- since the capture, so we may have to re-link the frame
- pointers. */
- memcpy (vp->stack_top - cp->stack_size,
- cp->stack_bottom,
- cp->stack_size * sizeof (*cp->stack_bottom));
- vp->fp = vp->stack_top - cp->fp_offset;
- vm_restore_sp (vp, vp->stack_top - cp->stack_size);
-
- return NULL;
-}
-
static void reinstate_continuation_x (scm_thread *thread, SCM cont)
SCM_NORETURN;
static void
@@ -1120,7 +1075,6 @@ reinstate_continuation_x (scm_thread *thread, SCM cont)
struct scm_vm_cont *cp;
size_t n, i, frame_overhead = 3;
union scm_vm_stack_element *argv;
- struct return_to_continuation_data data;
if (!scm_is_eq (continuation->root, thread->continuation_root))
scm_misc_error
@@ -1134,9 +1088,17 @@ reinstate_continuation_x (scm_thread *thread, SCM cont)
cp = SCM_VM_CONT_DATA (continuation->vm_cont);
- data.cp = cp;
- data.vp = vp;
- GC_call_with_alloc_lock (vm_return_to_continuation_inner, &data);
+ gc_inhibit_preemption (thread->mutator);
+ /* We know that there is enough space for the continuation, because we
+ captured it in the past. However there may have been an expansion
+ since the capture, so we may have to re-link the frame
+ pointers. */
+ memcpy (vp->stack_top - cp->stack_size,
+ cp->stack_bottom,
+ cp->stack_size * sizeof (*cp->stack_bottom));
+ vp->fp = vp->stack_top - cp->fp_offset;
+ vm_restore_sp (vp, vp->stack_top - cp->stack_size);
+ gc_reallow_preemption (thread->mutator);
/* Now we have the continuation properly copied over. We just need to
copy on an empty frame and the return values, as the continuation
@@ -1170,39 +1132,14 @@ capture_continuation (scm_thread *thread)
return scm_i_make_continuation (thread, vm_cont);
}
-struct compose_continuation_data
-{
- struct scm_vm *vp;
- struct scm_vm_cont *cp;
-};
-
-static void *
-compose_continuation_inner (void *data_ptr)
-{
- struct compose_continuation_data *data = data_ptr;
- struct scm_vm *vp = data->vp;
- struct scm_vm_cont *cp = data->cp;
-
- memcpy (vp->fp - cp->stack_size,
- cp->stack_bottom,
- cp->stack_size * sizeof (*cp->stack_bottom));
-
- vp->fp -= cp->fp_offset;
- vp->ip = cp->vra;
-
- return cp->mra;
-}
-
static uint8_t*
compose_continuation (scm_thread *thread, SCM cont)
{
struct scm_vm *vp = &thread->vm;
size_t nargs;
- struct compose_continuation_data data;
struct scm_vm_cont *cp;
union scm_vm_stack_element *args;
ptrdiff_t old_fp_offset;
- uint8_t *mra;
if (SCM_UNLIKELY (! SCM_VM_CONT_REWINDABLE_P (cont)))
scm_wrong_type_arg_msg (NULL, 0, cont, "resumable continuation");
@@ -1223,9 +1160,13 @@ compose_continuation (scm_thread *thread, SCM cont)
vm_push_sp (vp, vp->fp - (cp->stack_size + nargs));
- data.vp = vp;
- data.cp = cp;
- mra = GC_call_with_alloc_lock (compose_continuation_inner, &data);
+ gc_inhibit_preemption (thread->mutator);
+ memcpy (vp->fp - cp->stack_size,
+ cp->stack_bottom,
+ cp->stack_size * sizeof (*cp->stack_bottom));
+ vp->fp -= cp->fp_offset;
+ vp->ip = cp->vra;
+ gc_reallow_preemption (thread->mutator);
/* The resumed continuation will expect ARGS on the stack as if from a
multiple-value return. */
@@ -1251,7 +1192,7 @@ compose_continuation (scm_thread *thread, SCM cont)
}
}
- return mra;
+ return cp->mra;
}
static void
