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the dynamic stack is really a stack now, instead of a list

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* libguile/dynstack.h:
* libguile/dynstack.c: New files, implementing the dynamic stack as a
  true stack instead of a linked list.  This lowers the cost of
  dynwinds: frames, winders, prompts, with-fluids, and dynamic-wind.
  For the most part, we allocate these items directly on the stack.

* libguile/dynwinds.h:
* libguile/dynwinds.c: Adapt all manipulators of the wind stack to use
  interfaces from dynstack.c.  Remove heap-allocated winder and frame
  object types.
  (scm_dowinds, scm_i_dowinds): Remove these.  The first was exported,
  but it was not a public interface.

* libguile/continuations.c:
* libguile/continuations.h (scm_t_contregs): Continuation objects
  reference scm_t_dynstack* values now.  Adapt to the new interfaces.

* libguile/control.c:
* libguile/control.h: There is no longer a scm_tc7_prompt kind of object
  that can be allocated on the heap.  Instead, the prompt flags, key,
  and registers are pushed on the dynwind stack.  (The registers are
  still on the heap.)  Also, since the vm_cont will reference the
  dynwinds, make the partial continuation stub take just one extra arg,
  instead of storing the intwinds separately in the object table.

* libguile/fluids.c:
* libguile/fluids.h: No more with-fluids objects; instead, the fluids go
  on the dynstack.  The values still have to be on the heap, though.
  (scm_prepare_fluids, scm_swap_fluids): New internal functions,
  replacing scm_i_make_with_fluids and scm_i_swap_with_fluids.

* libguile/print.c: Remove prompt and with-fluids printers.

* libguile/tags.h: Revert prompt and with-fluids tc7 values to what they
  were before they were allocated.

* libguile/vm-i-system.c (partial_cont_call): Just pop the vmcont, the
  intwinds will not be passed as a second arg.  Rewind the dynamic stack
  from within the VM, so that any rewinder sees valid prompt entries.
  (call_cc, tail_call_cc): Adapt to pass the dynstack to
  scm_i_vm_capture_stack.
  (prompt, wind, unwind, wind_fluids, unwind_fluids): Adapt to the new
  interfaces.

* libguile/vm.h (scm_i_capture_current_stack): Rename from
  scm_i_vm_capture_continuation.
  (scm_i_vm_capture_stack): Take a dynstack as an argument.
* libguile/vm.c (vm_reinstate_partial_continuation): Don't wind here, as
  that could result in winders seeing invalid prompts.

* libguile/eval.c:
* libguile/root.c:
* libguile/stacks.c:
* libguile/threads.c:
* libguile/threads.h:
* libguile/throw.c: Adapt other users of dynwinds to use the dynstack.
This commit is contained in:
Andy Wingo 2012-03-03 17:01:16 +01:00
parent 05b4d9106d
commit 9ede013f68
22 changed files with 1079 additions and 534 deletions
Download patch file Download diff file Expand all files Collapse all files

544
libguile/dynstack.c Normal file
View file

@ -0,0 +1,544 @@
/* Copyright (C) 2012 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 License
* as published by the Free Software Foundation; either version 3 of
* the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301 USA
*/
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <assert.h>
#include "libguile/_scm.h"
#include "libguile/control.h"
#include "libguile/eval.h"
#include "libguile/fluids.h"
#include "libguile/dynstack.h"
#define PROMPT_WORDS 2
#define PROMPT_KEY(top) (SCM_PACK ((top)[0]))
#define PROMPT_REGS(top) ((scm_t_prompt_registers*) ((top)[1]))
#define WINDER_WORDS 2
#define WINDER_PROC(top) ((scm_t_guard) ((top)[0]))
#define WINDER_DATA(top) ((void *) ((top)[1]))
#define DYNWIND_WORDS 2
#define DYNWIND_ENTER(top) (SCM_PACK ((top)[0]))
#define DYNWIND_LEAVE(top) (SCM_PACK ((top)[1]))
#define WITH_FLUIDS_FLUIDS(top) ((SCM*)((top) + 1))
#define WITH_FLUIDS_VALUES(top) ((SCM*)((top)[0]))
static void
copy_scm_t_bits (scm_t_bits *dst, scm_t_bits *src, size_t n)
{
size_t i;
for (i = 0; i < n; i++)
dst[i] = src[i];
}
static void
copy_scm (SCM *dst, SCM *src, size_t n)
{
size_t i;
for (i = 0; i < n; i++)
dst[i] = src[i];
}
static void
clear_scm_t_bits (scm_t_bits *items, size_t n)
{
size_t i;
for (i = 0; i < n; i++)
items[i] = 0;
}
/* Ensure space for N additional words. */
static void
dynstack_ensure_space (scm_t_dynstack *dynstack, size_t n)
{
size_t capacity = SCM_DYNSTACK_CAPACITY (dynstack);
size_t height = SCM_DYNSTACK_HEIGHT (dynstack);
n += SCM_DYNSTACK_HEADER_LEN;
if (capacity < height + n)
{
scm_t_bits *new_base;
while (capacity < height + n)
capacity = (capacity < 4) ? 8 : (capacity * 2);
new_base = scm_gc_malloc (capacity * sizeof(scm_t_bits), "dynstack");
copy_scm_t_bits (new_base, dynstack->base, height);
clear_scm_t_bits (dynstack->base, height);
dynstack->base = new_base;
dynstack->top = new_base + height;
dynstack->limit = new_base + capacity;
}
}
static inline scm_t_bits *
push_dynstack_entry_unchecked (scm_t_dynstack *dynstack,
scm_t_dynstack_item_type type,
scm_t_bits flags, size_t len)
{
scm_t_bits *ret = dynstack->top;
SCM_DYNSTACK_SET_TAG (dynstack->top, SCM_MAKE_DYNSTACK_TAG (type, flags, len));
dynstack->top += SCM_DYNSTACK_HEADER_LEN + len;
SCM_DYNSTACK_SET_PREV_OFFSET (dynstack->top, SCM_DYNSTACK_HEADER_LEN + len);
return ret;
}
static inline scm_t_bits *
push_dynstack_entry (scm_t_dynstack *dynstack,
scm_t_dynstack_item_type type,
scm_t_bits flags, size_t len)
{
if (SCM_UNLIKELY (!SCM_DYNSTACK_HAS_SPACE (dynstack, len)))
dynstack_ensure_space (dynstack, len);
return push_dynstack_entry_unchecked (dynstack, type, flags, len);
}
void
scm_dynstack_push_frame (scm_t_dynstack *dynstack,
scm_t_dynstack_frame_flags flags)
{
push_dynstack_entry (dynstack, SCM_DYNSTACK_TYPE_FRAME, flags, 0);
}
void
scm_dynstack_push_rewinder (scm_t_dynstack *dynstack,
scm_t_dynstack_winder_flags flags,
scm_t_guard proc, void *data)
{
scm_t_bits *words;
words = push_dynstack_entry (dynstack, SCM_DYNSTACK_TYPE_REWINDER, flags, 2);
words[0] = (scm_t_bits) proc;
words[1] = (scm_t_bits) data;
}
void
scm_dynstack_push_unwinder (scm_t_dynstack *dynstack,
scm_t_dynstack_winder_flags flags,
scm_t_guard proc, void *data)
{
scm_t_bits *words;
words = push_dynstack_entry (dynstack, SCM_DYNSTACK_TYPE_UNWINDER, flags, 2);
words[0] = (scm_t_bits) proc;
words[1] = (scm_t_bits) data;
}
/* The fluids are stored on the stack. However, the values have to be
stored on the heap, so that all continuations that capture this
dynamic scope capture the same bindings. */
void
scm_dynstack_push_fluids (scm_t_dynstack *dynstack, size_t n,
SCM *fluids, SCM *values, SCM dynamic_state)
{
scm_t_bits *words;
SCM *heap_values;
n = scm_prepare_fluids (n, fluids, values);
heap_values = scm_gc_malloc (n * sizeof (scm_t_bits), "with-fluids");
copy_scm (heap_values, values, n);
words = push_dynstack_entry (dynstack, SCM_DYNSTACK_TYPE_WITH_FLUIDS,
0, n + 1);
words[0] = (scm_t_bits) heap_values;
copy_scm (WITH_FLUIDS_FLUIDS (words), fluids, n);
/* Go ahead and swap them. */
scm_swap_fluids (n, WITH_FLUIDS_FLUIDS (words), WITH_FLUIDS_VALUES (words),
dynamic_state);
}
void
scm_dynstack_push_prompt (scm_t_dynstack *dynstack,
scm_t_dynstack_prompt_flags flags,
SCM key, scm_t_prompt_registers *regs)
{
scm_t_bits *words;
words = push_dynstack_entry (dynstack, SCM_DYNSTACK_TYPE_PROMPT, flags, 2);
words[0] = SCM_UNPACK (key);
words[1] = (scm_t_bits) regs;
}
void
scm_dynstack_push_dynwind (scm_t_dynstack *dynstack, SCM enter, SCM leave)
{
scm_t_bits *words;
words = push_dynstack_entry (dynstack, SCM_DYNSTACK_TYPE_DYNWIND, 0, 2);
words[0] = SCM_UNPACK (enter);
words[1] = SCM_UNPACK (leave);
}
static inline scm_t_bits
dynstack_pop (scm_t_dynstack *dynstack, scm_t_bits **words)
{
scm_t_bits *prev = SCM_DYNSTACK_PREV (dynstack->top);
scm_t_bits tag;
if (SCM_UNLIKELY (!prev))
abort ();
SCM_DYNSTACK_SET_PREV_OFFSET (dynstack->top, 0);
dynstack->top = prev;
tag = SCM_DYNSTACK_TAG (dynstack->top);
SCM_DYNSTACK_SET_TAG (dynstack->top, 0);
*words = dynstack->top;
return tag;
}
void
scm_dynstack_pop (scm_t_dynstack *dynstack)
{
scm_t_bits tag, *words;
tag = dynstack_pop (dynstack, &words);
clear_scm_t_bits (words, SCM_DYNSTACK_TAG_LEN (tag));
}
scm_t_dynstack *
scm_dynstack_capture_all (scm_t_dynstack *dynstack)
{
return scm_dynstack_capture (dynstack, SCM_DYNSTACK_FIRST (dynstack));
}
scm_t_dynstack *
scm_dynstack_capture (scm_t_dynstack *dynstack, scm_t_bits *item)
{
char *mem;
scm_t_dynstack *ret;
size_t len;
assert (item >= SCM_DYNSTACK_FIRST (dynstack));
assert (item <= dynstack->top);
len = dynstack->top - item + SCM_DYNSTACK_HEADER_LEN;
mem = scm_gc_malloc (sizeof (*ret) + len * sizeof(scm_t_bits), "dynstack");
ret = (scm_t_dynstack *) mem;
ret->base = (scm_t_bits *) (mem + sizeof (*ret));
ret->limit = ret->base + len;
ret->top = ret->base + len;
copy_scm_t_bits (ret->base, item - SCM_DYNSTACK_HEADER_LEN, len);
SCM_DYNSTACK_SET_PREV_OFFSET (SCM_DYNSTACK_FIRST (ret), 0);
return ret;
}
void
scm_dynstack_wind_1 (scm_t_dynstack *dynstack, scm_t_bits *item)
{
scm_t_bits tag = SCM_DYNSTACK_TAG (item);
scm_t_dynstack_item_type type = SCM_DYNSTACK_TAG_TYPE (tag);
scm_t_bits flags = SCM_DYNSTACK_TAG_FLAGS (tag);
size_t len = SCM_DYNSTACK_TAG_LEN (tag);
switch (type)
{
case SCM_DYNSTACK_TYPE_FRAME:
if (!(flags & SCM_F_DYNSTACK_FRAME_REWINDABLE))
scm_misc_error ("scm_dynstack_wind_1",
"cannot invoke continuation from this context",
SCM_EOL);
break;
case SCM_DYNSTACK_TYPE_UNWINDER:
break;
case SCM_DYNSTACK_TYPE_REWINDER:
WINDER_PROC (item) (WINDER_DATA (item));
break;
case SCM_DYNSTACK_TYPE_WITH_FLUIDS:
scm_swap_fluids (len - 1, WITH_FLUIDS_FLUIDS (item),
WITH_FLUIDS_VALUES (item),
SCM_I_CURRENT_THREAD->dynamic_state);
break;
case SCM_DYNSTACK_TYPE_PROMPT:
/* see vm_reinstate_partial_continuation */
break;
case SCM_DYNSTACK_TYPE_DYNWIND:
scm_call_0 (DYNWIND_ENTER (item));
break;
case SCM_DYNSTACK_TYPE_NONE:
default:
abort ();
}
{
scm_t_bits *words = push_dynstack_entry (dynstack, type, flags, len);
copy_scm_t_bits (words, item, len);
}
}
scm_t_bits
scm_dynstack_unwind_1 (scm_t_dynstack *dynstack)
{
scm_t_bits tag;
scm_t_bits *words;
scm_t_dynstack_item_type type;
size_t len;
tag = dynstack_pop (dynstack, &words);
type = SCM_DYNSTACK_TAG_TYPE (tag);
len = SCM_DYNSTACK_TAG_LEN (tag);
switch (type)
{
case SCM_DYNSTACK_TYPE_FRAME:
break;
case SCM_DYNSTACK_TYPE_UNWINDER:
WINDER_PROC (words) (WINDER_DATA (words));
clear_scm_t_bits (words, WINDER_WORDS);
break;
case SCM_DYNSTACK_TYPE_REWINDER:
clear_scm_t_bits (words, WINDER_WORDS);
break;
case SCM_DYNSTACK_TYPE_WITH_FLUIDS:
scm_swap_fluids (len - 1, WITH_FLUIDS_FLUIDS (words),
WITH_FLUIDS_VALUES (words),
SCM_I_CURRENT_THREAD->dynamic_state);
clear_scm_t_bits (words, len);
break;
case SCM_DYNSTACK_TYPE_PROMPT:
/* we could invalidate the prompt */
clear_scm_t_bits (words, PROMPT_WORDS);
break;
case SCM_DYNSTACK_TYPE_DYNWIND:
{
SCM proc = DYNWIND_LEAVE (words);
clear_scm_t_bits (words, DYNWIND_WORDS);
scm_call_0 (proc);
}
break;
case SCM_DYNSTACK_TYPE_NONE:
default:
abort ();
}
return tag;
}
void
scm_dynstack_wind (scm_t_dynstack *dynstack, scm_t_bits *item)
{
for (; SCM_DYNSTACK_TAG (item); item = SCM_DYNSTACK_NEXT (item))
scm_dynstack_wind_1 (dynstack, item);
}
void
scm_dynstack_unwind (scm_t_dynstack *dynstack, scm_t_bits *base)
{
while (dynstack->top > base)
scm_dynstack_unwind_1 (dynstack);
}
static int
same_entries (scm_t_bits *walk_a, scm_t_bits *next_a,
scm_t_bits *walk_b, scm_t_bits *next_b)
{
if (SCM_DYNSTACK_TAG (walk_a) != SCM_DYNSTACK_TAG (walk_b))
return 0;
if (next_a - walk_a != next_b - walk_b)
return 0;
assert (SCM_DYNSTACK_PREV_OFFSET (next_a) == next_a - walk_a);
assert (SCM_DYNSTACK_PREV_OFFSET (next_b) == next_b - walk_b);
while (walk_a != next_a)
if (*(walk_a++) != *(walk_b++))
return 0;
return 1;
}
static ptrdiff_t
shared_prefix_length (scm_t_dynstack *a, scm_t_dynstack *b)
{
scm_t_bits *walk_a, *next_a, *walk_b, *next_b;
walk_a = SCM_DYNSTACK_FIRST (a);
walk_b = SCM_DYNSTACK_FIRST (b);
next_a = SCM_DYNSTACK_NEXT (walk_a);
next_b = SCM_DYNSTACK_NEXT (walk_b);
while (next_a && next_b && same_entries (walk_a, next_a, walk_b, next_b))
{
walk_a = next_a;
walk_b = next_b;
next_a = SCM_DYNSTACK_NEXT (walk_a);
next_b = SCM_DYNSTACK_NEXT (walk_b);
}
return walk_a - a->base;
}
scm_t_bits *
scm_dynstack_unwind_fork (scm_t_dynstack *dynstack, scm_t_dynstack *branch)
{
ptrdiff_t join_height;
join_height = shared_prefix_length (dynstack, branch);
scm_dynstack_unwind (dynstack, dynstack->base + join_height);
return branch->base + join_height;
}
scm_t_bits*
scm_dynstack_find_prompt (scm_t_dynstack *dynstack, SCM key,
scm_t_prompt_registers **regs,
scm_t_dynstack_prompt_flags *flags)
{
scm_t_bits *walk;
for (walk = SCM_DYNSTACK_PREV (dynstack->top); walk;
walk = SCM_DYNSTACK_PREV (walk))
{
scm_t_bits tag = SCM_DYNSTACK_TAG (walk);
if (SCM_DYNSTACK_TAG_TYPE (tag) == SCM_DYNSTACK_TYPE_PROMPT
&& scm_is_eq (PROMPT_KEY (walk), key))
{
if (regs)
*regs = PROMPT_REGS (walk);
if (flags)
*flags = SCM_DYNSTACK_TAG_FLAGS (tag);
return walk;
}
}
return NULL;
}
scm_t_prompt_registers*
scm_dynstack_relocate_prompt (scm_t_dynstack *dynstack, scm_t_ptrdiff reloc,
scm_t_uint64 vm_cookie)
{
scm_t_bits *item;
scm_t_prompt_registers *prev, *rewound;
item = SCM_DYNSTACK_PREV (dynstack->top);
if (SCM_DYNSTACK_TAG_TYPE (SCM_DYNSTACK_TAG (item))
!= SCM_DYNSTACK_TYPE_PROMPT)
abort ();
prev = PROMPT_REGS (item);
rewound = scm_c_make_prompt_registers (prev->fp + reloc,
prev->sp + reloc,
prev->ip,
vm_cookie);
item[1] = (scm_t_bits) rewound;
return rewound;
}
void
scm_dynstack_unwind_frame (scm_t_dynstack *dynstack)
{
/* Unwind up to and including the next frame entry. */
while (1)
{
scm_t_bits tag, *words;
tag = dynstack_pop (dynstack, &words);
switch (SCM_DYNSTACK_TAG_TYPE (tag))
{
case SCM_DYNSTACK_TYPE_FRAME:
return;
case SCM_DYNSTACK_TYPE_REWINDER:
clear_scm_t_bits (words, WINDER_WORDS);
continue;
case SCM_DYNSTACK_TYPE_UNWINDER:
{
scm_t_guard proc = WINDER_PROC (words);
void *data = WINDER_DATA (words);
clear_scm_t_bits (words, WINDER_WORDS);
if (SCM_DYNSTACK_TAG_FLAGS (tag) & SCM_F_DYNSTACK_WINDER_EXPLICIT)
proc (data);
continue;
}
default:
/* We should only see winders. */
abort ();
}
}
}
/* This function must not allocate. */
void
scm_dynstack_unwind_fluids (scm_t_dynstack *dynstack, SCM dynamic_state)
{
scm_t_bits tag, *words;
size_t len;
tag = dynstack_pop (dynstack, &words);
len = SCM_DYNSTACK_TAG_LEN (tag);
assert (SCM_DYNSTACK_TAG_TYPE (tag) == SCM_DYNSTACK_TYPE_WITH_FLUIDS);
assert (len >= 1);
scm_swap_fluids (len - 1, WITH_FLUIDS_FLUIDS (words),
WITH_FLUIDS_VALUES (words), dynamic_state);
clear_scm_t_bits (words, len);
}
/*
Local Variables:
c-file-style: "gnu"
End:
*/