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VM stack grows downward

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Adapt VM stack to grow downward.  This will make native compilation look
more like the VM code, as we will be able to use native CALL
instructions, taking proper advantage of the return address buffer.

* libguile/continuations.c (scm_i_continuation_to_frame): Record offsets
  from stack top.

* libguile/control.c (scm_i_prompt_pop_abort_args_x): Adapt for reversed
  order of arguments, and instead of relying on the abort to push on the
  number of arguments, make the caller save the stack depth, which
  allows us to compute the number of arguments ourselves.
  (reify_partial_continuation, scm_c_abort): Adapt to reversed stack
  order.

* libguile/dynstack.c (scm_dynstack_wind_prompt): Since we wind the
  stack in a downward direction, subtract the reloc instead of adding
  it.

* libguile/dynstack.h (SCM_F_DYNSTACK_PROMPT_ESCAPE_ONLY): Remove flag;
  instead rely on prompt-establishing code to save the stack depth.

* libguile/eval.c (eval): Remove extraneous "volatile" declarations for
  variables that are not re-set between the setjmp and any longjmp.
  Adapt to save stack depth before instating the prompt.

* libguile/foreign.c (scm_i_foreign_call): Adapt to receive arguments in
  reverse order.

* libguile/frames.c (frame_stack_top, scm_i_frame_stack_top): Adapt to
  compute stack top instead of stack bottom.
  (scm_c_frame_closure): Adapt to stack growth change.
  (scm_frame_num_locals, scm_frame_local_ref, scm_frame_set_x): Use
  union data type to access stack.
  (RELOC): Reformat.
  (scm_c_frame_previous): Adapt to stack growth change.

* libguile/frames.h: Adapt stack diagram to indicate that the stack
  grows up.
  (union scm_vm_stack_element): New data type used to access items on
  the stack.
  (SCM_FRAME_PREVIOUS_SP)
  (SCM_FRAME_RETURN_ADDRESS, SCM_FRAME_SET_RETURN_ADDRESS)
  (SCM_FRAME_DYNAMIC_LINK, SCM_FRAME_SET_DYNAMIC_LINK)
  (SCM_FRAME_LOCAL, SCM_FRAME_NUM_LOCALS): Adapt to stack representation
  change.
  (SCM_FRAME_SLOT): New helper.
  (SCM_VM_FRAME_FP, SCM_VM_FRAME_SP): Adapt to stack growth change.

* libguile/stacks.c (scm_make_stack): Record offsets from top of stack.

* libguile/throw.c (catch): Adapt to scm_i_prompt_pop_abort_args_x
  change.

* libguile/vm-engine.c (ALLOC_FRAME, RESET_FRAME):
  (FRAME_LOCALS_COUNT_FROM): Adapt to stack growth change.
  (LOCAL_ADDRESS): Use SCM_FRAME_SLOT to get the address as the proper
  data type.
  (RETURN_ONE_VALUE, RETURN_VALUE_LIST): Adapt to stack growth change.
  (apply): Shuffling up the SMOB apply args can cause the stack to
  expand, so use ALLOC_FRAME instead of RESET_FRAME.
  (vm_engine): Adapt for stack growth change.

* libguile/vm.c (vm_increase_sp, vm_push_sp, vm_restore_sp): Adapt to
  stack representation change.
  (scm_i_vm_cont_to_frame): Adapt to take offsets from the top.
  (scm_i_vm_capture_stack): Adapt to capture from the top.
  (vm_return_to_continuation_inner): Adapt for data type changes.
  (vm_return_to_continuation): Likewise, and instead of looping, just
  splat the saved arguments on with memcpy.
  (vm_dispatch_hook): Adapt to receive arguments in the reverse order.
  Adapt callers.
  (vm_abort): There is never a tail argument.  Adapt to stack
  representation change.
  (vm_reinstate_partial_continuation)
  (vm_reinstate_partial_continuation_inner): Adapt to stack growth
  change.
  (allocate_stack, free_stack): Adapt to data type change.
  (expand_stack): Don't try to mremap(), as you can't grow a mapping
  from the bottom.  Without knowing that there's a free mapping space
  right below the old stack, which there usually isn't on Linux, we have
  to copy.  We can't use MAP_GROWSDOWN because Linux is buggy.
  (make_vm): Adapt to stack representation changes.
  (return_unused_stack_to_os): Round down instead of up, as the stack
  grows down.
  (scm_i_vm_mark_stack): Adapt to walk up the stack.
  (scm_i_vm_free_stack): Adapt to scm_vm changes.
  (vm_expand_stack_inner, reset_stack_limit, vm_expand_stack): Adapt to
  the stack growing down.
  (scm_call_n): Adapt to the stack growing down.  Don't allow argv to
  point into the stack.

* libguile/vm.h (struct scm_vm, struct scm_vm_cont): Adapt to hold the
  stack top and bottom.
This commit is contained in:
Andy Wingo 2015-09-22 10:24:30 +00:00
parent d7199da8c9
commit 0007507340
15 changed files with 400 additions and 392 deletions
Download patch file Download diff file Expand all files Collapse all files

62
libguile/frames.c
View file

@ -1,4 +1,4 @@
/* Copyright (C) 2001, 2009, 2010, 2011, 2012, 2013, 2014 Free Software Foundation, Inc.
/* Copyright (C) 2001, 2009, 2010, 2011, 2012, 2013, 2014, 2015 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
@ -25,14 +25,6 @@
#include "_scm.h"
#include "frames.h"
#include "vm.h"
#include <verify.h>
/* Make sure assumptions on the layout of `struct scm_vm_frame' hold. */
verify (sizeof (SCM) == sizeof (SCM *));
verify (sizeof (struct scm_vm_frame) == 3 * sizeof (SCM));
verify (offsetof (struct scm_vm_frame, dynamic_link) == 0);
SCM
scm_c_make_frame (enum scm_vm_frame_kind kind, const struct scm_frame *frame)
@ -57,16 +49,19 @@ scm_i_frame_print (SCM frame, SCM port, scm_print_state *pstate)
scm_puts_unlocked (">", port);
}
static SCM*
frame_stack_base (enum scm_vm_frame_kind kind, const struct scm_frame *frame)
static union scm_vm_stack_element*
frame_stack_top (enum scm_vm_frame_kind kind, const struct scm_frame *frame)
{
switch (kind)
{
case SCM_VM_FRAME_KIND_CONT:
return ((struct scm_vm_cont *) frame->stack_holder)->stack_base;
case SCM_VM_FRAME_KIND_CONT:
{
struct scm_vm_cont *cont = frame->stack_holder;
return cont->stack_bottom + cont->stack_size;
}
case SCM_VM_FRAME_KIND_VM:
return ((struct scm_vm *) frame->stack_holder)->stack_base;
return ((struct scm_vm *) frame->stack_holder)->stack_top;
default:
abort ();
@ -89,14 +84,14 @@ frame_offset (enum scm_vm_frame_kind kind, const struct scm_frame *frame)
}
}
SCM*
scm_i_frame_stack_base (SCM frame)
#define FUNC_NAME "frame-stack-base"
union scm_vm_stack_element*
scm_i_frame_stack_top (SCM frame)
#define FUNC_NAME "frame-stack-top"
{
SCM_VALIDATE_VM_FRAME (1, frame);
return frame_stack_base (SCM_VM_FRAME_KIND (frame),
SCM_VM_FRAME_DATA (frame));
return frame_stack_top (SCM_VM_FRAME_KIND (frame),
SCM_VM_FRAME_DATA (frame));
}
#undef FUNC_NAME
@ -130,10 +125,10 @@ SCM_DEFINE (scm_frame_p, "frame?", 1, 0, 0,
SCM
scm_c_frame_closure (enum scm_vm_frame_kind kind, const struct scm_frame *frame)
{
SCM *fp, *sp;
union scm_vm_stack_element *fp, *sp;
fp = frame_stack_base (kind, frame) + frame->fp_offset;
sp = frame_stack_base (kind, frame) + frame->sp_offset;
fp = frame_stack_top (kind, frame) - frame->fp_offset;
sp = frame_stack_top (kind, frame) - frame->sp_offset;
if (SCM_FRAME_NUM_LOCALS (fp, sp) > 0)
return SCM_FRAME_LOCAL (fp, 0);
@ -214,7 +209,7 @@ SCM_DEFINE (scm_frame_num_locals, "frame-num-locals", 1, 0, 0,
"")
#define FUNC_NAME s_scm_frame_num_locals
{
SCM *fp, *sp;
union scm_vm_stack_element *fp, *sp;
SCM_VALIDATE_VM_FRAME (1, frame);
@ -230,7 +225,7 @@ SCM_DEFINE (scm_frame_local_ref, "frame-local-ref", 2, 0, 0,
"")
#define FUNC_NAME s_scm_frame_local_ref
{
SCM *fp, *sp;
union scm_vm_stack_element *fp, *sp;
unsigned int i;
SCM_VALIDATE_VM_FRAME (1, frame);
@ -252,7 +247,7 @@ SCM_DEFINE (scm_frame_local_set_x, "frame-local-set!", 3, 0, 0,
"")
#define FUNC_NAME s_scm_frame_local_set_x
{
SCM *fp, *sp;
union scm_vm_stack_element *fp, *sp;
unsigned int i;
SCM_VALIDATE_VM_FRAME (1, frame);
@ -314,8 +309,7 @@ SCM_DEFINE (scm_frame_return_address, "frame-return-address", 1, 0, 0,
}
#undef FUNC_NAME
#define RELOC(kind, frame, val) \
(((SCM *) (val)) + frame_offset (kind, frame))
#define RELOC(kind, frame, val) ((val) + frame_offset (kind, frame))
SCM_DEFINE (scm_frame_dynamic_link, "frame-dynamic-link", 1, 0, 0,
(SCM frame),
@ -334,13 +328,13 @@ SCM_DEFINE (scm_frame_dynamic_link, "frame-dynamic-link", 1, 0, 0,
int
scm_c_frame_previous (enum scm_vm_frame_kind kind, struct scm_frame *frame)
{
SCM *this_fp, *new_fp, *new_sp;
SCM *stack_base = frame_stack_base (kind, frame);
union scm_vm_stack_element *this_fp, *new_fp, *new_sp;
union scm_vm_stack_element *stack_top = frame_stack_top (kind, frame);
again:
this_fp = frame->fp_offset + stack_base;
this_fp = stack_top - frame->fp_offset;
if (this_fp == stack_base)
if (this_fp == stack_top)
return 0;
new_fp = SCM_FRAME_DYNAMIC_LINK (this_fp);
@ -350,12 +344,12 @@ scm_c_frame_previous (enum scm_vm_frame_kind kind, struct scm_frame *frame)
new_fp = RELOC (kind, frame, new_fp);
if (new_fp < stack_base)
if (new_fp > stack_top)
return 0;
new_sp = SCM_FRAME_PREVIOUS_SP (this_fp);
frame->fp_offset = new_fp - stack_base;
frame->sp_offset = new_sp - stack_base;
frame->fp_offset = stack_top - new_fp;
frame->sp_offset = stack_top - new_sp;
frame->ip = SCM_FRAME_RETURN_ADDRESS (this_fp);
{