diff options
Diffstat (limited to 'libguile/control.c')
-rw-r--r-- | libguile/control.c | 137 |
1 files changed, 55 insertions, 82 deletions
diff --git a/libguile/control.c b/libguile/control.c index f8d2d60ae..54c1cd3f4 100644 --- a/libguile/control.c +++ b/libguile/control.c @@ -30,30 +30,14 @@ +#define PROMPT_ESCAPE_P(p) \ + (SCM_DYNSTACK_TAG_FLAGS (SCM_DYNSTACK_TAG (p)) \ + & SCM_F_DYNSTACK_PROMPT_ESCAPE_ONLY) -SCM -scm_c_make_prompt (SCM k, SCM *fp, SCM *sp, scm_t_uint8 *abort_ip, - scm_t_uint8 escape_only_p, scm_t_int64 vm_cookie, - SCM winds) -{ - scm_t_bits tag; - struct scm_prompt_registers *regs; - - tag = scm_tc7_prompt; - if (escape_only_p) - tag |= (SCM_F_PROMPT_ESCAPE<<8); - - regs = scm_gc_malloc_pointerless (sizeof (*regs), "prompt registers"); - regs->fp = fp; - regs->sp = sp; - regs->ip = abort_ip; - regs->cookie = vm_cookie; + - return scm_double_cell (tag, SCM_UNPACK (k), (scm_t_bits)regs, - SCM_UNPACK (winds)); -} -/* Only to be called if the SCM_PROMPT_SETJMP returns 1 */ +/* Only to be called if the SCM_I_SETJMP returns 1 */ SCM scm_i_prompt_pop_abort_args_x (SCM vm) { @@ -115,9 +99,9 @@ SCM_STATIC_OBJCODE (cont_objcode) = { OBJCODE_HEADER (8, 19), /* leave args on the stack */ /* 0 */ scm_op_object_ref, 0, /* push scm_vm_cont object */ - /* 2 */ scm_op_object_ref, 1, /* push internal winds */ - /* 4 */ scm_op_partial_cont_call, /* and go! */ - /* 5 */ scm_op_nop, scm_op_nop, scm_op_nop, /* pad to 8 bytes */ + /* 2 */ scm_op_partial_cont_call, /* and go! */ + /* 3 */ scm_op_nop, + /* 4 */ scm_op_nop, scm_op_nop, scm_op_nop, scm_op_nop, /* pad to 8 bytes */ /* 8 */ /* We could put some meta-info to say that this proc is a continuation. Not sure @@ -125,7 +109,7 @@ SCM_STATIC_OBJCODE (cont_objcode) = { META_HEADER (19), /* 0 */ scm_op_make_eol, /* bindings */ /* 1 */ scm_op_make_eol, /* sources */ - /* 2 */ scm_op_make_int8, 0, scm_op_make_int8, 5, /* arity: from ip 0 to ip 7 */ + /* 2 */ scm_op_make_int8, 0, scm_op_make_int8, 3, /* arity: from ip 0 to ip 3 */ /* 6 */ scm_op_make_int8_0, /* the arity is 0 required args */ /* 7 */ scm_op_make_int8_0, /* 0 optionals */ /* 8 */ scm_op_make_true, /* and a rest arg */ @@ -138,45 +122,41 @@ SCM_STATIC_OBJCODE (cont_objcode) = { static SCM -reify_partial_continuation (SCM vm, SCM prompt, SCM extwinds, - scm_t_int64 cookie) +reify_partial_continuation (SCM vm, + SCM *saved_fp, SCM *saved_sp, scm_t_uint8 *saved_ip, + scm_i_jmp_buf *saved_registers, + scm_t_dynstack *dynstack, + scm_i_jmp_buf *current_registers) { - SCM vm_cont, dynwinds, intwinds = SCM_EOL, ret; + SCM vm_cont, ret; scm_t_uint32 flags; - /* No need to reify if the continuation is never referenced in the handler. */ - if (SCM_PROMPT_ESCAPE_P (prompt)) - return SCM_BOOL_F; - - dynwinds = scm_i_dynwinds (); - while (!scm_is_eq (dynwinds, extwinds)) - { - intwinds = scm_cons (scm_car (dynwinds), intwinds); - dynwinds = scm_cdr (dynwinds); - } - flags = SCM_F_VM_CONT_PARTIAL; - if (cookie >= 0 && SCM_PROMPT_REGISTERS (prompt)->cookie == cookie) + /* If we are aborting to a prompt that has the same registers as those + of the abort, it means there are no intervening C frames on the + stack, and so the continuation can be relocated elsewhere on the + stack: it is rewindable. */ + if (saved_registers && saved_registers == current_registers) flags |= SCM_F_VM_CONT_REWINDABLE; /* Since non-escape continuations should begin with a thunk application, the first bit of the stack should be a frame, with the saved fp equal to the fp that was current when the prompt was made. */ - if ((SCM*)SCM_UNPACK (SCM_PROMPT_REGISTERS (prompt)->sp[1]) - != SCM_PROMPT_REGISTERS (prompt)->fp) + if ((SCM*)SCM_UNPACK (saved_sp[1]) != saved_fp) abort (); /* Capture from the top of the thunk application frame up to the end. Set an MVRA only, as the post-abort code is in an MV context. */ - vm_cont = scm_i_vm_capture_stack (SCM_PROMPT_REGISTERS (prompt)->sp + 4, + vm_cont = scm_i_vm_capture_stack (saved_sp + 4, SCM_VM_DATA (vm)->fp, SCM_VM_DATA (vm)->sp, NULL, SCM_VM_DATA (vm)->ip, + dynstack, flags); ret = scm_make_program (cont_objcode, - scm_vector (scm_list_2 (vm_cont, intwinds)), + scm_c_make_vector (1, vm_cont), SCM_BOOL_F); SCM_SET_CELL_WORD_0 (ret, SCM_CELL_WORD_0 (ret) | SCM_F_PROGRAM_IS_PARTIAL_CONTINUATION); @@ -184,48 +164,49 @@ reify_partial_continuation (SCM vm, SCM prompt, SCM extwinds, } void -scm_c_abort (SCM vm, SCM tag, size_t n, SCM *argv, scm_t_int64 cookie) +scm_c_abort (SCM vm, SCM tag, size_t n, SCM *argv, + scm_i_jmp_buf *current_registers) { - SCM cont, winds, prompt = SCM_BOOL_F; - long delta; + SCM cont; + scm_t_dynstack *dynstack = &SCM_I_CURRENT_THREAD->dynstack; + scm_t_bits *prompt; + scm_t_dynstack_prompt_flags flags; + SCM *fp, *sp; + scm_t_uint8 *ip; + scm_i_jmp_buf *registers; size_t i; - /* Search the wind list for an appropriate prompt. - "Waiter, please bring us the wind list." */ - for (winds = scm_i_dynwinds (), delta = 0; - scm_is_pair (winds); - winds = SCM_CDR (winds), delta++) - { - SCM elt = SCM_CAR (winds); - if (SCM_PROMPT_P (elt) && scm_is_eq (SCM_PROMPT_TAG (elt), tag)) - { - prompt = elt; - break; - } - } - - /* If we didn't find anything, raise an error. */ - if (scm_is_false (prompt)) + prompt = scm_dynstack_find_prompt (dynstack, tag, + &flags, &fp, &sp, &ip, ®isters); + + if (!prompt) scm_misc_error ("abort", "Abort to unknown prompt", scm_list_1 (tag)); - cont = reify_partial_continuation (vm, prompt, winds, cookie); + /* Only reify if the continuation referenced in the handler. */ + if (flags & SCM_F_DYNSTACK_PROMPT_ESCAPE_ONLY) + cont = SCM_BOOL_F; + else + { + scm_t_dynstack *captured; - /* Unwind once more, beyond the prompt. */ - winds = SCM_CDR (winds), delta++; + captured = scm_dynstack_capture (dynstack, SCM_DYNSTACK_NEXT (prompt)); + cont = reify_partial_continuation (vm, fp, sp, ip, registers, captured, + current_registers); + } - /* Unwind */ - scm_dowinds (winds, delta); + /* Unwind. */ + scm_dynstack_unwind (dynstack, prompt); /* Unwinding may have changed the current thread's VM, so use the new one. */ vm = scm_the_vm (); /* Restore VM regs */ - SCM_VM_DATA (vm)->fp = SCM_PROMPT_REGISTERS (prompt)->fp; - SCM_VM_DATA (vm)->sp = SCM_PROMPT_REGISTERS (prompt)->sp; - SCM_VM_DATA (vm)->ip = SCM_PROMPT_REGISTERS (prompt)->ip; + SCM_VM_DATA (vm)->fp = fp; + SCM_VM_DATA (vm)->sp = sp; + SCM_VM_DATA (vm)->ip = ip; - /* Since we're jumping down, we should always have enough space */ + /* Since we're jumping down, we should always have enough space. */ if (SCM_VM_DATA (vm)->sp + n + 1 >= SCM_VM_DATA (vm)->stack_limit) abort (); @@ -236,7 +217,7 @@ scm_c_abort (SCM vm, SCM tag, size_t n, SCM *argv, scm_t_int64 cookie) *(++(SCM_VM_DATA (vm)->sp)) = scm_from_size_t (n+1); /* +1 for continuation */ /* Jump! */ - SCM_I_LONGJMP (SCM_PROMPT_REGISTERS (prompt)->regs, 1); + SCM_I_LONGJMP (*registers, 1); /* Shouldn't get here */ abort (); @@ -255,7 +236,7 @@ SCM_DEFINE (scm_at_abort, "@abort", 2, 0, 0, (SCM tag, SCM args), for (i = 0; i < n; i++, args = scm_cdr (args)) argv[i] = scm_car (args); - scm_c_abort (scm_the_vm (), tag, n, argv, -1); + scm_c_abort (scm_the_vm (), tag, n, argv, NULL); /* Oh, what, you're still here? The abort must have been reinstated. Actually, that's quite impossible, given that we're already in C-land here, so... @@ -266,14 +247,6 @@ SCM_DEFINE (scm_at_abort, "@abort", 2, 0, 0, (SCM tag, SCM args), #undef FUNC_NAME void -scm_i_prompt_print (SCM exp, SCM port, scm_print_state *pstate SCM_UNUSED) -{ - scm_puts ("#<prompt ", port); - scm_intprint (SCM_UNPACK (exp), 16, port); - scm_putc ('>', port); -} - -void scm_init_control (void) { #include "libguile/control.x" |