1 /* Copyright (C) 2010, 2011, 2012, 2013 Free Software Foundation, Inc.
3 * This library is free software; you can redistribute it and/or
4 * modify it under the terms of the GNU Lesser General Public License
5 * as published by the Free Software Foundation; either version 3 of
6 * the License, or (at your option) any later version.
8 * This library is distributed in the hope that it will be useful, but
9 * WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * Lesser General Public License for more details.
13 * You should have received a copy of the GNU Lesser General Public
14 * License along with this library; if not, write to the Free Software
15 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
25 #include "libguile/_scm.h"
26 #include "libguile/control.h"
27 #include "libguile/programs.h"
28 #include "libguile/instructions.h"
29 #include "libguile/vm.h"
33 #define PROMPT_ESCAPE_P(p) \
34 (SCM_DYNSTACK_TAG_FLAGS (SCM_DYNSTACK_TAG (p)) \
35 & SCM_F_DYNSTACK_PROMPT_ESCAPE_ONLY)
40 /* Only to be called if the SCM_I_SETJMP returns 1 */
42 scm_i_prompt_pop_abort_args_x (SCM vm
)
47 n
= scm_to_size_t (SCM_VM_DATA (vm
)->sp
[0]);
48 for (i
= 0; i
< n
; i
++)
49 vals
= scm_cons (SCM_VM_DATA (vm
)->sp
[-(i
+ 1)], vals
);
51 /* The abort did reset the VM's registers, but then these values
52 were pushed on; so we need to pop them ourselves. */
53 SCM_VM_DATA (vm
)->sp
-= n
+ 1;
60 static const scm_t_uint32 compose_continuation_code
[] =
62 SCM_PACK_RTL_24 (scm_rtl_op_compose_continuation
, 0)
67 make_partial_continuation (SCM vm_cont
)
70 scm_t_bits flags
= SCM_F_PROGRAM_IS_PARTIAL_CONTINUATION
;
73 ret
= scm_words (scm_tc7_program
| (nfree
<< 16) | flags
, nfree
+ 2);
74 SCM_SET_CELL_WORD_1 (ret
, compose_continuation_code
);
75 SCM_PROGRAM_FREE_VARIABLE_SET (ret
, 0, vm_cont
);
81 reify_partial_continuation (SCM vm
,
84 scm_t_uint32
*saved_ip
,
85 scm_i_jmp_buf
*saved_registers
,
86 scm_t_dynstack
*dynstack
,
87 scm_i_jmp_buf
*current_registers
)
93 flags
= SCM_F_VM_CONT_PARTIAL
;
94 /* If we are aborting to a prompt that has the same registers as those
95 of the abort, it means there are no intervening C frames on the
96 stack, and so the continuation can be relocated elsewhere on the
97 stack: it is rewindable. */
98 if (saved_registers
&& saved_registers
== current_registers
)
99 flags
|= SCM_F_VM_CONT_REWINDABLE
;
101 /* Walk the stack down until we find the first frame after saved_fp.
102 We will save the stack down to that frame. It used to be that we
103 could determine the stack bottom in O(1) time, but that's no longer
104 the case, since the thunk application doesn't occur where the
106 for (bottom_fp
= SCM_VM_DATA (vm
)->fp
;
107 SCM_FRAME_DYNAMIC_LINK (bottom_fp
) > saved_fp
;
108 bottom_fp
= SCM_FRAME_DYNAMIC_LINK (bottom_fp
));
110 if (SCM_FRAME_DYNAMIC_LINK (bottom_fp
) != saved_fp
)
113 /* Capture from the top of the thunk application frame up to the end. */
114 vm_cont
= scm_i_vm_capture_stack (&SCM_FRAME_LOCAL (bottom_fp
, 0),
115 SCM_VM_DATA (vm
)->fp
,
116 SCM_VM_DATA (vm
)->sp
,
117 SCM_VM_DATA (vm
)->ip
,
121 return make_partial_continuation (vm_cont
);
125 scm_c_abort (SCM vm
, SCM tag
, size_t n
, SCM
*argv
,
126 scm_i_jmp_buf
*current_registers
)
129 scm_t_dynstack
*dynstack
= &SCM_I_CURRENT_THREAD
->dynstack
;
131 scm_t_dynstack_prompt_flags flags
;
134 scm_i_jmp_buf
*registers
;
137 prompt
= scm_dynstack_find_prompt (dynstack
, tag
,
138 &flags
, &fp
, &sp
, &ip
, ®isters
);
141 scm_misc_error ("abort", "Abort to unknown prompt", scm_list_1 (tag
));
143 /* Only reify if the continuation referenced in the handler. */
144 if (flags
& SCM_F_DYNSTACK_PROMPT_ESCAPE_ONLY
)
148 scm_t_dynstack
*captured
;
150 captured
= scm_dynstack_capture (dynstack
, SCM_DYNSTACK_NEXT (prompt
));
151 cont
= reify_partial_continuation (vm
, fp
, sp
, ip
, registers
, captured
,
156 scm_dynstack_unwind (dynstack
, prompt
);
158 /* Unwinding may have changed the current thread's VM, so use the
162 /* Restore VM regs */
163 SCM_VM_DATA (vm
)->fp
= fp
;
164 SCM_VM_DATA (vm
)->sp
= sp
;
165 SCM_VM_DATA (vm
)->ip
= ip
;
167 /* Since we're jumping down, we should always have enough space. */
168 if (SCM_VM_DATA (vm
)->sp
+ n
+ 1 >= SCM_VM_DATA (vm
)->stack_limit
)
172 *(++(SCM_VM_DATA (vm
)->sp
)) = cont
;
173 for (i
= 0; i
< n
; i
++)
174 *(++(SCM_VM_DATA (vm
)->sp
)) = argv
[i
];
175 if (flags
& SCM_F_DYNSTACK_PROMPT_PUSH_NARGS
)
176 *(++(SCM_VM_DATA (vm
)->sp
)) = scm_from_size_t (n
+1); /* +1 for continuation */
179 SCM_I_LONGJMP (*registers
, 1);
181 /* Shouldn't get here */
185 SCM_DEFINE (scm_abort_to_prompt_star
, "abort-to-prompt*", 2, 0, 0,
187 "Abort to the nearest prompt with tag @var{tag}, yielding the\n"
188 "values in the list, @var{args}.")
189 #define FUNC_NAME s_scm_abort_to_prompt_star
195 SCM_VALIDATE_LIST_COPYLEN (SCM_ARG2
, args
, n
);
196 argv
= alloca (sizeof (SCM
)*n
);
197 for (i
= 0; i
< n
; i
++, args
= scm_cdr (args
))
198 argv
[i
] = scm_car (args
);
200 scm_c_abort (scm_the_vm (), tag
, n
, argv
, NULL
);
202 /* Oh, what, you're still here? The abort must have been reinstated. Actually,
203 that's quite impossible, given that we're already in C-land here, so...
211 scm_init_control (void)
213 #include "libguile/control.x"