| 1 | /* Copyright (C) 2010, 2011, 2012, 2013 Free Software Foundation, Inc. |
| 2 | * |
| 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. |
| 7 | * |
| 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. |
| 12 | * |
| 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 |
| 16 | * 02110-1301 USA |
| 17 | */ |
| 18 | |
| 19 | #if HAVE_CONFIG_H |
| 20 | # include <config.h> |
| 21 | #endif |
| 22 | |
| 23 | #include <alloca.h> |
| 24 | |
| 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" |
| 30 | |
| 31 | \f |
| 32 | |
| 33 | #define PROMPT_ESCAPE_P(p) \ |
| 34 | (SCM_DYNSTACK_TAG_FLAGS (SCM_DYNSTACK_TAG (p)) \ |
| 35 | & SCM_F_DYNSTACK_PROMPT_ESCAPE_ONLY) |
| 36 | |
| 37 | \f |
| 38 | |
| 39 | |
| 40 | /* Only to be called if the SCM_I_SETJMP returns 1 */ |
| 41 | SCM |
| 42 | scm_i_prompt_pop_abort_args_x (struct scm_vm *vp) |
| 43 | { |
| 44 | size_t i, n; |
| 45 | SCM vals = SCM_EOL; |
| 46 | |
| 47 | n = scm_to_size_t (vp->sp[0]); |
| 48 | for (i = 0; i < n; i++) |
| 49 | vals = scm_cons (vp->sp[-(i + 1)], vals); |
| 50 | |
| 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 | vp->sp -= n + 1; |
| 54 | /* FIXME NULLSTACK */ |
| 55 | |
| 56 | return vals; |
| 57 | } |
| 58 | |
| 59 | |
| 60 | static const scm_t_uint32 compose_continuation_code[] = |
| 61 | { |
| 62 | SCM_PACK_OP_24 (compose_continuation, 0) |
| 63 | }; |
| 64 | |
| 65 | |
| 66 | static SCM |
| 67 | make_partial_continuation (SCM vm_cont) |
| 68 | { |
| 69 | scm_t_bits nfree = 1; |
| 70 | scm_t_bits flags = SCM_F_PROGRAM_IS_PARTIAL_CONTINUATION; |
| 71 | SCM ret; |
| 72 | |
| 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); |
| 76 | |
| 77 | return ret; |
| 78 | } |
| 79 | |
| 80 | static SCM |
| 81 | reify_partial_continuation (struct scm_vm *vp, |
| 82 | SCM *saved_fp, |
| 83 | SCM *saved_sp, |
| 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) |
| 88 | { |
| 89 | SCM vm_cont; |
| 90 | scm_t_uint32 flags; |
| 91 | SCM *bottom_fp; |
| 92 | |
| 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; |
| 100 | |
| 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 |
| 105 | prompt is saved. */ |
| 106 | for (bottom_fp = vp->fp; |
| 107 | SCM_FRAME_DYNAMIC_LINK (bottom_fp) > saved_fp; |
| 108 | bottom_fp = SCM_FRAME_DYNAMIC_LINK (bottom_fp)); |
| 109 | |
| 110 | if (SCM_FRAME_DYNAMIC_LINK (bottom_fp) != saved_fp) |
| 111 | abort(); |
| 112 | |
| 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 | vp->fp, |
| 116 | vp->sp, |
| 117 | vp->ip, |
| 118 | dynstack, |
| 119 | flags); |
| 120 | |
| 121 | return make_partial_continuation (vm_cont); |
| 122 | } |
| 123 | |
| 124 | void |
| 125 | scm_c_abort (struct scm_vm *vp, SCM tag, size_t n, SCM *argv, |
| 126 | scm_i_jmp_buf *current_registers) |
| 127 | { |
| 128 | SCM cont; |
| 129 | scm_t_dynstack *dynstack = &SCM_I_CURRENT_THREAD->dynstack; |
| 130 | scm_t_bits *prompt; |
| 131 | scm_t_dynstack_prompt_flags flags; |
| 132 | scm_t_ptrdiff fp_offset, sp_offset; |
| 133 | SCM *fp, *sp; |
| 134 | scm_t_uint32 *ip; |
| 135 | scm_i_jmp_buf *registers; |
| 136 | size_t i; |
| 137 | |
| 138 | prompt = scm_dynstack_find_prompt (dynstack, tag, |
| 139 | &flags, &fp_offset, &sp_offset, &ip, |
| 140 | ®isters); |
| 141 | |
| 142 | if (!prompt) |
| 143 | scm_misc_error ("abort", "Abort to unknown prompt", scm_list_1 (tag)); |
| 144 | |
| 145 | fp = vp->stack_base + fp_offset; |
| 146 | sp = vp->stack_base + sp_offset; |
| 147 | |
| 148 | /* Only reify if the continuation referenced in the handler. */ |
| 149 | if (flags & SCM_F_DYNSTACK_PROMPT_ESCAPE_ONLY) |
| 150 | cont = SCM_BOOL_F; |
| 151 | else |
| 152 | { |
| 153 | scm_t_dynstack *captured; |
| 154 | |
| 155 | captured = scm_dynstack_capture (dynstack, SCM_DYNSTACK_NEXT (prompt)); |
| 156 | cont = reify_partial_continuation (vp, fp, sp, ip, registers, captured, |
| 157 | current_registers); |
| 158 | } |
| 159 | |
| 160 | /* Unwind. */ |
| 161 | scm_dynstack_unwind (dynstack, prompt); |
| 162 | |
| 163 | /* Restore VM regs */ |
| 164 | vp->fp = fp; |
| 165 | vp->sp = sp; |
| 166 | vp->ip = ip; |
| 167 | |
| 168 | /* Since we're jumping down, we should always have enough space. */ |
| 169 | if (vp->sp + n + 1 >= vp->stack_limit) |
| 170 | abort (); |
| 171 | |
| 172 | /* Push vals */ |
| 173 | *(++(vp->sp)) = cont; |
| 174 | for (i = 0; i < n; i++) |
| 175 | *(++(vp->sp)) = argv[i]; |
| 176 | if (flags & SCM_F_DYNSTACK_PROMPT_PUSH_NARGS) |
| 177 | *(++(vp->sp)) = scm_from_size_t (n+1); /* +1 for continuation */ |
| 178 | |
| 179 | /* Jump! */ |
| 180 | SCM_I_LONGJMP (*registers, 1); |
| 181 | |
| 182 | /* Shouldn't get here */ |
| 183 | abort (); |
| 184 | } |
| 185 | |
| 186 | SCM_DEFINE (scm_abort_to_prompt_star, "abort-to-prompt*", 2, 0, 0, |
| 187 | (SCM tag, SCM args), |
| 188 | "Abort to the nearest prompt with tag @var{tag}, yielding the\n" |
| 189 | "values in the list, @var{args}.") |
| 190 | #define FUNC_NAME s_scm_abort_to_prompt_star |
| 191 | { |
| 192 | SCM *argv; |
| 193 | size_t i; |
| 194 | long n; |
| 195 | |
| 196 | SCM_VALIDATE_LIST_COPYLEN (SCM_ARG2, args, n); |
| 197 | argv = alloca (sizeof (SCM)*n); |
| 198 | for (i = 0; i < n; i++, args = scm_cdr (args)) |
| 199 | argv[i] = scm_car (args); |
| 200 | |
| 201 | scm_c_abort (scm_the_vm (), tag, n, argv, NULL); |
| 202 | |
| 203 | /* Oh, what, you're still here? The abort must have been reinstated. Actually, |
| 204 | that's quite impossible, given that we're already in C-land here, so... |
| 205 | abort! */ |
| 206 | |
| 207 | abort (); |
| 208 | } |
| 209 | #undef FUNC_NAME |
| 210 | |
| 211 | void |
| 212 | scm_init_control (void) |
| 213 | { |
| 214 | #include "libguile/control.x" |
| 215 | } |
| 216 | |
| 217 | /* |
| 218 | Local Variables: |
| 219 | c-file-style: "gnu" |
| 220 | End: |
| 221 | */ |