| 1 | /* Copyright (C) 2010, 2011, 2012 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/objcodes.h" |
| 28 | #include "libguile/instructions.h" |
| 29 | #include "libguile/vm.h" |
| 30 | |
| 31 | \f |
| 32 | |
| 33 | |
| 34 | SCM |
| 35 | scm_c_make_prompt (SCM k, SCM *fp, SCM *sp, scm_t_uint8 *abort_ip, |
| 36 | scm_t_uint8 escape_only_p, scm_t_int64 vm_cookie, |
| 37 | SCM winds) |
| 38 | { |
| 39 | scm_t_bits tag; |
| 40 | struct scm_prompt_registers *regs; |
| 41 | |
| 42 | tag = scm_tc7_prompt; |
| 43 | if (escape_only_p) |
| 44 | tag |= (SCM_F_PROMPT_ESCAPE<<8); |
| 45 | |
| 46 | regs = scm_gc_malloc_pointerless (sizeof (*regs), "prompt registers"); |
| 47 | regs->fp = fp; |
| 48 | regs->sp = sp; |
| 49 | regs->ip = abort_ip; |
| 50 | regs->cookie = vm_cookie; |
| 51 | |
| 52 | return scm_double_cell (tag, SCM_UNPACK (k), (scm_t_bits)regs, |
| 53 | SCM_UNPACK (winds)); |
| 54 | } |
| 55 | |
| 56 | /* Only to be called if the SCM_PROMPT_SETJMP returns 1 */ |
| 57 | SCM |
| 58 | scm_i_prompt_pop_abort_args_x (SCM vm) |
| 59 | { |
| 60 | size_t i, n; |
| 61 | SCM vals = SCM_EOL; |
| 62 | |
| 63 | n = scm_to_size_t (SCM_VM_DATA (vm)->sp[0]); |
| 64 | for (i = 0; i < n; i++) |
| 65 | vals = scm_cons (SCM_VM_DATA (vm)->sp[-(i + 1)], vals); |
| 66 | |
| 67 | /* The abort did reset the VM's registers, but then these values |
| 68 | were pushed on; so we need to pop them ourselves. */ |
| 69 | SCM_VM_DATA (vm)->sp -= n + 1; |
| 70 | /* FIXME NULLSTACK */ |
| 71 | |
| 72 | return vals; |
| 73 | } |
| 74 | |
| 75 | |
| 76 | #ifdef WORDS_BIGENDIAN |
| 77 | #define OBJCODE_HEADER(main,meta) 0, 0, 0, main, 0, 0, 0, meta+8 |
| 78 | #define META_HEADER(meta) 0, 0, 0, meta, 0, 0, 0, 0 |
| 79 | #else |
| 80 | #define OBJCODE_HEADER(main,meta) main, 0, 0, 0, meta+8, 0, 0, 0 |
| 81 | #define META_HEADER(meta) meta, 0, 0, 0, 0, 0, 0, 0 |
| 82 | #endif |
| 83 | |
| 84 | #define OBJCODE_TAG SCM_MAKE_OBJCODE_TAG (SCM_OBJCODE_TYPE_STATIC, 0) |
| 85 | |
| 86 | #if defined (SCM_ALIGNED) |
| 87 | #define SCM_DECLARE_STATIC_ALIGNED_ARRAY(type, sym) \ |
| 88 | static const type sym[] |
| 89 | #define SCM_STATIC_ALIGNED_ARRAY(alignment, type, sym) \ |
| 90 | static SCM_ALIGNED (alignment) const type sym[] |
| 91 | #define SCM_STATIC_OBJCODE(sym) \ |
| 92 | SCM_DECLARE_STATIC_ALIGNED_ARRAY (scm_t_uint8, sym##__bytecode); \ |
| 93 | SCM_STATIC_ALIGNED_ARRAY (8, scm_t_cell, sym##__cells) = { \ |
| 94 | { SCM_PACK (OBJCODE_TAG), SCM_PACK (sym##__bytecode) }, \ |
| 95 | { SCM_BOOL_F, SCM_PACK (0) } \ |
| 96 | }; \ |
| 97 | static const SCM sym = SCM_PACK (sym##__cells); \ |
| 98 | SCM_STATIC_ALIGNED_ARRAY (8, scm_t_uint8, sym##__bytecode) |
| 99 | #else |
| 100 | #define SCM_STATIC_OBJCODE(sym) \ |
| 101 | static SCM sym; \ |
| 102 | static scm_t_uint8 *sym##_bytecode; \ |
| 103 | SCM_SNARF_INIT(sym##_bytecode = scm_gc_malloc_pointerless (sizeof(sym##_bytecode__unaligned), "partial continuation stub"); \ |
| 104 | memcpy (sym##_bytecode, sym##_bytecode__unaligned, sizeof(sym##_bytecode__unaligned));) \ |
| 105 | SCM_SNARF_INIT(sym = scm_double_cell (OBJCODE_TAG, \ |
| 106 | (scm_t_bits)sym##_bytecode, \ |
| 107 | SCM_UNPACK (SCM_BOOL_F), \ |
| 108 | 0);) \ |
| 109 | static const scm_t_uint8 sym##_bytecode__unaligned[] |
| 110 | #endif |
| 111 | |
| 112 | |
| 113 | SCM_STATIC_OBJCODE (cont_objcode) = { |
| 114 | /* Like in continuations.c, but with partial-cont-call. */ |
| 115 | OBJCODE_HEADER (8, 19), |
| 116 | /* leave args on the stack */ |
| 117 | /* 0 */ scm_op_object_ref, 0, /* push scm_vm_cont object */ |
| 118 | /* 2 */ scm_op_object_ref, 1, /* push internal winds */ |
| 119 | /* 4 */ scm_op_partial_cont_call, /* and go! */ |
| 120 | /* 5 */ scm_op_nop, scm_op_nop, scm_op_nop, /* pad to 8 bytes */ |
| 121 | /* 8 */ |
| 122 | |
| 123 | /* We could put some meta-info to say that this proc is a continuation. Not sure |
| 124 | how to do that, though. */ |
| 125 | META_HEADER (19), |
| 126 | /* 0 */ scm_op_make_eol, /* bindings */ |
| 127 | /* 1 */ scm_op_make_eol, /* sources */ |
| 128 | /* 2 */ scm_op_make_int8, 0, scm_op_make_int8, 5, /* arity: from ip 0 to ip 7 */ |
| 129 | /* 6 */ scm_op_make_int8_0, /* the arity is 0 required args */ |
| 130 | /* 7 */ scm_op_make_int8_0, /* 0 optionals */ |
| 131 | /* 8 */ scm_op_make_true, /* and a rest arg */ |
| 132 | /* 9 */ scm_op_list, 0, 5, /* make a list of those 5 vals */ |
| 133 | /* 12 */ scm_op_list, 0, 1, /* and the arities will be a list of that one list */ |
| 134 | /* 15 */ scm_op_list, 0, 3, /* pack bindings, sources, and arities into list */ |
| 135 | /* 18 */ scm_op_return /* and return */ |
| 136 | /* 19 */ |
| 137 | }; |
| 138 | |
| 139 | |
| 140 | static SCM |
| 141 | reify_partial_continuation (SCM vm, SCM prompt, SCM extwinds, |
| 142 | scm_t_int64 cookie) |
| 143 | { |
| 144 | SCM vm_cont, dynwinds, intwinds = SCM_EOL, ret; |
| 145 | scm_t_uint32 flags; |
| 146 | |
| 147 | /* No need to reify if the continuation is never referenced in the handler. */ |
| 148 | if (SCM_PROMPT_ESCAPE_P (prompt)) |
| 149 | return SCM_BOOL_F; |
| 150 | |
| 151 | dynwinds = scm_i_dynwinds (); |
| 152 | while (!scm_is_eq (dynwinds, extwinds)) |
| 153 | { |
| 154 | intwinds = scm_cons (scm_car (dynwinds), intwinds); |
| 155 | dynwinds = scm_cdr (dynwinds); |
| 156 | } |
| 157 | |
| 158 | flags = SCM_F_VM_CONT_PARTIAL; |
| 159 | if (cookie >= 0 && SCM_PROMPT_REGISTERS (prompt)->cookie == cookie) |
| 160 | flags |= SCM_F_VM_CONT_REWINDABLE; |
| 161 | |
| 162 | /* Since non-escape continuations should begin with a thunk application, the |
| 163 | first bit of the stack should be a frame, with the saved fp equal to the fp |
| 164 | that was current when the prompt was made. */ |
| 165 | if ((SCM*)SCM_UNPACK (SCM_PROMPT_REGISTERS (prompt)->sp[1]) |
| 166 | != SCM_PROMPT_REGISTERS (prompt)->fp) |
| 167 | abort (); |
| 168 | |
| 169 | /* Capture from the top of the thunk application frame up to the end. Set an |
| 170 | MVRA only, as the post-abort code is in an MV context. */ |
| 171 | vm_cont = scm_i_vm_capture_stack (SCM_PROMPT_REGISTERS (prompt)->sp + 4, |
| 172 | SCM_VM_DATA (vm)->fp, |
| 173 | SCM_VM_DATA (vm)->sp, |
| 174 | NULL, |
| 175 | SCM_VM_DATA (vm)->ip, |
| 176 | flags); |
| 177 | |
| 178 | ret = scm_make_program (cont_objcode, |
| 179 | scm_vector (scm_list_2 (vm_cont, intwinds)), |
| 180 | SCM_BOOL_F); |
| 181 | SCM_SET_CELL_WORD_0 (ret, |
| 182 | SCM_CELL_WORD_0 (ret) | SCM_F_PROGRAM_IS_PARTIAL_CONTINUATION); |
| 183 | return ret; |
| 184 | } |
| 185 | |
| 186 | void |
| 187 | scm_c_abort (SCM vm, SCM tag, size_t n, SCM *argv, scm_t_int64 cookie) |
| 188 | { |
| 189 | SCM cont, winds, prompt = SCM_BOOL_F; |
| 190 | long delta; |
| 191 | size_t i; |
| 192 | |
| 193 | /* Search the wind list for an appropriate prompt. |
| 194 | "Waiter, please bring us the wind list." */ |
| 195 | for (winds = scm_i_dynwinds (), delta = 0; |
| 196 | scm_is_pair (winds); |
| 197 | winds = SCM_CDR (winds), delta++) |
| 198 | { |
| 199 | SCM elt = SCM_CAR (winds); |
| 200 | if (SCM_PROMPT_P (elt) && scm_is_eq (SCM_PROMPT_TAG (elt), tag)) |
| 201 | { |
| 202 | prompt = elt; |
| 203 | break; |
| 204 | } |
| 205 | } |
| 206 | |
| 207 | /* If we didn't find anything, raise an error. */ |
| 208 | if (scm_is_false (prompt)) |
| 209 | scm_misc_error ("abort", "Abort to unknown prompt", scm_list_1 (tag)); |
| 210 | |
| 211 | cont = reify_partial_continuation (vm, prompt, winds, cookie); |
| 212 | |
| 213 | /* Unwind once more, beyond the prompt. */ |
| 214 | winds = SCM_CDR (winds), delta++; |
| 215 | |
| 216 | /* Unwind */ |
| 217 | scm_dowinds (winds, delta); |
| 218 | |
| 219 | /* Unwinding may have changed the current thread's VM, so use the |
| 220 | new one. */ |
| 221 | vm = scm_the_vm (); |
| 222 | |
| 223 | /* Restore VM regs */ |
| 224 | SCM_VM_DATA (vm)->fp = SCM_PROMPT_REGISTERS (prompt)->fp; |
| 225 | SCM_VM_DATA (vm)->sp = SCM_PROMPT_REGISTERS (prompt)->sp; |
| 226 | SCM_VM_DATA (vm)->ip = SCM_PROMPT_REGISTERS (prompt)->ip; |
| 227 | |
| 228 | /* Since we're jumping down, we should always have enough space */ |
| 229 | if (SCM_VM_DATA (vm)->sp + n + 1 >= SCM_VM_DATA (vm)->stack_limit) |
| 230 | abort (); |
| 231 | |
| 232 | /* Push vals */ |
| 233 | *(++(SCM_VM_DATA (vm)->sp)) = cont; |
| 234 | for (i = 0; i < n; i++) |
| 235 | *(++(SCM_VM_DATA (vm)->sp)) = argv[i]; |
| 236 | *(++(SCM_VM_DATA (vm)->sp)) = scm_from_size_t (n+1); /* +1 for continuation */ |
| 237 | |
| 238 | /* Jump! */ |
| 239 | SCM_I_LONGJMP (SCM_PROMPT_REGISTERS (prompt)->regs, 1); |
| 240 | |
| 241 | /* Shouldn't get here */ |
| 242 | abort (); |
| 243 | } |
| 244 | |
| 245 | SCM_DEFINE (scm_at_abort, "@abort", 2, 0, 0, (SCM tag, SCM args), |
| 246 | "Abort to the nearest prompt with tag @var{tag}.") |
| 247 | #define FUNC_NAME s_scm_at_abort |
| 248 | { |
| 249 | SCM *argv; |
| 250 | size_t i; |
| 251 | long n; |
| 252 | |
| 253 | SCM_VALIDATE_LIST_COPYLEN (SCM_ARG2, args, n); |
| 254 | argv = alloca (sizeof (SCM)*n); |
| 255 | for (i = 0; i < n; i++, args = scm_cdr (args)) |
| 256 | argv[i] = scm_car (args); |
| 257 | |
| 258 | scm_c_abort (scm_the_vm (), tag, n, argv, -1); |
| 259 | |
| 260 | /* Oh, what, you're still here? The abort must have been reinstated. Actually, |
| 261 | that's quite impossible, given that we're already in C-land here, so... |
| 262 | abort! */ |
| 263 | |
| 264 | abort (); |
| 265 | } |
| 266 | #undef FUNC_NAME |
| 267 | |
| 268 | void |
| 269 | scm_i_prompt_print (SCM exp, SCM port, scm_print_state *pstate SCM_UNUSED) |
| 270 | { |
| 271 | scm_puts_unlocked ("#<prompt ", port); |
| 272 | scm_intprint (SCM_UNPACK (exp), 16, port); |
| 273 | scm_putc_unlocked ('>', port); |
| 274 | } |
| 275 | |
| 276 | void |
| 277 | scm_init_control (void) |
| 278 | { |
| 279 | #include "libguile/control.x" |
| 280 | } |
| 281 | |
| 282 | /* |
| 283 | Local Variables: |
| 284 | c-file-style: "gnu" |
| 285 | End: |
| 286 | */ |