/* Copyright (C) 2010, 2011, 2012 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 * as published by the Free Software Foundation; either version 3 of * the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA * 02110-1301 USA */ #if HAVE_CONFIG_H # include #endif #include #include "libguile/_scm.h" #include "libguile/control.h" #include "libguile/objcodes.h" #include "libguile/instructions.h" #include "libguile/vm.h" #define PROMPT_ESCAPE_P(p) \ (SCM_DYNSTACK_TAG_FLAGS (SCM_DYNSTACK_TAG (p)) \ & SCM_F_DYNSTACK_PROMPT_ESCAPE_ONLY) /* Only to be called if the SCM_I_SETJMP returns 1 */ SCM scm_i_prompt_pop_abort_args_x (SCM vm) { size_t i, n; SCM vals = SCM_EOL; n = scm_to_size_t (SCM_VM_DATA (vm)->sp[0]); for (i = 0; i < n; i++) vals = scm_cons (SCM_VM_DATA (vm)->sp[-(i + 1)], vals); /* The abort did reset the VM's registers, but then these values were pushed on; so we need to pop them ourselves. */ SCM_VM_DATA (vm)->sp -= n + 1; /* FIXME NULLSTACK */ return vals; } #ifdef WORDS_BIGENDIAN #define OBJCODE_HEADER(main,meta) 0, 0, 0, main, 0, 0, 0, meta+8 #define META_HEADER(meta) 0, 0, 0, meta, 0, 0, 0, 0 #else #define OBJCODE_HEADER(main,meta) main, 0, 0, 0, meta+8, 0, 0, 0 #define META_HEADER(meta) meta, 0, 0, 0, 0, 0, 0, 0 #endif #define OBJCODE_TAG SCM_MAKE_OBJCODE_TAG (SCM_OBJCODE_TYPE_STATIC, 0) #if defined (SCM_ALIGNED) #define SCM_DECLARE_STATIC_ALIGNED_ARRAY(type, sym) \ static const type sym[] #define SCM_STATIC_ALIGNED_ARRAY(alignment, type, sym) \ static SCM_ALIGNED (alignment) const type sym[] #define SCM_STATIC_OBJCODE(sym) \ SCM_DECLARE_STATIC_ALIGNED_ARRAY (scm_t_uint8, sym##__bytecode); \ SCM_STATIC_ALIGNED_ARRAY (8, scm_t_cell, sym##__cells) = { \ { SCM_PACK (OBJCODE_TAG), SCM_PACK (sym##__bytecode) }, \ { SCM_BOOL_F, SCM_PACK (0) } \ }; \ static const SCM sym = SCM_PACK (sym##__cells); \ SCM_STATIC_ALIGNED_ARRAY (8, scm_t_uint8, sym##__bytecode) #else #define SCM_STATIC_OBJCODE(sym) \ static SCM sym; \ static scm_t_uint8 *sym##_bytecode; \ SCM_SNARF_INIT(sym##_bytecode = scm_gc_malloc_pointerless (sizeof(sym##_bytecode__unaligned), "partial continuation stub"); \ memcpy (sym##_bytecode, sym##_bytecode__unaligned, sizeof(sym##_bytecode__unaligned));) \ SCM_SNARF_INIT(sym = scm_double_cell (OBJCODE_TAG, \ (scm_t_bits)sym##_bytecode, \ SCM_UNPACK (SCM_BOOL_F), \ 0);) \ static const scm_t_uint8 sym##_bytecode__unaligned[] #endif SCM_STATIC_OBJCODE (cont_objcode) = { /* Like in continuations.c, but with partial-cont-call. */ OBJCODE_HEADER (8, 19), /* leave args on the stack */ /* 0 */ scm_op_object_ref, 0, /* push scm_vm_cont object */ /* 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 how to do that, though. */ 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, 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 */ /* 9 */ scm_op_list, 0, 5, /* make a list of those 5 vals */ /* 12 */ scm_op_list, 0, 1, /* and the arities will be a list of that one list */ /* 15 */ scm_op_list, 0, 3, /* pack bindings, sources, and arities into list */ /* 18 */ scm_op_return /* and return */ /* 19 */ }; static SCM 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, ret; scm_t_uint32 flags; flags = SCM_F_VM_CONT_PARTIAL; /* 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 (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 (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_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); return ret; } void scm_c_abort (SCM vm, SCM tag, size_t n, SCM *argv, scm_i_jmp_buf *current_registers) { 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; 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)); /* 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; captured = scm_dynstack_capture (dynstack, SCM_DYNSTACK_NEXT (prompt)); cont = reify_partial_continuation (vm, fp, sp, ip, registers, captured, current_registers); } /* 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 = fp; SCM_VM_DATA (vm)->sp = sp; SCM_VM_DATA (vm)->ip = ip; /* 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 (); /* Push vals */ *(++(SCM_VM_DATA (vm)->sp)) = cont; for (i = 0; i < n; i++) *(++(SCM_VM_DATA (vm)->sp)) = argv[i]; *(++(SCM_VM_DATA (vm)->sp)) = scm_from_size_t (n+1); /* +1 for continuation */ /* Jump! */ SCM_I_LONGJMP (*registers, 1); /* Shouldn't get here */ abort (); } SCM_DEFINE (scm_at_abort, "@abort", 2, 0, 0, (SCM tag, SCM args), "Abort to the nearest prompt with tag @var{tag}.") #define FUNC_NAME s_scm_at_abort { SCM *argv; size_t i; long n; SCM_VALIDATE_LIST_COPYLEN (SCM_ARG2, args, n); argv = alloca (sizeof (SCM)*n); for (i = 0; i < n; i++, args = scm_cdr (args)) argv[i] = scm_car (args); 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... abort! */ abort (); } #undef FUNC_NAME void scm_init_control (void) { #include "libguile/control.x" } /* Local Variables: c-file-style: "gnu" End: */