/* Copyright (C) 2010, 2011, 2012, 2013 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/programs.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; } static const scm_t_uint32 compose_continuation_code[] = { SCM_PACK_RTL_24 (scm_rtl_op_compose_continuation, 0) }; static SCM make_partial_continuation (SCM vm_cont) { scm_t_bits nfree = 1; scm_t_bits flags = SCM_F_PROGRAM_IS_PARTIAL_CONTINUATION; SCM ret; ret = scm_words (scm_tc7_rtl_program | (nfree << 16) | flags, nfree + 2); SCM_SET_CELL_WORD_1 (ret, compose_continuation_code); SCM_RTL_PROGRAM_FREE_VARIABLE_SET (ret, 0, vm_cont); return ret; } 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; 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); return make_partial_continuation (vm_cont); } 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]; if (flags & SCM_F_DYNSTACK_PROMPT_PUSH_NARGS) *(++(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_abort_to_prompt_star, "abort-to-prompt*", 2, 0, 0, (SCM tag, SCM args), "Abort to the nearest prompt with tag @var{tag}, yielding the\n" "values in the list, @var{args}.") #define FUNC_NAME s_scm_abort_to_prompt_star { 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: */