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177 lines
6.4 KiB
C
177 lines
6.4 KiB
C
/* Copyright 2001,2009-2015,2018
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Free Software Foundation, Inc.
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This file is part of Guile.
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Guile is free software: you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published
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by the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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Guile is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with Guile. If not, see
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<https://www.gnu.org/licenses/>. */
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#ifndef _SCM_FRAMES_H_
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#define _SCM_FRAMES_H_
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#include <libguile/gc.h>
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#include "programs.h"
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/* Stack frames
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------------
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It's a little confusing, but there are two representations of frames
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in this file: frame pointers, and Scheme objects wrapping those frame
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pointers. The former uses the SCM_FRAME macro prefix, the latter
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SCM_VM_FRAME prefix.
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The confusing thing is that only Scheme frame objects have functions
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that use them, and they use the lower-case scm_frame prefix.
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Stack frame layout
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------------------
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| ... |
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+==============================+ <- fp + 3 = SCM_FRAME_PREVIOUS_SP (fp)
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| Dynamic link |
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+------------------------------+
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| Virtual return address (vRA) |
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+------------------------------+
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| Machine return address (mRA) |
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+==============================+ <- fp
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| Local 0 |
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+------------------------------+
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| Local 1 |
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+------------------------------+
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| ... |
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+------------------------------+
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| Local N-1 |
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\------------------------------/ <- sp
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The stack grows down.
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The calling convention is that a caller prepares a stack frame
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consisting of the saved FP, the saved virtual return address, and the
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saved machine return address of the calling function, followed by the
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procedure and then the arguments to the call, in order. Thus in the
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beginning of a call, the procedure being called is in slot 0, the
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first argument is in slot 1, and the SP points to the last argument.
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The number of arguments, including the procedure, is thus FP - SP.
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After ensuring that the correct number of arguments have been passed,
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a function will set the stack pointer to point to the last local
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slot. This lets a function allocate the temporary space that it
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needs once in the beginning of the call, instead of pushing and
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popping the stack pointer during the call's extent.
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When a program returns, it returns its values in the slots starting
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from local 0. The callee resets the stack pointer to point to the
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last value. In this way the caller knows how many values there are:
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it's the number of words between the stack pointer and the slot at
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which the caller placed the procedure.
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After checking that the number of values returned is appropriate, the
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caller shuffles the values around (if needed), and resets the stack
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pointer back to its original value from before the call. */
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/* Each element on the stack occupies the same amount of space. */
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union scm_vm_stack_element
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{
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uintptr_t as_uint;
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uint32_t *as_vcode;
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uint8_t *as_mcode;
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SCM as_scm;
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double as_f64;
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uint64_t as_u64;
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int64_t as_s64;
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/* For GC purposes. */
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void *as_ptr;
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scm_t_bits as_bits;
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};
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#define SCM_FRAME_PREVIOUS_SP(fp) ((fp) + 3)
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#define SCM_FRAME_MACHINE_RETURN_ADDRESS(fp) ((fp)[0].as_mcode)
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#define SCM_FRAME_SET_MACHINE_RETURN_ADDRESS(fp, ra) ((fp)[0].as_mcode = (ra))
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#define SCM_FRAME_VIRTUAL_RETURN_ADDRESS(fp) ((fp)[1].as_vcode)
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#define SCM_FRAME_SET_VIRTUAL_RETURN_ADDRESS(fp, ra) ((fp)[1].as_vcode = (ra))
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#define SCM_FRAME_DYNAMIC_LINK(fp) ((fp) + (fp)[2].as_uint)
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#define SCM_FRAME_SET_DYNAMIC_LINK(fp, dl) ((fp)[2].as_uint = ((dl) - (fp)))
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#define SCM_FRAME_SLOT(fp,i) ((fp) - (i) - 1)
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#define SCM_FRAME_LOCAL(fp,i) (SCM_FRAME_SLOT (fp, i)->as_scm)
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#define SCM_FRAME_NUM_LOCALS(fp, sp) ((fp) - (sp))
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/*
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* Heap frames
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*/
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#ifdef BUILDING_LIBGUILE
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struct scm_frame
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{
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void *stack_holder;
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ptrdiff_t fp_offset;
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ptrdiff_t sp_offset;
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uint32_t *ip;
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};
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enum scm_vm_frame_kind
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{
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SCM_VM_FRAME_KIND_VM,
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SCM_VM_FRAME_KIND_CONT
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};
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#define SCM_VM_FRAME_P(x) (SCM_HAS_TYP7 (x, scm_tc7_frame))
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#define SCM_VM_FRAME_KIND(x) ((enum scm_vm_frame_kind) (SCM_CELL_WORD_0 (x) >> 8))
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#define SCM_VM_FRAME_DATA(x) ((struct scm_frame *)SCM_CELL_WORD_1 (x))
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#define SCM_VM_FRAME_STACK_HOLDER(f) SCM_VM_FRAME_DATA (f)->stack_holder
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#define SCM_VM_FRAME_FP_OFFSET(f) SCM_VM_FRAME_DATA (f)->fp_offset
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#define SCM_VM_FRAME_SP_OFFSET(f) SCM_VM_FRAME_DATA (f)->sp_offset
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#define SCM_VM_FRAME_FP(f) (scm_i_frame_stack_top (f) - SCM_VM_FRAME_FP_OFFSET (f))
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#define SCM_VM_FRAME_SP(f) (scm_i_frame_stack_top (f) - SCM_VM_FRAME_SP_OFFSET (f))
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#define SCM_VM_FRAME_IP(f) SCM_VM_FRAME_DATA (f)->ip
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#define SCM_VALIDATE_VM_FRAME(p,x) SCM_MAKE_VALIDATE (p, x, VM_FRAME_P)
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SCM_INTERNAL union scm_vm_stack_element* scm_i_frame_stack_top (SCM frame);
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/* See notes in frames.c before using this. */
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SCM_INTERNAL SCM scm_c_frame_closure (enum scm_vm_frame_kind kind,
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const struct scm_frame *frame);
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SCM_INTERNAL SCM scm_c_make_frame (enum scm_vm_frame_kind kind,
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const struct scm_frame *frame);
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SCM_INTERNAL int scm_c_frame_previous (enum scm_vm_frame_kind kind,
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struct scm_frame *frame);
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#endif
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SCM_API SCM scm_frame_p (SCM obj);
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SCM_API SCM scm_frame_procedure_name (SCM frame);
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SCM_API SCM scm_frame_call_representation (SCM frame);
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SCM_API SCM scm_frame_arguments (SCM frame);
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SCM_API SCM scm_frame_source (SCM frame);
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SCM_API SCM scm_frame_address (SCM frame);
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SCM_API SCM scm_frame_stack_pointer (SCM frame);
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SCM_API SCM scm_frame_instruction_pointer (SCM frame);
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SCM_API SCM scm_frame_return_address (SCM frame);
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SCM_API SCM scm_frame_dynamic_link (SCM frame);
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SCM_API SCM scm_frame_previous (SCM frame);
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SCM_INTERNAL void scm_i_frame_print (SCM frame, SCM port,
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scm_print_state *pstate);
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SCM_INTERNAL void scm_init_frames (void);
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#endif /* _SCM_FRAMES_H_ */
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