2 * Copyright (C) 1995-2008 University of Karlsruhe. All right reserved.
4 * This file is part of libFirm.
6 * This file may be distributed and/or modified under the terms of the
7 * GNU General Public License version 2 as published by the Free Software
8 * Foundation and appearing in the file LICENSE.GPL included in the
9 * packaging of this file.
11 * Licensees holding valid libFirm Professional Edition licenses may use
12 * this file in accordance with the libFirm Commercial License.
13 * Agreement provided with the Software.
15 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
16 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * @brief Interface for machine code output
23 * @author Matthias Braun
32 #include "beemitter_binary.h"
37 static code_fragment_t *first_fragment;
38 static code_fragment_t *last_fragment;
39 static const unsigned CODE_FRAGMENT_MAGIC = 0x4643414d; /* "CFMA" */
41 struct obstack code_fragment_obst;
43 /** returns current fragment (the address stays only valid until the next
44 be_emit(8/16/32/entity) call!) */
45 code_fragment_t *be_get_current_fragment(void)
47 code_fragment_t *fragment = obstack_base(&code_fragment_obst);
48 assert(obstack_object_size(&code_fragment_obst) >= sizeof(code_fragment_t));
49 assert(fragment->magic == CODE_FRAGMENT_MAGIC);
54 /** allocates a new fragment on the obstack (warning: address is only valid
56 static void alloc_fragment(void)
58 code_fragment_t *fragment;
60 /* shouldn't have any growing fragments */
61 assert(obstack_object_size(&code_fragment_obst) == 0);
63 obstack_blank(&code_fragment_obst, sizeof(*fragment));
64 fragment = obstack_base(&code_fragment_obst);
65 memset(fragment, 0, sizeof(*fragment));
67 fragment->magic = CODE_FRAGMENT_MAGIC;
70 fragment->alignment = 1;
72 fragment->max_offset = UINT_MAX;
75 static code_fragment_t *finish_fragment(void)
77 code_fragment_t *fragment = be_get_current_fragment();
79 = obstack_object_size(&code_fragment_obst) - sizeof(*fragment);
81 fragment = (code_fragment_t*) obstack_finish(&code_fragment_obst);
82 last_fragment = fragment;
84 if (first_fragment == NULL)
85 first_fragment = fragment;
90 void be_start_code_emitter(void)
92 obstack_init(&code_fragment_obst);
93 first_fragment = NULL;
97 void be_start_new_fragment(void)
103 static void emit(FILE *file, const unsigned char *buffer, size_t len)
106 for (i = 0; i < len; ++i) {
108 fputs("\t.byte ", file);
109 for (i2 = i; i2 < i + 30 && i2 < len; ++i2) {
110 fprintf(file, "0x%02X", buffer[i2]);
117 static unsigned align(unsigned offset, unsigned alignment)
119 if (offset % alignment != 0) {
120 offset += alignment - (offset % alignment);
125 static bool determine_jumpsize_iteration(
126 const binary_emiter_interface_t *interface)
129 unsigned max_offset = 0;
130 bool changed = false;
131 code_fragment_t *fragment;
133 for (fragment = first_fragment; fragment != NULL;
134 fragment = fragment->next) {
135 unsigned alignment = fragment->alignment;
137 /* assure alignment */
138 offset = align(offset, alignment);
139 max_offset = align(max_offset, alignment);
141 if (offset != fragment->offset) {
143 fragment->offset = offset;
145 fragment->max_offset = max_offset;
148 offset += fragment->len;
149 max_offset += fragment->len;
150 interface->determine_jumpsize(fragment);
151 offset += fragment->jumpsize_min;
152 max_offset += fragment->jumpsize_max;
158 static void determine_offsets(const binary_emiter_interface_t *interface)
162 assert(first_fragment->alignment == 1);
163 first_fragment->offset = 0;
164 first_fragment->max_offset = 0;
166 /* The algorithm calculates a lower and upper bound for the offset of each
167 * fragment. With this information we can calculate a lower and upper bound
168 * for the size of each jump instruction.
169 * A single iteration updates the offset bounds for all fragments and jump
170 * sizes for each fragment. We iterate until we had an iteration where
171 * none of the minimum offsets changed. */
173 changed = determine_jumpsize_iteration(interface);
174 /* TODO: we should have an abort mode for the case when the offsets
175 don't converge fast enough. We could simply use a pessimistic
176 solution after a few iterations... */
180 void be_emit_entity(ir_entity *entity, bool entity_sign, int offset,
187 panic("not implemented yet");
190 void be_emit_code(FILE *output, const binary_emiter_interface_t *interface)
194 code_fragment_t *fragment;
198 /* determine near/far jumps */
199 determine_offsets(interface);
203 for (fragment = first_fragment; fragment != NULL;
204 fragment = fragment->next) {
205 unsigned char *jmpbuffer;
208 /* assure alignment by emitting nops */
209 assert(fragment->offset >= offset);
210 nops = fragment->offset - offset;
212 unsigned char *nopbuffer = obstack_alloc(&code_fragment_obst, nops);
213 interface->create_nops(nopbuffer, nops);
214 emit(output, nopbuffer, nops);
215 offset = fragment->offset;
216 obstack_free(&code_fragment_obst, nopbuffer);
219 /* emit the fragment */
220 emit(output, fragment->data, fragment->len);
221 offset += fragment->len;
224 jmpbuffer = obstack_alloc(&code_fragment_obst, fragment->jumpsize_min);
225 interface->emit_jump(fragment, jmpbuffer);
226 emit(output, jmpbuffer, fragment->jumpsize_min);
227 offset += fragment->jumpsize_min;
228 obstack_free(&code_fragment_obst, jmpbuffer);