1 #ifdef USE_PRAGMA_IDENT_SRC
2 #pragma ident "@(#)assembler.cpp 1.41 07/05/05 17:05:03 JVM"
3 #endif
4 /*
5 * Copyright 1997-2006 Sun Microsystems, Inc. All Rights Reserved.
6 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
7 *
8 * This code is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License version 2 only, as
10 * published by the Free Software Foundation.
11 *
12 * This code is distributed in the hope that it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 * version 2 for more details (a copy is included in the LICENSE file that
16 * accompanied this code).
17 *
18 * You should have received a copy of the GNU General Public License version
19 * 2 along with this work; if not, write to the Free Software Foundation,
20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
21 *
22 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
23 * CA 95054 USA or visit www.sun.com if you need additional information or
24 * have any questions.
25 *
26 */
27
28 #include "incls/_precompiled.incl"
29 #include "incls/_assembler.cpp.incl"
30
31
32 // Implementation of AbstractAssembler
33 //
34 // The AbstractAssembler is generating code into a CodeBuffer. To make code generation faster,
35 // the assembler keeps a copy of the code buffers boundaries & modifies them when
36 // emitting bytes rather than using the code buffers accessor functions all the time.
37 // The code buffer is updated via set_code_end(...) after emiting a whole instruction.
38
39 AbstractAssembler::AbstractAssembler(CodeBuffer* code) {
40 if (code == NULL) return;
41 CodeSection* cs = code->insts();
42 cs->clear_mark(); // new assembler kills old mark
43 _code_section = cs;
44 _code_begin = cs->start();
45 _code_limit = cs->limit();
46 _code_pos = cs->end();
47 _oop_recorder= code->oop_recorder();
48 if (_code_begin == NULL) {
49 vm_exit_out_of_memory1(0, "CodeCache: no room for %s", code->name());
50 }
51 }
52
53 void AbstractAssembler::set_code_section(CodeSection* cs) {
54 assert(cs->outer() == code_section()->outer(), "sanity");
55 assert(cs->is_allocated(), "need to pre-allocate this section");
56 cs->clear_mark(); // new assembly into this section kills old mark
57 _code_section = cs;
58 _code_begin = cs->start();
59 _code_limit = cs->limit();
60 _code_pos = cs->end();
61 }
62
63 // Inform CodeBuffer that incoming code and relocation will be for stubs
64 address AbstractAssembler::start_a_stub(int required_space) {
65 CodeBuffer* cb = code();
66 CodeSection* cs = cb->stubs();
67 assert(_code_section == cb->insts(), "not in insts?");
68 sync();
69 if (cs->maybe_expand_to_ensure_remaining(required_space)
70 && cb->blob() == NULL) {
71 return NULL;
72 }
73 set_code_section(cs);
74 return pc();
75 }
76
77 // Inform CodeBuffer that incoming code and relocation will be code
78 // Should not be called if start_a_stub() returned NULL
79 void AbstractAssembler::end_a_stub() {
80 assert(_code_section == code()->stubs(), "not in stubs?");
81 sync();
82 set_code_section(code()->insts());
83 }
84
85 // Inform CodeBuffer that incoming code and relocation will be for stubs
86 address AbstractAssembler::start_a_const(int required_space, int required_align) {
87 CodeBuffer* cb = code();
88 CodeSection* cs = cb->consts();
89 assert(_code_section == cb->insts(), "not in insts?");
90 sync();
91 address end = cs->end();
92 int pad = -(intptr_t)end & (required_align-1);
93 if (cs->maybe_expand_to_ensure_remaining(pad + required_space)) {
94 if (cb->blob() == NULL) return NULL;
95 end = cs->end(); // refresh pointer
96 }
97 if (pad > 0) {
98 while (--pad >= 0) { *end++ = 0; }
99 cs->set_end(end);
100 }
101 set_code_section(cs);
102 return end;
103 }
104
105 // Inform CodeBuffer that incoming code and relocation will be code
106 // Should not be called if start_a_const() returned NULL
107 void AbstractAssembler::end_a_const() {
108 assert(_code_section == code()->consts(), "not in consts?");
109 sync();
110 set_code_section(code()->insts());
111 }
112
113
114 void AbstractAssembler::flush() {
115 sync();
116 ICache::invalidate_range(addr_at(0), offset());
117 }
118
119
120 void AbstractAssembler::a_byte(int x) {
121 emit_byte(x);
122 }
123
124
125 void AbstractAssembler::a_long(jint x) {
126 emit_long(x);
127 }
128
129 // Labels refer to positions in the (to be) generated code. There are bound
130 // and unbound
131 //
132 // Bound labels refer to known positions in the already generated code.
133 // offset() is the position the label refers to.
134 //
135 // Unbound labels refer to unknown positions in the code to be generated; it
136 // may contain a list of unresolved displacements that refer to it
137 #ifndef PRODUCT
138 void AbstractAssembler::print(Label& L) {
139 if (L.is_bound()) {
140 tty->print_cr("bound label to %d|%d", L.loc_pos(), L.loc_sect());
141 } else if (L.is_unbound()) {
142 L.print_instructions((MacroAssembler*)this);
143 } else {
144 tty->print_cr("label in inconsistent state (loc = %d)", L.loc());
145 }
146 }
147 #endif // PRODUCT
148
149
150 void AbstractAssembler::bind(Label& L) {
151 if (L.is_bound()) {
152 // Assembler can bind a label more than once to the same place.
153 guarantee(L.loc() == locator(), "attempt to redefine label");
154 return;
155 }
156 L.bind_loc(locator());
157 L.patch_instructions((MacroAssembler*)this);
158 }
159
160 void AbstractAssembler::generate_stack_overflow_check( int frame_size_in_bytes) {
161 if (UseStackBanging) {
162 // Each code entry causes one stack bang n pages down the stack where n
163 // is configurable by StackBangPages. The setting depends on the maximum
164 // depth of VM call stack or native before going back into java code,
165 // since only java code can raise a stack overflow exception using the
166 // stack banging mechanism. The VM and native code does not detect stack
167 // overflow.
168 // The code in JavaCalls::call() checks that there is at least n pages
169 // available, so all entry code needs to do is bang once for the end of
170 // this shadow zone.
171 // The entry code may need to bang additional pages if the framesize
172 // is greater than a page.
173
174 const int page_size = os::vm_page_size();
175 int bang_end = StackShadowPages*page_size;
176
177 // This is how far the previous frame's stack banging extended.
178 const int bang_end_safe = bang_end;
179
180 if (frame_size_in_bytes > page_size) {
181 bang_end += frame_size_in_bytes;
182 }
183
184 int bang_offset = bang_end_safe;
185 while (bang_offset <= bang_end) {
186 // Need at least one stack bang at end of shadow zone.
187 bang_stack_with_offset(bang_offset);
188 bang_offset += page_size;
189 }
190 } // end (UseStackBanging)
191 }
192
193 void Label::add_patch_at(CodeBuffer* cb, int branch_loc) {
194 assert(_loc == -1, "Label is unbound");
195 if (_patch_index < PatchCacheSize) {
196 _patches[_patch_index] = branch_loc;
197 } else {
198 if (_patch_overflow == NULL) {
199 _patch_overflow = cb->create_patch_overflow();
200 }
201 _patch_overflow->push(branch_loc);
202 }
203 ++_patch_index;
204 }
205
206 void Label::patch_instructions(MacroAssembler* masm) {
207 assert(is_bound(), "Label is bound");
208 CodeBuffer* cb = masm->code();
209 int target_sect = CodeBuffer::locator_sect(loc());
210 address target = cb->locator_address(loc());
211 while (_patch_index > 0) {
212 --_patch_index;
213 int branch_loc;
214 if (_patch_index >= PatchCacheSize) {
215 branch_loc = _patch_overflow->pop();
216 } else {
217 branch_loc = _patches[_patch_index];
218 }
219 int branch_sect = CodeBuffer::locator_sect(branch_loc);
220 address branch = cb->locator_address(branch_loc);
221 if (branch_sect == CodeBuffer::SECT_CONSTS) {
222 // The thing to patch is a constant word.
223 *(address*)branch = target;
224 continue;
225 }
226
227 #ifdef ASSERT
228 // Cross-section branches only work if the
229 // intermediate section boundaries are frozen.
230 if (target_sect != branch_sect) {
231 for (int n = MIN2(target_sect, branch_sect),
232 nlimit = (target_sect + branch_sect) - n;
233 n < nlimit; n++) {
234 CodeSection* cs = cb->code_section(n);
235 assert(cs->is_frozen(), "cross-section branch needs stable offsets");
236 }
237 }
238 #endif //ASSERT
239
240 // Push the target offset into the branch instruction.
241 masm->pd_patch_instruction(branch, target);
242 }
243 }
244
245
246 void AbstractAssembler::block_comment(const char* comment) {
247 if (sect() == CodeBuffer::SECT_INSTS) {
248 code_section()->outer()->block_comment(offset(), comment);
249 }
250 }
251
252
253 #ifndef PRODUCT
254 void Label::print_instructions(MacroAssembler* masm) const {
255 CodeBuffer* cb = masm->code();
256 for (int i = 0; i < _patch_index; ++i) {
257 int branch_loc;
258 if (i >= PatchCacheSize) {
259 branch_loc = _patch_overflow->at(i - PatchCacheSize);
260 } else {
261 branch_loc = _patches[i];
262 }
263 int branch_pos = CodeBuffer::locator_pos(branch_loc);
264 int branch_sect = CodeBuffer::locator_sect(branch_loc);
265 address branch = cb->locator_address(branch_loc);
266 tty->print_cr("unbound label");
267 tty->print("@ %d|%d ", branch_pos, branch_sect);
268 if (branch_sect == CodeBuffer::SECT_CONSTS) {
269 tty->print_cr(PTR_FORMAT, *(address*)branch);
270 continue;
271 }
272 masm->pd_print_patched_instruction(branch);
273 tty->cr();
274 }
275 }
276 #endif // ndef PRODUCT