1 /*
2 * Copyright 1997-2006 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 #include "incls/_precompiled.incl"
26 #include "incls/_assembler.cpp.incl"
27
28
29 // Implementation of AbstractAssembler
30 //
31 // The AbstractAssembler is generating code into a CodeBuffer. To make code generation faster,
32 // the assembler keeps a copy of the code buffers boundaries & modifies them when
33 // emitting bytes rather than using the code buffers accessor functions all the time.
34 // The code buffer is updated via set_code_end(...) after emiting a whole instruction.
35
36 AbstractAssembler::AbstractAssembler(CodeBuffer* code) {
37 if (code == NULL) return;
38 CodeSection* cs = code->insts();
39 cs->clear_mark(); // new assembler kills old mark
40 _code_section = cs;
41 _code_begin = cs->start();
42 _code_limit = cs->limit();
43 _code_pos = cs->end();
44 _oop_recorder= code->oop_recorder();
45 if (_code_begin == NULL) {
46 vm_exit_out_of_memory1(0, "CodeCache: no room for %s", code->name());
47 }
48 }
49
50 void AbstractAssembler::set_code_section(CodeSection* cs) {
51 assert(cs->outer() == code_section()->outer(), "sanity");
52 assert(cs->is_allocated(), "need to pre-allocate this section");
53 cs->clear_mark(); // new assembly into this section kills old mark
54 _code_section = cs;
55 _code_begin = cs->start();
56 _code_limit = cs->limit();
57 _code_pos = cs->end();
58 }
59
60 // Inform CodeBuffer that incoming code and relocation will be for stubs
61 address AbstractAssembler::start_a_stub(int required_space) {
62 CodeBuffer* cb = code();
63 CodeSection* cs = cb->stubs();
64 assert(_code_section == cb->insts(), "not in insts?");
65 sync();
66 if (cs->maybe_expand_to_ensure_remaining(required_space)
67 && cb->blob() == NULL) {
68 return NULL;
69 }
70 set_code_section(cs);
71 return pc();
72 }
73
74 // Inform CodeBuffer that incoming code and relocation will be code
75 // Should not be called if start_a_stub() returned NULL
76 void AbstractAssembler::end_a_stub() {
77 assert(_code_section == code()->stubs(), "not in stubs?");
78 sync();
79 set_code_section(code()->insts());
80 }
81
82 // Inform CodeBuffer that incoming code and relocation will be for stubs
83 address AbstractAssembler::start_a_const(int required_space, int required_align) {
84 CodeBuffer* cb = code();
85 CodeSection* cs = cb->consts();
86 assert(_code_section == cb->insts(), "not in insts?");
87 sync();
88 address end = cs->end();
89 int pad = -(intptr_t)end & (required_align-1);
90 if (cs->maybe_expand_to_ensure_remaining(pad + required_space)) {
91 if (cb->blob() == NULL) return NULL;
92 end = cs->end(); // refresh pointer
93 }
94 if (pad > 0) {
95 while (--pad >= 0) { *end++ = 0; }
96 cs->set_end(end);
97 }
98 set_code_section(cs);
99 return end;
100 }
101
102 // Inform CodeBuffer that incoming code and relocation will be code
103 // Should not be called if start_a_const() returned NULL
104 void AbstractAssembler::end_a_const() {
105 assert(_code_section == code()->consts(), "not in consts?");
106 sync();
107 set_code_section(code()->insts());
108 }
109
110
111 void AbstractAssembler::flush() {
112 sync();
113 ICache::invalidate_range(addr_at(0), offset());
114 }
115
116
117 void AbstractAssembler::a_byte(int x) {
118 emit_byte(x);
119 }
120
121
122 void AbstractAssembler::a_long(jint x) {
123 emit_long(x);
124 }
125
126 // Labels refer to positions in the (to be) generated code. There are bound
127 // and unbound
128 //
129 // Bound labels refer to known positions in the already generated code.
130 // offset() is the position the label refers to.
131 //
132 // Unbound labels refer to unknown positions in the code to be generated; it
133 // may contain a list of unresolved displacements that refer to it
134 #ifndef PRODUCT
135 void AbstractAssembler::print(Label& L) {
136 if (L.is_bound()) {
137 tty->print_cr("bound label to %d|%d", L.loc_pos(), L.loc_sect());
138 } else if (L.is_unbound()) {
139 L.print_instructions((MacroAssembler*)this);
140 } else {
141 tty->print_cr("label in inconsistent state (loc = %d)", L.loc());
142 }
143 }
144 #endif // PRODUCT
145
146
147 void AbstractAssembler::bind(Label& L) {
148 if (L.is_bound()) {
149 // Assembler can bind a label more than once to the same place.
150 guarantee(L.loc() == locator(), "attempt to redefine label");
151 return;
152 }
153 L.bind_loc(locator());
154 L.patch_instructions((MacroAssembler*)this);
155 }
156
157 void AbstractAssembler::generate_stack_overflow_check( int frame_size_in_bytes) {
158 if (UseStackBanging) {
159 // Each code entry causes one stack bang n pages down the stack where n
160 // is configurable by StackBangPages. The setting depends on the maximum
161 // depth of VM call stack or native before going back into java code,
162 // since only java code can raise a stack overflow exception using the
163 // stack banging mechanism. The VM and native code does not detect stack
164 // overflow.
165 // The code in JavaCalls::call() checks that there is at least n pages
166 // available, so all entry code needs to do is bang once for the end of
167 // this shadow zone.
168 // The entry code may need to bang additional pages if the framesize
169 // is greater than a page.
170
171 const int page_size = os::vm_page_size();
172 int bang_end = StackShadowPages*page_size;
173
174 // This is how far the previous frame's stack banging extended.
175 const int bang_end_safe = bang_end;
176
177 if (frame_size_in_bytes > page_size) {
178 bang_end += frame_size_in_bytes;
179 }
180
181 int bang_offset = bang_end_safe;
182 while (bang_offset <= bang_end) {
183 // Need at least one stack bang at end of shadow zone.
184 bang_stack_with_offset(bang_offset);
185 bang_offset += page_size;
186 }
187 } // end (UseStackBanging)
188 }
189
190 void Label::add_patch_at(CodeBuffer* cb, int branch_loc) {
191 assert(_loc == -1, "Label is unbound");
192 if (_patch_index < PatchCacheSize) {
193 _patches[_patch_index] = branch_loc;
194 } else {
195 if (_patch_overflow == NULL) {
196 _patch_overflow = cb->create_patch_overflow();
197 }
198 _patch_overflow->push(branch_loc);
199 }
200 ++_patch_index;
201 }
202
203 void Label::patch_instructions(MacroAssembler* masm) {
204 assert(is_bound(), "Label is bound");
205 CodeBuffer* cb = masm->code();
206 int target_sect = CodeBuffer::locator_sect(loc());
207 address target = cb->locator_address(loc());
208 while (_patch_index > 0) {
209 --_patch_index;
210 int branch_loc;
211 if (_patch_index >= PatchCacheSize) {
212 branch_loc = _patch_overflow->pop();
213 } else {
214 branch_loc = _patches[_patch_index];
215 }
216 int branch_sect = CodeBuffer::locator_sect(branch_loc);
217 address branch = cb->locator_address(branch_loc);
218 if (branch_sect == CodeBuffer::SECT_CONSTS) {
219 // The thing to patch is a constant word.
220 *(address*)branch = target;
221 continue;
222 }
223
224 #ifdef ASSERT
225 // Cross-section branches only work if the
226 // intermediate section boundaries are frozen.
227 if (target_sect != branch_sect) {
228 for (int n = MIN2(target_sect, branch_sect),
229 nlimit = (target_sect + branch_sect) - n;
230 n < nlimit; n++) {
231 CodeSection* cs = cb->code_section(n);
232 assert(cs->is_frozen(), "cross-section branch needs stable offsets");
233 }
234 }
235 #endif //ASSERT
236
237 // Push the target offset into the branch instruction.
238 masm->pd_patch_instruction(branch, target);
239 }
240 }
241
242
243 void AbstractAssembler::block_comment(const char* comment) {
244 if (sect() == CodeBuffer::SECT_INSTS) {
245 code_section()->outer()->block_comment(offset(), comment);
246 }
247 }
248
249 bool MacroAssembler::needs_explicit_null_check(intptr_t offset) {
250 // Exception handler checks the nmethod's implicit null checks table
251 // only when this method returns false.
252 #ifndef SPARC
253 // Sparc does not have based addressing
254 if (UseCompressedOops) {
255 // The first page after heap_base is unmapped and
256 // the 'offset' is equal to [heap_base + offset] for
257 // narrow oop implicit null checks.
258 uintptr_t heap_base = (uintptr_t)Universe::heap_base();
259 if ((uintptr_t)offset >= heap_base) {
260 // Normalize offset for the next check.
261 offset = (intptr_t)(pointer_delta((void*)offset, (void*)heap_base, 1));
262 }
263 }
264 #endif // SPARC
265 return offset < 0 || os::vm_page_size() <= offset;
266 }
267
268 #ifndef PRODUCT
269 void Label::print_instructions(MacroAssembler* masm) const {
270 CodeBuffer* cb = masm->code();
271 for (int i = 0; i < _patch_index; ++i) {
272 int branch_loc;
273 if (i >= PatchCacheSize) {
274 branch_loc = _patch_overflow->at(i - PatchCacheSize);
275 } else {
276 branch_loc = _patches[i];
277 }
278 int branch_pos = CodeBuffer::locator_pos(branch_loc);
279 int branch_sect = CodeBuffer::locator_sect(branch_loc);
280 address branch = cb->locator_address(branch_loc);
281 tty->print_cr("unbound label");
282 tty->print("@ %d|%d ", branch_pos, branch_sect);
283 if (branch_sect == CodeBuffer::SECT_CONSTS) {
284 tty->print_cr(PTR_FORMAT, *(address*)branch);
285 continue;
286 }
287 masm->pd_print_patched_instruction(branch);
288 tty->cr();
289 }
290 }
291 #endif // ndef PRODUCT