1 /*
2 * Copyright (c) 1997, 2009, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * 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 emitting 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_memory(0, err_msg("CodeCache: no room for %s",
47 code->name()));
48 }
49 }
50
51 void AbstractAssembler::set_code_section(CodeSection* cs) {
52 assert(cs->outer() == code_section()->outer(), "sanity");
53 assert(cs->is_allocated(), "need to pre-allocate this section");
54 cs->clear_mark(); // new assembly into this section kills old mark
55 _code_section = cs;
56 _code_begin = cs->start();
57 _code_limit = cs->limit();
58 _code_pos = cs->end();
59 }
60
61 // Inform CodeBuffer that incoming code and relocation will be for stubs
62 address AbstractAssembler::start_a_stub(int required_space) {
63 CodeBuffer* cb = code();
64 CodeSection* cs = cb->stubs();
65 assert(_code_section == cb->insts(), "not in insts?");
66 sync();
67 if (cs->maybe_expand_to_ensure_remaining(required_space)
68 && cb->blob() == NULL) {
69 return NULL;
70 }
71 set_code_section(cs);
72 return pc();
73 }
74
75 // Inform CodeBuffer that incoming code and relocation will be code
76 // Should not be called if start_a_stub() returned NULL
77 void AbstractAssembler::end_a_stub() {
78 assert(_code_section == code()->stubs(), "not in stubs?");
79 sync();
80 set_code_section(code()->insts());
81 }
82
83 // Inform CodeBuffer that incoming code and relocation will be for stubs
84 address AbstractAssembler::start_a_const(int required_space, int required_align) {
85 CodeBuffer* cb = code();
86 CodeSection* cs = cb->consts();
87 assert(_code_section == cb->insts(), "not in insts?");
88 sync();
89 address end = cs->end();
90 int pad = -(intptr_t)end & (required_align-1);
91 if (cs->maybe_expand_to_ensure_remaining(pad + required_space)) {
92 if (cb->blob() == NULL) return NULL;
93 end = cs->end(); // refresh pointer
94 }
95 if (pad > 0) {
96 while (--pad >= 0) { *end++ = 0; }
97 cs->set_end(end);
98 }
99 set_code_section(cs);
100 return end;
101 }
102
103 // Inform CodeBuffer that incoming code and relocation will be code
104 // Should not be called if start_a_const() returned NULL
105 void AbstractAssembler::end_a_const() {
106 assert(_code_section == code()->consts(), "not in consts?");
107 sync();
108 set_code_section(code()->insts());
109 }
110
111
112 void AbstractAssembler::flush() {
113 sync();
114 ICache::invalidate_range(addr_at(0), offset());
115 }
116
117
118 void AbstractAssembler::a_byte(int x) {
119 emit_byte(x);
120 }
121
122
123 void AbstractAssembler::a_long(jint x) {
124 emit_long(x);
125 }
126
127 // Labels refer to positions in the (to be) generated code. There are bound
128 // and unbound
129 //
130 // Bound labels refer to known positions in the already generated code.
131 // offset() is the position the label refers to.
132 //
133 // Unbound labels refer to unknown positions in the code to be generated; it
134 // may contain a list of unresolved displacements that refer to it
135 #ifndef PRODUCT
136 void AbstractAssembler::print(Label& L) {
137 if (L.is_bound()) {
138 tty->print_cr("bound label to %d|%d", L.loc_pos(), L.loc_sect());
139 } else if (L.is_unbound()) {
140 L.print_instructions((MacroAssembler*)this);
141 } else {
142 tty->print_cr("label in inconsistent state (loc = %d)", L.loc());
143 }
144 }
145 #endif // PRODUCT
146
147
148 void AbstractAssembler::bind(Label& L) {
149 if (L.is_bound()) {
150 // Assembler can bind a label more than once to the same place.
151 guarantee(L.loc() == locator(), "attempt to redefine label");
152 return;
153 }
154 L.bind_loc(locator());
155 L.patch_instructions((MacroAssembler*)this);
156 }
157
158 void AbstractAssembler::generate_stack_overflow_check( int frame_size_in_bytes) {
159 if (UseStackBanging) {
160 // Each code entry causes one stack bang n pages down the stack where n
161 // is configurable by StackBangPages. The setting depends on the maximum
162 // depth of VM call stack or native before going back into java code,
163 // since only java code can raise a stack overflow exception using the
164 // stack banging mechanism. The VM and native code does not detect stack
165 // overflow.
166 // The code in JavaCalls::call() checks that there is at least n pages
167 // available, so all entry code needs to do is bang once for the end of
168 // this shadow zone.
169 // The entry code may need to bang additional pages if the framesize
170 // is greater than a page.
171
172 const int page_size = os::vm_page_size();
173 int bang_end = StackShadowPages*page_size;
174
175 // This is how far the previous frame's stack banging extended.
176 const int bang_end_safe = bang_end;
177
178 if (frame_size_in_bytes > page_size) {
179 bang_end += frame_size_in_bytes;
180 }
181
182 int bang_offset = bang_end_safe;
183 while (bang_offset <= bang_end) {
184 // Need at least one stack bang at end of shadow zone.
185 bang_stack_with_offset(bang_offset);
186 bang_offset += page_size;
187 }
188 } // end (UseStackBanging)
189 }
190
191 void Label::add_patch_at(CodeBuffer* cb, int branch_loc) {
192 assert(_loc == -1, "Label is unbound");
193 if (_patch_index < PatchCacheSize) {
194 _patches[_patch_index] = branch_loc;
195 } else {
196 if (_patch_overflow == NULL) {
197 _patch_overflow = cb->create_patch_overflow();
198 }
199 _patch_overflow->push(branch_loc);
200 }
201 ++_patch_index;
202 }
203
204 void Label::patch_instructions(MacroAssembler* masm) {
205 assert(is_bound(), "Label is bound");
206 CodeBuffer* cb = masm->code();
207 int target_sect = CodeBuffer::locator_sect(loc());
208 address target = cb->locator_address(loc());
209 while (_patch_index > 0) {
210 --_patch_index;
211 int branch_loc;
212 if (_patch_index >= PatchCacheSize) {
213 branch_loc = _patch_overflow->pop();
214 } else {
215 branch_loc = _patches[_patch_index];
216 }
217 int branch_sect = CodeBuffer::locator_sect(branch_loc);
218 address branch = cb->locator_address(branch_loc);
219 if (branch_sect == CodeBuffer::SECT_CONSTS) {
220 // The thing to patch is a constant word.
221 *(address*)branch = target;
222 continue;
223 }
224
225 #ifdef ASSERT
226 // Cross-section branches only work if the
227 // intermediate section boundaries are frozen.
228 if (target_sect != branch_sect) {
229 for (int n = MIN2(target_sect, branch_sect),
230 nlimit = (target_sect + branch_sect) - n;
231 n < nlimit; n++) {
232 CodeSection* cs = cb->code_section(n);
233 assert(cs->is_frozen(), "cross-section branch needs stable offsets");
234 }
235 }
236 #endif //ASSERT
237
238 // Push the target offset into the branch instruction.
239 masm->pd_patch_instruction(branch, target);
240 }
241 }
242
243 struct DelayedConstant {
244 typedef void (*value_fn_t)();
245 BasicType type;
246 intptr_t value;
247 value_fn_t value_fn;
248 // This limit of 20 is generous for initial uses.
249 // The limit needs to be large enough to store the field offsets
250 // into classes which do not have statically fixed layouts.
251 // (Initial use is for method handle object offsets.)
252 // Look for uses of "delayed_value" in the source code
253 // and make sure this number is generous enough to handle all of them.
254 enum { DC_LIMIT = 20 };
255 static DelayedConstant delayed_constants[DC_LIMIT];
256 static DelayedConstant* add(BasicType type, value_fn_t value_fn);
257 bool match(BasicType t, value_fn_t cfn) {
258 return type == t && value_fn == cfn;
259 }
260 static void update_all();
261 };
262
263 DelayedConstant DelayedConstant::delayed_constants[DC_LIMIT];
264 // Default C structure initialization rules have the following effect here:
265 // = { { (BasicType)0, (intptr_t)NULL }, ... };
266
267 DelayedConstant* DelayedConstant::add(BasicType type,
268 DelayedConstant::value_fn_t cfn) {
269 for (int i = 0; i < DC_LIMIT; i++) {
270 DelayedConstant* dcon = &delayed_constants[i];
271 if (dcon->match(type, cfn))
272 return dcon;
273 if (dcon->value_fn == NULL) {
274 // (cmpxchg not because this is multi-threaded but because I'm paranoid)
275 if (Atomic::cmpxchg_ptr(CAST_FROM_FN_PTR(void*, cfn), &dcon->value_fn, NULL) == NULL) {
276 dcon->type = type;
277 return dcon;
278 }
279 }
280 }
281 // If this assert is hit (in pre-integration testing!) then re-evaluate
282 // the comment on the definition of DC_LIMIT.
283 guarantee(false, "too many delayed constants");
284 return NULL;
285 }
286
287 void DelayedConstant::update_all() {
288 for (int i = 0; i < DC_LIMIT; i++) {
289 DelayedConstant* dcon = &delayed_constants[i];
290 if (dcon->value_fn != NULL && dcon->value == 0) {
291 typedef int (*int_fn_t)();
292 typedef address (*address_fn_t)();
293 switch (dcon->type) {
294 case T_INT: dcon->value = (intptr_t) ((int_fn_t) dcon->value_fn)(); break;
295 case T_ADDRESS: dcon->value = (intptr_t) ((address_fn_t)dcon->value_fn)(); break;
296 }
297 }
298 }
299 }
300
301 intptr_t* AbstractAssembler::delayed_value_addr(int(*value_fn)()) {
302 DelayedConstant* dcon = DelayedConstant::add(T_INT, (DelayedConstant::value_fn_t) value_fn);
303 return &dcon->value;
304 }
305 intptr_t* AbstractAssembler::delayed_value_addr(address(*value_fn)()) {
306 DelayedConstant* dcon = DelayedConstant::add(T_ADDRESS, (DelayedConstant::value_fn_t) value_fn);
307 return &dcon->value;
308 }
309 void AbstractAssembler::update_delayed_values() {
310 DelayedConstant::update_all();
311 }
312
313
314
315
316 void AbstractAssembler::block_comment(const char* comment) {
317 if (sect() == CodeBuffer::SECT_INSTS) {
318 code_section()->outer()->block_comment(offset(), comment);
319 }
320 }
321
322 bool MacroAssembler::needs_explicit_null_check(intptr_t offset) {
323 // Exception handler checks the nmethod's implicit null checks table
324 // only when this method returns false.
325 #ifdef _LP64
326 if (UseCompressedOops && Universe::narrow_oop_base() != NULL) {
327 assert (Universe::heap() != NULL, "java heap should be initialized");
328 // The first page after heap_base is unmapped and
329 // the 'offset' is equal to [heap_base + offset] for
330 // narrow oop implicit null checks.
331 uintptr_t base = (uintptr_t)Universe::narrow_oop_base();
332 if ((uintptr_t)offset >= base) {
333 // Normalize offset for the next check.
334 offset = (intptr_t)(pointer_delta((void*)offset, (void*)base, 1));
335 }
336 }
337 #endif
338 return offset < 0 || os::vm_page_size() <= offset;
339 }
340
341 #ifndef PRODUCT
342 void Label::print_instructions(MacroAssembler* masm) const {
343 CodeBuffer* cb = masm->code();
344 for (int i = 0; i < _patch_index; ++i) {
345 int branch_loc;
346 if (i >= PatchCacheSize) {
347 branch_loc = _patch_overflow->at(i - PatchCacheSize);
348 } else {
349 branch_loc = _patches[i];
350 }
351 int branch_pos = CodeBuffer::locator_pos(branch_loc);
352 int branch_sect = CodeBuffer::locator_sect(branch_loc);
353 address branch = cb->locator_address(branch_loc);
354 tty->print_cr("unbound label");
355 tty->print("@ %d|%d ", branch_pos, branch_sect);
356 if (branch_sect == CodeBuffer::SECT_CONSTS) {
357 tty->print_cr(PTR_FORMAT, *(address*)branch);
358 continue;
359 }
360 masm->pd_print_patched_instruction(branch);
361 tty->cr();
362 }
363 }
364 #endif // ndef PRODUCT