1 /*
2 * Copyright (c) 1997, 2010, 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 "precompiled.hpp"
26 #include "asm/assembler.hpp"
27 #include "asm/assembler.inline.hpp"
28 #include "asm/codeBuffer.hpp"
29 #include "runtime/icache.hpp"
30 #include "runtime/os.hpp"
31 #ifdef TARGET_ARCH_x86
32 # include "assembler_x86.inline.hpp"
33 #endif
34 #ifdef TARGET_ARCH_sparc
35 # include "assembler_sparc.inline.hpp"
36 #endif
37 #ifdef TARGET_ARCH_zero
38 # include "assembler_zero.inline.hpp"
39 #endif
40
41
42 // Implementation of AbstractAssembler
43 //
44 // The AbstractAssembler is generating code into a CodeBuffer. To make code generation faster,
45 // the assembler keeps a copy of the code buffers boundaries & modifies them when
46 // emitting bytes rather than using the code buffers accessor functions all the time.
47 // The code buffer is updated via set_code_end(...) after emitting a whole instruction.
48
49 AbstractAssembler::AbstractAssembler(CodeBuffer* code) {
50 if (code == NULL) return;
51 CodeSection* cs = code->insts();
52 cs->clear_mark(); // new assembler kills old mark
53 _code_section = cs;
54 _code_begin = cs->start();
55 _code_limit = cs->limit();
56 _code_pos = cs->end();
57 _oop_recorder= code->oop_recorder();
58 if (_code_begin == NULL) {
59 vm_exit_out_of_memory(0, err_msg("CodeCache: no room for %s",
60 code->name()));
61 }
62 }
63
64 void AbstractAssembler::set_code_section(CodeSection* cs) {
65 assert(cs->outer() == code_section()->outer(), "sanity");
66 assert(cs->is_allocated(), "need to pre-allocate this section");
67 cs->clear_mark(); // new assembly into this section kills old mark
68 _code_section = cs;
69 _code_begin = cs->start();
70 _code_limit = cs->limit();
71 _code_pos = cs->end();
72 }
73
74 // Inform CodeBuffer that incoming code and relocation will be for stubs
75 address AbstractAssembler::start_a_stub(int required_space) {
76 CodeBuffer* cb = code();
77 CodeSection* cs = cb->stubs();
78 assert(_code_section == cb->insts(), "not in insts?");
79 sync();
80 if (cs->maybe_expand_to_ensure_remaining(required_space)
81 && cb->blob() == NULL) {
82 return NULL;
83 }
84 set_code_section(cs);
85 return pc();
86 }
87
88 // Inform CodeBuffer that incoming code and relocation will be code
89 // Should not be called if start_a_stub() returned NULL
90 void AbstractAssembler::end_a_stub() {
91 assert(_code_section == code()->stubs(), "not in stubs?");
92 sync();
93 set_code_section(code()->insts());
94 }
95
96 // Inform CodeBuffer that incoming code and relocation will be for stubs
97 address AbstractAssembler::start_a_const(int required_space, int required_align) {
98 CodeBuffer* cb = code();
99 CodeSection* cs = cb->consts();
100 assert(_code_section == cb->insts(), "not in insts?");
101 sync();
102 address end = cs->end();
103 int pad = -(intptr_t)end & (required_align-1);
104 if (cs->maybe_expand_to_ensure_remaining(pad + required_space)) {
105 if (cb->blob() == NULL) return NULL;
106 end = cs->end(); // refresh pointer
107 }
108 if (pad > 0) {
109 while (--pad >= 0) { *end++ = 0; }
110 cs->set_end(end);
111 }
112 set_code_section(cs);
113 return end;
114 }
115
116 // Inform CodeBuffer that incoming code and relocation will be code
117 // Should not be called if start_a_const() returned NULL
118 void AbstractAssembler::end_a_const() {
119 assert(_code_section == code()->consts(), "not in consts?");
120 sync();
121 set_code_section(code()->insts());
122 }
123
124
125 void AbstractAssembler::flush() {
126 sync();
127 ICache::invalidate_range(addr_at(0), offset());
128 }
129
130
131 void AbstractAssembler::a_byte(int x) {
132 emit_byte(x);
133 }
134
135
136 void AbstractAssembler::a_long(jint x) {
137 emit_long(x);
138 }
139
140 // Labels refer to positions in the (to be) generated code. There are bound
141 // and unbound
142 //
143 // Bound labels refer to known positions in the already generated code.
144 // offset() is the position the label refers to.
145 //
146 // Unbound labels refer to unknown positions in the code to be generated; it
147 // may contain a list of unresolved displacements that refer to it
148 #ifndef PRODUCT
149 void AbstractAssembler::print(Label& L) {
150 if (L.is_bound()) {
151 tty->print_cr("bound label to %d|%d", L.loc_pos(), L.loc_sect());
152 } else if (L.is_unbound()) {
153 L.print_instructions((MacroAssembler*)this);
154 } else {
155 tty->print_cr("label in inconsistent state (loc = %d)", L.loc());
156 }
157 }
158 #endif // PRODUCT
159
160
161 void AbstractAssembler::bind(Label& L) {
162 if (L.is_bound()) {
163 // Assembler can bind a label more than once to the same place.
164 guarantee(L.loc() == locator(), "attempt to redefine label");
165 return;
166 }
167 L.bind_loc(locator());
168 L.patch_instructions((MacroAssembler*)this);
169 }
170
171 void AbstractAssembler::generate_stack_overflow_check( int frame_size_in_bytes) {
172 if (UseStackBanging) {
173 // Each code entry causes one stack bang n pages down the stack where n
174 // is configurable by StackBangPages. The setting depends on the maximum
175 // depth of VM call stack or native before going back into java code,
176 // since only java code can raise a stack overflow exception using the
177 // stack banging mechanism. The VM and native code does not detect stack
178 // overflow.
179 // The code in JavaCalls::call() checks that there is at least n pages
180 // available, so all entry code needs to do is bang once for the end of
181 // this shadow zone.
182 // The entry code may need to bang additional pages if the framesize
183 // is greater than a page.
184
185 const int page_size = os::vm_page_size();
186 int bang_end = StackShadowPages*page_size;
187
188 // This is how far the previous frame's stack banging extended.
189 const int bang_end_safe = bang_end;
190
191 if (frame_size_in_bytes > page_size) {
192 bang_end += frame_size_in_bytes;
193 }
194
195 int bang_offset = bang_end_safe;
196 while (bang_offset <= bang_end) {
197 // Need at least one stack bang at end of shadow zone.
198 bang_stack_with_offset(bang_offset);
199 bang_offset += page_size;
200 }
201 } // end (UseStackBanging)
202 }
203
204 void Label::add_patch_at(CodeBuffer* cb, int branch_loc) {
205 assert(_loc == -1, "Label is unbound");
206 if (_patch_index < PatchCacheSize) {
207 _patches[_patch_index] = branch_loc;
208 } else {
209 if (_patch_overflow == NULL) {
210 _patch_overflow = cb->create_patch_overflow();
211 }
212 _patch_overflow->push(branch_loc);
213 }
214 ++_patch_index;
215 }
216
217 void Label::patch_instructions(MacroAssembler* masm) {
218 assert(is_bound(), "Label is bound");
219 CodeBuffer* cb = masm->code();
220 int target_sect = CodeBuffer::locator_sect(loc());
221 address target = cb->locator_address(loc());
222 while (_patch_index > 0) {
223 --_patch_index;
224 int branch_loc;
225 if (_patch_index >= PatchCacheSize) {
226 branch_loc = _patch_overflow->pop();
227 } else {
228 branch_loc = _patches[_patch_index];
229 }
230 int branch_sect = CodeBuffer::locator_sect(branch_loc);
231 address branch = cb->locator_address(branch_loc);
232 if (branch_sect == CodeBuffer::SECT_CONSTS) {
233 // The thing to patch is a constant word.
234 *(address*)branch = target;
235 continue;
236 }
237
238 #ifdef ASSERT
239 // Cross-section branches only work if the
240 // intermediate section boundaries are frozen.
241 if (target_sect != branch_sect) {
242 for (int n = MIN2(target_sect, branch_sect),
243 nlimit = (target_sect + branch_sect) - n;
244 n < nlimit; n++) {
245 CodeSection* cs = cb->code_section(n);
246 assert(cs->is_frozen(), "cross-section branch needs stable offsets");
247 }
248 }
249 #endif //ASSERT
250
251 // Push the target offset into the branch instruction.
252 masm->pd_patch_instruction(branch, target);
253 }
254 }
255
256 struct DelayedConstant {
257 typedef void (*value_fn_t)();
258 BasicType type;
259 intptr_t value;
260 value_fn_t value_fn;
261 // This limit of 20 is generous for initial uses.
262 // The limit needs to be large enough to store the field offsets
263 // into classes which do not have statically fixed layouts.
264 // (Initial use is for method handle object offsets.)
265 // Look for uses of "delayed_value" in the source code
266 // and make sure this number is generous enough to handle all of them.
267 enum { DC_LIMIT = 20 };
268 static DelayedConstant delayed_constants[DC_LIMIT];
269 static DelayedConstant* add(BasicType type, value_fn_t value_fn);
270 bool match(BasicType t, value_fn_t cfn) {
271 return type == t && value_fn == cfn;
272 }
273 static void update_all();
274 };
275
276 DelayedConstant DelayedConstant::delayed_constants[DC_LIMIT];
277 // Default C structure initialization rules have the following effect here:
278 // = { { (BasicType)0, (intptr_t)NULL }, ... };
279
280 DelayedConstant* DelayedConstant::add(BasicType type,
281 DelayedConstant::value_fn_t cfn) {
282 for (int i = 0; i < DC_LIMIT; i++) {
283 DelayedConstant* dcon = &delayed_constants[i];
284 if (dcon->match(type, cfn))
285 return dcon;
286 if (dcon->value_fn == NULL) {
287 // (cmpxchg not because this is multi-threaded but because I'm paranoid)
288 if (Atomic::cmpxchg_ptr(CAST_FROM_FN_PTR(void*, cfn), &dcon->value_fn, NULL) == NULL) {
289 dcon->type = type;
290 return dcon;
291 }
292 }
293 }
294 // If this assert is hit (in pre-integration testing!) then re-evaluate
295 // the comment on the definition of DC_LIMIT.
296 guarantee(false, "too many delayed constants");
297 return NULL;
298 }
299
300 void DelayedConstant::update_all() {
301 for (int i = 0; i < DC_LIMIT; i++) {
302 DelayedConstant* dcon = &delayed_constants[i];
303 if (dcon->value_fn != NULL && dcon->value == 0) {
304 typedef int (*int_fn_t)();
305 typedef address (*address_fn_t)();
306 switch (dcon->type) {
307 case T_INT: dcon->value = (intptr_t) ((int_fn_t) dcon->value_fn)(); break;
308 case T_ADDRESS: dcon->value = (intptr_t) ((address_fn_t)dcon->value_fn)(); break;
309 }
310 }
311 }
312 }
313
314 intptr_t* AbstractAssembler::delayed_value_addr(int(*value_fn)()) {
315 DelayedConstant* dcon = DelayedConstant::add(T_INT, (DelayedConstant::value_fn_t) value_fn);
316 return &dcon->value;
317 }
318 intptr_t* AbstractAssembler::delayed_value_addr(address(*value_fn)()) {
319 DelayedConstant* dcon = DelayedConstant::add(T_ADDRESS, (DelayedConstant::value_fn_t) value_fn);
320 return &dcon->value;
321 }
322 void AbstractAssembler::update_delayed_values() {
323 DelayedConstant::update_all();
324 }
325
326
327
328
329 void AbstractAssembler::block_comment(const char* comment) {
330 if (sect() == CodeBuffer::SECT_INSTS) {
331 code_section()->outer()->block_comment(offset(), comment);
332 }
333 }
334
335 bool MacroAssembler::needs_explicit_null_check(intptr_t offset) {
336 // Exception handler checks the nmethod's implicit null checks table
337 // only when this method returns false.
338 #ifdef _LP64
339 if (UseCompressedOops && Universe::narrow_oop_base() != NULL) {
340 assert (Universe::heap() != NULL, "java heap should be initialized");
341 // The first page after heap_base is unmapped and
342 // the 'offset' is equal to [heap_base + offset] for
343 // narrow oop implicit null checks.
344 uintptr_t base = (uintptr_t)Universe::narrow_oop_base();
345 if ((uintptr_t)offset >= base) {
346 // Normalize offset for the next check.
347 offset = (intptr_t)(pointer_delta((void*)offset, (void*)base, 1));
348 }
349 }
350 #endif
351 return offset < 0 || os::vm_page_size() <= offset;
352 }
353
354 #ifndef PRODUCT
355 void Label::print_instructions(MacroAssembler* masm) const {
356 CodeBuffer* cb = masm->code();
357 for (int i = 0; i < _patch_index; ++i) {
358 int branch_loc;
359 if (i >= PatchCacheSize) {
360 branch_loc = _patch_overflow->at(i - PatchCacheSize);
361 } else {
362 branch_loc = _patches[i];
363 }
364 int branch_pos = CodeBuffer::locator_pos(branch_loc);
365 int branch_sect = CodeBuffer::locator_sect(branch_loc);
366 address branch = cb->locator_address(branch_loc);
367 tty->print_cr("unbound label");
368 tty->print("@ %d|%d ", branch_pos, branch_sect);
369 if (branch_sect == CodeBuffer::SECT_CONSTS) {
370 tty->print_cr(PTR_FORMAT, *(address*)branch);
371 continue;
372 }
373 masm->pd_print_patched_instruction(branch);
374 tty->cr();
375 }
376 }
377 #endif // ndef PRODUCT