1 /*
2 * Copyright (c) 1997, 2011, 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 #ifdef TARGET_ARCH_arm
41 # include "assembler_arm.inline.hpp"
42 #endif
43 #ifdef TARGET_ARCH_ppc
44 # include "assembler_ppc.inline.hpp"
45 #endif
46
47
48 // Implementation of AbstractAssembler
49 //
50 // The AbstractAssembler is generating code into a CodeBuffer. To make code generation faster,
51 // the assembler keeps a copy of the code buffers boundaries & modifies them when
52 // emitting bytes rather than using the code buffers accessor functions all the time.
53 // The code buffer is updated via set_code_end(...) after emitting a whole instruction.
54
55 AbstractAssembler::AbstractAssembler(CodeBuffer* code) {
56 if (code == NULL) return;
57 CodeSection* cs = code->insts();
58 cs->clear_mark(); // new assembler kills old mark
59 _code_section = cs;
60 _code_begin = cs->start();
61 _code_limit = cs->limit();
62 _code_pos = cs->end();
63 _oop_recorder= code->oop_recorder();
64 DEBUG_ONLY( _short_branch_delta = 0; )
65 if (_code_begin == NULL) {
66 vm_exit_out_of_memory(0, err_msg("CodeCache: no room for %s",
67 code->name()));
68 }
69 }
70
71 void AbstractAssembler::set_code_section(CodeSection* cs) {
72 assert(cs->outer() == code_section()->outer(), "sanity");
73 assert(cs->is_allocated(), "need to pre-allocate this section");
74 cs->clear_mark(); // new assembly into this section kills old mark
75 _code_section = cs;
76 _code_begin = cs->start();
77 _code_limit = cs->limit();
78 _code_pos = cs->end();
79 }
80
81 // Inform CodeBuffer that incoming code and relocation will be for stubs
82 address AbstractAssembler::start_a_stub(int required_space) {
83 CodeBuffer* cb = code();
84 CodeSection* cs = cb->stubs();
85 assert(_code_section == cb->insts(), "not in insts?");
86 sync();
87 if (cs->maybe_expand_to_ensure_remaining(required_space)
88 && cb->blob() == NULL) {
89 return NULL;
90 }
91 set_code_section(cs);
92 return pc();
93 }
94
95 // Inform CodeBuffer that incoming code and relocation will be code
96 // Should not be called if start_a_stub() returned NULL
97 void AbstractAssembler::end_a_stub() {
98 assert(_code_section == code()->stubs(), "not in stubs?");
99 sync();
100 set_code_section(code()->insts());
101 }
102
103 // Inform CodeBuffer that incoming code and relocation will be for stubs
104 address AbstractAssembler::start_a_const(int required_space, int required_align) {
105 CodeBuffer* cb = code();
106 CodeSection* cs = cb->consts();
107 assert(_code_section == cb->insts(), "not in insts?");
108 sync();
109 address end = cs->end();
110 int pad = -(intptr_t)end & (required_align-1);
111 if (cs->maybe_expand_to_ensure_remaining(pad + required_space)) {
112 if (cb->blob() == NULL) return NULL;
113 end = cs->end(); // refresh pointer
114 }
115 if (pad > 0) {
116 while (--pad >= 0) { *end++ = 0; }
117 cs->set_end(end);
118 }
119 set_code_section(cs);
120 return end;
121 }
122
123 // Inform CodeBuffer that incoming code and relocation will be code
124 // Should not be called if start_a_const() returned NULL
125 void AbstractAssembler::end_a_const() {
126 assert(_code_section == code()->consts(), "not in consts?");
127 sync();
128 set_code_section(code()->insts());
129 }
130
131
132 void AbstractAssembler::flush() {
133 sync();
134 ICache::invalidate_range(addr_at(0), offset());
135 }
136
137
138 void AbstractAssembler::a_byte(int x) {
139 emit_byte(x);
140 }
141
142
143 void AbstractAssembler::a_long(jint x) {
144 emit_long(x);
145 }
146
147 // Labels refer to positions in the (to be) generated code. There are bound
148 // and unbound
149 //
150 // Bound labels refer to known positions in the already generated code.
151 // offset() is the position the label refers to.
152 //
153 // Unbound labels refer to unknown positions in the code to be generated; it
154 // may contain a list of unresolved displacements that refer to it
155 #ifndef PRODUCT
156 void AbstractAssembler::print(Label& L) {
157 if (L.is_bound()) {
158 tty->print_cr("bound label to %d|%d", L.loc_pos(), L.loc_sect());
159 } else if (L.is_unbound()) {
160 L.print_instructions((MacroAssembler*)this);
161 } else {
162 tty->print_cr("label in inconsistent state (loc = %d)", L.loc());
163 }
164 }
165 #endif // PRODUCT
166
167
168 void AbstractAssembler::bind(Label& L) {
169 if (L.is_bound()) {
170 // Assembler can bind a label more than once to the same place.
171 guarantee(L.loc() == locator(), "attempt to redefine label");
172 return;
173 }
174 L.bind_loc(locator());
175 L.patch_instructions((MacroAssembler*)this);
176 }
177
178 void AbstractAssembler::generate_stack_overflow_check( int frame_size_in_bytes) {
179 if (UseStackBanging) {
180 // Each code entry causes one stack bang n pages down the stack where n
181 // is configurable by StackBangPages. The setting depends on the maximum
182 // depth of VM call stack or native before going back into java code,
183 // since only java code can raise a stack overflow exception using the
184 // stack banging mechanism. The VM and native code does not detect stack
185 // overflow.
186 // The code in JavaCalls::call() checks that there is at least n pages
187 // available, so all entry code needs to do is bang once for the end of
188 // this shadow zone.
189 // The entry code may need to bang additional pages if the framesize
190 // is greater than a page.
191
192 const int page_size = os::vm_page_size();
193 int bang_end = StackShadowPages*page_size;
194
195 // This is how far the previous frame's stack banging extended.
196 const int bang_end_safe = bang_end;
197
198 if (frame_size_in_bytes > page_size) {
199 bang_end += frame_size_in_bytes;
200 }
201
202 int bang_offset = bang_end_safe;
203 while (bang_offset <= bang_end) {
204 // Need at least one stack bang at end of shadow zone.
205 bang_stack_with_offset(bang_offset);
206 bang_offset += page_size;
207 }
208 } // end (UseStackBanging)
209 }
210
211 void Label::add_patch_at(CodeBuffer* cb, int branch_loc) {
212 assert(_loc == -1, "Label is unbound");
213 if (_patch_index < PatchCacheSize) {
214 _patches[_patch_index] = branch_loc;
215 } else {
216 if (_patch_overflow == NULL) {
217 _patch_overflow = cb->create_patch_overflow();
218 }
219 _patch_overflow->push(branch_loc);
220 }
221 ++_patch_index;
222 }
223
224 void Label::patch_instructions(MacroAssembler* masm) {
225 assert(is_bound(), "Label is bound");
226 CodeBuffer* cb = masm->code();
227 int target_sect = CodeBuffer::locator_sect(loc());
228 address target = cb->locator_address(loc());
229 while (_patch_index > 0) {
230 --_patch_index;
231 int branch_loc;
232 if (_patch_index >= PatchCacheSize) {
233 branch_loc = _patch_overflow->pop();
234 } else {
235 branch_loc = _patches[_patch_index];
236 }
237 int branch_sect = CodeBuffer::locator_sect(branch_loc);
238 address branch = cb->locator_address(branch_loc);
239 if (branch_sect == CodeBuffer::SECT_CONSTS) {
240 // The thing to patch is a constant word.
241 *(address*)branch = target;
242 continue;
243 }
244
245 #ifdef ASSERT
246 // Cross-section branches only work if the
247 // intermediate section boundaries are frozen.
248 if (target_sect != branch_sect) {
249 for (int n = MIN2(target_sect, branch_sect),
250 nlimit = (target_sect + branch_sect) - n;
251 n < nlimit; n++) {
252 CodeSection* cs = cb->code_section(n);
253 assert(cs->is_frozen(), "cross-section branch needs stable offsets");
254 }
255 }
256 #endif //ASSERT
257
258 // Push the target offset into the branch instruction.
259 masm->pd_patch_instruction(branch, target);
260 }
261 }
262
263 struct DelayedConstant {
264 typedef void (*value_fn_t)();
265 BasicType type;
266 intptr_t value;
267 value_fn_t value_fn;
268 // This limit of 20 is generous for initial uses.
269 // The limit needs to be large enough to store the field offsets
270 // into classes which do not have statically fixed layouts.
271 // (Initial use is for method handle object offsets.)
272 // Look for uses of "delayed_value" in the source code
273 // and make sure this number is generous enough to handle all of them.
274 enum { DC_LIMIT = 20 };
275 static DelayedConstant delayed_constants[DC_LIMIT];
276 static DelayedConstant* add(BasicType type, value_fn_t value_fn);
277 bool match(BasicType t, value_fn_t cfn) {
278 return type == t && value_fn == cfn;
279 }
280 static void update_all();
281 };
282
283 DelayedConstant DelayedConstant::delayed_constants[DC_LIMIT];
284 // Default C structure initialization rules have the following effect here:
285 // = { { (BasicType)0, (intptr_t)NULL }, ... };
286
287 DelayedConstant* DelayedConstant::add(BasicType type,
288 DelayedConstant::value_fn_t cfn) {
289 for (int i = 0; i < DC_LIMIT; i++) {
290 DelayedConstant* dcon = &delayed_constants[i];
291 if (dcon->match(type, cfn))
292 return dcon;
293 if (dcon->value_fn == NULL) {
294 // (cmpxchg not because this is multi-threaded but because I'm paranoid)
295 if (Atomic::cmpxchg_ptr(CAST_FROM_FN_PTR(void*, cfn), &dcon->value_fn, NULL) == NULL) {
296 dcon->type = type;
297 return dcon;
298 }
299 }
300 }
301 // If this assert is hit (in pre-integration testing!) then re-evaluate
302 // the comment on the definition of DC_LIMIT.
303 guarantee(false, "too many delayed constants");
304 return NULL;
305 }
306
307 void DelayedConstant::update_all() {
308 for (int i = 0; i < DC_LIMIT; i++) {
309 DelayedConstant* dcon = &delayed_constants[i];
310 if (dcon->value_fn != NULL && dcon->value == 0) {
311 typedef int (*int_fn_t)();
312 typedef address (*address_fn_t)();
313 switch (dcon->type) {
314 case T_INT: dcon->value = (intptr_t) ((int_fn_t) dcon->value_fn)(); break;
315 case T_ADDRESS: dcon->value = (intptr_t) ((address_fn_t)dcon->value_fn)(); break;
316 }
317 }
318 }
319 }
320
321 intptr_t* AbstractAssembler::delayed_value_addr(int(*value_fn)()) {
322 DelayedConstant* dcon = DelayedConstant::add(T_INT, (DelayedConstant::value_fn_t) value_fn);
323 return &dcon->value;
324 }
325 intptr_t* AbstractAssembler::delayed_value_addr(address(*value_fn)()) {
326 DelayedConstant* dcon = DelayedConstant::add(T_ADDRESS, (DelayedConstant::value_fn_t) value_fn);
327 return &dcon->value;
328 }
329 void AbstractAssembler::update_delayed_values() {
330 DelayedConstant::update_all();
331 }
332
333
334
335
336 void AbstractAssembler::block_comment(const char* comment) {
337 if (sect() == CodeBuffer::SECT_INSTS) {
338 code_section()->outer()->block_comment(offset(), comment);
339 }
340 }
341
342 bool MacroAssembler::needs_explicit_null_check(intptr_t offset) {
343 // Exception handler checks the nmethod's implicit null checks table
344 // only when this method returns false.
345 #ifdef _LP64
346 if (UseCompressedOops && Universe::narrow_oop_base() != NULL) {
347 assert (Universe::heap() != NULL, "java heap should be initialized");
348 // The first page after heap_base is unmapped and
349 // the 'offset' is equal to [heap_base + offset] for
350 // narrow oop implicit null checks.
351 uintptr_t base = (uintptr_t)Universe::narrow_oop_base();
352 if ((uintptr_t)offset >= base) {
353 // Normalize offset for the next check.
354 offset = (intptr_t)(pointer_delta((void*)offset, (void*)base, 1));
355 }
356 }
357 #endif
358 return offset < 0 || os::vm_page_size() <= offset;
359 }
360
361 #ifndef PRODUCT
362 void Label::print_instructions(MacroAssembler* masm) const {
363 CodeBuffer* cb = masm->code();
364 for (int i = 0; i < _patch_index; ++i) {
365 int branch_loc;
366 if (i >= PatchCacheSize) {
367 branch_loc = _patch_overflow->at(i - PatchCacheSize);
368 } else {
369 branch_loc = _patches[i];
370 }
371 int branch_pos = CodeBuffer::locator_pos(branch_loc);
372 int branch_sect = CodeBuffer::locator_sect(branch_loc);
373 address branch = cb->locator_address(branch_loc);
374 tty->print_cr("unbound label");
375 tty->print("@ %d|%d ", branch_pos, branch_sect);
376 if (branch_sect == CodeBuffer::SECT_CONSTS) {
377 tty->print_cr(PTR_FORMAT, *(address*)branch);
378 continue;
379 }
380 masm->pd_print_patched_instruction(branch);
381 tty->cr();
382 }
383 }
384 #endif // ndef PRODUCT