Fri, 30 Nov 2012 11:44:05 -0800
8003195: AbstractAssembler should not store code pointers but use the CodeSection directly
Reviewed-by: twisti, kvn
Contributed-by: Bharadwaj Yadavalli <bharadwaj.yadavalli@oracle.com>
1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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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
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.
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 if (cs->start() == NULL) {
60 vm_exit_out_of_memory(0, err_msg("CodeCache: no room for %s",
61 code->name()));
62 }
63 _code_section = cs;
64 _oop_recorder= code->oop_recorder();
65 DEBUG_ONLY( _short_branch_delta = 0; )
66 }
68 void AbstractAssembler::set_code_section(CodeSection* cs) {
69 assert(cs->outer() == code_section()->outer(), "sanity");
70 assert(cs->is_allocated(), "need to pre-allocate this section");
71 cs->clear_mark(); // new assembly into this section kills old mark
72 _code_section = cs;
73 }
75 // Inform CodeBuffer that incoming code and relocation will be for stubs
76 address AbstractAssembler::start_a_stub(int required_space) {
77 CodeBuffer* cb = code();
78 CodeSection* cs = cb->stubs();
79 assert(_code_section == cb->insts(), "not in insts?");
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 }
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 set_code_section(code()->insts());
93 }
95 // Inform CodeBuffer that incoming code and relocation will be for stubs
96 address AbstractAssembler::start_a_const(int required_space, int required_align) {
97 CodeBuffer* cb = code();
98 CodeSection* cs = cb->consts();
99 assert(_code_section == cb->insts() || _code_section == cb->stubs(), "not in insts/stubs?");
100 address end = cs->end();
101 int pad = -(intptr_t)end & (required_align-1);
102 if (cs->maybe_expand_to_ensure_remaining(pad + required_space)) {
103 if (cb->blob() == NULL) return NULL;
104 end = cs->end(); // refresh pointer
105 }
106 if (pad > 0) {
107 while (--pad >= 0) { *end++ = 0; }
108 cs->set_end(end);
109 }
110 set_code_section(cs);
111 return end;
112 }
114 // Inform CodeBuffer that incoming code and relocation will be code
115 // in section cs (insts or stubs).
116 void AbstractAssembler::end_a_const(CodeSection* cs) {
117 assert(_code_section == code()->consts(), "not in consts?");
118 set_code_section(cs);
119 }
121 void AbstractAssembler::flush() {
122 ICache::invalidate_range(addr_at(0), offset());
123 }
126 void AbstractAssembler::a_byte(int x) {
127 emit_byte(x);
128 }
131 void AbstractAssembler::a_long(jint x) {
132 emit_long(x);
133 }
135 // Labels refer to positions in the (to be) generated code. There are bound
136 // and unbound
137 //
138 // Bound labels refer to known positions in the already generated code.
139 // offset() is the position the label refers to.
140 //
141 // Unbound labels refer to unknown positions in the code to be generated; it
142 // may contain a list of unresolved displacements that refer to it
143 #ifndef PRODUCT
144 void AbstractAssembler::print(Label& L) {
145 if (L.is_bound()) {
146 tty->print_cr("bound label to %d|%d", L.loc_pos(), L.loc_sect());
147 } else if (L.is_unbound()) {
148 L.print_instructions((MacroAssembler*)this);
149 } else {
150 tty->print_cr("label in inconsistent state (loc = %d)", L.loc());
151 }
152 }
153 #endif // PRODUCT
156 void AbstractAssembler::bind(Label& L) {
157 if (L.is_bound()) {
158 // Assembler can bind a label more than once to the same place.
159 guarantee(L.loc() == locator(), "attempt to redefine label");
160 return;
161 }
162 L.bind_loc(locator());
163 L.patch_instructions((MacroAssembler*)this);
164 }
166 void AbstractAssembler::generate_stack_overflow_check( int frame_size_in_bytes) {
167 if (UseStackBanging) {
168 // Each code entry causes one stack bang n pages down the stack where n
169 // is configurable by StackBangPages. The setting depends on the maximum
170 // depth of VM call stack or native before going back into java code,
171 // since only java code can raise a stack overflow exception using the
172 // stack banging mechanism. The VM and native code does not detect stack
173 // overflow.
174 // The code in JavaCalls::call() checks that there is at least n pages
175 // available, so all entry code needs to do is bang once for the end of
176 // this shadow zone.
177 // The entry code may need to bang additional pages if the framesize
178 // is greater than a page.
180 const int page_size = os::vm_page_size();
181 int bang_end = StackShadowPages*page_size;
183 // This is how far the previous frame's stack banging extended.
184 const int bang_end_safe = bang_end;
186 if (frame_size_in_bytes > page_size) {
187 bang_end += frame_size_in_bytes;
188 }
190 int bang_offset = bang_end_safe;
191 while (bang_offset <= bang_end) {
192 // Need at least one stack bang at end of shadow zone.
193 bang_stack_with_offset(bang_offset);
194 bang_offset += page_size;
195 }
196 } // end (UseStackBanging)
197 }
199 void Label::add_patch_at(CodeBuffer* cb, int branch_loc) {
200 assert(_loc == -1, "Label is unbound");
201 if (_patch_index < PatchCacheSize) {
202 _patches[_patch_index] = branch_loc;
203 } else {
204 if (_patch_overflow == NULL) {
205 _patch_overflow = cb->create_patch_overflow();
206 }
207 _patch_overflow->push(branch_loc);
208 }
209 ++_patch_index;
210 }
212 void Label::patch_instructions(MacroAssembler* masm) {
213 assert(is_bound(), "Label is bound");
214 CodeBuffer* cb = masm->code();
215 int target_sect = CodeBuffer::locator_sect(loc());
216 address target = cb->locator_address(loc());
217 while (_patch_index > 0) {
218 --_patch_index;
219 int branch_loc;
220 if (_patch_index >= PatchCacheSize) {
221 branch_loc = _patch_overflow->pop();
222 } else {
223 branch_loc = _patches[_patch_index];
224 }
225 int branch_sect = CodeBuffer::locator_sect(branch_loc);
226 address branch = cb->locator_address(branch_loc);
227 if (branch_sect == CodeBuffer::SECT_CONSTS) {
228 // The thing to patch is a constant word.
229 *(address*)branch = target;
230 continue;
231 }
233 #ifdef ASSERT
234 // Cross-section branches only work if the
235 // intermediate section boundaries are frozen.
236 if (target_sect != branch_sect) {
237 for (int n = MIN2(target_sect, branch_sect),
238 nlimit = (target_sect + branch_sect) - n;
239 n < nlimit; n++) {
240 CodeSection* cs = cb->code_section(n);
241 assert(cs->is_frozen(), "cross-section branch needs stable offsets");
242 }
243 }
244 #endif //ASSERT
246 // Push the target offset into the branch instruction.
247 masm->pd_patch_instruction(branch, target);
248 }
249 }
251 struct DelayedConstant {
252 typedef void (*value_fn_t)();
253 BasicType type;
254 intptr_t value;
255 value_fn_t value_fn;
256 // This limit of 20 is generous for initial uses.
257 // The limit needs to be large enough to store the field offsets
258 // into classes which do not have statically fixed layouts.
259 // (Initial use is for method handle object offsets.)
260 // Look for uses of "delayed_value" in the source code
261 // and make sure this number is generous enough to handle all of them.
262 enum { DC_LIMIT = 20 };
263 static DelayedConstant delayed_constants[DC_LIMIT];
264 static DelayedConstant* add(BasicType type, value_fn_t value_fn);
265 bool match(BasicType t, value_fn_t cfn) {
266 return type == t && value_fn == cfn;
267 }
268 static void update_all();
269 };
271 DelayedConstant DelayedConstant::delayed_constants[DC_LIMIT];
272 // Default C structure initialization rules have the following effect here:
273 // = { { (BasicType)0, (intptr_t)NULL }, ... };
275 DelayedConstant* DelayedConstant::add(BasicType type,
276 DelayedConstant::value_fn_t cfn) {
277 for (int i = 0; i < DC_LIMIT; i++) {
278 DelayedConstant* dcon = &delayed_constants[i];
279 if (dcon->match(type, cfn))
280 return dcon;
281 if (dcon->value_fn == NULL) {
282 // (cmpxchg not because this is multi-threaded but because I'm paranoid)
283 if (Atomic::cmpxchg_ptr(CAST_FROM_FN_PTR(void*, cfn), &dcon->value_fn, NULL) == NULL) {
284 dcon->type = type;
285 return dcon;
286 }
287 }
288 }
289 // If this assert is hit (in pre-integration testing!) then re-evaluate
290 // the comment on the definition of DC_LIMIT.
291 guarantee(false, "too many delayed constants");
292 return NULL;
293 }
295 void DelayedConstant::update_all() {
296 for (int i = 0; i < DC_LIMIT; i++) {
297 DelayedConstant* dcon = &delayed_constants[i];
298 if (dcon->value_fn != NULL && dcon->value == 0) {
299 typedef int (*int_fn_t)();
300 typedef address (*address_fn_t)();
301 switch (dcon->type) {
302 case T_INT: dcon->value = (intptr_t) ((int_fn_t) dcon->value_fn)(); break;
303 case T_ADDRESS: dcon->value = (intptr_t) ((address_fn_t)dcon->value_fn)(); break;
304 }
305 }
306 }
307 }
309 RegisterOrConstant AbstractAssembler::delayed_value(int(*value_fn)(), Register tmp, int offset) {
310 intptr_t val = (intptr_t) (*value_fn)();
311 if (val != 0) return val + offset;
312 return delayed_value_impl(delayed_value_addr(value_fn), tmp, offset);
313 }
314 RegisterOrConstant AbstractAssembler::delayed_value(address(*value_fn)(), Register tmp, int offset) {
315 intptr_t val = (intptr_t) (*value_fn)();
316 if (val != 0) return val + offset;
317 return delayed_value_impl(delayed_value_addr(value_fn), tmp, offset);
318 }
319 intptr_t* AbstractAssembler::delayed_value_addr(int(*value_fn)()) {
320 DelayedConstant* dcon = DelayedConstant::add(T_INT, (DelayedConstant::value_fn_t) value_fn);
321 return &dcon->value;
322 }
323 intptr_t* AbstractAssembler::delayed_value_addr(address(*value_fn)()) {
324 DelayedConstant* dcon = DelayedConstant::add(T_ADDRESS, (DelayedConstant::value_fn_t) value_fn);
325 return &dcon->value;
326 }
327 void AbstractAssembler::update_delayed_values() {
328 DelayedConstant::update_all();
329 }
334 void AbstractAssembler::block_comment(const char* comment) {
335 if (sect() == CodeBuffer::SECT_INSTS) {
336 code_section()->outer()->block_comment(offset(), comment);
337 }
338 }
340 bool MacroAssembler::needs_explicit_null_check(intptr_t offset) {
341 // Exception handler checks the nmethod's implicit null checks table
342 // only when this method returns false.
343 #ifdef _LP64
344 if (UseCompressedOops && Universe::narrow_oop_base() != NULL) {
345 assert (Universe::heap() != NULL, "java heap should be initialized");
346 // The first page after heap_base is unmapped and
347 // the 'offset' is equal to [heap_base + offset] for
348 // narrow oop implicit null checks.
349 uintptr_t base = (uintptr_t)Universe::narrow_oop_base();
350 if ((uintptr_t)offset >= base) {
351 // Normalize offset for the next check.
352 offset = (intptr_t)(pointer_delta((void*)offset, (void*)base, 1));
353 }
354 }
355 #endif
356 return offset < 0 || os::vm_page_size() <= offset;
357 }
359 #ifndef PRODUCT
360 void Label::print_instructions(MacroAssembler* masm) const {
361 CodeBuffer* cb = masm->code();
362 for (int i = 0; i < _patch_index; ++i) {
363 int branch_loc;
364 if (i >= PatchCacheSize) {
365 branch_loc = _patch_overflow->at(i - PatchCacheSize);
366 } else {
367 branch_loc = _patches[i];
368 }
369 int branch_pos = CodeBuffer::locator_pos(branch_loc);
370 int branch_sect = CodeBuffer::locator_sect(branch_loc);
371 address branch = cb->locator_address(branch_loc);
372 tty->print_cr("unbound label");
373 tty->print("@ %d|%d ", branch_pos, branch_sect);
374 if (branch_sect == CodeBuffer::SECT_CONSTS) {
375 tty->print_cr(PTR_FORMAT, *(address*)branch);
376 continue;
377 }
378 masm->pd_print_patched_instruction(branch);
379 tty->cr();
380 }
381 }
382 #endif // ndef PRODUCT