assembler.cpp revision 1472:c18cbe5936b8
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 36AbstractAssembler::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 51void 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 62address 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 77void 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 84address 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 105void AbstractAssembler::end_a_const() { 106 assert(_code_section == code()->consts(), "not in consts?"); 107 sync(); 108 set_code_section(code()->insts()); 109} 110 111 112void AbstractAssembler::flush() { 113 sync(); 114 ICache::invalidate_range(addr_at(0), offset()); 115} 116 117 118void AbstractAssembler::a_byte(int x) { 119 emit_byte(x); 120} 121 122 123void 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 136void 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 148void 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 158void 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 191void 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 204void 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 243struct 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 263DelayedConstant DelayedConstant::delayed_constants[DC_LIMIT]; 264// Default C structure initialization rules have the following effect here: 265// = { { (BasicType)0, (intptr_t)NULL }, ... }; 266 267DelayedConstant* 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 287void 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 301intptr_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} 305intptr_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} 309void AbstractAssembler::update_delayed_values() { 310 DelayedConstant::update_all(); 311} 312 313 314 315 316void AbstractAssembler::block_comment(const char* comment) { 317 if (sect() == CodeBuffer::SECT_INSTS) { 318 code_section()->outer()->block_comment(offset(), comment); 319 } 320} 321 322bool 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 342void 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 365