assembler.cpp revision 605:98cb887364d3
1/* 2 * Copyright 1997-2008 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, 20 * CA 95054 USA or visit www.sun.com if you need additional information or 21 * have any 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_memory1(0, "CodeCache: no room for %s", code->name()); 47 } 48} 49 50void AbstractAssembler::set_code_section(CodeSection* cs) { 51 assert(cs->outer() == code_section()->outer(), "sanity"); 52 assert(cs->is_allocated(), "need to pre-allocate this section"); 53 cs->clear_mark(); // new assembly into this section kills old mark 54 _code_section = cs; 55 _code_begin = cs->start(); 56 _code_limit = cs->limit(); 57 _code_pos = cs->end(); 58} 59 60// Inform CodeBuffer that incoming code and relocation will be for stubs 61address AbstractAssembler::start_a_stub(int required_space) { 62 CodeBuffer* cb = code(); 63 CodeSection* cs = cb->stubs(); 64 assert(_code_section == cb->insts(), "not in insts?"); 65 sync(); 66 if (cs->maybe_expand_to_ensure_remaining(required_space) 67 && cb->blob() == NULL) { 68 return NULL; 69 } 70 set_code_section(cs); 71 return pc(); 72} 73 74// Inform CodeBuffer that incoming code and relocation will be code 75// Should not be called if start_a_stub() returned NULL 76void AbstractAssembler::end_a_stub() { 77 assert(_code_section == code()->stubs(), "not in stubs?"); 78 sync(); 79 set_code_section(code()->insts()); 80} 81 82// Inform CodeBuffer that incoming code and relocation will be for stubs 83address AbstractAssembler::start_a_const(int required_space, int required_align) { 84 CodeBuffer* cb = code(); 85 CodeSection* cs = cb->consts(); 86 assert(_code_section == cb->insts(), "not in insts?"); 87 sync(); 88 address end = cs->end(); 89 int pad = -(intptr_t)end & (required_align-1); 90 if (cs->maybe_expand_to_ensure_remaining(pad + required_space)) { 91 if (cb->blob() == NULL) return NULL; 92 end = cs->end(); // refresh pointer 93 } 94 if (pad > 0) { 95 while (--pad >= 0) { *end++ = 0; } 96 cs->set_end(end); 97 } 98 set_code_section(cs); 99 return end; 100} 101 102// Inform CodeBuffer that incoming code and relocation will be code 103// Should not be called if start_a_const() returned NULL 104void AbstractAssembler::end_a_const() { 105 assert(_code_section == code()->consts(), "not in consts?"); 106 sync(); 107 set_code_section(code()->insts()); 108} 109 110 111void AbstractAssembler::flush() { 112 sync(); 113 ICache::invalidate_range(addr_at(0), offset()); 114} 115 116 117void AbstractAssembler::a_byte(int x) { 118 emit_byte(x); 119} 120 121 122void AbstractAssembler::a_long(jint x) { 123 emit_long(x); 124} 125 126// Labels refer to positions in the (to be) generated code. There are bound 127// and unbound 128// 129// Bound labels refer to known positions in the already generated code. 130// offset() is the position the label refers to. 131// 132// Unbound labels refer to unknown positions in the code to be generated; it 133// may contain a list of unresolved displacements that refer to it 134#ifndef PRODUCT 135void AbstractAssembler::print(Label& L) { 136 if (L.is_bound()) { 137 tty->print_cr("bound label to %d|%d", L.loc_pos(), L.loc_sect()); 138 } else if (L.is_unbound()) { 139 L.print_instructions((MacroAssembler*)this); 140 } else { 141 tty->print_cr("label in inconsistent state (loc = %d)", L.loc()); 142 } 143} 144#endif // PRODUCT 145 146 147void AbstractAssembler::bind(Label& L) { 148 if (L.is_bound()) { 149 // Assembler can bind a label more than once to the same place. 150 guarantee(L.loc() == locator(), "attempt to redefine label"); 151 return; 152 } 153 L.bind_loc(locator()); 154 L.patch_instructions((MacroAssembler*)this); 155} 156 157void AbstractAssembler::generate_stack_overflow_check( int frame_size_in_bytes) { 158 if (UseStackBanging) { 159 // Each code entry causes one stack bang n pages down the stack where n 160 // is configurable by StackBangPages. The setting depends on the maximum 161 // depth of VM call stack or native before going back into java code, 162 // since only java code can raise a stack overflow exception using the 163 // stack banging mechanism. The VM and native code does not detect stack 164 // overflow. 165 // The code in JavaCalls::call() checks that there is at least n pages 166 // available, so all entry code needs to do is bang once for the end of 167 // this shadow zone. 168 // The entry code may need to bang additional pages if the framesize 169 // is greater than a page. 170 171 const int page_size = os::vm_page_size(); 172 int bang_end = StackShadowPages*page_size; 173 174 // This is how far the previous frame's stack banging extended. 175 const int bang_end_safe = bang_end; 176 177 if (frame_size_in_bytes > page_size) { 178 bang_end += frame_size_in_bytes; 179 } 180 181 int bang_offset = bang_end_safe; 182 while (bang_offset <= bang_end) { 183 // Need at least one stack bang at end of shadow zone. 184 bang_stack_with_offset(bang_offset); 185 bang_offset += page_size; 186 } 187 } // end (UseStackBanging) 188} 189 190void Label::add_patch_at(CodeBuffer* cb, int branch_loc) { 191 assert(_loc == -1, "Label is unbound"); 192 if (_patch_index < PatchCacheSize) { 193 _patches[_patch_index] = branch_loc; 194 } else { 195 if (_patch_overflow == NULL) { 196 _patch_overflow = cb->create_patch_overflow(); 197 } 198 _patch_overflow->push(branch_loc); 199 } 200 ++_patch_index; 201} 202 203void Label::patch_instructions(MacroAssembler* masm) { 204 assert(is_bound(), "Label is bound"); 205 CodeBuffer* cb = masm->code(); 206 int target_sect = CodeBuffer::locator_sect(loc()); 207 address target = cb->locator_address(loc()); 208 while (_patch_index > 0) { 209 --_patch_index; 210 int branch_loc; 211 if (_patch_index >= PatchCacheSize) { 212 branch_loc = _patch_overflow->pop(); 213 } else { 214 branch_loc = _patches[_patch_index]; 215 } 216 int branch_sect = CodeBuffer::locator_sect(branch_loc); 217 address branch = cb->locator_address(branch_loc); 218 if (branch_sect == CodeBuffer::SECT_CONSTS) { 219 // The thing to patch is a constant word. 220 *(address*)branch = target; 221 continue; 222 } 223 224#ifdef ASSERT 225 // Cross-section branches only work if the 226 // intermediate section boundaries are frozen. 227 if (target_sect != branch_sect) { 228 for (int n = MIN2(target_sect, branch_sect), 229 nlimit = (target_sect + branch_sect) - n; 230 n < nlimit; n++) { 231 CodeSection* cs = cb->code_section(n); 232 assert(cs->is_frozen(), "cross-section branch needs stable offsets"); 233 } 234 } 235#endif //ASSERT 236 237 // Push the target offset into the branch instruction. 238 masm->pd_patch_instruction(branch, target); 239 } 240} 241 242 243void AbstractAssembler::block_comment(const char* comment) { 244 if (sect() == CodeBuffer::SECT_INSTS) { 245 code_section()->outer()->block_comment(offset(), comment); 246 } 247} 248 249bool MacroAssembler::needs_explicit_null_check(intptr_t offset) { 250 // Exception handler checks the nmethod's implicit null checks table 251 // only when this method returns false. 252 if (UseCompressedOops) { 253 // The first page after heap_base is unmapped and 254 // the 'offset' is equal to [heap_base + offset] for 255 // narrow oop implicit null checks. 256 uintptr_t heap_base = (uintptr_t)Universe::heap_base(); 257 if ((uintptr_t)offset >= heap_base) { 258 // Normalize offset for the next check. 259 offset = (intptr_t)(pointer_delta((void*)offset, (void*)heap_base, 1)); 260 } 261 } 262 return offset < 0 || os::vm_page_size() <= offset; 263} 264 265#ifndef PRODUCT 266void Label::print_instructions(MacroAssembler* masm) const { 267 CodeBuffer* cb = masm->code(); 268 for (int i = 0; i < _patch_index; ++i) { 269 int branch_loc; 270 if (i >= PatchCacheSize) { 271 branch_loc = _patch_overflow->at(i - PatchCacheSize); 272 } else { 273 branch_loc = _patches[i]; 274 } 275 int branch_pos = CodeBuffer::locator_pos(branch_loc); 276 int branch_sect = CodeBuffer::locator_sect(branch_loc); 277 address branch = cb->locator_address(branch_loc); 278 tty->print_cr("unbound label"); 279 tty->print("@ %d|%d ", branch_pos, branch_sect); 280 if (branch_sect == CodeBuffer::SECT_CONSTS) { 281 tty->print_cr(PTR_FORMAT, *(address*)branch); 282 continue; 283 } 284 masm->pd_print_patched_instruction(branch); 285 tty->cr(); 286 } 287} 288#endif // ndef PRODUCT 289