assembler.cpp revision 6646:b596a1063e90
1179237Sjb/* 2179237Sjb * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved. 3179237Sjb * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4179237Sjb * 5179237Sjb * This code is free software; you can redistribute it and/or modify it 6179237Sjb * under the terms of the GNU General Public License version 2 only, as 7179237Sjb * published by the Free Software Foundation. 8179237Sjb * 9179237Sjb * This code is distributed in the hope that it will be useful, but WITHOUT 10179237Sjb * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11179237Sjb * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12179237Sjb * version 2 for more details (a copy is included in the LICENSE file that 13179237Sjb * accompanied this code). 14179237Sjb * 15179237Sjb * You should have received a copy of the GNU General Public License version 16179237Sjb * 2 along with this work; if not, write to the Free Software Foundation, 17179237Sjb * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18179237Sjb * 19179237Sjb * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20179237Sjb * or visit www.oracle.com if you need additional information or have any 21179237Sjb * questions. 22179237Sjb * 23179237Sjb */ 24179237Sjb 25179237Sjb#include "precompiled.hpp" 26179237Sjb#include "asm/macroAssembler.hpp" 27179237Sjb#include "asm/macroAssembler.inline.hpp" 28179237Sjb#include "asm/codeBuffer.hpp" 29179237Sjb#include "runtime/atomic.inline.hpp" 30236567Sgnn#include "runtime/icache.hpp" 31236567Sgnn#include "runtime/os.hpp" 32236567Sgnn 33236567Sgnn 34179237Sjb// Implementation of AbstractAssembler 35179237Sjb// 36179237Sjb// The AbstractAssembler is generating code into a CodeBuffer. To make code generation faster, 37222813Sattilio// the assembler keeps a copy of the code buffers boundaries & modifies them when 38179237Sjb// emitting bytes rather than using the code buffers accessor functions all the time. 39179237Sjb// The code buffer is updated via set_code_end(...) after emitting a whole instruction. 40179237Sjb 41179237SjbAbstractAssembler::AbstractAssembler(CodeBuffer* code) { 42179237Sjb if (code == NULL) return; 43179237Sjb CodeSection* cs = code->insts(); 44179237Sjb cs->clear_mark(); // new assembler kills old mark 45179237Sjb if (cs->start() == NULL) { 46179237Sjb vm_exit_out_of_memory(0, OOM_MMAP_ERROR, err_msg("CodeCache: no room for %s", 47179237Sjb code->name())); 48179237Sjb } 49179237Sjb _code_section = cs; 50179237Sjb _oop_recorder= code->oop_recorder(); 51179237Sjb DEBUG_ONLY( _short_branch_delta = 0; ) 52238537Sgnn} 53238537Sgnn 54179237Sjbvoid AbstractAssembler::set_code_section(CodeSection* cs) { 55179237Sjb assert(cs->outer() == code_section()->outer(), "sanity"); 56179237Sjb assert(cs->is_allocated(), "need to pre-allocate this section"); 57179237Sjb cs->clear_mark(); // new assembly into this section kills old mark 58179237Sjb _code_section = cs; 59179237Sjb} 60179237Sjb 61179237Sjb// Inform CodeBuffer that incoming code and relocation will be for stubs 62179237Sjbaddress AbstractAssembler::start_a_stub(int required_space) { 63179237Sjb CodeBuffer* cb = code(); 64179237Sjb CodeSection* cs = cb->stubs(); 65179237Sjb assert(_code_section == cb->insts(), "not in insts?"); 66179237Sjb if (cs->maybe_expand_to_ensure_remaining(required_space) 67179237Sjb && cb->blob() == NULL) { 68179237Sjb return NULL; 69179237Sjb } 70179237Sjb set_code_section(cs); 71179237Sjb return pc(); 72179237Sjb} 73179237Sjb 74179237Sjb// Inform CodeBuffer that incoming code and relocation will be code 75179237Sjb// Should not be called if start_a_stub() returned NULL 76179237Sjbvoid AbstractAssembler::end_a_stub() { 77179237Sjb assert(_code_section == code()->stubs(), "not in stubs?"); 78179237Sjb set_code_section(code()->insts()); 79179237Sjb} 80179237Sjb 81179237Sjb// Inform CodeBuffer that incoming code and relocation will be for stubs 82179237Sjbaddress AbstractAssembler::start_a_const(int required_space, int required_align) { 83179237Sjb CodeBuffer* cb = code(); 84179237Sjb CodeSection* cs = cb->consts(); 85179237Sjb assert(_code_section == cb->insts() || _code_section == cb->stubs(), "not in insts/stubs?"); 86179237Sjb address end = cs->end(); 87179237Sjb int pad = -(intptr_t)end & (required_align-1); 88179237Sjb if (cs->maybe_expand_to_ensure_remaining(pad + required_space)) { 89179237Sjb if (cb->blob() == NULL) return NULL; 90179237Sjb end = cs->end(); // refresh pointer 91179237Sjb } 92179237Sjb if (pad > 0) { 93179237Sjb while (--pad >= 0) { *end++ = 0; } 94179237Sjb cs->set_end(end); 95179237Sjb } 96179237Sjb set_code_section(cs); 97179237Sjb return end; 98179237Sjb} 99179237Sjb 100179237Sjb// Inform CodeBuffer that incoming code and relocation will be code 101179237Sjb// in section cs (insts or stubs). 102179237Sjbvoid AbstractAssembler::end_a_const(CodeSection* cs) { 103179237Sjb assert(_code_section == code()->consts(), "not in consts?"); 104179237Sjb set_code_section(cs); 105179237Sjb} 106179237Sjb 107179237Sjbvoid AbstractAssembler::flush() { 108179237Sjb ICache::invalidate_range(addr_at(0), offset()); 109179237Sjb} 110179237Sjb 111179237Sjbvoid AbstractAssembler::bind(Label& L) { 112179237Sjb if (L.is_bound()) { 113179237Sjb // Assembler can bind a label more than once to the same place. 114179237Sjb guarantee(L.loc() == locator(), "attempt to redefine label"); 115179237Sjb return; 116179237Sjb } 117179237Sjb L.bind_loc(locator()); 118179237Sjb L.patch_instructions((MacroAssembler*)this); 119179237Sjb} 120179237Sjb 121179237Sjbvoid AbstractAssembler::generate_stack_overflow_check(int frame_size_in_bytes) { 122179237Sjb if (UseStackBanging) { 123222813Sattilio // Each code entry causes one stack bang n pages down the stack where n 124179237Sjb // is configurable by StackShadowPages. The setting depends on the maximum 125179237Sjb // depth of VM call stack or native before going back into java code, 126179237Sjb // since only java code can raise a stack overflow exception using the 127179237Sjb // stack banging mechanism. The VM and native code does not detect stack 128222813Sattilio // overflow. 129179237Sjb // The code in JavaCalls::call() checks that there is at least n pages 130216251Savg // available, so all entry code needs to do is bang once for the end of 131216251Savg // this shadow zone. 132179237Sjb // The entry code may need to bang additional pages if the framesize 133179237Sjb // is greater than a page. 134179237Sjb 135179237Sjb const int page_size = os::vm_page_size(); 136179237Sjb int bang_end = StackShadowPages * page_size; 137179237Sjb 138179237Sjb // This is how far the previous frame's stack banging extended. 139179237Sjb const int bang_end_safe = bang_end; 140179237Sjb 141179237Sjb if (frame_size_in_bytes > page_size) { 142179237Sjb bang_end += frame_size_in_bytes; 143179237Sjb } 144179237Sjb 145179237Sjb int bang_offset = bang_end_safe; 146179237Sjb while (bang_offset <= bang_end) { 147179237Sjb // Need at least one stack bang at end of shadow zone. 148179237Sjb bang_stack_with_offset(bang_offset); 149179237Sjb bang_offset += page_size; 150179237Sjb } 151179237Sjb } // end (UseStackBanging) 152179237Sjb} 153179237Sjb 154179237Sjbvoid Label::add_patch_at(CodeBuffer* cb, int branch_loc) { 155179237Sjb assert(_loc == -1, "Label is unbound"); 156179237Sjb if (_patch_index < PatchCacheSize) { 157179237Sjb _patches[_patch_index] = branch_loc; 158179237Sjb } else { 159179237Sjb if (_patch_overflow == NULL) { 160179237Sjb _patch_overflow = cb->create_patch_overflow(); 161179237Sjb } 162179237Sjb _patch_overflow->push(branch_loc); 163179237Sjb } 164179237Sjb ++_patch_index; 165179237Sjb} 166179237Sjb 167179237Sjbvoid Label::patch_instructions(MacroAssembler* masm) { 168179237Sjb assert(is_bound(), "Label is bound"); 169179237Sjb CodeBuffer* cb = masm->code(); 170179237Sjb int target_sect = CodeBuffer::locator_sect(loc()); 171179237Sjb address target = cb->locator_address(loc()); 172179237Sjb while (_patch_index > 0) { 173179237Sjb --_patch_index; 174179237Sjb int branch_loc; 175179237Sjb if (_patch_index >= PatchCacheSize) { 176179237Sjb branch_loc = _patch_overflow->pop(); 177179237Sjb } else { 178179237Sjb branch_loc = _patches[_patch_index]; 179179237Sjb } 180179237Sjb int branch_sect = CodeBuffer::locator_sect(branch_loc); 181179237Sjb address branch = cb->locator_address(branch_loc); 182179237Sjb if (branch_sect == CodeBuffer::SECT_CONSTS) { 183179237Sjb // The thing to patch is a constant word. 184179237Sjb *(address*)branch = target; 185179237Sjb continue; 186179237Sjb } 187179237Sjb 188179237Sjb#ifdef ASSERT 189179237Sjb // Cross-section branches only work if the 190179237Sjb // intermediate section boundaries are frozen. 191179237Sjb if (target_sect != branch_sect) { 192179237Sjb for (int n = MIN2(target_sect, branch_sect), 193179237Sjb nlimit = (target_sect + branch_sect) - n; 194179237Sjb n < nlimit; n++) { 195179237Sjb CodeSection* cs = cb->code_section(n); 196179237Sjb assert(cs->is_frozen(), "cross-section branch needs stable offsets"); 197179237Sjb } 198179237Sjb } 199179237Sjb#endif //ASSERT 200179237Sjb 201179237Sjb // Push the target offset into the branch instruction. 202179237Sjb masm->pd_patch_instruction(branch, target); 203179237Sjb } 204179237Sjb} 205179237Sjb 206179237Sjbstruct DelayedConstant { 207179237Sjb typedef void (*value_fn_t)(); 208179237Sjb BasicType type; 209179237Sjb intptr_t value; 210179237Sjb value_fn_t value_fn; 211179237Sjb // This limit of 20 is generous for initial uses. 212179237Sjb // The limit needs to be large enough to store the field offsets 213179237Sjb // into classes which do not have statically fixed layouts. 214179237Sjb // (Initial use is for method handle object offsets.) 215179237Sjb // Look for uses of "delayed_value" in the source code 216179237Sjb // and make sure this number is generous enough to handle all of them. 217179237Sjb enum { DC_LIMIT = 20 }; 218179237Sjb static DelayedConstant delayed_constants[DC_LIMIT]; 219179237Sjb static DelayedConstant* add(BasicType type, value_fn_t value_fn); 220179237Sjb bool match(BasicType t, value_fn_t cfn) { 221179237Sjb return type == t && value_fn == cfn; 222179237Sjb } 223179237Sjb static void update_all(); 224179237Sjb}; 225179237Sjb 226179237SjbDelayedConstant DelayedConstant::delayed_constants[DC_LIMIT]; 227179237Sjb// Default C structure initialization rules have the following effect here: 228179237Sjb// = { { (BasicType)0, (intptr_t)NULL }, ... }; 229179237Sjb 230179237SjbDelayedConstant* DelayedConstant::add(BasicType type, 231179237Sjb DelayedConstant::value_fn_t cfn) { 232179237Sjb for (int i = 0; i < DC_LIMIT; i++) { 233179237Sjb DelayedConstant* dcon = &delayed_constants[i]; 234179237Sjb if (dcon->match(type, cfn)) 235179237Sjb return dcon; 236179237Sjb if (dcon->value_fn == NULL) { 237179237Sjb // (cmpxchg not because this is multi-threaded but because I'm paranoid) 238179237Sjb if (Atomic::cmpxchg_ptr(CAST_FROM_FN_PTR(void*, cfn), &dcon->value_fn, NULL) == NULL) { 239179237Sjb dcon->type = type; 240179237Sjb return dcon; 241179237Sjb } 242179237Sjb } 243179237Sjb } 244179237Sjb // If this assert is hit (in pre-integration testing!) then re-evaluate 245179237Sjb // the comment on the definition of DC_LIMIT. 246179237Sjb guarantee(false, "too many delayed constants"); 247179237Sjb return NULL; 248179237Sjb} 249179237Sjb 250179237Sjbvoid DelayedConstant::update_all() { 251179237Sjb for (int i = 0; i < DC_LIMIT; i++) { 252179237Sjb DelayedConstant* dcon = &delayed_constants[i]; 253179237Sjb if (dcon->value_fn != NULL && dcon->value == 0) { 254179237Sjb typedef int (*int_fn_t)(); 255179237Sjb typedef address (*address_fn_t)(); 256179237Sjb switch (dcon->type) { 257179237Sjb case T_INT: dcon->value = (intptr_t) ((int_fn_t) dcon->value_fn)(); break; 258179237Sjb case T_ADDRESS: dcon->value = (intptr_t) ((address_fn_t)dcon->value_fn)(); break; 259179237Sjb } 260179237Sjb } 261179237Sjb } 262179237Sjb} 263179237Sjb 264179237SjbRegisterOrConstant AbstractAssembler::delayed_value(int(*value_fn)(), Register tmp, int offset) { 265179237Sjb intptr_t val = (intptr_t) (*value_fn)(); 266179237Sjb if (val != 0) return val + offset; 267179237Sjb return delayed_value_impl(delayed_value_addr(value_fn), tmp, offset); 268179237Sjb} 269179237SjbRegisterOrConstant AbstractAssembler::delayed_value(address(*value_fn)(), Register tmp, int offset) { 270179237Sjb intptr_t val = (intptr_t) (*value_fn)(); 271179237Sjb if (val != 0) return val + offset; 272179237Sjb return delayed_value_impl(delayed_value_addr(value_fn), tmp, offset); 273179237Sjb} 274179237Sjbintptr_t* AbstractAssembler::delayed_value_addr(int(*value_fn)()) { 275179237Sjb DelayedConstant* dcon = DelayedConstant::add(T_INT, (DelayedConstant::value_fn_t) value_fn); 276179237Sjb return &dcon->value; 277179237Sjb} 278179237Sjbintptr_t* AbstractAssembler::delayed_value_addr(address(*value_fn)()) { 279179237Sjb DelayedConstant* dcon = DelayedConstant::add(T_ADDRESS, (DelayedConstant::value_fn_t) value_fn); 280179237Sjb return &dcon->value; 281179237Sjb} 282179237Sjbvoid AbstractAssembler::update_delayed_values() { 283179237Sjb DelayedConstant::update_all(); 284179237Sjb} 285179237Sjb 286179237Sjbvoid AbstractAssembler::block_comment(const char* comment) { 287179237Sjb if (sect() == CodeBuffer::SECT_INSTS) { 288179237Sjb code_section()->outer()->block_comment(offset(), comment); 289179237Sjb } 290179237Sjb} 291179237Sjb 292179237Sjbconst char* AbstractAssembler::code_string(const char* str) { 293179237Sjb if (sect() == CodeBuffer::SECT_INSTS || sect() == CodeBuffer::SECT_STUBS) { 294179237Sjb return code_section()->outer()->code_string(str); 295179237Sjb } 296179237Sjb return NULL; 297179237Sjb} 298179237Sjb 299179237Sjbbool MacroAssembler::needs_explicit_null_check(intptr_t offset) { 300179237Sjb // Exception handler checks the nmethod's implicit null checks table 301179237Sjb // only when this method returns false. 302179237Sjb#ifdef _LP64 303179237Sjb if (UseCompressedOops && Universe::narrow_oop_base() != NULL) { 304179237Sjb assert (Universe::heap() != NULL, "java heap should be initialized"); 305179237Sjb // The first page after heap_base is unmapped and 306179237Sjb // the 'offset' is equal to [heap_base + offset] for 307236567Sgnn // narrow oop implicit null checks. 308236567Sgnn uintptr_t base = (uintptr_t)Universe::narrow_oop_base(); 309236567Sgnn if ((uintptr_t)offset >= base) { 310236567Sgnn // Normalize offset for the next check. 311236567Sgnn offset = (intptr_t)(pointer_delta((void*)offset, (void*)base, 1)); 312236567Sgnn } 313179237Sjb } 314236567Sgnn#endif 315236567Sgnn return offset < 0 || os::vm_page_size() <= offset; 316179237Sjb} 317179237Sjb