1 /*
   2  * Copyright (c) 1999, 2015, 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 "c1/c1_MacroAssembler.hpp"
  27 #include "c1/c1_Runtime1.hpp"
  28 #include "classfile/systemDictionary.hpp"
  29 #include "gc/shared/collectedHeap.hpp"
  30 #include "interpreter/interpreter.hpp"
  31 #include "oops/arrayOop.hpp"
  32 #include "oops/markOop.hpp"
  33 #include "runtime/basicLock.hpp"
  34 #include "runtime/biasedLocking.hpp"
  35 #include "runtime/os.hpp"
  36 #include "runtime/sharedRuntime.hpp"
  37 #include "runtime/stubRoutines.hpp"
  38 
  39 int C1_MacroAssembler::lock_object(Register hdr, Register obj, Register disp_hdr, Register scratch, Label& slow_case) {
  40   const int aligned_mask = BytesPerWord -1;
  41   const int hdr_offset = oopDesc::mark_offset_in_bytes();
  42   assert(hdr == rax, "hdr must be rax, for the cmpxchg instruction");
  43   assert(hdr != obj && hdr != disp_hdr && obj != disp_hdr, "registers must be different");
  44   Label done;
  45   int null_check_offset = -1;
  46 
  47   verify_oop(obj);
  48 
  49   // save object being locked into the BasicObjectLock
  50   movptr(Address(disp_hdr, BasicObjectLock::obj_offset_in_bytes()), obj);
  51 
  52   if (UseBiasedLocking) {
  53     assert(scratch != noreg, "should have scratch register at this point");
  54     null_check_offset = biased_locking_enter(disp_hdr, obj, hdr, scratch, false, done, &slow_case);
  55   } else {
  56     null_check_offset = offset();
  57   }
  58 
  59   // Load object header
  60   movptr(hdr, Address(obj, hdr_offset));
  61   // and mark it as unlocked
  62   orptr(hdr, markOopDesc::unlocked_value);
  63   // save unlocked object header into the displaced header location on the stack
  64   movptr(Address(disp_hdr, 0), hdr);
  65   // test if object header is still the same (i.e. unlocked), and if so, store the
  66   // displaced header address in the object header - if it is not the same, get the
  67   // object header instead
  68   if (os::is_MP()) MacroAssembler::lock(); // must be immediately before cmpxchg!
  69   cmpxchgptr(disp_hdr, Address(obj, hdr_offset));
  70   // if the object header was the same, we're done
  71   if (PrintBiasedLockingStatistics) {
  72     cond_inc32(Assembler::equal,
  73                ExternalAddress((address)BiasedLocking::fast_path_entry_count_addr()));
  74   }
  75   jcc(Assembler::equal, done);
  76   // if the object header was not the same, it is now in the hdr register
  77   // => test if it is a stack pointer into the same stack (recursive locking), i.e.:
  78   //
  79   // 1) (hdr & aligned_mask) == 0
  80   // 2) rsp <= hdr
  81   // 3) hdr <= rsp + page_size
  82   //
  83   // these 3 tests can be done by evaluating the following expression:
  84   //
  85   // (hdr - rsp) & (aligned_mask - page_size)
  86   //
  87   // assuming both the stack pointer and page_size have their least
  88   // significant 2 bits cleared and page_size is a power of 2
  89   subptr(hdr, rsp);
  90   andptr(hdr, aligned_mask - os::vm_page_size());
  91   // for recursive locking, the result is zero => save it in the displaced header
  92   // location (NULL in the displaced hdr location indicates recursive locking)
  93   movptr(Address(disp_hdr, 0), hdr);
  94   // otherwise we don't care about the result and handle locking via runtime call
  95   jcc(Assembler::notZero, slow_case);
  96   // done
  97   bind(done);
  98   return null_check_offset;
  99 }
 100 
 101 
 102 void C1_MacroAssembler::unlock_object(Register hdr, Register obj, Register disp_hdr, Label& slow_case) {
 103   const int aligned_mask = BytesPerWord -1;
 104   const int hdr_offset = oopDesc::mark_offset_in_bytes();
 105   assert(disp_hdr == rax, "disp_hdr must be rax, for the cmpxchg instruction");
 106   assert(hdr != obj && hdr != disp_hdr && obj != disp_hdr, "registers must be different");
 107   Label done;
 108 
 109   if (UseBiasedLocking) {
 110     // load object
 111     movptr(obj, Address(disp_hdr, BasicObjectLock::obj_offset_in_bytes()));
 112     biased_locking_exit(obj, hdr, done);
 113   }
 114 
 115   // load displaced header
 116   movptr(hdr, Address(disp_hdr, 0));
 117   // if the loaded hdr is NULL we had recursive locking
 118   testptr(hdr, hdr);
 119   // if we had recursive locking, we are done
 120   jcc(Assembler::zero, done);
 121   if (!UseBiasedLocking) {
 122     // load object
 123     movptr(obj, Address(disp_hdr, BasicObjectLock::obj_offset_in_bytes()));
 124   }
 125   verify_oop(obj);
 126   // test if object header is pointing to the displaced header, and if so, restore
 127   // the displaced header in the object - if the object header is not pointing to
 128   // the displaced header, get the object header instead
 129   if (os::is_MP()) MacroAssembler::lock(); // must be immediately before cmpxchg!
 130   cmpxchgptr(hdr, Address(obj, hdr_offset));
 131   // if the object header was not pointing to the displaced header,
 132   // we do unlocking via runtime call
 133   jcc(Assembler::notEqual, slow_case);
 134   // done
 135   bind(done);
 136 }
 137 
 138 
 139 // Defines obj, preserves var_size_in_bytes
 140 void C1_MacroAssembler::try_allocate(Register obj, Register var_size_in_bytes, int con_size_in_bytes, Register t1, Register t2, Label& slow_case) {
 141   if (UseTLAB) {
 142     tlab_allocate(obj, var_size_in_bytes, con_size_in_bytes, t1, t2, slow_case);
 143   } else {
 144     eden_allocate(obj, var_size_in_bytes, con_size_in_bytes, t1, slow_case);
 145     incr_allocated_bytes(noreg, var_size_in_bytes, con_size_in_bytes, t1);
 146   }
 147 }
 148 
 149 
 150 void C1_MacroAssembler::initialize_header(Register obj, Register klass, Register len, Register t1, Register t2) {
 151   assert_different_registers(obj, klass, len);
 152   if (UseBiasedLocking && !len->is_valid()) {
 153     assert_different_registers(obj, klass, len, t1, t2);
 154     movptr(t1, Address(klass, Klass::prototype_header_offset()));
 155     movptr(Address(obj, oopDesc::mark_offset_in_bytes()), t1);
 156   } else {
 157     // This assumes that all prototype bits fit in an int32_t
 158     movptr(Address(obj, oopDesc::mark_offset_in_bytes ()), (int32_t)(intptr_t)markOopDesc::prototype());
 159   }
 160 #ifdef _LP64
 161   if (UseCompressedClassPointers) { // Take care not to kill klass
 162     movptr(t1, klass);
 163     encode_klass_not_null(t1);
 164     movl(Address(obj, oopDesc::klass_offset_in_bytes()), t1);
 165   } else
 166 #endif
 167   {
 168     movptr(Address(obj, oopDesc::klass_offset_in_bytes()), klass);
 169   }
 170 
 171   if (len->is_valid()) {
 172     movl(Address(obj, arrayOopDesc::length_offset_in_bytes()), len);
 173   }
 174 #ifdef _LP64
 175   else if (UseCompressedClassPointers) {
 176     xorptr(t1, t1);
 177     store_klass_gap(obj, t1);
 178   }
 179 #endif
 180 }
 181 
 182 
 183 // preserves obj, destroys len_in_bytes
 184 void C1_MacroAssembler::initialize_body(Register obj, Register len_in_bytes, int hdr_size_in_bytes, Register t1) {
 185   assert(hdr_size_in_bytes >= 0, "header size must be positive or 0");
 186   Label done;
 187 
 188   // len_in_bytes is positive and ptr sized
 189   subptr(len_in_bytes, hdr_size_in_bytes);
 190   jcc(Assembler::zero, done);
 191   zero_memory(obj, len_in_bytes, hdr_size_in_bytes, t1);
 192   bind(done);
 193 }
 194 
 195 
 196 void C1_MacroAssembler::allocate_object(Register obj, Register t1, Register t2, int header_size, int object_size, Register klass, Label& slow_case) {
 197   assert(obj == rax, "obj must be in rax, for cmpxchg");
 198   assert_different_registers(obj, t1, t2); // XXX really?
 199   assert(header_size >= 0 && object_size >= header_size, "illegal sizes");
 200 
 201   try_allocate(obj, noreg, object_size * BytesPerWord, t1, t2, slow_case);
 202 
 203   initialize_object(obj, klass, noreg, object_size * HeapWordSize, t1, t2, UseTLAB);
 204 }
 205 
 206 void C1_MacroAssembler::initialize_object(Register obj, Register klass, Register var_size_in_bytes, int con_size_in_bytes, Register t1, Register t2, bool is_tlab_allocated) {
 207   assert((con_size_in_bytes & MinObjAlignmentInBytesMask) == 0,
 208          "con_size_in_bytes is not multiple of alignment");
 209   const int hdr_size_in_bytes = instanceOopDesc::header_size() * HeapWordSize;
 210 
 211   initialize_header(obj, klass, noreg, t1, t2);
 212 
 213   if (!(UseTLAB && ZeroTLAB && is_tlab_allocated)) {
 214     // clear rest of allocated space
 215     const Register t1_zero = t1;
 216     const Register index = t2;
 217     const int threshold = 6 * BytesPerWord;   // approximate break even point for code size (see comments below)
 218     if (var_size_in_bytes != noreg) {
 219       mov(index, var_size_in_bytes);
 220       initialize_body(obj, index, hdr_size_in_bytes, t1_zero);
 221     } else if (con_size_in_bytes <= threshold) {
 222       // use explicit null stores
 223       // code size = 2 + 3*n bytes (n = number of fields to clear)
 224       xorptr(t1_zero, t1_zero); // use t1_zero reg to clear memory (shorter code)
 225       for (int i = hdr_size_in_bytes; i < con_size_in_bytes; i += BytesPerWord)
 226         movptr(Address(obj, i), t1_zero);
 227     } else if (con_size_in_bytes > hdr_size_in_bytes) {
 228       // use loop to null out the fields
 229       // code size = 16 bytes for even n (n = number of fields to clear)
 230       // initialize last object field first if odd number of fields
 231       xorptr(t1_zero, t1_zero); // use t1_zero reg to clear memory (shorter code)
 232       movptr(index, (con_size_in_bytes - hdr_size_in_bytes) >> 3);
 233       // initialize last object field if constant size is odd
 234       if (((con_size_in_bytes - hdr_size_in_bytes) & 4) != 0)
 235         movptr(Address(obj, con_size_in_bytes - (1*BytesPerWord)), t1_zero);
 236       // initialize remaining object fields: rdx is a multiple of 2
 237       { Label loop;
 238         bind(loop);
 239         movptr(Address(obj, index, Address::times_8, hdr_size_in_bytes - (1*BytesPerWord)),
 240                t1_zero);
 241         NOT_LP64(movptr(Address(obj, index, Address::times_8, hdr_size_in_bytes - (2*BytesPerWord)),
 242                t1_zero);)
 243         decrement(index);
 244         jcc(Assembler::notZero, loop);
 245       }
 246     }
 247   }
 248 
 249   if (CURRENT_ENV->dtrace_alloc_probes()) {
 250     assert(obj == rax, "must be");
 251     call(RuntimeAddress(Runtime1::entry_for(Runtime1::dtrace_object_alloc_id)));
 252   }
 253 
 254   verify_oop(obj);
 255 }
 256 
 257 void C1_MacroAssembler::allocate_array(Register obj, Register len, Register t1, Register t2, int header_size, Address::ScaleFactor f, Register klass, Label& slow_case) {
 258   assert(obj == rax, "obj must be in rax, for cmpxchg");
 259   assert_different_registers(obj, len, t1, t2, klass);
 260 
 261   // determine alignment mask
 262   assert(!(BytesPerWord & 1), "must be a multiple of 2 for masking code to work");
 263 
 264   // check for negative or excessive length
 265   cmpptr(len, (int32_t)max_array_allocation_length);
 266   jcc(Assembler::above, slow_case);
 267 
 268   const Register arr_size = t2; // okay to be the same
 269   // align object end
 270   movptr(arr_size, (int32_t)header_size * BytesPerWord + MinObjAlignmentInBytesMask);
 271   lea(arr_size, Address(arr_size, len, f));
 272   andptr(arr_size, ~MinObjAlignmentInBytesMask);
 273 
 274   try_allocate(obj, arr_size, 0, t1, t2, slow_case);
 275 
 276   initialize_header(obj, klass, len, t1, t2);
 277 
 278   // clear rest of allocated space
 279   const Register len_zero = len;
 280   initialize_body(obj, arr_size, header_size * BytesPerWord, len_zero);
 281 
 282   if (CURRENT_ENV->dtrace_alloc_probes()) {
 283     assert(obj == rax, "must be");
 284     call(RuntimeAddress(Runtime1::entry_for(Runtime1::dtrace_object_alloc_id)));
 285   }
 286 
 287   verify_oop(obj);
 288 }
 289 
 290 
 291 
 292 void C1_MacroAssembler::inline_cache_check(Register receiver, Register iCache) {
 293   verify_oop(receiver);
 294   // explicit NULL check not needed since load from [klass_offset] causes a trap
 295   // check against inline cache
 296   assert(!MacroAssembler::needs_explicit_null_check(oopDesc::klass_offset_in_bytes()), "must add explicit null check");
 297   int start_offset = offset();
 298 
 299   if (UseCompressedClassPointers) {
 300     load_klass(rscratch1, receiver);
 301     cmpptr(rscratch1, iCache);
 302   } else {
 303     cmpptr(iCache, Address(receiver, oopDesc::klass_offset_in_bytes()));
 304   }
 305   // if icache check fails, then jump to runtime routine
 306   // Note: RECEIVER must still contain the receiver!
 307   jump_cc(Assembler::notEqual,
 308           RuntimeAddress(SharedRuntime::get_ic_miss_stub()));
 309   const int ic_cmp_size = LP64_ONLY(10) NOT_LP64(9);
 310   assert(UseCompressedClassPointers || offset() - start_offset == ic_cmp_size, "check alignment in emit_method_entry");
 311 }
 312 
 313 
 314 void C1_MacroAssembler::build_frame(int frame_size_in_bytes, int bang_size_in_bytes) {
 315   assert(bang_size_in_bytes >= frame_size_in_bytes, "stack bang size incorrect");
 316   // Make sure there is enough stack space for this method's activation.
 317   // Note that we do this before doing an enter(). This matches the
 318   // ordering of C2's stack overflow check / rsp decrement and allows
 319   // the SharedRuntime stack overflow handling to be consistent
 320   // between the two compilers.
 321   generate_stack_overflow_check(bang_size_in_bytes);
 322 
 323   push(rbp);
 324   if (PreserveFramePointer) {
 325     mov(rbp, rsp);
 326   }
 327 #ifdef TIERED
 328   // c2 leaves fpu stack dirty. Clean it on entry
 329   if (UseSSE < 2 ) {
 330     empty_FPU_stack();
 331   }
 332 #endif // TIERED
 333   decrement(rsp, frame_size_in_bytes); // does not emit code for frame_size == 0
 334 }
 335 
 336 
 337 void C1_MacroAssembler::remove_frame(int frame_size_in_bytes) {
 338   increment(rsp, frame_size_in_bytes);  // Does not emit code for frame_size == 0
 339   pop(rbp);
 340 }
 341 
 342 
 343 void C1_MacroAssembler::unverified_entry(Register receiver, Register ic_klass) {
 344   if (C1Breakpoint) int3();
 345   inline_cache_check(receiver, ic_klass);
 346 }
 347 
 348 
 349 void C1_MacroAssembler::verified_entry() {
 350   if (C1Breakpoint || VerifyFPU || !UseStackBanging) {
 351     // Verified Entry first instruction should be 5 bytes long for correct
 352     // patching by patch_verified_entry().
 353     //
 354     // C1Breakpoint and VerifyFPU have one byte first instruction.
 355     // Also first instruction will be one byte "push(rbp)" if stack banging
 356     // code is not generated (see build_frame() above).
 357     // For all these cases generate long instruction first.
 358     fat_nop();
 359   }
 360   if (C1Breakpoint)int3();
 361   // build frame
 362   verify_FPU(0, "method_entry");
 363 }
 364 
 365 
 366 #ifndef PRODUCT
 367 
 368 void C1_MacroAssembler::verify_stack_oop(int stack_offset) {
 369   if (!VerifyOops) return;
 370   verify_oop_addr(Address(rsp, stack_offset));
 371 }
 372 
 373 void C1_MacroAssembler::verify_not_null_oop(Register r) {
 374   if (!VerifyOops) return;
 375   Label not_null;
 376   testptr(r, r);
 377   jcc(Assembler::notZero, not_null);
 378   stop("non-null oop required");
 379   bind(not_null);
 380   verify_oop(r);
 381 }
 382 
 383 void C1_MacroAssembler::invalidate_registers(bool inv_rax, bool inv_rbx, bool inv_rcx, bool inv_rdx, bool inv_rsi, bool inv_rdi) {
 384 #ifdef ASSERT
 385   if (inv_rax) movptr(rax, 0xDEAD);
 386   if (inv_rbx) movptr(rbx, 0xDEAD);
 387   if (inv_rcx) movptr(rcx, 0xDEAD);
 388   if (inv_rdx) movptr(rdx, 0xDEAD);
 389   if (inv_rsi) movptr(rsi, 0xDEAD);
 390   if (inv_rdi) movptr(rdi, 0xDEAD);
 391 #endif
 392 }
 393 
 394 #endif // ifndef PRODUCT