1 /*
  2  * Copyright (c) 1999, 2021, 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 "gc/shared/barrierSet.hpp"
 29 #include "gc/shared/barrierSetAssembler.hpp"
 30 #include "gc/shared/collectedHeap.hpp"
 31 #include "gc/shared/tlab_globals.hpp"
 32 #include "interpreter/interpreter.hpp"
 33 #include "oops/arrayOop.hpp"
 34 #include "oops/markWord.hpp"
 35 #include "runtime/basicLock.hpp"
 36 #include "runtime/biasedLocking.hpp"
 37 #include "runtime/os.hpp"
 38 #include "runtime/sharedRuntime.hpp"
 39 #include "runtime/stubRoutines.hpp"
 40 
 41 int C1_MacroAssembler::lock_object(Register hdr, Register obj, Register disp_hdr, Register scratch, Label& slow_case) {
 42   const Register rklass_decode_tmp = LP64_ONLY(rscratch1) NOT_LP64(noreg);
 43   const int aligned_mask = BytesPerWord -1;
 44   const int hdr_offset = oopDesc::mark_offset_in_bytes();
 45   assert(hdr == rax, "hdr must be rax, for the cmpxchg instruction");
 46   assert(hdr != obj && hdr != disp_hdr && obj != disp_hdr, "registers must be different");
 47   Label done;
 48   int null_check_offset = -1;
 49 
 50   verify_oop(obj);
 51 
 52   // save object being locked into the BasicObjectLock
 53   movptr(Address(disp_hdr, BasicObjectLock::obj_offset_in_bytes()), obj);
 54 
 55   null_check_offset = offset();
 56 
 57   if (DiagnoseSyncOnValueBasedClasses != 0) {
 58     load_klass(hdr, obj, rklass_decode_tmp);
 59     movl(hdr, Address(hdr, Klass::access_flags_offset()));
 60     testl(hdr, JVM_ACC_IS_VALUE_BASED_CLASS);
 61     jcc(Assembler::notZero, slow_case);
 62   }
 63 
 64   if (UseBiasedLocking) {
 65     assert(scratch != noreg, "should have scratch register at this point");
 66     biased_locking_enter(disp_hdr, obj, hdr, scratch, rklass_decode_tmp, false, done, &slow_case);
 67   }








 68 
 69   // Load object header
 70   movptr(hdr, Address(obj, hdr_offset));
 71   // and mark it as unlocked
 72   orptr(hdr, markWord::unlocked_value);
 73   // save unlocked object header into the displaced header location on the stack
 74   movptr(Address(disp_hdr, 0), hdr);
 75   // test if object header is still the same (i.e. unlocked), and if so, store the
 76   // displaced header address in the object header - if it is not the same, get the
 77   // object header instead
 78   MacroAssembler::lock(); // must be immediately before cmpxchg!
 79   cmpxchgptr(disp_hdr, Address(obj, hdr_offset));
 80   // if the object header was the same, we're done
 81   if (PrintBiasedLockingStatistics) {
 82     cond_inc32(Assembler::equal,
 83                ExternalAddress((address)BiasedLocking::fast_path_entry_count_addr()));





























 84   }
 85   jcc(Assembler::equal, done);
 86   // if the object header was not the same, it is now in the hdr register
 87   // => test if it is a stack pointer into the same stack (recursive locking), i.e.:
 88   //
 89   // 1) (hdr & aligned_mask) == 0
 90   // 2) rsp <= hdr
 91   // 3) hdr <= rsp + page_size
 92   //
 93   // these 3 tests can be done by evaluating the following expression:
 94   //
 95   // (hdr - rsp) & (aligned_mask - page_size)
 96   //
 97   // assuming both the stack pointer and page_size have their least
 98   // significant 2 bits cleared and page_size is a power of 2
 99   subptr(hdr, rsp);
100   andptr(hdr, aligned_mask - os::vm_page_size());
101   // for recursive locking, the result is zero => save it in the displaced header
102   // location (NULL in the displaced hdr location indicates recursive locking)
103   movptr(Address(disp_hdr, 0), hdr);
104   // otherwise we don't care about the result and handle locking via runtime call
105   jcc(Assembler::notZero, slow_case);
106   // done
107   bind(done);
108   return null_check_offset;
109 }
110 
111 
112 void C1_MacroAssembler::unlock_object(Register hdr, Register obj, Register disp_hdr, Label& slow_case) {
113   const int aligned_mask = BytesPerWord -1;
114   const int hdr_offset = oopDesc::mark_offset_in_bytes();
115   assert(disp_hdr == rax, "disp_hdr must be rax, for the cmpxchg instruction");
116   assert(hdr != obj && hdr != disp_hdr && obj != disp_hdr, "registers must be different");
117   Label done;
118 
119   if (UseBiasedLocking) {
120     // load object
121     movptr(obj, Address(disp_hdr, BasicObjectLock::obj_offset_in_bytes()));
122     biased_locking_exit(obj, hdr, done);
123   }




124 
125   // load displaced header
126   movptr(hdr, Address(disp_hdr, 0));
127   // if the loaded hdr is NULL we had recursive locking
128   testptr(hdr, hdr);
129   // if we had recursive locking, we are done
130   jcc(Assembler::zero, done);
131   if (!UseBiasedLocking) {
132     // load object
133     movptr(obj, Address(disp_hdr, BasicObjectLock::obj_offset_in_bytes()));


















134   }
135   verify_oop(obj);
136   // test if object header is pointing to the displaced header, and if so, restore
137   // the displaced header in the object - if the object header is not pointing to
138   // the displaced header, get the object header instead
139   MacroAssembler::lock(); // must be immediately before cmpxchg!
140   cmpxchgptr(hdr, Address(obj, hdr_offset));
141   // if the object header was not pointing to the displaced header,
142   // we do unlocking via runtime call
143   jcc(Assembler::notEqual, slow_case);
144   // done
145   bind(done);
146 }
147 
148 
149 // Defines obj, preserves var_size_in_bytes
150 void C1_MacroAssembler::try_allocate(Register obj, Register var_size_in_bytes, int con_size_in_bytes, Register t1, Register t2, Label& slow_case) {
151   if (UseTLAB) {
152     tlab_allocate(noreg, obj, var_size_in_bytes, con_size_in_bytes, t1, t2, slow_case);
153   } else {
154     eden_allocate(noreg, obj, var_size_in_bytes, con_size_in_bytes, t1, slow_case);
155   }
156 }
157 
158 
159 void C1_MacroAssembler::initialize_header(Register obj, Register klass, Register len, Register t1, Register t2) {
160   assert_different_registers(obj, klass, len);
161   Register tmp_encode_klass = LP64_ONLY(rscratch1) NOT_LP64(noreg);
162   if (UseBiasedLocking && !len->is_valid()) {
163     assert_different_registers(obj, klass, len, t1, t2);
164     movptr(t1, Address(klass, Klass::prototype_header_offset()));
165     movptr(Address(obj, oopDesc::mark_offset_in_bytes()), t1);
166   } else {
167     // This assumes that all prototype bits fit in an int32_t
168     movptr(Address(obj, oopDesc::mark_offset_in_bytes ()), (int32_t)(intptr_t)markWord::prototype().value());
169   }


170 #ifdef _LP64
171   if (UseCompressedClassPointers) { // Take care not to kill klass
172     movptr(t1, klass);
173     encode_klass_not_null(t1, tmp_encode_klass);
174     movl(Address(obj, oopDesc::klass_offset_in_bytes()), t1);
175   } else
176 #endif
177   {
178     movptr(Address(obj, oopDesc::klass_offset_in_bytes()), klass);

179   }
180 
181   if (len->is_valid()) {
182     movl(Address(obj, arrayOopDesc::length_offset_in_bytes()), len);
183   }
184 #ifdef _LP64
185   else if (UseCompressedClassPointers) {
186     xorptr(t1, t1);
187     store_klass_gap(obj, t1);
188   }
189 #endif
190 }
191 
192 
193 // preserves obj, destroys len_in_bytes
194 void C1_MacroAssembler::initialize_body(Register obj, Register len_in_bytes, int hdr_size_in_bytes, Register t1) {
195   assert(hdr_size_in_bytes >= 0, "header size must be positive or 0");
196   Label done;
197 
198   // len_in_bytes is positive and ptr sized
199   subptr(len_in_bytes, hdr_size_in_bytes);
200   jcc(Assembler::zero, done);
201   zero_memory(obj, len_in_bytes, hdr_size_in_bytes, t1);
202   bind(done);
203 }
204 
205 
206 void C1_MacroAssembler::allocate_object(Register obj, Register t1, Register t2, int header_size, int object_size, Register klass, Label& slow_case) {
207   assert(obj == rax, "obj must be in rax, for cmpxchg");
208   assert_different_registers(obj, t1, t2); // XXX really?
209   assert(header_size >= 0 && object_size >= header_size, "illegal sizes");
210 
211   try_allocate(obj, noreg, object_size * BytesPerWord, t1, t2, slow_case);
212 
213   initialize_object(obj, klass, noreg, object_size * HeapWordSize, t1, t2, UseTLAB);
214 }
215 
216 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) {
217   assert((con_size_in_bytes & MinObjAlignmentInBytesMask) == 0,
218          "con_size_in_bytes is not multiple of alignment");
219   const int hdr_size_in_bytes = instanceOopDesc::header_size() * HeapWordSize;
220 
221   initialize_header(obj, klass, noreg, t1, t2);
222 
223   if (!(UseTLAB && ZeroTLAB && is_tlab_allocated)) {
224     // clear rest of allocated space
225     const Register t1_zero = t1;
226     const Register index = t2;
227     const int threshold = 6 * BytesPerWord;   // approximate break even point for code size (see comments below)

228     if (var_size_in_bytes != noreg) {
229       mov(index, var_size_in_bytes);
230       initialize_body(obj, index, hdr_size_in_bytes, t1_zero);
231     } else if (con_size_in_bytes <= threshold) {
232       // use explicit null stores
233       // code size = 2 + 3*n bytes (n = number of fields to clear)
234       xorptr(t1_zero, t1_zero); // use t1_zero reg to clear memory (shorter code)
235       for (int i = hdr_size_in_bytes; i < con_size_in_bytes; i += BytesPerWord)
236         movptr(Address(obj, i), t1_zero);
237     } else if (con_size_in_bytes > hdr_size_in_bytes) {
238       // use loop to null out the fields
239       // code size = 16 bytes for even n (n = number of fields to clear)
240       // initialize last object field first if odd number of fields
241       xorptr(t1_zero, t1_zero); // use t1_zero reg to clear memory (shorter code)
242       movptr(index, (con_size_in_bytes - hdr_size_in_bytes) >> 3);
243       // initialize last object field if constant size is odd
244       if (((con_size_in_bytes - hdr_size_in_bytes) & 4) != 0)
245         movptr(Address(obj, con_size_in_bytes - (1*BytesPerWord)), t1_zero);
246       // initialize remaining object fields: rdx is a multiple of 2
247       { Label loop;
248         bind(loop);
249         movptr(Address(obj, index, Address::times_8, hdr_size_in_bytes - (1*BytesPerWord)),
250                t1_zero);
251         NOT_LP64(movptr(Address(obj, index, Address::times_8, hdr_size_in_bytes - (2*BytesPerWord)),
252                t1_zero);)
253         decrement(index);
254         jcc(Assembler::notZero, loop);
255       }
256     }
257   }
258 
259   if (CURRENT_ENV->dtrace_alloc_probes()) {
260     assert(obj == rax, "must be");
261     call(RuntimeAddress(Runtime1::entry_for(Runtime1::dtrace_object_alloc_id)));
262   }
263 
264   verify_oop(obj);
265 }
266 
267 void C1_MacroAssembler::allocate_array(Register obj, Register len, Register t1, Register t2, int header_size, Address::ScaleFactor f, Register klass, Label& slow_case) {
268   assert(obj == rax, "obj must be in rax, for cmpxchg");
269   assert_different_registers(obj, len, t1, t2, klass);
270 
271   // determine alignment mask
272   assert(!(BytesPerWord & 1), "must be a multiple of 2 for masking code to work");
273 
274   // check for negative or excessive length
275   cmpptr(len, (int32_t)max_array_allocation_length);
276   jcc(Assembler::above, slow_case);
277 
278   const Register arr_size = t2; // okay to be the same
279   // align object end
280   movptr(arr_size, (int32_t)header_size * BytesPerWord + MinObjAlignmentInBytesMask);
281   lea(arr_size, Address(arr_size, len, f));
282   andptr(arr_size, ~MinObjAlignmentInBytesMask);
283 
284   try_allocate(obj, arr_size, 0, t1, t2, slow_case);
285 
286   initialize_header(obj, klass, len, t1, t2);
287 
288   // clear rest of allocated space
289   const Register len_zero = len;
290   initialize_body(obj, arr_size, header_size * BytesPerWord, len_zero);
291 
292   if (CURRENT_ENV->dtrace_alloc_probes()) {
293     assert(obj == rax, "must be");
294     call(RuntimeAddress(Runtime1::entry_for(Runtime1::dtrace_object_alloc_id)));
295   }
296 
297   verify_oop(obj);
298 }
299 
300 
301 
302 void C1_MacroAssembler::inline_cache_check(Register receiver, Register iCache) {
303   verify_oop(receiver);
304   // explicit NULL check not needed since load from [klass_offset] causes a trap
305   // check against inline cache
306   assert(!MacroAssembler::needs_explicit_null_check(oopDesc::klass_offset_in_bytes()), "must add explicit null check");
307   int start_offset = offset();
308   Register tmp_load_klass = LP64_ONLY(rscratch2) NOT_LP64(noreg);
309 
310   if (UseCompressedClassPointers) {
311     load_klass(rscratch1, receiver, tmp_load_klass);
312     cmpptr(rscratch1, iCache);
313   } else {
314     cmpptr(iCache, Address(receiver, oopDesc::klass_offset_in_bytes()));
315   }
316   // if icache check fails, then jump to runtime routine
317   // Note: RECEIVER must still contain the receiver!
318   jump_cc(Assembler::notEqual,
319           RuntimeAddress(SharedRuntime::get_ic_miss_stub()));
320   const int ic_cmp_size = LP64_ONLY(10) NOT_LP64(9);
321   assert(UseCompressedClassPointers || offset() - start_offset == ic_cmp_size, "check alignment in emit_method_entry");
322 }
323 
324 
325 void C1_MacroAssembler::build_frame(int frame_size_in_bytes, int bang_size_in_bytes) {
326   assert(bang_size_in_bytes >= frame_size_in_bytes, "stack bang size incorrect");
327   // Make sure there is enough stack space for this method's activation.
328   // Note that we do this before doing an enter(). This matches the
329   // ordering of C2's stack overflow check / rsp decrement and allows
330   // the SharedRuntime stack overflow handling to be consistent
331   // between the two compilers.
332   generate_stack_overflow_check(bang_size_in_bytes);
333 
334   push(rbp);
335   if (PreserveFramePointer) {
336     mov(rbp, rsp);
337   }
338 #if !defined(_LP64) && defined(COMPILER2)
339   if (UseSSE < 2 && !CompilerConfig::is_c1_only_no_jvmci()) {
340     // c2 leaves fpu stack dirty. Clean it on entry
341     empty_FPU_stack();
342   }
343 #endif // !_LP64 && COMPILER2
344   decrement(rsp, frame_size_in_bytes); // does not emit code for frame_size == 0
345 
346   BarrierSetAssembler* bs = BarrierSet::barrier_set()->barrier_set_assembler();
347   bs->nmethod_entry_barrier(this);
348 }
349 
350 
351 void C1_MacroAssembler::remove_frame(int frame_size_in_bytes) {
352   increment(rsp, frame_size_in_bytes);  // Does not emit code for frame_size == 0
353   pop(rbp);
354 }
355 
356 
357 void C1_MacroAssembler::verified_entry(bool breakAtEntry) {
358   if (breakAtEntry || VerifyFPU) {
359     // Verified Entry first instruction should be 5 bytes long for correct
360     // patching by patch_verified_entry().
361     //
362     // Breakpoint and VerifyFPU have one byte first instruction.
363     // Also first instruction will be one byte "push(rbp)" if stack banging
364     // code is not generated (see build_frame() above).
365     // For all these cases generate long instruction first.
366     fat_nop();
367   }
368   if (breakAtEntry) int3();
369   // build frame
370   IA32_ONLY( verify_FPU(0, "method_entry"); )
371 }
372 
373 void C1_MacroAssembler::load_parameter(int offset_in_words, Register reg) {
374   // rbp, + 0: link
375   //     + 1: return address
376   //     + 2: argument with offset 0
377   //     + 3: argument with offset 1
378   //     + 4: ...
379 
380   movptr(reg, Address(rbp, (offset_in_words + 2) * BytesPerWord));
381 }
382 
383 #ifndef PRODUCT
384 
385 void C1_MacroAssembler::verify_stack_oop(int stack_offset) {
386   if (!VerifyOops) return;
387   verify_oop_addr(Address(rsp, stack_offset));
388 }
389 
390 void C1_MacroAssembler::verify_not_null_oop(Register r) {
391   if (!VerifyOops) return;
392   Label not_null;
393   testptr(r, r);
394   jcc(Assembler::notZero, not_null);
395   stop("non-null oop required");
396   bind(not_null);
397   verify_oop(r);
398 }
399 
400 void C1_MacroAssembler::invalidate_registers(bool inv_rax, bool inv_rbx, bool inv_rcx, bool inv_rdx, bool inv_rsi, bool inv_rdi) {
401 #ifdef ASSERT
402   if (inv_rax) movptr(rax, 0xDEAD);
403   if (inv_rbx) movptr(rbx, 0xDEAD);
404   if (inv_rcx) movptr(rcx, 0xDEAD);
405   if (inv_rdx) movptr(rdx, 0xDEAD);
406   if (inv_rsi) movptr(rsi, 0xDEAD);
407   if (inv_rdi) movptr(rdi, 0xDEAD);
408 #endif
409 }
410 
411 #endif // ifndef PRODUCT
--- EOF ---