1 /*
  2  * Copyright (c) 1999, 2023, Oracle and/or its affiliates. All rights reserved.
  3  * Copyright (c) 2014, 2021, Red Hat Inc. All rights reserved.
  4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  5  *
  6  * This code is free software; you can redistribute it and/or modify it
  7  * under the terms of the GNU General Public License version 2 only, as
  8  * published by the Free Software Foundation.
  9  *
 10  * This code is distributed in the hope that it will be useful, but WITHOUT
 11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 13  * version 2 for more details (a copy is included in the LICENSE file that
 14  * accompanied this code).
 15  *
 16  * You should have received a copy of the GNU General Public License version
 17  * 2 along with this work; if not, write to the Free Software Foundation,
 18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 19  *
 20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 21  * or visit www.oracle.com if you need additional information or have any
 22  * questions.
 23  *
 24  */
 25 
 26 #include "precompiled.hpp"
 27 #include "c1/c1_MacroAssembler.hpp"
 28 #include "c1/c1_Runtime1.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/os.hpp"
 37 #include "runtime/sharedRuntime.hpp"
 38 #include "runtime/stubRoutines.hpp"
 39 
 40 void C1_MacroAssembler::float_cmp(bool is_float, int unordered_result,
 41                                   FloatRegister f0, FloatRegister f1,
 42                                   Register result)
 43 {
 44   Label done;
 45   if (is_float) {
 46     fcmps(f0, f1);
 47   } else {
 48     fcmpd(f0, f1);
 49   }
 50   if (unordered_result < 0) {
 51     // we want -1 for unordered or less than, 0 for equal and 1 for
 52     // greater than.
 53     cset(result, NE);  // Not equal or unordered
 54     cneg(result, result, LT);  // Less than or unordered
 55   } else {
 56     // we want -1 for less than, 0 for equal and 1 for unordered or
 57     // greater than.
 58     cset(result, NE);  // Not equal or unordered
 59     cneg(result, result, LO);  // Less than
 60   }
 61 }
 62 
 63 int C1_MacroAssembler::lock_object(Register hdr, Register obj, Register disp_hdr, Label& slow_case) {
 64   const int aligned_mask = BytesPerWord -1;
 65   const int hdr_offset = oopDesc::mark_offset_in_bytes();
 66   assert_different_registers(hdr, obj, disp_hdr);
 67   int null_check_offset = -1;
 68 
 69   verify_oop(obj);
 70 
 71   // save object being locked into the BasicObjectLock
 72   str(obj, Address(disp_hdr, BasicObjectLock::obj_offset()));
 73 
 74   null_check_offset = offset();
 75 
 76   if (DiagnoseSyncOnValueBasedClasses != 0) {
 77     load_klass(hdr, obj);
 78     ldrw(hdr, Address(hdr, Klass::access_flags_offset()));
 79     tstw(hdr, JVM_ACC_IS_VALUE_BASED_CLASS);
 80     br(Assembler::NE, slow_case);
 81   }
 82 
 83   // Load object header
 84   ldr(hdr, Address(obj, hdr_offset));
 85   if (LockingMode == LM_LIGHTWEIGHT) {
 86     fast_lock(obj, hdr, rscratch1, rscratch2, slow_case);
 87   } else if (LockingMode == LM_LEGACY) {
 88     Label done;
 89     // and mark it as unlocked
 90     orr(hdr, hdr, markWord::unlocked_value);
 91     // save unlocked object header into the displaced header location on the stack
 92     str(hdr, Address(disp_hdr, 0));
 93     // test if object header is still the same (i.e. unlocked), and if so, store the
 94     // displaced header address in the object header - if it is not the same, get the
 95     // object header instead
 96     lea(rscratch2, Address(obj, hdr_offset));
 97     cmpxchgptr(hdr, disp_hdr, rscratch2, rscratch1, done, /*fallthough*/nullptr);
 98     // if the object header was the same, we're done
 99     // if the object header was not the same, it is now in the hdr register
100     // => test if it is a stack pointer into the same stack (recursive locking), i.e.:
101     //
102     // 1) (hdr & aligned_mask) == 0
103     // 2) sp <= hdr
104     // 3) hdr <= sp + page_size
105     //
106     // these 3 tests can be done by evaluating the following expression:
107     //
108     // (hdr - sp) & (aligned_mask - page_size)
109     //
110     // assuming both the stack pointer and page_size have their least
111     // significant 2 bits cleared and page_size is a power of 2
112     mov(rscratch1, sp);
113     sub(hdr, hdr, rscratch1);
114     ands(hdr, hdr, aligned_mask - (int)os::vm_page_size());
115     // for recursive locking, the result is zero => save it in the displaced header
116     // location (null in the displaced hdr location indicates recursive locking)
117     str(hdr, Address(disp_hdr, 0));
118     // otherwise we don't care about the result and handle locking via runtime call
119     cbnz(hdr, slow_case);
120     // done
121     bind(done);
122   }
123   increment(Address(rthread, JavaThread::held_monitor_count_offset()));
124   return null_check_offset;
125 }
126 
127 
128 void C1_MacroAssembler::unlock_object(Register hdr, Register obj, Register disp_hdr, Label& slow_case) {
129   const int aligned_mask = BytesPerWord -1;
130   const int hdr_offset = oopDesc::mark_offset_in_bytes();
131   assert(hdr != obj && hdr != disp_hdr && obj != disp_hdr, "registers must be different");
132   Label done;
133 
134   if (LockingMode != LM_LIGHTWEIGHT) {
135     // load displaced header
136     ldr(hdr, Address(disp_hdr, 0));
137     // if the loaded hdr is null we had recursive locking
138     // if we had recursive locking, we are done
139     cbz(hdr, done);
140   }
141 
142   // load object
143   ldr(obj, Address(disp_hdr, BasicObjectLock::obj_offset()));
144   verify_oop(obj);
145 
146   if (LockingMode == LM_LIGHTWEIGHT) {
147     ldr(hdr, Address(obj, oopDesc::mark_offset_in_bytes()));
148     // We cannot use tbnz here, the target might be too far away and cannot
149     // be encoded.
150     tst(hdr, markWord::monitor_value);
151     br(Assembler::NE, slow_case);
152     fast_unlock(obj, hdr, rscratch1, rscratch2, slow_case);
153   } else if (LockingMode == LM_LEGACY) {
154     // test if object header is pointing to the displaced header, and if so, restore
155     // the displaced header in the object - if the object header is not pointing to
156     // the displaced header, get the object header instead
157     // if the object header was not pointing to the displaced header,
158     // we do unlocking via runtime call
159     if (hdr_offset) {
160       lea(rscratch1, Address(obj, hdr_offset));
161       cmpxchgptr(disp_hdr, hdr, rscratch1, rscratch2, done, &slow_case);
162     } else {
163       cmpxchgptr(disp_hdr, hdr, obj, rscratch2, done, &slow_case);
164     }
165     // done
166     bind(done);
167   }
168   decrement(Address(rthread, JavaThread::held_monitor_count_offset()));
169 }
170 
171 
172 // Defines obj, preserves var_size_in_bytes
173 void C1_MacroAssembler::try_allocate(Register obj, Register var_size_in_bytes, int con_size_in_bytes, Register t1, Register t2, Label& slow_case) {
174   if (UseTLAB) {
175     tlab_allocate(obj, var_size_in_bytes, con_size_in_bytes, t1, t2, slow_case);
176   } else {
177     b(slow_case);
178   }
179 }
180 
181 void C1_MacroAssembler::initialize_header(Register obj, Register klass, Register len, Register t1, Register t2) {
182   assert_different_registers(obj, klass, len);
183   if (UseCompactObjectHeaders) {
184     ldr(t1, Address(klass, Klass::prototype_header_offset()));
185     str(t1, Address(obj, oopDesc::mark_offset_in_bytes()));
186   } else {
187     // This assumes that all prototype bits fit in an int32_t
188     mov(t1, (int32_t)(intptr_t)markWord::prototype().value());
189     str(t1, Address(obj, oopDesc::mark_offset_in_bytes()));
190 
191     if (UseCompressedClassPointers) { // Take care not to kill klass
192       encode_klass_not_null(t1, klass);
193       strw(t1, Address(obj, oopDesc::klass_offset_in_bytes()));
194     } else {
195       str(klass, Address(obj, oopDesc::klass_offset_in_bytes()));
196     }
197   }
198 
199   if (len->is_valid()) {
200     strw(len, Address(obj, arrayOopDesc::length_offset_in_bytes()));
201   } else if (UseCompressedClassPointers && !UseCompactObjectHeaders) {
202     store_klass_gap(obj, zr);
203   }
204 }
205 
206 // preserves obj, destroys len_in_bytes
207 //
208 // Scratch registers: t1 = r10, t2 = r11
209 //
210 void C1_MacroAssembler::initialize_body(Register obj, Register len_in_bytes, int hdr_size_in_bytes, Register t1, Register t2) {
211   assert(hdr_size_in_bytes >= 0, "header size must be positive or 0");
212   assert(t1 == r10 && t2 == r11, "must be");
213 
214   Label done;
215 
216   // len_in_bytes is positive and ptr sized
217   subs(len_in_bytes, len_in_bytes, hdr_size_in_bytes);
218   br(Assembler::EQ, done);
219 
220   // Zero first 4 bytes, if start offset is not word aligned.
221   if (!is_aligned(hdr_size_in_bytes, BytesPerWord)) {
222     strw(zr, Address(obj, hdr_size_in_bytes));
223     hdr_size_in_bytes += BytesPerInt;
224   }
225 
226   // zero_words() takes ptr in r10 and count in words in r11
227   mov(rscratch1, len_in_bytes);
228   lea(t1, Address(obj, hdr_size_in_bytes));
229   lsr(t2, rscratch1, LogBytesPerWord);
230   address tpc = zero_words(t1, t2);
231 
232   bind(done);
233   if (tpc == nullptr) {
234     Compilation::current()->bailout("no space for trampoline stub");
235   }
236 }
237 
238 
239 void C1_MacroAssembler::allocate_object(Register obj, Register t1, Register t2, int header_size, int object_size, Register klass, Label& slow_case) {
240   assert_different_registers(obj, t1, t2); // XXX really?
241   assert(header_size >= 0 && object_size >= header_size, "illegal sizes");
242 
243   try_allocate(obj, noreg, object_size * BytesPerWord, t1, t2, slow_case);
244 
245   initialize_object(obj, klass, noreg, object_size * HeapWordSize, t1, t2, UseTLAB);
246 }
247 
248 // Scratch registers: t1 = r10, t2 = r11
249 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) {
250   assert((con_size_in_bytes & MinObjAlignmentInBytesMask) == 0,
251          "con_size_in_bytes is not multiple of alignment");
252   const int hdr_size_in_bytes = instanceOopDesc::header_size() * HeapWordSize;
253 
254   initialize_header(obj, klass, noreg, t1, t2);
255 
256   if (!(UseTLAB && ZeroTLAB && is_tlab_allocated)) {
257      // clear rest of allocated space
258      const Register index = t2;
259      if (var_size_in_bytes != noreg) {
260        mov(index, var_size_in_bytes);
261        initialize_body(obj, index, hdr_size_in_bytes, t1, t2);
262        if (Compilation::current()->bailed_out()) {
263          return;
264        }
265      } else if (con_size_in_bytes > hdr_size_in_bytes) {
266        con_size_in_bytes -= hdr_size_in_bytes;
267        lea(t1, Address(obj, hdr_size_in_bytes));
268        address tpc = zero_words(t1, con_size_in_bytes / BytesPerWord);
269        if (tpc == nullptr) {
270          Compilation::current()->bailout("no space for trampoline stub");
271          return;
272        }
273      }
274   }
275 
276   membar(StoreStore);
277 
278   if (CURRENT_ENV->dtrace_alloc_probes()) {
279     assert(obj == r0, "must be");
280     far_call(RuntimeAddress(Runtime1::entry_for(Runtime1::dtrace_object_alloc_id)));
281   }
282 
283   verify_oop(obj);
284 }
285 void C1_MacroAssembler::allocate_array(Register obj, Register len, Register t1, Register t2, int base_offset_in_bytes, int f, Register klass, Label& slow_case) {
286   assert_different_registers(obj, len, t1, t2, klass);
287 
288   // determine alignment mask
289   assert(!(BytesPerWord & 1), "must be a multiple of 2 for masking code to work");
290 
291   // check for negative or excessive length
292   mov(rscratch1, (int32_t)max_array_allocation_length);
293   cmp(len, rscratch1);
294   br(Assembler::HS, slow_case);
295 
296   const Register arr_size = t2; // okay to be the same
297   // align object end
298   mov(arr_size, (int32_t)base_offset_in_bytes + MinObjAlignmentInBytesMask);
299   add(arr_size, arr_size, len, ext::uxtw, f);
300   andr(arr_size, arr_size, ~MinObjAlignmentInBytesMask);
301 
302   try_allocate(obj, arr_size, 0, t1, t2, slow_case);
303 
304   initialize_header(obj, klass, len, t1, t2);
305 
306   // clear rest of allocated space
307   initialize_body(obj, arr_size, base_offset_in_bytes, t1, t2);
308   if (Compilation::current()->bailed_out()) {
309     return;
310   }
311 
312   membar(StoreStore);
313 
314   if (CURRENT_ENV->dtrace_alloc_probes()) {
315     assert(obj == r0, "must be");
316     far_call(RuntimeAddress(Runtime1::entry_for(Runtime1::dtrace_object_alloc_id)));
317   }
318 
319   verify_oop(obj);
320 }
321 
322 
323 void C1_MacroAssembler::inline_cache_check(Register receiver, Register iCache) {
324   verify_oop(receiver);
325   // explicit null check not needed since load from [klass_offset] causes a trap
326   // check against inline cache
327   if (UseCompactObjectHeaders) {
328     assert(!MacroAssembler::needs_explicit_null_check(oopDesc::mark_offset_in_bytes()), "must add explicit null check");
329   } else {
330     assert(!MacroAssembler::needs_explicit_null_check(oopDesc::klass_offset_in_bytes()), "must add explicit null check");
331   }
332 
333   cmp_klass(receiver, iCache, rscratch1);
334 }
335 
336 
337 void C1_MacroAssembler::build_frame(int framesize, int bang_size_in_bytes) {
338   assert(bang_size_in_bytes >= framesize, "stack bang size incorrect");
339   // Make sure there is enough stack space for this method's activation.
340   // Note that we do this before creating a frame.
341   generate_stack_overflow_check(bang_size_in_bytes);
342   MacroAssembler::build_frame(framesize);
343 
344   // Insert nmethod entry barrier into frame.
345   BarrierSetAssembler* bs = BarrierSet::barrier_set()->barrier_set_assembler();
346   bs->nmethod_entry_barrier(this, nullptr /* slow_path */, nullptr /* continuation */, nullptr /* guard */);
347 }
348 
349 void C1_MacroAssembler::remove_frame(int framesize) {
350   MacroAssembler::remove_frame(framesize);
351 }
352 
353 
354 void C1_MacroAssembler::verified_entry(bool breakAtEntry) {
355   // If we have to make this method not-entrant we'll overwrite its
356   // first instruction with a jump.  For this action to be legal we
357   // must ensure that this first instruction is a B, BL, NOP, BKPT,
358   // SVC, HVC, or SMC.  Make it a NOP.
359   nop();
360 }
361 
362 void C1_MacroAssembler::load_parameter(int offset_in_words, Register reg) {
363   // rfp, + 0: link
364   //     + 1: return address
365   //     + 2: argument with offset 0
366   //     + 3: argument with offset 1
367   //     + 4: ...
368 
369   ldr(reg, Address(rfp, (offset_in_words + 2) * BytesPerWord));
370 }
371 
372 #ifndef PRODUCT
373 
374 void C1_MacroAssembler::verify_stack_oop(int stack_offset) {
375   if (!VerifyOops) return;
376   verify_oop_addr(Address(sp, stack_offset));
377 }
378 
379 void C1_MacroAssembler::verify_not_null_oop(Register r) {
380   if (!VerifyOops) return;
381   Label not_null;
382   cbnz(r, not_null);
383   stop("non-null oop required");
384   bind(not_null);
385   verify_oop(r);
386 }
387 
388 void C1_MacroAssembler::invalidate_registers(bool inv_r0, bool inv_r19, bool inv_r2, bool inv_r3, bool inv_r4, bool inv_r5) {
389 #ifdef ASSERT
390   static int nn;
391   if (inv_r0) mov(r0, 0xDEAD);
392   if (inv_r19) mov(r19, 0xDEAD);
393   if (inv_r2) mov(r2, nn++);
394   if (inv_r3) mov(r3, 0xDEAD);
395   if (inv_r4) mov(r4, 0xDEAD);
396   if (inv_r5) mov(r5, 0xDEAD);
397 #endif
398 }
399 #endif // ifndef PRODUCT