1 /*
  2  * Copyright (c) 1999, 2024, 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, Register temp, 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, temp, rscratch2);
 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   if (LockingMode == LM_LIGHTWEIGHT) {
 84     lightweight_lock(obj, hdr, temp, rscratch2, slow_case);

 85   } else if (LockingMode == LM_LEGACY) {
 86     Label done;
 87     // Load object header
 88     ldr(hdr, Address(obj, hdr_offset));
 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, Register temp, Label& slow_case) {
129   const int aligned_mask = BytesPerWord -1;
130   const int hdr_offset = oopDesc::mark_offset_in_bytes();
131   assert_different_registers(hdr, obj, disp_hdr, temp, rscratch2);
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     lightweight_unlock(obj, hdr, temp, rscratch2, slow_case);

148   } else if (LockingMode == LM_LEGACY) {
149     // test if object header is pointing to the displaced header, and if so, restore
150     // the displaced header in the object - if the object header is not pointing to
151     // the displaced header, get the object header instead
152     // if the object header was not pointing to the displaced header,
153     // we do unlocking via runtime call
154     if (hdr_offset) {
155       lea(rscratch1, Address(obj, hdr_offset));
156       cmpxchgptr(disp_hdr, hdr, rscratch1, rscratch2, done, &slow_case);
157     } else {
158       cmpxchgptr(disp_hdr, hdr, obj, rscratch2, done, &slow_case);
159     }
160     // done
161     bind(done);

162   }
163   decrement(Address(rthread, JavaThread::held_monitor_count_offset()));
164 }
165 
166 
167 // Defines obj, preserves var_size_in_bytes
168 void C1_MacroAssembler::try_allocate(Register obj, Register var_size_in_bytes, int con_size_in_bytes, Register t1, Register t2, Label& slow_case) {
169   if (UseTLAB) {
170     tlab_allocate(obj, var_size_in_bytes, con_size_in_bytes, t1, t2, slow_case);
171   } else {
172     b(slow_case);
173   }
174 }
175 
176 void C1_MacroAssembler::initialize_header(Register obj, Register klass, Register len, Register t1, Register t2) {
177   assert_different_registers(obj, klass, len);
178   // This assumes that all prototype bits fit in an int32_t
179   mov(t1, (int32_t)(intptr_t)markWord::prototype().value());
180   str(t1, Address(obj, oopDesc::mark_offset_in_bytes()));
181 
182   if (UseCompressedClassPointers) { // Take care not to kill klass
183     encode_klass_not_null(t1, klass);
184     strw(t1, Address(obj, oopDesc::klass_offset_in_bytes()));
185   } else {
186     str(klass, Address(obj, oopDesc::klass_offset_in_bytes()));
187   }
188 
189   if (len->is_valid()) {
190     strw(len, Address(obj, arrayOopDesc::length_offset_in_bytes()));
191     int base_offset = arrayOopDesc::length_offset_in_bytes() + BytesPerInt;
192     if (!is_aligned(base_offset, BytesPerWord)) {
193       assert(is_aligned(base_offset, BytesPerInt), "must be 4-byte aligned");
194       // Clear gap/first 4 bytes following the length field.
195       strw(zr, Address(obj, base_offset));
196     }
197   } else if (UseCompressedClassPointers) {
198     store_klass_gap(obj, zr);
199   }
200 }
201 
202 // preserves obj, destroys len_in_bytes
203 //
204 // Scratch registers: t1 = r10, t2 = r11
205 //
206 void C1_MacroAssembler::initialize_body(Register obj, Register len_in_bytes, int hdr_size_in_bytes, Register t1, Register t2) {
207   assert(hdr_size_in_bytes >= 0, "header size must be positive or 0");
208   assert(t1 == r10 && t2 == r11, "must be");
209 
210   Label done;
211 
212   // len_in_bytes is positive and ptr sized
213   subs(len_in_bytes, len_in_bytes, hdr_size_in_bytes);
214   br(Assembler::EQ, done);
215 
216   // zero_words() takes ptr in r10 and count in words in r11
217   mov(rscratch1, len_in_bytes);
218   lea(t1, Address(obj, hdr_size_in_bytes));
219   lsr(t2, rscratch1, LogBytesPerWord);
220   address tpc = zero_words(t1, t2);
221 
222   bind(done);
223   if (tpc == nullptr) {
224     Compilation::current()->bailout("no space for trampoline stub");
225   }
226 }
227 
228 
229 void C1_MacroAssembler::allocate_object(Register obj, Register t1, Register t2, int header_size, int object_size, Register klass, Label& slow_case) {
230   assert_different_registers(obj, t1, t2); // XXX really?
231   assert(header_size >= 0 && object_size >= header_size, "illegal sizes");
232 
233   try_allocate(obj, noreg, object_size * BytesPerWord, t1, t2, slow_case);
234 
235   initialize_object(obj, klass, noreg, object_size * HeapWordSize, t1, t2, UseTLAB);
236 }
237 
238 // Scratch registers: t1 = r10, t2 = r11
239 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) {
240   assert((con_size_in_bytes & MinObjAlignmentInBytesMask) == 0,
241          "con_size_in_bytes is not multiple of alignment");
242   const int hdr_size_in_bytes = instanceOopDesc::header_size() * HeapWordSize;
243 
244   initialize_header(obj, klass, noreg, t1, t2);
245 
246   if (!(UseTLAB && ZeroTLAB && is_tlab_allocated)) {
247      // clear rest of allocated space
248      const Register index = t2;
249      if (var_size_in_bytes != noreg) {
250        mov(index, var_size_in_bytes);
251        initialize_body(obj, index, hdr_size_in_bytes, t1, t2);
252        if (Compilation::current()->bailed_out()) {
253          return;
254        }
255      } else if (con_size_in_bytes > hdr_size_in_bytes) {
256        con_size_in_bytes -= hdr_size_in_bytes;
257        lea(t1, Address(obj, hdr_size_in_bytes));
258        address tpc = zero_words(t1, con_size_in_bytes / BytesPerWord);
259        if (tpc == nullptr) {
260          Compilation::current()->bailout("no space for trampoline stub");
261          return;
262        }
263      }
264   }
265 
266   membar(StoreStore);
267 
268   if (CURRENT_ENV->dtrace_alloc_probes()) {
269     assert(obj == r0, "must be");
270     far_call(RuntimeAddress(Runtime1::entry_for(Runtime1::dtrace_object_alloc_id)));
271   }
272 
273   verify_oop(obj);
274 }
275 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) {
276   assert_different_registers(obj, len, t1, t2, klass);
277 
278   // determine alignment mask
279   assert(!(BytesPerWord & 1), "must be a multiple of 2 for masking code to work");
280 
281   // check for negative or excessive length
282   mov(rscratch1, (int32_t)max_array_allocation_length);
283   cmp(len, rscratch1);
284   br(Assembler::HS, slow_case);
285 
286   const Register arr_size = t2; // okay to be the same
287   // align object end
288   mov(arr_size, (int32_t)base_offset_in_bytes + MinObjAlignmentInBytesMask);
289   add(arr_size, arr_size, len, ext::uxtw, f);
290   andr(arr_size, arr_size, ~MinObjAlignmentInBytesMask);
291 
292   try_allocate(obj, arr_size, 0, t1, t2, slow_case);
293 
294   initialize_header(obj, klass, len, t1, t2);
295 
296   // Align-up to word boundary, because we clear the 4 bytes potentially
297   // following the length field in initialize_header().
298   int base_offset = align_up(base_offset_in_bytes, BytesPerWord);
299   // clear rest of allocated space
300   initialize_body(obj, arr_size, base_offset, t1, t2);
301   if (Compilation::current()->bailed_out()) {
302     return;
303   }
304 
305   membar(StoreStore);
306 
307   if (CURRENT_ENV->dtrace_alloc_probes()) {
308     assert(obj == r0, "must be");
309     far_call(RuntimeAddress(Runtime1::entry_for(Runtime1::dtrace_object_alloc_id)));
310   }
311 
312   verify_oop(obj);
313 }
314 
315 void C1_MacroAssembler::build_frame(int framesize, int bang_size_in_bytes) {
316   assert(bang_size_in_bytes >= framesize, "stack bang size incorrect");
317   // Make sure there is enough stack space for this method's activation.
318   // Note that we do this before creating a frame.
319   generate_stack_overflow_check(bang_size_in_bytes);
320   MacroAssembler::build_frame(framesize);
321 
322   // Insert nmethod entry barrier into frame.
323   BarrierSetAssembler* bs = BarrierSet::barrier_set()->barrier_set_assembler();
324   bs->nmethod_entry_barrier(this, nullptr /* slow_path */, nullptr /* continuation */, nullptr /* guard */);
325 }
326 
327 void C1_MacroAssembler::remove_frame(int framesize) {
328   MacroAssembler::remove_frame(framesize);
329 }
330 
331 
332 void C1_MacroAssembler::verified_entry(bool breakAtEntry) {
333   // If we have to make this method not-entrant we'll overwrite its
334   // first instruction with a jump.  For this action to be legal we
335   // must ensure that this first instruction is a B, BL, NOP, BKPT,
336   // SVC, HVC, or SMC.  Make it a NOP.
337   nop();
338 }
339 
340 void C1_MacroAssembler::load_parameter(int offset_in_words, Register reg) {
341   // rfp, + 0: link
342   //     + 1: return address
343   //     + 2: argument with offset 0
344   //     + 3: argument with offset 1
345   //     + 4: ...
346 
347   ldr(reg, Address(rfp, (offset_in_words + 2) * BytesPerWord));
348 }
349 
350 #ifndef PRODUCT
351 
352 void C1_MacroAssembler::verify_stack_oop(int stack_offset) {
353   if (!VerifyOops) return;
354   verify_oop_addr(Address(sp, stack_offset));
355 }
356 
357 void C1_MacroAssembler::verify_not_null_oop(Register r) {
358   if (!VerifyOops) return;
359   Label not_null;
360   cbnz(r, not_null);
361   stop("non-null oop required");
362   bind(not_null);
363   verify_oop(r);
364 }
365 
366 void C1_MacroAssembler::invalidate_registers(bool inv_r0, bool inv_r19, bool inv_r2, bool inv_r3, bool inv_r4, bool inv_r5) {
367 #ifdef ASSERT
368   static int nn;
369   if (inv_r0) mov(r0, 0xDEAD);
370   if (inv_r19) mov(r19, 0xDEAD);
371   if (inv_r2) mov(r2, nn++);
372   if (inv_r3) mov(r3, 0xDEAD);
373   if (inv_r4) mov(r4, 0xDEAD);
374   if (inv_r5) mov(r5, 0xDEAD);
375 #endif
376 }
377 #endif // ifndef PRODUCT
--- EOF ---