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   if (UseCompactObjectHeaders) {
179     ldr(t1, Address(klass, Klass::prototype_header_offset()));
180     str(t1, Address(obj, oopDesc::mark_offset_in_bytes()));
181   } else {
182     // This assumes that all prototype bits fit in an int32_t
183     mov(t1, (int32_t)(intptr_t)markWord::prototype().value());
184     str(t1, Address(obj, oopDesc::mark_offset_in_bytes()));
185 
186     if (UseCompressedClassPointers) { // Take care not to kill klass
187       encode_klass_not_null(t1, klass);
188       strw(t1, Address(obj, oopDesc::klass_offset_in_bytes()));
189     } else {
190       str(klass, Address(obj, oopDesc::klass_offset_in_bytes()));
191     }
192   }
193 
194   if (len->is_valid()) {
195     strw(len, Address(obj, arrayOopDesc::length_offset_in_bytes()));
196     int base_offset = arrayOopDesc::length_offset_in_bytes() + BytesPerInt;
197     if (!is_aligned(base_offset, BytesPerWord)) {
198       assert(is_aligned(base_offset, BytesPerInt), "must be 4-byte aligned");
199       // Clear gap/first 4 bytes following the length field.
200       strw(zr, Address(obj, base_offset));
201     }
202   } else if (UseCompressedClassPointers && !UseCompactObjectHeaders) {
203     store_klass_gap(obj, zr);
204   }
205 }
206 
207 // preserves obj, destroys len_in_bytes
208 //
209 // Scratch registers: t1 = r10, t2 = r11
210 //
211 void C1_MacroAssembler::initialize_body(Register obj, Register len_in_bytes, int hdr_size_in_bytes, Register t1, Register t2) {
212   assert(hdr_size_in_bytes >= 0, "header size must be positive or 0");
213   assert(t1 == r10 && t2 == r11, "must be");
214 
215   Label done;
216 
217   // len_in_bytes is positive and ptr sized
218   subs(len_in_bytes, len_in_bytes, hdr_size_in_bytes);
219   br(Assembler::EQ, done);
220 
221   // zero_words() takes ptr in r10 and count in words in r11
222   mov(rscratch1, len_in_bytes);
223   lea(t1, Address(obj, hdr_size_in_bytes));
224   lsr(t2, rscratch1, LogBytesPerWord);
225   address tpc = zero_words(t1, t2);
226 
227   bind(done);
228   if (tpc == nullptr) {
229     Compilation::current()->bailout("no space for trampoline stub");
230   }
231 }
232 
233 
234 void C1_MacroAssembler::allocate_object(Register obj, Register t1, Register t2, int header_size, int object_size, Register klass, Label& slow_case) {
235   assert_different_registers(obj, t1, t2); // XXX really?
236   assert(header_size >= 0 && object_size >= header_size, "illegal sizes");
237 
238   try_allocate(obj, noreg, object_size * BytesPerWord, t1, t2, slow_case);
239 
240   initialize_object(obj, klass, noreg, object_size * HeapWordSize, t1, t2, UseTLAB);
241 }
242 
243 // Scratch registers: t1 = r10, t2 = r11
244 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) {
245   assert((con_size_in_bytes & MinObjAlignmentInBytesMask) == 0,
246          "con_size_in_bytes is not multiple of alignment");
247   const int hdr_size_in_bytes = instanceOopDesc::header_size() * HeapWordSize;
248 
249   initialize_header(obj, klass, noreg, t1, t2);
250 
251   if (!(UseTLAB && ZeroTLAB && is_tlab_allocated)) {
252      // clear rest of allocated space
253      const Register index = t2;
254      if (var_size_in_bytes != noreg) {
255        mov(index, var_size_in_bytes);
256        initialize_body(obj, index, hdr_size_in_bytes, t1, t2);
257        if (Compilation::current()->bailed_out()) {
258          return;
259        }
260      } else if (con_size_in_bytes > hdr_size_in_bytes) {
261        con_size_in_bytes -= hdr_size_in_bytes;
262        lea(t1, Address(obj, hdr_size_in_bytes));
263        address tpc = zero_words(t1, con_size_in_bytes / BytesPerWord);
264        if (tpc == nullptr) {
265          Compilation::current()->bailout("no space for trampoline stub");
266          return;
267        }
268      }
269   }
270 
271   membar(StoreStore);
272 
273   if (CURRENT_ENV->dtrace_alloc_probes()) {
274     assert(obj == r0, "must be");
275     far_call(RuntimeAddress(Runtime1::entry_for(Runtime1::dtrace_object_alloc_id)));
276   }
277 
278   verify_oop(obj);
279 }
280 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) {
281   assert_different_registers(obj, len, t1, t2, klass);
282 
283   // determine alignment mask
284   assert(!(BytesPerWord & 1), "must be a multiple of 2 for masking code to work");
285 
286   // check for negative or excessive length
287   mov(rscratch1, (int32_t)max_array_allocation_length);
288   cmp(len, rscratch1);
289   br(Assembler::HS, slow_case);
290 
291   const Register arr_size = t2; // okay to be the same
292   // align object end
293   mov(arr_size, (int32_t)base_offset_in_bytes + MinObjAlignmentInBytesMask);
294   add(arr_size, arr_size, len, ext::uxtw, f);
295   andr(arr_size, arr_size, ~MinObjAlignmentInBytesMask);
296 
297   try_allocate(obj, arr_size, 0, t1, t2, slow_case);
298 
299   initialize_header(obj, klass, len, t1, t2);
300 
301   // Align-up to word boundary, because we clear the 4 bytes potentially
302   // following the length field in initialize_header().
303   int base_offset = align_up(base_offset_in_bytes, BytesPerWord);
304   // clear rest of allocated space
305   initialize_body(obj, arr_size, base_offset, t1, t2);
306   if (Compilation::current()->bailed_out()) {
307     return;
308   }
309 
310   membar(StoreStore);
311 
312   if (CURRENT_ENV->dtrace_alloc_probes()) {
313     assert(obj == r0, "must be");
314     far_call(RuntimeAddress(Runtime1::entry_for(Runtime1::dtrace_object_alloc_id)));
315   }
316 
317   verify_oop(obj);
318 }
319 
320 void C1_MacroAssembler::build_frame(int framesize, int bang_size_in_bytes) {
321   assert(bang_size_in_bytes >= framesize, "stack bang size incorrect");
322   // Make sure there is enough stack space for this method's activation.
323   // Note that we do this before creating a frame.
324   generate_stack_overflow_check(bang_size_in_bytes);
325   MacroAssembler::build_frame(framesize);
326 
327   // Insert nmethod entry barrier into frame.
328   BarrierSetAssembler* bs = BarrierSet::barrier_set()->barrier_set_assembler();
329   bs->nmethod_entry_barrier(this, nullptr /* slow_path */, nullptr /* continuation */, nullptr /* guard */);
330 }
331 
332 void C1_MacroAssembler::remove_frame(int framesize) {
333   MacroAssembler::remove_frame(framesize);
334 }
335 
336 
337 void C1_MacroAssembler::verified_entry(bool breakAtEntry) {
338   // If we have to make this method not-entrant we'll overwrite its
339   // first instruction with a jump.  For this action to be legal we
340   // must ensure that this first instruction is a B, BL, NOP, BKPT,
341   // SVC, HVC, or SMC.  Make it a NOP.
342   nop();
343 }
344 
345 void C1_MacroAssembler::load_parameter(int offset_in_words, Register reg) {
346   // rfp, + 0: link
347   //     + 1: return address
348   //     + 2: argument with offset 0
349   //     + 3: argument with offset 1
350   //     + 4: ...
351 
352   ldr(reg, Address(rfp, (offset_in_words + 2) * BytesPerWord));
353 }
354 
355 #ifndef PRODUCT
356 
357 void C1_MacroAssembler::verify_stack_oop(int stack_offset) {
358   if (!VerifyOops) return;
359   verify_oop_addr(Address(sp, stack_offset));
360 }
361 
362 void C1_MacroAssembler::verify_not_null_oop(Register r) {
363   if (!VerifyOops) return;
364   Label not_null;
365   cbnz(r, not_null);
366   stop("non-null oop required");
367   bind(not_null);
368   verify_oop(r);
369 }
370 
371 void C1_MacroAssembler::invalidate_registers(bool inv_r0, bool inv_r19, bool inv_r2, bool inv_r3, bool inv_r4, bool inv_r5) {
372 #ifdef ASSERT
373   static int nn;
374   if (inv_r0) mov(r0, 0xDEAD);
375   if (inv_r19) mov(r19, 0xDEAD);
376   if (inv_r2) mov(r2, nn++);
377   if (inv_r3) mov(r3, 0xDEAD);
378   if (inv_r4) mov(r4, 0xDEAD);
379   if (inv_r5) mov(r5, 0xDEAD);
380 #endif
381 }
382 #endif // ifndef PRODUCT