1 /*
  2  * Copyright (c) 1999, 2022, 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(hdr != obj && hdr != disp_hdr && obj != disp_hdr, "registers must be different");
 67   Label done;
 68   int null_check_offset = -1;
 69 
 70   verify_oop(obj);
 71 
 72   // save object being locked into the BasicObjectLock
 73   str(obj, Address(disp_hdr, BasicObjectLock::obj_offset_in_bytes()));
 74 
 75   null_check_offset = offset();
 76 
 77   if (DiagnoseSyncOnValueBasedClasses != 0) {
 78     load_klass(hdr, obj);
 79     ldrw(hdr, Address(hdr, Klass::access_flags_offset()));
 80     tstw(hdr, JVM_ACC_IS_VALUE_BASED_CLASS);
 81     br(Assembler::NE, slow_case);
 82   }
 83 
 84   // Load object header
 85   ldr(hdr, Address(obj, hdr_offset));
 86   // and mark it as unlocked
 87   orr(hdr, hdr, markWord::unlocked_value);
 88   // save unlocked object header into the displaced header location on the stack
 89   str(hdr, Address(disp_hdr, 0));
 90   // test if object header is still the same (i.e. unlocked), and if so, store the
 91   // displaced header address in the object header - if it is not the same, get the
 92   // object header instead
 93   lea(rscratch2, Address(obj, hdr_offset));
 94   cmpxchgptr(hdr, disp_hdr, rscratch2, rscratch1, done, /*fallthough*/NULL);
 95   // if the object header was the same, we're done
 96   // if the object header was not the same, it is now in the hdr register
 97   // => test if it is a stack pointer into the same stack (recursive locking), i.e.:
 98   //
 99   // 1) (hdr & aligned_mask) == 0
100   // 2) sp <= hdr
101   // 3) hdr <= sp + page_size
102   //
103   // these 3 tests can be done by evaluating the following expression:
104   //
105   // (hdr - sp) & (aligned_mask - page_size)
106   //
107   // assuming both the stack pointer and page_size have their least
108   // significant 2 bits cleared and page_size is a power of 2
109   mov(rscratch1, sp);
110   sub(hdr, hdr, rscratch1);
111   ands(hdr, hdr, aligned_mask - os::vm_page_size());
112   // for recursive locking, the result is zero => save it in the displaced header
113   // location (NULL in the displaced hdr location indicates recursive locking)
114   str(hdr, Address(disp_hdr, 0));
115   // otherwise we don't care about the result and handle locking via runtime call
116   cbnz(hdr, slow_case);
117   // done
118   bind(done);
119   increment(Address(rthread, JavaThread::held_monitor_count_offset()));
120   return null_check_offset;
121 }
122 
123 
124 void C1_MacroAssembler::unlock_object(Register hdr, Register obj, Register disp_hdr, Label& slow_case) {
125   const int aligned_mask = BytesPerWord -1;
126   const int hdr_offset = oopDesc::mark_offset_in_bytes();
127   assert(hdr != obj && hdr != disp_hdr && obj != disp_hdr, "registers must be different");
128   Label done;
129 
130   // load displaced header
131   ldr(hdr, Address(disp_hdr, 0));
132   // if the loaded hdr is NULL we had recursive locking
133   // if we had recursive locking, we are done
134   cbz(hdr, done);
135   // load object
136   ldr(obj, Address(disp_hdr, BasicObjectLock::obj_offset_in_bytes()));
137   verify_oop(obj);
138   // test if object header is pointing to the displaced header, and if so, restore
139   // the displaced header in the object - if the object header is not pointing to
140   // the displaced header, get the object header instead
141   // if the object header was not pointing to the displaced header,
142   // we do unlocking via runtime call
143   if (hdr_offset) {
144     lea(rscratch1, Address(obj, hdr_offset));
145     cmpxchgptr(disp_hdr, hdr, rscratch1, rscratch2, done, &slow_case);
146   } else {
147     cmpxchgptr(disp_hdr, hdr, obj, rscratch2, done, &slow_case);
148   }
149   // done
150   bind(done);
151   decrement(Address(rthread, JavaThread::held_monitor_count_offset()));
152 }
153 
154 
155 // Defines obj, preserves var_size_in_bytes
156 void C1_MacroAssembler::try_allocate(Register obj, Register var_size_in_bytes, int con_size_in_bytes, Register t1, Register t2, Label& slow_case) {
157   if (UseTLAB) {
158     tlab_allocate(obj, var_size_in_bytes, con_size_in_bytes, t1, t2, slow_case);
159   } else {
160     b(slow_case);
161   }
162 }
163 
164 void C1_MacroAssembler::initialize_header(Register obj, Register klass, Register len, Register t1, Register t2) {
165   assert_different_registers(obj, klass, len);
166   ldr(t1, Address(klass, Klass::prototype_header_offset()));
167   str(t1, Address(obj, oopDesc::mark_offset_in_bytes()));
168 
169   if (len->is_valid()) {
170     strw(len, Address(obj, arrayOopDesc::length_offset_in_bytes()));
171   }
172 }
173 
174 // preserves obj, destroys len_in_bytes
175 //
176 // Scratch registers: t1 = r10, t2 = r11
177 //
178 void C1_MacroAssembler::initialize_body(Register obj, Register len_in_bytes, int hdr_size_in_bytes, Register t1, Register t2) {
179   assert(hdr_size_in_bytes >= 0, "header size must be positive or 0");
180   assert(t1 == r10 && t2 == r11, "must be");
181 
182   Label done;
183 
184   // len_in_bytes is positive and ptr sized
185   subs(len_in_bytes, len_in_bytes, hdr_size_in_bytes);
186   br(Assembler::EQ, done);
187 
188   // Zero first 4 bytes, if start offset is not word aligned.
189   if (!is_aligned(hdr_size_in_bytes, BytesPerWord)) {
190     strw(zr, Address(obj, hdr_size_in_bytes));
191     hdr_size_in_bytes += BytesPerInt;
192   }
193 
194   // zero_words() takes ptr in r10 and count in words in r11
195   mov(rscratch1, len_in_bytes);
196   lea(t1, Address(obj, hdr_size_in_bytes));
197   lsr(t2, rscratch1, LogBytesPerWord);
198   zero_words(t1, t2);
199 
200   bind(done);
201 }
202 
203 
204 void C1_MacroAssembler::allocate_object(Register obj, Register t1, Register t2, int header_size, int object_size, Register klass, Label& slow_case) {
205   assert_different_registers(obj, t1, t2); // XXX really?
206   assert(header_size >= 0 && object_size >= header_size, "illegal sizes");
207 
208   try_allocate(obj, noreg, object_size * BytesPerWord, t1, t2, slow_case);
209 
210   initialize_object(obj, klass, noreg, object_size * HeapWordSize, t1, t2, UseTLAB);
211 }
212 
213 // Scratch registers: t1 = r10, t2 = r11
214 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) {
215   assert((con_size_in_bytes & MinObjAlignmentInBytesMask) == 0,
216          "con_size_in_bytes is not multiple of alignment");
217   const int hdr_size_in_bytes = instanceOopDesc::header_size() * HeapWordSize;
218 
219   initialize_header(obj, klass, noreg, t1, t2);
220 
221   if (!(UseTLAB && ZeroTLAB && is_tlab_allocated)) {
222      // clear rest of allocated space
223      const Register index = t2;
224      if (var_size_in_bytes != noreg) {
225        mov(index, var_size_in_bytes);
226        initialize_body(obj, index, hdr_size_in_bytes, t1, t2);
227      } else if (con_size_in_bytes > hdr_size_in_bytes) {
228        con_size_in_bytes -= hdr_size_in_bytes;
229        lea(t1, Address(obj, hdr_size_in_bytes));
230        zero_words(t1, con_size_in_bytes / BytesPerWord);
231      }
232   }
233 
234   membar(StoreStore);
235 
236   if (CURRENT_ENV->dtrace_alloc_probes()) {
237     assert(obj == r0, "must be");
238     far_call(RuntimeAddress(Runtime1::entry_for(Runtime1::dtrace_object_alloc_id)));
239   }
240 
241   verify_oop(obj);
242 }
243 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) {
244   assert_different_registers(obj, len, t1, t2, klass);
245 
246   // determine alignment mask
247   assert(!(BytesPerWord & 1), "must be a multiple of 2 for masking code to work");
248 
249   // check for negative or excessive length
250   mov(rscratch1, (int32_t)max_array_allocation_length);
251   cmp(len, rscratch1);
252   br(Assembler::HS, slow_case);
253 
254   const Register arr_size = t2; // okay to be the same
255   // align object end
256   mov(arr_size, (int32_t)base_offset_in_bytes + MinObjAlignmentInBytesMask);
257   add(arr_size, arr_size, len, ext::uxtw, f);
258   andr(arr_size, arr_size, ~MinObjAlignmentInBytesMask);
259 
260   try_allocate(obj, arr_size, 0, t1, t2, slow_case);
261 
262   initialize_header(obj, klass, len, t1, t2);
263 
264   // clear rest of allocated space
265   initialize_body(obj, arr_size, base_offset_in_bytes, t1, t2);
266 
267   membar(StoreStore);
268 
269   if (CURRENT_ENV->dtrace_alloc_probes()) {
270     assert(obj == r0, "must be");
271     far_call(RuntimeAddress(Runtime1::entry_for(Runtime1::dtrace_object_alloc_id)));
272   }
273 
274   verify_oop(obj);
275 }
276 
277 
278 void C1_MacroAssembler::inline_cache_check(Register receiver, Register iCache) {
279   verify_oop(receiver);
280   // explicit NULL check not needed since load from [klass_offset] causes a trap
281   // check against inline cache
282   assert(!MacroAssembler::needs_explicit_null_check(oopDesc::mark_offset_in_bytes()), "must add explicit null check");
283 
284   cmp_klass(receiver, iCache, rscratch1);
285 }
286 
287 
288 void C1_MacroAssembler::build_frame(int framesize, int bang_size_in_bytes) {
289   assert(bang_size_in_bytes >= framesize, "stack bang size incorrect");
290   // Make sure there is enough stack space for this method's activation.
291   // Note that we do this before creating a frame.
292   generate_stack_overflow_check(bang_size_in_bytes);
293   MacroAssembler::build_frame(framesize);
294 
295   // Insert nmethod entry barrier into frame.
296   BarrierSetAssembler* bs = BarrierSet::barrier_set()->barrier_set_assembler();
297   bs->nmethod_entry_barrier(this, NULL /* slow_path */, NULL /* continuation */, NULL /* guard */);
298 }
299 
300 void C1_MacroAssembler::remove_frame(int framesize) {
301   MacroAssembler::remove_frame(framesize);
302 }
303 
304 
305 void C1_MacroAssembler::verified_entry(bool breakAtEntry) {
306   // If we have to make this method not-entrant we'll overwrite its
307   // first instruction with a jump.  For this action to be legal we
308   // must ensure that this first instruction is a B, BL, NOP, BKPT,
309   // SVC, HVC, or SMC.  Make it a NOP.
310   nop();
311 }
312 
313 void C1_MacroAssembler::load_parameter(int offset_in_words, Register reg) {
314   // rfp, + 0: link
315   //     + 1: return address
316   //     + 2: argument with offset 0
317   //     + 3: argument with offset 1
318   //     + 4: ...
319 
320   ldr(reg, Address(rfp, (offset_in_words + 2) * BytesPerWord));
321 }
322 
323 #ifndef PRODUCT
324 
325 void C1_MacroAssembler::verify_stack_oop(int stack_offset) {
326   if (!VerifyOops) return;
327   verify_oop_addr(Address(sp, stack_offset));
328 }
329 
330 void C1_MacroAssembler::verify_not_null_oop(Register r) {
331   if (!VerifyOops) return;
332   Label not_null;
333   cbnz(r, not_null);
334   stop("non-null oop required");
335   bind(not_null);
336   verify_oop(r);
337 }
338 
339 void C1_MacroAssembler::invalidate_registers(bool inv_r0, bool inv_r19, bool inv_r2, bool inv_r3, bool inv_r4, bool inv_r5) {
340 #ifdef ASSERT
341   static int nn;
342   if (inv_r0) mov(r0, 0xDEAD);
343   if (inv_r19) mov(r19, 0xDEAD);
344   if (inv_r2) mov(r2, nn++);
345   if (inv_r3) mov(r3, 0xDEAD);
346   if (inv_r4) mov(r4, 0xDEAD);
347   if (inv_r5) mov(r5, 0xDEAD);
348 #endif
349 }
350 #endif // ifndef PRODUCT