1 /*
  2  * Copyright (c) 1999, 2024, 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.
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 23  */
 24 
 25 #include "precompiled.hpp"
 26 #include "c1/c1_MacroAssembler.hpp"
 27 #include "c1/c1_Runtime1.hpp"
 28 #include "code/compiledIC.hpp"
 29 #include "compiler/compilerDefinitions.inline.hpp"
 30 #include "gc/shared/barrierSet.hpp"
 31 #include "gc/shared/barrierSetAssembler.hpp"
 32 #include "gc/shared/collectedHeap.hpp"
 33 #include "gc/shared/tlab_globals.hpp"
 34 #include "interpreter/interpreter.hpp"
 35 #include "oops/arrayOop.hpp"
 36 #include "oops/markWord.hpp"
 37 #include "runtime/basicLock.hpp"
 38 #include "runtime/globals.hpp"
 39 #include "runtime/os.hpp"
 40 #include "runtime/sharedRuntime.hpp"
 41 #include "runtime/stubRoutines.hpp"
 42 #include "utilities/checkedCast.hpp"
 43 #include "utilities/globalDefinitions.hpp"
 44 
 45 int C1_MacroAssembler::lock_object(Register hdr, Register obj, Register disp_hdr, Register tmp, Label& slow_case) {
 46   const int aligned_mask = BytesPerWord -1;
 47   const int hdr_offset = oopDesc::mark_offset_in_bytes();
 48   assert(hdr == rax, "hdr must be rax, for the cmpxchg instruction");
 49   assert_different_registers(hdr, obj, disp_hdr, tmp);
 50   int null_check_offset = -1;

 51 
 52   verify_oop(obj);
 53 
 54   // save object being locked into the BasicObjectLock
 55   movptr(Address(disp_hdr, BasicObjectLock::obj_offset()), obj);
 56 
 57   null_check_offset = offset();
 58 
 59   if (DiagnoseSyncOnValueBasedClasses != 0) {
 60     load_klass(hdr, obj, rscratch1);
 61     movl(hdr, Address(hdr, Klass::access_flags_offset()));
 62     testl(hdr, JVM_ACC_IS_VALUE_BASED_CLASS);
 63     jcc(Assembler::notZero, slow_case);
 64   }
 65 
 66   if (LockingMode == LM_LIGHTWEIGHT) {
 67 #ifdef _LP64
 68     const Register thread = r15_thread;
 69 #else
 70     const Register thread = disp_hdr;
 71     get_thread(thread);
 72 #endif
 73     lightweight_lock(obj, hdr, thread, tmp, slow_case);
 74   } else  if (LockingMode == LM_LEGACY) {
 75     Label done;
 76     // Load object header
 77     movptr(hdr, Address(obj, hdr_offset));
 78     // and mark it as unlocked
 79     orptr(hdr, markWord::unlocked_value);
 80     // save unlocked object header into the displaced header location on the stack
 81     movptr(Address(disp_hdr, 0), hdr);
 82     // test if object header is still the same (i.e. unlocked), and if so, store the
 83     // displaced header address in the object header - if it is not the same, get the
 84     // object header instead
 85     MacroAssembler::lock(); // must be immediately before cmpxchg!
 86     cmpxchgptr(disp_hdr, Address(obj, hdr_offset));
 87     // if the object header was the same, we're done
 88     jcc(Assembler::equal, done);
 89     // if the object header was not the same, it is now in the hdr register
 90     // => test if it is a stack pointer into the same stack (recursive locking), i.e.:
 91     //
 92     // 1) (hdr & aligned_mask) == 0
 93     // 2) rsp <= hdr
 94     // 3) hdr <= rsp + page_size
 95     //
 96     // these 3 tests can be done by evaluating the following expression:
 97     //
 98     // (hdr - rsp) & (aligned_mask - page_size)
 99     //
100     // assuming both the stack pointer and page_size have their least
101     // significant 2 bits cleared and page_size is a power of 2
102     subptr(hdr, rsp);
103     andptr(hdr, aligned_mask - (int)os::vm_page_size());
104     // for recursive locking, the result is zero => save it in the displaced header
105     // location (null in the displaced hdr location indicates recursive locking)
106     movptr(Address(disp_hdr, 0), hdr);
107     // otherwise we don't care about the result and handle locking via runtime call
108     jcc(Assembler::notZero, slow_case);
109     // done
110     bind(done);
111   }

112 

113   inc_held_monitor_count();

114 
115   return null_check_offset;
116 }
117 
118 void C1_MacroAssembler::unlock_object(Register hdr, Register obj, Register disp_hdr, Label& slow_case) {
119   const int aligned_mask = BytesPerWord -1;
120   const int hdr_offset = oopDesc::mark_offset_in_bytes();
121   assert(disp_hdr == rax, "disp_hdr must be rax, for the cmpxchg instruction");
122   assert(hdr != obj && hdr != disp_hdr && obj != disp_hdr, "registers must be different");
123   Label done;
124 
125   if (LockingMode != LM_LIGHTWEIGHT) {
126     // load displaced header
127     movptr(hdr, Address(disp_hdr, 0));
128     // if the loaded hdr is null we had recursive locking
129     testptr(hdr, hdr);
130     // if we had recursive locking, we are done
131     jcc(Assembler::zero, done);
132   }
133 
134   // load object
135   movptr(obj, Address(disp_hdr, BasicObjectLock::obj_offset()));
136   verify_oop(obj);
137 
138   if (LockingMode == LM_LIGHTWEIGHT) {
139 #ifdef _LP64
140     lightweight_unlock(obj, disp_hdr, r15_thread, hdr, slow_case);
141 #else
142     // This relies on the implementation of lightweight_unlock being able to handle
143     // that the reg_rax and thread Register parameters may alias each other.
144     get_thread(disp_hdr);
145     lightweight_unlock(obj, disp_hdr, disp_hdr, hdr, slow_case);
146 #endif
147   } else if (LockingMode == LM_LEGACY) {
148     // test if object header is pointing to the displaced header, and if so, restore
149     // the displaced header in the object - if the object header is not pointing to
150     // the displaced header, get the object header instead
151     MacroAssembler::lock(); // must be immediately before cmpxchg!
152     cmpxchgptr(hdr, Address(obj, hdr_offset));
153     // if the object header was not pointing to the displaced header,
154     // we do unlocking via runtime call
155     jcc(Assembler::notEqual, slow_case);

156     // done
157   }
158   bind(done);
159   dec_held_monitor_count();
160 }
161 
162 
163 // Defines obj, preserves var_size_in_bytes
164 void C1_MacroAssembler::try_allocate(Register obj, Register var_size_in_bytes, int con_size_in_bytes, Register t1, Register t2, Label& slow_case) {
165   if (UseTLAB) {
166     tlab_allocate(noreg, obj, var_size_in_bytes, con_size_in_bytes, t1, t2, slow_case);
167   } else {
168     jmp(slow_case);
169   }
170 }
171 
172 
173 void C1_MacroAssembler::initialize_header(Register obj, Register klass, Register len, Register t1, Register t2) {
174   assert_different_registers(obj, klass, len);
175   movptr(Address(obj, oopDesc::mark_offset_in_bytes()), checked_cast<int32_t>(markWord::prototype().value()));
176 #ifdef _LP64
177   if (UseCompressedClassPointers) { // Take care not to kill klass
178     movptr(t1, klass);
179     encode_klass_not_null(t1, rscratch1);
180     movl(Address(obj, oopDesc::klass_offset_in_bytes()), t1);
181   } else
182 #endif
183   {
184     movptr(Address(obj, oopDesc::klass_offset_in_bytes()), klass);
185   }
186 
187   if (len->is_valid()) {
188     movl(Address(obj, arrayOopDesc::length_offset_in_bytes()), len);
189 #ifdef _LP64
190     int base_offset = arrayOopDesc::length_offset_in_bytes() + BytesPerInt;
191     if (!is_aligned(base_offset, BytesPerWord)) {
192       assert(is_aligned(base_offset, BytesPerInt), "must be 4-byte aligned");
193       // Clear gap/first 4 bytes following the length field.
194       xorl(t1, t1);
195       movl(Address(obj, base_offset), t1);
196     }
197 #endif
198   }
199 #ifdef _LP64
200   else if (UseCompressedClassPointers) {
201     xorptr(t1, t1);
202     store_klass_gap(obj, t1);
203   }
204 #endif
205 }
206 
207 
208 // preserves obj, destroys len_in_bytes
209 void C1_MacroAssembler::initialize_body(Register obj, Register len_in_bytes, int hdr_size_in_bytes, Register t1) {
210   assert(hdr_size_in_bytes >= 0, "header size must be positive or 0");
211   Label done;
212 
213   // len_in_bytes is positive and ptr sized
214   subptr(len_in_bytes, hdr_size_in_bytes);
215   zero_memory(obj, len_in_bytes, hdr_size_in_bytes, t1);
216   bind(done);
217 }
218 
219 
220 void C1_MacroAssembler::allocate_object(Register obj, Register t1, Register t2, int header_size, int object_size, Register klass, Label& slow_case) {
221   assert(obj == rax, "obj must be in rax, for cmpxchg");
222   assert_different_registers(obj, t1, t2); // XXX really?
223   assert(header_size >= 0 && object_size >= header_size, "illegal sizes");
224 
225   try_allocate(obj, noreg, object_size * BytesPerWord, t1, t2, slow_case);
226 
227   initialize_object(obj, klass, noreg, object_size * HeapWordSize, t1, t2, UseTLAB);
228 }
229 
230 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) {
231   assert((con_size_in_bytes & MinObjAlignmentInBytesMask) == 0,
232          "con_size_in_bytes is not multiple of alignment");
233   const int hdr_size_in_bytes = instanceOopDesc::header_size() * HeapWordSize;
234 
235   initialize_header(obj, klass, noreg, t1, t2);
236 
237   if (!(UseTLAB && ZeroTLAB && is_tlab_allocated)) {
238     // clear rest of allocated space
239     const Register t1_zero = t1;
240     const Register index = t2;
241     const int threshold = 6 * BytesPerWord;   // approximate break even point for code size (see comments below)
242     if (var_size_in_bytes != noreg) {
243       mov(index, var_size_in_bytes);
244       initialize_body(obj, index, hdr_size_in_bytes, t1_zero);
245     } else if (con_size_in_bytes <= threshold) {
246       // use explicit null stores
247       // code size = 2 + 3*n bytes (n = number of fields to clear)
248       xorptr(t1_zero, t1_zero); // use t1_zero reg to clear memory (shorter code)
249       for (int i = hdr_size_in_bytes; i < con_size_in_bytes; i += BytesPerWord)
250         movptr(Address(obj, i), t1_zero);
251     } else if (con_size_in_bytes > hdr_size_in_bytes) {
252       // use loop to null out the fields
253       // code size = 16 bytes for even n (n = number of fields to clear)
254       // initialize last object field first if odd number of fields
255       xorptr(t1_zero, t1_zero); // use t1_zero reg to clear memory (shorter code)
256       movptr(index, (con_size_in_bytes - hdr_size_in_bytes) >> 3);
257       // initialize last object field if constant size is odd
258       if (((con_size_in_bytes - hdr_size_in_bytes) & 4) != 0)
259         movptr(Address(obj, con_size_in_bytes - (1*BytesPerWord)), t1_zero);
260       // initialize remaining object fields: rdx is a multiple of 2
261       { Label loop;
262         bind(loop);
263         movptr(Address(obj, index, Address::times_8, hdr_size_in_bytes - (1*BytesPerWord)),
264                t1_zero);
265         NOT_LP64(movptr(Address(obj, index, Address::times_8, hdr_size_in_bytes - (2*BytesPerWord)),
266                t1_zero);)
267         decrement(index);
268         jcc(Assembler::notZero, loop);
269       }
270     }
271   }
272 
273   if (CURRENT_ENV->dtrace_alloc_probes()) {
274     assert(obj == rax, "must be");
275     call(RuntimeAddress(Runtime1::entry_for(Runtime1::dtrace_object_alloc_id)));
276   }
277 
278   verify_oop(obj);
279 }
280 
281 void C1_MacroAssembler::allocate_array(Register obj, Register len, Register t1, Register t2, int base_offset_in_bytes, Address::ScaleFactor f, Register klass, Label& slow_case) {
282   assert(obj == rax, "obj must be in rax, for cmpxchg");
283   assert_different_registers(obj, len, t1, t2, klass);
284 
285   // determine alignment mask
286   assert(!(BytesPerWord & 1), "must be a multiple of 2 for masking code to work");
287 
288   // check for negative or excessive length
289   cmpptr(len, checked_cast<int32_t>(max_array_allocation_length));
290   jcc(Assembler::above, slow_case);
291 
292   const Register arr_size = t2; // okay to be the same
293   // align object end
294   movptr(arr_size, base_offset_in_bytes + MinObjAlignmentInBytesMask);
295   lea(arr_size, Address(arr_size, len, f));
296   andptr(arr_size, ~MinObjAlignmentInBytesMask);
297 
298   try_allocate(obj, arr_size, 0, t1, t2, slow_case);
299 
300   initialize_header(obj, klass, len, t1, t2);
301 
302   // clear rest of allocated space
303   const Register len_zero = len;
304   // Align-up to word boundary, because we clear the 4 bytes potentially
305   // following the length field in initialize_header().
306   int base_offset = align_up(base_offset_in_bytes, BytesPerWord);
307   initialize_body(obj, arr_size, base_offset, len_zero);
308 
309   if (CURRENT_ENV->dtrace_alloc_probes()) {
310     assert(obj == rax, "must be");
311     call(RuntimeAddress(Runtime1::entry_for(Runtime1::dtrace_object_alloc_id)));
312   }
313 
314   verify_oop(obj);
315 }
316 
317 void C1_MacroAssembler::build_frame(int frame_size_in_bytes, int bang_size_in_bytes) {
318   assert(bang_size_in_bytes >= frame_size_in_bytes, "stack bang size incorrect");
319   // Make sure there is enough stack space for this method's activation.
320   // Note that we do this before doing an enter(). This matches the
321   // ordering of C2's stack overflow check / rsp decrement and allows
322   // the SharedRuntime stack overflow handling to be consistent
323   // between the two compilers.
324   generate_stack_overflow_check(bang_size_in_bytes);
325 
326   push(rbp);
327   if (PreserveFramePointer) {
328     mov(rbp, rsp);
329   }
330 #if !defined(_LP64) && defined(COMPILER2)
331   if (UseSSE < 2 && !CompilerConfig::is_c1_only_no_jvmci()) {
332     // c2 leaves fpu stack dirty. Clean it on entry
333     empty_FPU_stack();
334   }
335 #endif // !_LP64 && COMPILER2
336   decrement(rsp, frame_size_in_bytes); // does not emit code for frame_size == 0
337 
338   BarrierSetAssembler* bs = BarrierSet::barrier_set()->barrier_set_assembler();
339   // C1 code is not hot enough to micro optimize the nmethod entry barrier with an out-of-line stub
340   bs->nmethod_entry_barrier(this, nullptr /* slow_path */, nullptr /* continuation */);
341 }
342 
343 
344 void C1_MacroAssembler::remove_frame(int frame_size_in_bytes) {
345   increment(rsp, frame_size_in_bytes);  // Does not emit code for frame_size == 0
346   pop(rbp);
347 }
348 
349 
350 void C1_MacroAssembler::verified_entry(bool breakAtEntry) {
351   if (breakAtEntry || VerifyFPU) {
352     // Verified Entry first instruction should be 5 bytes long for correct
353     // patching by patch_verified_entry().
354     //
355     // Breakpoint and VerifyFPU have one byte first instruction.
356     // Also first instruction will be one byte "push(rbp)" if stack banging
357     // code is not generated (see build_frame() above).
358     // For all these cases generate long instruction first.
359     fat_nop();
360   }
361   if (breakAtEntry) int3();
362   // build frame
363   IA32_ONLY( verify_FPU(0, "method_entry"); )
364 }
365 
366 void C1_MacroAssembler::load_parameter(int offset_in_words, Register reg) {
367   // rbp, + 0: link
368   //     + 1: return address
369   //     + 2: argument with offset 0
370   //     + 3: argument with offset 1
371   //     + 4: ...
372 
373   movptr(reg, Address(rbp, (offset_in_words + 2) * BytesPerWord));
374 }
375 
376 #ifndef PRODUCT
377 
378 void C1_MacroAssembler::verify_stack_oop(int stack_offset) {
379   if (!VerifyOops) return;
380   verify_oop_addr(Address(rsp, stack_offset));
381 }
382 
383 void C1_MacroAssembler::verify_not_null_oop(Register r) {
384   if (!VerifyOops) return;
385   Label not_null;
386   testptr(r, r);
387   jcc(Assembler::notZero, not_null);
388   stop("non-null oop required");
389   bind(not_null);
390   verify_oop(r);
391 }
392 
393 void C1_MacroAssembler::invalidate_registers(bool inv_rax, bool inv_rbx, bool inv_rcx, bool inv_rdx, bool inv_rsi, bool inv_rdi) {
394 #ifdef ASSERT
395   if (inv_rax) movptr(rax, 0xDEAD);
396   if (inv_rbx) movptr(rbx, 0xDEAD);
397   if (inv_rcx) movptr(rcx, 0xDEAD);
398   if (inv_rdx) movptr(rdx, 0xDEAD);
399   if (inv_rsi) movptr(rsi, 0xDEAD);
400   if (inv_rdi) movptr(rdi, 0xDEAD);
401 #endif
402 }
403 
404 #endif // ifndef PRODUCT
--- EOF ---