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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 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     testb(Address(hdr, Klass::misc_flags_offset()), KlassFlags::_misc_is_value_based_class);
 62     jcc(Assembler::notZero, slow_case);
 63   }
 64 
 65   if (LockingMode == LM_LIGHTWEIGHT) {
 66 #ifdef _LP64
 67     const Register thread = r15_thread;
 68     lightweight_lock(disp_hdr, obj, hdr, thread, tmp, slow_case);
 69 #else
 70     // Implicit null check.
 71     movptr(hdr, Address(obj, oopDesc::mark_offset_in_bytes()));
 72     // Lacking registers and thread on x86_32. Always take slow path.
 73     jmp(slow_case);
 74 #endif
 75   } else  if (LockingMode == LM_LEGACY) {
 76     Label done;
 77     // Load object header
 78     movptr(hdr, Address(obj, hdr_offset));
 79     // and mark it as unlocked
 80     orptr(hdr, markWord::unlocked_value);
 81     // save unlocked object header into the displaced header location on the stack
 82     movptr(Address(disp_hdr, 0), hdr);
 83     // test if object header is still the same (i.e. unlocked), and if so, store the
 84     // displaced header address in the object header - if it is not the same, get the
 85     // object header instead
 86     MacroAssembler::lock(); // must be immediately before cmpxchg!
 87     cmpxchgptr(disp_hdr, Address(obj, hdr_offset));
 88     // if the object header was the same, we're done
 89     jcc(Assembler::equal, done);
 90     // if the object header was not the same, it is now in the hdr register
 91     // => test if it is a stack pointer into the same stack (recursive locking), i.e.:
 92     //
 93     // 1) (hdr & aligned_mask) == 0
 94     // 2) rsp <= hdr
 95     // 3) hdr <= rsp + page_size
 96     //
 97     // these 3 tests can be done by evaluating the following expression:
 98     //
 99     // (hdr - rsp) & (aligned_mask - page_size)
100     //
101     // assuming both the stack pointer and page_size have their least
102     // significant 2 bits cleared and page_size is a power of 2
103     subptr(hdr, rsp);
104     andptr(hdr, aligned_mask - (int)os::vm_page_size());
105     // for recursive locking, the result is zero => save it in the displaced header
106     // location (null in the displaced hdr location indicates recursive locking)
107     movptr(Address(disp_hdr, 0), hdr);
108     // otherwise we don't care about the result and handle locking via runtime call
109     jcc(Assembler::notZero, slow_case);
110     // done
111     bind(done);
112     inc_held_monitor_count();
113   }
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     // Lacking registers and thread on x86_32. Always take slow path.
143     jmp(slow_case);
144 #endif
145   } else if (LockingMode == LM_LEGACY) {
146     // test if object header is pointing to the displaced header, and if so, restore
147     // the displaced header in the object - if the object header is not pointing to
148     // the displaced header, get the object header instead
149     MacroAssembler::lock(); // must be immediately before cmpxchg!
150     cmpxchgptr(hdr, Address(obj, hdr_offset));
151     // if the object header was not pointing to the displaced header,
152     // we do unlocking via runtime call
153     jcc(Assembler::notEqual, slow_case);
154     // done
155     bind(done);
156     dec_held_monitor_count();
157   }
158 }
159 
160 
161 // Defines obj, preserves var_size_in_bytes
162 void C1_MacroAssembler::try_allocate(Register obj, Register var_size_in_bytes, int con_size_in_bytes, Register t1, Register t2, Label& slow_case) {
163   if (UseTLAB) {
164     tlab_allocate(noreg, obj, var_size_in_bytes, con_size_in_bytes, t1, t2, slow_case);
165   } else {
166     jmp(slow_case);
167   }
168 }
169 
170 
171 void C1_MacroAssembler::initialize_header(Register obj, Register klass, Register len, Register t1, Register t2) {
172   assert_different_registers(obj, klass, len);
173   movptr(Address(obj, oopDesc::mark_offset_in_bytes()), checked_cast<int32_t>(markWord::prototype().value()));
174 #ifdef _LP64
175   if (UseCompressedClassPointers) { // Take care not to kill klass
176     movptr(t1, klass);
177     encode_klass_not_null(t1, rscratch1);
178     movl(Address(obj, oopDesc::klass_offset_in_bytes()), t1);
179   } else
180 #endif
181   {
182     movptr(Address(obj, oopDesc::klass_offset_in_bytes()), klass);
183   }
184 
185   if (len->is_valid()) {
186     movl(Address(obj, arrayOopDesc::length_offset_in_bytes()), len);
187 #ifdef _LP64
188     int base_offset = arrayOopDesc::length_offset_in_bytes() + BytesPerInt;
189     if (!is_aligned(base_offset, BytesPerWord)) {
190       assert(is_aligned(base_offset, BytesPerInt), "must be 4-byte aligned");
191       // Clear gap/first 4 bytes following the length field.
192       xorl(t1, t1);
193       movl(Address(obj, base_offset), t1);
194     }
195 #endif
196   }
197 #ifdef _LP64
198   else if (UseCompressedClassPointers) {
199     xorptr(t1, t1);
200     store_klass_gap(obj, t1);
201   }
202 #endif
203 }
204 
205 
206 // preserves obj, destroys len_in_bytes
207 void C1_MacroAssembler::initialize_body(Register obj, Register len_in_bytes, int hdr_size_in_bytes, Register t1) {
208   assert(hdr_size_in_bytes >= 0, "header size must be positive or 0");
209   Label done;
210 
211   // len_in_bytes is positive and ptr sized
212   subptr(len_in_bytes, hdr_size_in_bytes);
213   zero_memory(obj, len_in_bytes, hdr_size_in_bytes, t1);
214   bind(done);
215 }
216 
217 
218 void C1_MacroAssembler::allocate_object(Register obj, Register t1, Register t2, int header_size, int object_size, Register klass, Label& slow_case) {
219   assert(obj == rax, "obj must be in rax, for cmpxchg");
220   assert_different_registers(obj, t1, t2); // XXX really?
221   assert(header_size >= 0 && object_size >= header_size, "illegal sizes");
222 
223   try_allocate(obj, noreg, object_size * BytesPerWord, t1, t2, slow_case);
224 
225   initialize_object(obj, klass, noreg, object_size * HeapWordSize, t1, t2, UseTLAB);
226 }
227 
228 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) {
229   assert((con_size_in_bytes & MinObjAlignmentInBytesMask) == 0,
230          "con_size_in_bytes is not multiple of alignment");
231   const int hdr_size_in_bytes = instanceOopDesc::header_size() * HeapWordSize;
232 
233   initialize_header(obj, klass, noreg, t1, t2);
234 
235   if (!(UseTLAB && ZeroTLAB && is_tlab_allocated)) {
236     // clear rest of allocated space
237     const Register t1_zero = t1;
238     const Register index = t2;
239     const int threshold = 6 * BytesPerWord;   // approximate break even point for code size (see comments below)
240     if (var_size_in_bytes != noreg) {
241       mov(index, var_size_in_bytes);
242       initialize_body(obj, index, hdr_size_in_bytes, t1_zero);
243     } else if (con_size_in_bytes <= threshold) {
244       // use explicit null stores
245       // code size = 2 + 3*n bytes (n = number of fields to clear)
246       xorptr(t1_zero, t1_zero); // use t1_zero reg to clear memory (shorter code)
247       for (int i = hdr_size_in_bytes; i < con_size_in_bytes; i += BytesPerWord)
248         movptr(Address(obj, i), t1_zero);
249     } else if (con_size_in_bytes > hdr_size_in_bytes) {
250       // use loop to null out the fields
251       // code size = 16 bytes for even n (n = number of fields to clear)
252       // initialize last object field first if odd number of fields
253       xorptr(t1_zero, t1_zero); // use t1_zero reg to clear memory (shorter code)
254       movptr(index, (con_size_in_bytes - hdr_size_in_bytes) >> 3);
255       // initialize last object field if constant size is odd
256       if (((con_size_in_bytes - hdr_size_in_bytes) & 4) != 0)
257         movptr(Address(obj, con_size_in_bytes - (1*BytesPerWord)), t1_zero);
258       // initialize remaining object fields: rdx is a multiple of 2
259       { Label loop;
260         bind(loop);
261         movptr(Address(obj, index, Address::times_8, hdr_size_in_bytes - (1*BytesPerWord)),
262                t1_zero);
263         NOT_LP64(movptr(Address(obj, index, Address::times_8, hdr_size_in_bytes - (2*BytesPerWord)),
264                t1_zero);)
265         decrement(index);
266         jcc(Assembler::notZero, loop);
267       }
268     }
269   }
270 
271   if (CURRENT_ENV->dtrace_alloc_probes()) {
272     assert(obj == rax, "must be");
273     call(RuntimeAddress(Runtime1::entry_for(C1StubId::dtrace_object_alloc_id)));
274   }
275 
276   verify_oop(obj);
277 }
278 
279 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, bool zero_array) {
280   assert(obj == rax, "obj must be in rax, for cmpxchg");
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   cmpptr(len, checked_cast<int32_t>(max_array_allocation_length));
288   jcc(Assembler::above, slow_case);
289 
290   const Register arr_size = t2; // okay to be the same
291   // align object end
292   movptr(arr_size, base_offset_in_bytes + MinObjAlignmentInBytesMask);
293   lea(arr_size, Address(arr_size, len, f));
294   andptr(arr_size, ~MinObjAlignmentInBytesMask);
295 
296   try_allocate(obj, arr_size, 0, t1, t2, slow_case);
297 
298   initialize_header(obj, klass, len, t1, t2);
299 
300   // clear rest of allocated space
301   if (zero_array) {
302     const Register len_zero = len;
303     // Align-up to word boundary, because we clear the 4 bytes potentially
304     // following the length field in initialize_header().
305     int base_offset = align_up(base_offset_in_bytes, BytesPerWord);
306     initialize_body(obj, arr_size, base_offset, len_zero);
307   }
308 
309   if (CURRENT_ENV->dtrace_alloc_probes()) {
310     assert(obj == rax, "must be");
311     call(RuntimeAddress(Runtime1::entry_for(C1StubId::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