quick_entrypoints_arm64.S revision d72945c6b18831630af8755fcf041f5a59c82cae
1/*
2 * Copyright (C) 2014 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include "asm_support_arm64.S"
18
19#include "arch/quick_alloc_entrypoints.S"
20
21
22    /*
23     * Macro that sets up the callee save frame to conform with
24     * Runtime::CreateCalleeSaveMethod(kSaveAll)
25     */
26.macro SETUP_SAVE_ALL_CALLEE_SAVE_FRAME
27    adrp xIP0, :got:_ZN3art7Runtime9instance_E
28    ldr xIP0, [xIP0, #:got_lo12:_ZN3art7Runtime9instance_E]
29
30    // Our registers aren't intermixed - just spill in order.
31    ldr xIP0, [xIP0]  // xIP0 = & (art::Runtime * art::Runtime.instance_) .
32
33    // xIP0 = (ArtMethod*) Runtime.instance_.callee_save_methods[kRefAndArgs]  .
34    // Loads appropriate callee-save-method.
35    ldr xIP0, [xIP0, RUNTIME_SAVE_ALL_CALLEE_SAVE_FRAME_OFFSET ]
36
37    sub sp, sp, #176
38    .cfi_adjust_cfa_offset 176
39
40    // Ugly compile-time check, but we only have the preprocessor.
41#if (FRAME_SIZE_SAVE_ALL_CALLEE_SAVE != 176)
42#error "SAVE_ALL_CALLEE_SAVE_FRAME(ARM64) size not as expected."
43#endif
44
45    // Stack alignment filler [sp, #8].
46    // FP callee-saves.
47    stp d8, d9,   [sp, #16]
48    stp d10, d11, [sp, #32]
49    stp d12, d13, [sp, #48]
50    stp d14, d15, [sp, #64]
51
52    // GP callee-saves
53    stp x19, x20, [sp, #80]
54    .cfi_rel_offset x19, 80
55    .cfi_rel_offset x20, 88
56
57    stp x21, x22, [sp, #96]
58    .cfi_rel_offset x21, 96
59    .cfi_rel_offset x22, 104
60
61    stp x23, x24, [sp, #112]
62    .cfi_rel_offset x23, 112
63    .cfi_rel_offset x24, 120
64
65    stp x25, x26, [sp, #128]
66    .cfi_rel_offset x25, 128
67    .cfi_rel_offset x26, 136
68
69    stp x27, x28, [sp, #144]
70    .cfi_rel_offset x27, 144
71    .cfi_rel_offset x28, 152
72
73    stp x29, xLR, [sp, #160]
74    .cfi_rel_offset x29, 160
75    .cfi_rel_offset x30, 168
76
77    // Store ArtMethod* Runtime::callee_save_methods_[kRefsAndArgs].
78    str xIP0, [sp]
79    // Place sp in Thread::Current()->top_quick_frame.
80    mov xIP0, sp
81    str xIP0, [xSELF, # THREAD_TOP_QUICK_FRAME_OFFSET]
82.endm
83
84    /*
85     * Macro that sets up the callee save frame to conform with
86     * Runtime::CreateCalleeSaveMethod(kRefsOnly).
87     */
88.macro SETUP_REFS_ONLY_CALLEE_SAVE_FRAME
89    adrp xIP0, :got:_ZN3art7Runtime9instance_E
90    ldr xIP0, [xIP0, #:got_lo12:_ZN3art7Runtime9instance_E]
91
92    // Our registers aren't intermixed - just spill in order.
93    ldr xIP0, [xIP0]  // xIP0 = & (art::Runtime * art::Runtime.instance_) .
94
95    // xIP0 = (ArtMethod*) Runtime.instance_.callee_save_methods[kRefOnly]  .
96    // Loads appropriate callee-save-method.
97    ldr xIP0, [xIP0, RUNTIME_REFS_ONLY_CALLEE_SAVE_FRAME_OFFSET ]
98
99    sub sp, sp, #96
100    .cfi_adjust_cfa_offset 96
101
102    // Ugly compile-time check, but we only have the preprocessor.
103#if (FRAME_SIZE_REFS_ONLY_CALLEE_SAVE != 96)
104#error "REFS_ONLY_CALLEE_SAVE_FRAME(ARM64) size not as expected."
105#endif
106
107    // GP callee-saves.
108    // x20 paired with ArtMethod* - see below.
109    stp x21, x22, [sp, #16]
110    .cfi_rel_offset x21, 16
111    .cfi_rel_offset x22, 24
112
113    stp x23, x24, [sp, #32]
114    .cfi_rel_offset x23, 32
115    .cfi_rel_offset x24, 40
116
117    stp x25, x26, [sp, #48]
118    .cfi_rel_offset x25, 48
119    .cfi_rel_offset x26, 56
120
121    stp x27, x28, [sp, #64]
122    .cfi_rel_offset x27, 64
123    .cfi_rel_offset x28, 72
124
125    stp x29, xLR, [sp, #80]
126    .cfi_rel_offset x29, 80
127    .cfi_rel_offset x30, 88
128
129    // Store ArtMethod* Runtime::callee_save_methods_[kRefsOnly].
130    stp xIP0, x20, [sp]
131    .cfi_rel_offset x20, 8
132
133    // Place sp in Thread::Current()->top_quick_frame.
134    mov xIP0, sp
135    str xIP0, [xSELF, # THREAD_TOP_QUICK_FRAME_OFFSET]
136.endm
137
138// TODO: Probably no need to restore registers preserved by aapcs64.
139.macro RESTORE_REFS_ONLY_CALLEE_SAVE_FRAME
140    // Callee-saves.
141    ldr x20, [sp, #8]
142    .cfi_restore x20
143
144    ldp x21, x22, [sp, #16]
145    .cfi_restore x21
146    .cfi_restore x22
147
148    ldp x23, x24, [sp, #32]
149    .cfi_restore x23
150    .cfi_restore x24
151
152    ldp x25, x26, [sp, #48]
153    .cfi_restore x25
154    .cfi_restore x26
155
156    ldp x27, x28, [sp, #64]
157    .cfi_restore x27
158    .cfi_restore x28
159
160    ldp x29, xLR, [sp, #80]
161    .cfi_restore x29
162    .cfi_restore x30
163
164    add sp, sp, #96
165    .cfi_adjust_cfa_offset -96
166.endm
167
168.macro POP_REFS_ONLY_CALLEE_SAVE_FRAME
169    add sp, sp, #96
170    .cfi_adjust_cfa_offset - 96
171.endm
172
173.macro RESTORE_REFS_ONLY_CALLEE_SAVE_FRAME_AND_RETURN
174    RESTORE_REFS_ONLY_CALLEE_SAVE_FRAME
175    ret
176.endm
177
178
179.macro SETUP_REFS_AND_ARGS_CALLEE_SAVE_FRAME_INTERNAL
180    sub sp, sp, #224
181    .cfi_adjust_cfa_offset 224
182
183    // Ugly compile-time check, but we only have the preprocessor.
184#if (FRAME_SIZE_REFS_AND_ARGS_CALLEE_SAVE != 224)
185#error "REFS_AND_ARGS_CALLEE_SAVE_FRAME(ARM64) size not as expected."
186#endif
187
188    // Stack alignment filler [sp, #8].
189    // FP args.
190    stp d0, d1, [sp, #16]
191    stp d2, d3, [sp, #32]
192    stp d4, d5, [sp, #48]
193    stp d6, d7, [sp, #64]
194
195    // Core args.
196    stp x1, x2, [sp, #80]
197    .cfi_rel_offset x1, 80
198    .cfi_rel_offset x2, 88
199
200    stp x3, x4, [sp, #96]
201    .cfi_rel_offset x3, 96
202    .cfi_rel_offset x4, 104
203
204    stp x5, x6, [sp, #112]
205    .cfi_rel_offset x5, 112
206    .cfi_rel_offset x6, 120
207
208    // x7, Callee-saves.
209    stp x7, x20, [sp, #128]
210    .cfi_rel_offset x7, 128
211    .cfi_rel_offset x20, 136
212
213    stp x21, x22, [sp, #144]
214    .cfi_rel_offset x21, 144
215    .cfi_rel_offset x22, 152
216
217    stp x23, x24, [sp, #160]
218    .cfi_rel_offset x23, 160
219    .cfi_rel_offset x24, 168
220
221    stp x25, x26, [sp, #176]
222    .cfi_rel_offset x25, 176
223    .cfi_rel_offset x26, 184
224
225    stp x27, x28, [sp, #192]
226    .cfi_rel_offset x27, 192
227    .cfi_rel_offset x28, 200
228
229    // x29(callee-save) and LR.
230    stp x29, xLR, [sp, #208]
231    .cfi_rel_offset x29, 208
232    .cfi_rel_offset x30, 216
233
234.endm
235
236    /*
237     * Macro that sets up the callee save frame to conform with
238     * Runtime::CreateCalleeSaveMethod(kRefsAndArgs).
239     *
240     * TODO This is probably too conservative - saving FP & LR.
241     */
242.macro SETUP_REFS_AND_ARGS_CALLEE_SAVE_FRAME
243    adrp xIP0, :got:_ZN3art7Runtime9instance_E
244    ldr xIP0, [xIP0, #:got_lo12:_ZN3art7Runtime9instance_E]
245
246    // Our registers aren't intermixed - just spill in order.
247    ldr xIP0, [xIP0]  // xIP0 = & (art::Runtime * art::Runtime.instance_) .
248
249    // xIP0 = (ArtMethod*) Runtime.instance_.callee_save_methods[kRefAndArgs]  .
250    ldr xIP0, [xIP0, RUNTIME_REFS_AND_ARGS_CALLEE_SAVE_FRAME_OFFSET ]
251
252    SETUP_REFS_AND_ARGS_CALLEE_SAVE_FRAME_INTERNAL
253
254    str xIP0, [sp]    // Store ArtMethod* Runtime::callee_save_methods_[kRefsAndArgs]
255    // Place sp in Thread::Current()->top_quick_frame.
256    mov xIP0, sp
257    str xIP0, [xSELF, # THREAD_TOP_QUICK_FRAME_OFFSET]
258.endm
259
260.macro SETUP_REFS_AND_ARGS_CALLEE_SAVE_FRAME_WITH_METHOD_IN_X0
261    SETUP_REFS_AND_ARGS_CALLEE_SAVE_FRAME_INTERNAL
262    str x0, [sp, #0]  // Store ArtMethod* to bottom of stack.
263    // Place sp in Thread::Current()->top_quick_frame.
264    mov xIP0, sp
265    str xIP0, [xSELF, # THREAD_TOP_QUICK_FRAME_OFFSET]
266.endm
267
268// TODO: Probably no need to restore registers preserved by aapcs64.
269.macro RESTORE_REFS_AND_ARGS_CALLEE_SAVE_FRAME
270    // FP args.
271    ldp d0, d1, [sp, #16]
272    ldp d2, d3, [sp, #32]
273    ldp d4, d5, [sp, #48]
274    ldp d6, d7, [sp, #64]
275
276    // Core args.
277    ldp x1, x2, [sp, #80]
278    .cfi_restore x1
279    .cfi_restore x2
280
281    ldp x3, x4, [sp, #96]
282    .cfi_restore x3
283    .cfi_restore x4
284
285    ldp x5, x6, [sp, #112]
286    .cfi_restore x5
287    .cfi_restore x6
288
289    // x7, Callee-saves.
290    ldp x7, x20, [sp, #128]
291    .cfi_restore x7
292    .cfi_restore x20
293
294    ldp x21, x22, [sp, #144]
295    .cfi_restore x21
296    .cfi_restore x22
297
298    ldp x23, x24, [sp, #160]
299    .cfi_restore x23
300    .cfi_restore x24
301
302    ldp x25, x26, [sp, #176]
303    .cfi_restore x25
304    .cfi_restore x26
305
306    ldp x27, x28, [sp, #192]
307    .cfi_restore x27
308    .cfi_restore x28
309
310    // x29(callee-save) and LR.
311    ldp x29, xLR, [sp, #208]
312    .cfi_restore x29
313    .cfi_restore x30
314
315    add sp, sp, #224
316    .cfi_adjust_cfa_offset -224
317.endm
318
319.macro RETURN_IF_RESULT_IS_ZERO
320    cbnz x0, 1f                // result non-zero branch over
321    ret                        // return
3221:
323.endm
324
325.macro RETURN_IF_RESULT_IS_NON_ZERO
326    cbz x0, 1f                 // result zero branch over
327    ret                        // return
3281:
329.endm
330
331    /*
332     * Macro that set calls through to artDeliverPendingExceptionFromCode, where the pending
333     * exception is Thread::Current()->exception_
334     */
335.macro DELIVER_PENDING_EXCEPTION
336    SETUP_SAVE_ALL_CALLEE_SAVE_FRAME
337    mov x0, xSELF
338
339    // Point of no return.
340    b artDeliverPendingExceptionFromCode  // artDeliverPendingExceptionFromCode(Thread*)
341    brk 0  // Unreached
342.endm
343
344.macro RETURN_OR_DELIVER_PENDING_EXCEPTION_REG reg
345    ldr \reg, [xSELF, # THREAD_EXCEPTION_OFFSET]   // Get exception field.
346    cbnz \reg, 1f
347    ret
3481:
349    DELIVER_PENDING_EXCEPTION
350.endm
351
352.macro RETURN_OR_DELIVER_PENDING_EXCEPTION
353    RETURN_OR_DELIVER_PENDING_EXCEPTION_REG xIP0
354.endm
355
356// Same as above with x1. This is helpful in stubs that want to avoid clobbering another register.
357.macro RETURN_OR_DELIVER_PENDING_EXCEPTION_X1
358    RETURN_OR_DELIVER_PENDING_EXCEPTION_REG x1
359.endm
360
361.macro RETURN_IF_W0_IS_ZERO_OR_DELIVER
362    cbnz w0, 1f                // result non-zero branch over
363    ret                        // return
3641:
365    DELIVER_PENDING_EXCEPTION
366.endm
367
368.macro NO_ARG_RUNTIME_EXCEPTION c_name, cxx_name
369    .extern \cxx_name
370ENTRY \c_name
371    SETUP_SAVE_ALL_CALLEE_SAVE_FRAME  // save all registers as basis for long jump context
372    mov x0, xSELF                     // pass Thread::Current
373    b   \cxx_name                     // \cxx_name(Thread*)
374END \c_name
375.endm
376
377.macro ONE_ARG_RUNTIME_EXCEPTION c_name, cxx_name
378    .extern \cxx_name
379ENTRY \c_name
380    SETUP_SAVE_ALL_CALLEE_SAVE_FRAME  // save all registers as basis for long jump context.
381    mov x1, xSELF                     // pass Thread::Current.
382    b   \cxx_name                     // \cxx_name(arg, Thread*).
383    brk 0
384END \c_name
385.endm
386
387.macro TWO_ARG_RUNTIME_EXCEPTION c_name, cxx_name
388    .extern \cxx_name
389ENTRY \c_name
390    SETUP_SAVE_ALL_CALLEE_SAVE_FRAME  // save all registers as basis for long jump context
391    mov x2, xSELF                     // pass Thread::Current
392    b   \cxx_name                     // \cxx_name(arg1, arg2, Thread*)
393    brk 0
394END \c_name
395.endm
396
397    /*
398     * Called by managed code, saves callee saves and then calls artThrowException
399     * that will place a mock Method* at the bottom of the stack. Arg1 holds the exception.
400     */
401ONE_ARG_RUNTIME_EXCEPTION art_quick_deliver_exception, artDeliverExceptionFromCode
402
403    /*
404     * Called by managed code to create and deliver a NullPointerException.
405     */
406NO_ARG_RUNTIME_EXCEPTION art_quick_throw_null_pointer_exception, artThrowNullPointerExceptionFromCode
407
408    /*
409     * Called by managed code to create and deliver an ArithmeticException.
410     */
411NO_ARG_RUNTIME_EXCEPTION art_quick_throw_div_zero, artThrowDivZeroFromCode
412
413    /*
414     * Called by managed code to create and deliver an ArrayIndexOutOfBoundsException. Arg1 holds
415     * index, arg2 holds limit.
416     */
417TWO_ARG_RUNTIME_EXCEPTION art_quick_throw_array_bounds, artThrowArrayBoundsFromCode
418
419    /*
420     * Called by managed code to create and deliver a StackOverflowError.
421     */
422NO_ARG_RUNTIME_EXCEPTION art_quick_throw_stack_overflow, artThrowStackOverflowFromCode
423
424    /*
425     * Called by managed code to create and deliver a NoSuchMethodError.
426     */
427ONE_ARG_RUNTIME_EXCEPTION art_quick_throw_no_such_method, artThrowNoSuchMethodFromCode
428
429    /*
430     * All generated callsites for interface invokes and invocation slow paths will load arguments
431     * as usual - except instead of loading arg0/x0 with the target Method*, arg0/x0 will contain
432     * the method_idx.  This wrapper will save arg1-arg3, and call the appropriate C helper.
433     * NOTE: "this" is first visible argument of the target, and so can be found in arg1/x1.
434     *
435     * The helper will attempt to locate the target and return a 128-bit result in x0/x1 consisting
436     * of the target Method* in x0 and method->code_ in x1.
437     *
438     * If unsuccessful, the helper will return null/????. There will be a pending exception in the
439     * thread and we branch to another stub to deliver it.
440     *
441     * On success this wrapper will restore arguments and *jump* to the target, leaving the lr
442     * pointing back to the original caller.
443     *
444     * Adapted from ARM32 code.
445     *
446     * Clobbers xIP0.
447     */
448.macro INVOKE_TRAMPOLINE_BODY cxx_name
449    .extern \cxx_name
450    SETUP_REFS_AND_ARGS_CALLEE_SAVE_FRAME  // save callee saves in case allocation triggers GC
451    // Helper signature is always
452    // (method_idx, *this_object, *caller_method, *self, sp)
453
454    mov    x2, xSELF                      // pass Thread::Current
455    mov    x3, sp
456    bl     \cxx_name                      // (method_idx, this, Thread*, SP)
457    mov    xIP0, x1                       // save Method*->code_
458    RESTORE_REFS_AND_ARGS_CALLEE_SAVE_FRAME
459    cbz    x0, 1f                         // did we find the target? if not go to exception delivery
460    br     xIP0                           // tail call to target
4611:
462    DELIVER_PENDING_EXCEPTION
463.endm
464.macro INVOKE_TRAMPOLINE c_name, cxx_name
465ENTRY \c_name
466    INVOKE_TRAMPOLINE_BODY \cxx_name
467END \c_name
468.endm
469
470INVOKE_TRAMPOLINE art_quick_invoke_interface_trampoline_with_access_check, artInvokeInterfaceTrampolineWithAccessCheck
471
472INVOKE_TRAMPOLINE art_quick_invoke_static_trampoline_with_access_check, artInvokeStaticTrampolineWithAccessCheck
473INVOKE_TRAMPOLINE art_quick_invoke_direct_trampoline_with_access_check, artInvokeDirectTrampolineWithAccessCheck
474INVOKE_TRAMPOLINE art_quick_invoke_super_trampoline_with_access_check, artInvokeSuperTrampolineWithAccessCheck
475INVOKE_TRAMPOLINE art_quick_invoke_virtual_trampoline_with_access_check, artInvokeVirtualTrampolineWithAccessCheck
476
477
478.macro INVOKE_STUB_CREATE_FRAME
479
480SAVE_SIZE=15*8   // x4, x5, x19, x20, x21, x22, x23, x24, x25, x26, x27, x28, SP, LR, FP saved.
481SAVE_SIZE_AND_METHOD=SAVE_SIZE+8
482
483
484    mov x9, sp                             // Save stack pointer.
485    .cfi_register sp,x9
486
487    add x10, x2, # SAVE_SIZE_AND_METHOD    // calculate size of frame.
488    sub x10, sp, x10                       // Calculate SP position - saves + ArtMethod* + args
489    and x10, x10, # ~0xf                   // Enforce 16 byte stack alignment.
490    mov sp, x10                            // Set new SP.
491
492    sub x10, x9, #SAVE_SIZE                // Calculate new FP (later). Done here as we must move SP
493    .cfi_def_cfa_register x10              // before this.
494    .cfi_adjust_cfa_offset SAVE_SIZE
495
496    str x28, [x10, #112]
497    .cfi_rel_offset x28, 112
498
499    stp x26, x27, [x10, #96]
500    .cfi_rel_offset x26, 96
501    .cfi_rel_offset x27, 104
502
503    stp x24, x25, [x10, #80]
504    .cfi_rel_offset x24, 80
505    .cfi_rel_offset x25, 88
506
507    stp x22, x23, [x10, #64]
508    .cfi_rel_offset x22, 64
509    .cfi_rel_offset x23, 72
510
511    stp x20, x21, [x10, #48]
512    .cfi_rel_offset x20, 48
513    .cfi_rel_offset x21, 56
514
515    stp x9, x19, [x10, #32]                // Save old stack pointer and x19.
516    .cfi_rel_offset sp, 32
517    .cfi_rel_offset x19, 40
518
519    stp x4, x5, [x10, #16]                 // Save result and shorty addresses.
520    .cfi_rel_offset x4, 16
521    .cfi_rel_offset x5, 24
522
523    stp xFP, xLR, [x10]                    // Store LR & FP.
524    .cfi_rel_offset x29, 0
525    .cfi_rel_offset x30, 8
526
527    mov xFP, x10                           // Use xFP now, as it's callee-saved.
528    .cfi_def_cfa_register x29
529    mov xSELF, x3                          // Move thread pointer into SELF register.
530
531    // Copy arguments into stack frame.
532    // Use simple copy routine for now.
533    // 4 bytes per slot.
534    // X1 - source address
535    // W2 - args length
536    // X9 - destination address.
537    // W10 - temporary
538    add x9, sp, #8                         // Destination address is bottom of stack + null.
539
540    // Copy parameters into the stack. Use numeric label as this is a macro and Clang's assembler
541    // does not have unique-id variables.
5421:
543    cmp w2, #0
544    beq 2f
545    sub w2, w2, #4      // Need 65536 bytes of range.
546    ldr w10, [x1, x2]
547    str w10, [x9, x2]
548
549    b 1b
550
5512:
552    // Store null into ArtMethod* at bottom of frame.
553    str xzr, [sp]
554.endm
555
556.macro INVOKE_STUB_CALL_AND_RETURN
557
558    // load method-> METHOD_QUICK_CODE_OFFSET
559    ldr x9, [x0, #ART_METHOD_QUICK_CODE_OFFSET_64]
560    // Branch to method.
561    blr x9
562
563    // Restore return value address and shorty address.
564    ldp x4,x5, [xFP, #16]
565    .cfi_restore x4
566    .cfi_restore x5
567
568    ldr x28, [xFP, #112]
569    .cfi_restore x28
570
571    ldp x26, x27, [xFP, #96]
572    .cfi_restore x26
573    .cfi_restore x27
574
575    ldp x24, x25, [xFP, #80]
576    .cfi_restore x24
577    .cfi_restore x25
578
579    ldp x22, x23, [xFP, #64]
580    .cfi_restore x22
581    .cfi_restore x23
582
583    ldp x20, x21, [xFP, #48]
584    .cfi_restore x20
585    .cfi_restore x21
586
587    // Store result (w0/x0/s0/d0) appropriately, depending on resultType.
588    ldrb w10, [x5]
589
590    // Check the return type and store the correct register into the jvalue in memory.
591    // Use numeric label as this is a macro and Clang's assembler does not have unique-id variables.
592
593    // Don't set anything for a void type.
594    cmp w10, #'V'
595    beq 3f
596
597    // Is it a double?
598    cmp w10, #'D'
599    bne 1f
600    str d0, [x4]
601    b 3f
602
6031:  // Is it a float?
604    cmp w10, #'F'
605    bne 2f
606    str s0, [x4]
607    b 3f
608
6092:  // Just store x0. Doesn't matter if it is 64 or 32 bits.
610    str x0, [x4]
611
6123:  // Finish up.
613    ldp x2, x19, [xFP, #32]   // Restore stack pointer and x19.
614    .cfi_restore x19
615    mov sp, x2
616    .cfi_restore sp
617
618    ldp xFP, xLR, [xFP]    // Restore old frame pointer and link register.
619    .cfi_restore x29
620    .cfi_restore x30
621
622    ret
623
624.endm
625
626
627/*
628 *  extern"C" void art_quick_invoke_stub(ArtMethod *method,   x0
629 *                                       uint32_t  *args,     x1
630 *                                       uint32_t argsize,    w2
631 *                                       Thread *self,        x3
632 *                                       JValue *result,      x4
633 *                                       char   *shorty);     x5
634 *  +----------------------+
635 *  |                      |
636 *  |  C/C++ frame         |
637 *  |       LR''           |
638 *  |       FP''           | <- SP'
639 *  +----------------------+
640 *  +----------------------+
641 *  |        x28           | <- TODO: Remove callee-saves.
642 *  |         :            |
643 *  |        x19           |
644 *  |        SP'           |
645 *  |        X5            |
646 *  |        X4            |        Saved registers
647 *  |        LR'           |
648 *  |        FP'           | <- FP
649 *  +----------------------+
650 *  | uint32_t out[n-1]    |
651 *  |    :      :          |        Outs
652 *  | uint32_t out[0]      |
653 *  | ArtMethod*           | <- SP  value=null
654 *  +----------------------+
655 *
656 * Outgoing registers:
657 *  x0    - Method*
658 *  x1-x7 - integer parameters.
659 *  d0-d7 - Floating point parameters.
660 *  xSELF = self
661 *  SP = & of ArtMethod*
662 *  x1 = "this" pointer.
663 *
664 */
665ENTRY art_quick_invoke_stub
666    // Spill registers as per AACPS64 calling convention.
667    INVOKE_STUB_CREATE_FRAME
668
669    // Fill registers x/w1 to x/w7 and s/d0 to s/d7 with parameters.
670    // Parse the passed shorty to determine which register to load.
671    // Load addresses for routines that load WXSD registers.
672    adr  x11, .LstoreW2
673    adr  x12, .LstoreX2
674    adr  x13, .LstoreS0
675    adr  x14, .LstoreD0
676
677    // Initialize routine offsets to 0 for integers and floats.
678    // x8 for integers, x15 for floating point.
679    mov x8, #0
680    mov x15, #0
681
682    add x10, x5, #1         // Load shorty address, plus one to skip return value.
683    ldr w1, [x9],#4         // Load "this" parameter, and increment arg pointer.
684
685    // Loop to fill registers.
686.LfillRegisters:
687    ldrb w17, [x10], #1       // Load next character in signature, and increment.
688    cbz w17, .LcallFunction   // Exit at end of signature. Shorty 0 terminated.
689
690    cmp  w17, #'F' // is this a float?
691    bne .LisDouble
692
693    cmp x15, # 8*12         // Skip this load if all registers full.
694    beq .Ladvance4
695
696    add x17, x13, x15       // Calculate subroutine to jump to.
697    br  x17
698
699.LisDouble:
700    cmp w17, #'D'           // is this a double?
701    bne .LisLong
702
703    cmp x15, # 8*12         // Skip this load if all registers full.
704    beq .Ladvance8
705
706    add x17, x14, x15       // Calculate subroutine to jump to.
707    br x17
708
709.LisLong:
710    cmp w17, #'J'           // is this a long?
711    bne .LisOther
712
713    cmp x8, # 6*12          // Skip this load if all registers full.
714    beq .Ladvance8
715
716    add x17, x12, x8        // Calculate subroutine to jump to.
717    br x17
718
719.LisOther:                  // Everything else takes one vReg.
720    cmp x8, # 6*12          // Skip this load if all registers full.
721    beq .Ladvance4
722
723    add x17, x11, x8        // Calculate subroutine to jump to.
724    br x17
725
726.Ladvance4:
727    add x9, x9, #4
728    b .LfillRegisters
729
730.Ladvance8:
731    add x9, x9, #8
732    b .LfillRegisters
733
734// Macro for loading a parameter into a register.
735//  counter - the register with offset into these tables
736//  size - the size of the register - 4 or 8 bytes.
737//  register - the name of the register to be loaded.
738.macro LOADREG counter size register return
739    ldr \register , [x9], #\size
740    add \counter, \counter, 12
741    b \return
742.endm
743
744// Store ints.
745.LstoreW2:
746    LOADREG x8 4 w2 .LfillRegisters
747    LOADREG x8 4 w3 .LfillRegisters
748    LOADREG x8 4 w4 .LfillRegisters
749    LOADREG x8 4 w5 .LfillRegisters
750    LOADREG x8 4 w6 .LfillRegisters
751    LOADREG x8 4 w7 .LfillRegisters
752
753// Store longs.
754.LstoreX2:
755    LOADREG x8 8 x2 .LfillRegisters
756    LOADREG x8 8 x3 .LfillRegisters
757    LOADREG x8 8 x4 .LfillRegisters
758    LOADREG x8 8 x5 .LfillRegisters
759    LOADREG x8 8 x6 .LfillRegisters
760    LOADREG x8 8 x7 .LfillRegisters
761
762// Store singles.
763.LstoreS0:
764    LOADREG x15 4 s0 .LfillRegisters
765    LOADREG x15 4 s1 .LfillRegisters
766    LOADREG x15 4 s2 .LfillRegisters
767    LOADREG x15 4 s3 .LfillRegisters
768    LOADREG x15 4 s4 .LfillRegisters
769    LOADREG x15 4 s5 .LfillRegisters
770    LOADREG x15 4 s6 .LfillRegisters
771    LOADREG x15 4 s7 .LfillRegisters
772
773// Store doubles.
774.LstoreD0:
775    LOADREG x15 8 d0 .LfillRegisters
776    LOADREG x15 8 d1 .LfillRegisters
777    LOADREG x15 8 d2 .LfillRegisters
778    LOADREG x15 8 d3 .LfillRegisters
779    LOADREG x15 8 d4 .LfillRegisters
780    LOADREG x15 8 d5 .LfillRegisters
781    LOADREG x15 8 d6 .LfillRegisters
782    LOADREG x15 8 d7 .LfillRegisters
783
784
785.LcallFunction:
786
787    INVOKE_STUB_CALL_AND_RETURN
788
789END art_quick_invoke_stub
790
791/*  extern"C"
792 *     void art_quick_invoke_static_stub(ArtMethod *method,   x0
793 *                                       uint32_t  *args,     x1
794 *                                       uint32_t argsize,    w2
795 *                                       Thread *self,        x3
796 *                                       JValue *result,      x4
797 *                                       char   *shorty);     x5
798 */
799ENTRY art_quick_invoke_static_stub
800    // Spill registers as per AACPS64 calling convention.
801    INVOKE_STUB_CREATE_FRAME
802
803    // Fill registers x/w1 to x/w7 and s/d0 to s/d7 with parameters.
804    // Parse the passed shorty to determine which register to load.
805    // Load addresses for routines that load WXSD registers.
806    adr  x11, .LstoreW1_2
807    adr  x12, .LstoreX1_2
808    adr  x13, .LstoreS0_2
809    adr  x14, .LstoreD0_2
810
811    // Initialize routine offsets to 0 for integers and floats.
812    // x8 for integers, x15 for floating point.
813    mov x8, #0
814    mov x15, #0
815
816    add x10, x5, #1     // Load shorty address, plus one to skip return value.
817
818    // Loop to fill registers.
819.LfillRegisters2:
820    ldrb w17, [x10], #1         // Load next character in signature, and increment.
821    cbz w17, .LcallFunction2    // Exit at end of signature. Shorty 0 terminated.
822
823    cmp  w17, #'F'          // is this a float?
824    bne .LisDouble2
825
826    cmp x15, # 8*12         // Skip this load if all registers full.
827    beq .Ladvance4_2
828
829    add x17, x13, x15       // Calculate subroutine to jump to.
830    br  x17
831
832.LisDouble2:
833    cmp w17, #'D'           // is this a double?
834    bne .LisLong2
835
836    cmp x15, # 8*12         // Skip this load if all registers full.
837    beq .Ladvance8_2
838
839    add x17, x14, x15       // Calculate subroutine to jump to.
840    br x17
841
842.LisLong2:
843    cmp w17, #'J'           // is this a long?
844    bne .LisOther2
845
846    cmp x8, # 7*12          // Skip this load if all registers full.
847    beq .Ladvance8_2
848
849    add x17, x12, x8        // Calculate subroutine to jump to.
850    br x17
851
852.LisOther2:                 // Everything else takes one vReg.
853    cmp x8, # 7*12          // Skip this load if all registers full.
854    beq .Ladvance4_2
855
856    add x17, x11, x8        // Calculate subroutine to jump to.
857    br x17
858
859.Ladvance4_2:
860    add x9, x9, #4
861    b .LfillRegisters2
862
863.Ladvance8_2:
864    add x9, x9, #8
865    b .LfillRegisters2
866
867// Store ints.
868.LstoreW1_2:
869    LOADREG x8 4 w1 .LfillRegisters2
870    LOADREG x8 4 w2 .LfillRegisters2
871    LOADREG x8 4 w3 .LfillRegisters2
872    LOADREG x8 4 w4 .LfillRegisters2
873    LOADREG x8 4 w5 .LfillRegisters2
874    LOADREG x8 4 w6 .LfillRegisters2
875    LOADREG x8 4 w7 .LfillRegisters2
876
877// Store longs.
878.LstoreX1_2:
879    LOADREG x8 8 x1 .LfillRegisters2
880    LOADREG x8 8 x2 .LfillRegisters2
881    LOADREG x8 8 x3 .LfillRegisters2
882    LOADREG x8 8 x4 .LfillRegisters2
883    LOADREG x8 8 x5 .LfillRegisters2
884    LOADREG x8 8 x6 .LfillRegisters2
885    LOADREG x8 8 x7 .LfillRegisters2
886
887// Store singles.
888.LstoreS0_2:
889    LOADREG x15 4 s0 .LfillRegisters2
890    LOADREG x15 4 s1 .LfillRegisters2
891    LOADREG x15 4 s2 .LfillRegisters2
892    LOADREG x15 4 s3 .LfillRegisters2
893    LOADREG x15 4 s4 .LfillRegisters2
894    LOADREG x15 4 s5 .LfillRegisters2
895    LOADREG x15 4 s6 .LfillRegisters2
896    LOADREG x15 4 s7 .LfillRegisters2
897
898// Store doubles.
899.LstoreD0_2:
900    LOADREG x15 8 d0 .LfillRegisters2
901    LOADREG x15 8 d1 .LfillRegisters2
902    LOADREG x15 8 d2 .LfillRegisters2
903    LOADREG x15 8 d3 .LfillRegisters2
904    LOADREG x15 8 d4 .LfillRegisters2
905    LOADREG x15 8 d5 .LfillRegisters2
906    LOADREG x15 8 d6 .LfillRegisters2
907    LOADREG x15 8 d7 .LfillRegisters2
908
909
910.LcallFunction2:
911
912    INVOKE_STUB_CALL_AND_RETURN
913
914END art_quick_invoke_static_stub
915
916
917
918/*  extern"C" void art_quick_osr_stub(void** stack,                x0
919 *                                    size_t stack_size_in_bytes,  x1
920 *                                    const uin8_t* native_pc,     x2
921 *                                    JValue *result,              x3
922 *                                    char   *shorty,              x4
923 *                                    Thread *self)                x5
924 */
925ENTRY art_quick_osr_stub
926SAVE_SIZE=15*8   // x3, x4, x19, x20, x21, x22, x23, x24, x25, x26, x27, x28, SP, LR, FP saved.
927    mov x9, sp                             // Save stack pointer.
928    .cfi_register sp,x9
929
930    sub x10, sp, # SAVE_SIZE
931    and x10, x10, # ~0xf                   // Enforce 16 byte stack alignment.
932    mov sp, x10                            // Set new SP.
933
934    str x28, [sp, #112]
935    stp x26, x27, [sp, #96]
936    stp x24, x25, [sp, #80]
937    stp x22, x23, [sp, #64]
938    stp x20, x21, [sp, #48]
939    stp x9, x19, [sp, #32]                // Save old stack pointer and x19.
940    stp x3, x4, [sp, #16]                 // Save result and shorty addresses.
941    stp xFP, xLR, [sp]                    // Store LR & FP.
942    mov xSELF, x5                         // Move thread pointer into SELF register.
943
944    sub sp, sp, #16
945    str xzr, [sp]                         // Store null for ArtMethod* slot
946    // Branch to stub.
947    bl .Losr_entry
948    add sp, sp, #16
949
950    // Restore return value address and shorty address.
951    ldp x3,x4, [sp, #16]
952    ldr x28, [sp, #112]
953    ldp x26, x27, [sp, #96]
954    ldp x24, x25, [sp, #80]
955    ldp x22, x23, [sp, #64]
956    ldp x20, x21, [sp, #48]
957
958    // Store result (w0/x0/s0/d0) appropriately, depending on resultType.
959    ldrb w10, [x4]
960
961    // Check the return type and store the correct register into the jvalue in memory.
962
963    // Don't set anything for a void type.
964    cmp w10, #'V'
965    beq .Losr_exit
966
967    // Is it a double?
968    cmp w10, #'D'
969    bne .Lno_double
970    str d0, [x3]
971    b .Losr_exit
972
973.Lno_double:  // Is it a float?
974    cmp w10, #'F'
975    bne .Lno_float
976    str s0, [x3]
977    b .Losr_exit
978
979.Lno_float:  // Just store x0. Doesn't matter if it is 64 or 32 bits.
980    str x0, [x3]
981
982.Losr_exit:  // Finish up.
983    ldp x2, x19, [sp, #32]   // Restore stack pointer and x19.
984    ldp xFP, xLR, [sp]    // Restore old frame pointer and link register.
985    mov sp, x2
986    ret
987
988.Losr_entry:
989    // Update stack pointer for the callee
990    sub sp, sp, x1
991
992    // Update link register slot expected by the callee.
993    sub w1, w1, #8
994    str lr, [sp, x1]
995
996    // Copy arguments into stack frame.
997    // Use simple copy routine for now.
998    // 4 bytes per slot.
999    // X0 - source address
1000    // W1 - args length
1001    // SP - destination address.
1002    // W10 - temporary
1003.Losr_loop_entry:
1004    cmp w1, #0
1005    beq .Losr_loop_exit
1006    sub w1, w1, #4
1007    ldr w10, [x0, x1]
1008    str w10, [sp, x1]
1009    b .Losr_loop_entry
1010
1011.Losr_loop_exit:
1012    // Branch to the OSR entry point.
1013    br x2
1014
1015END art_quick_osr_stub
1016
1017    /*
1018     * On entry x0 is uintptr_t* gprs_ and x1 is uint64_t* fprs_
1019     */
1020
1021ENTRY art_quick_do_long_jump
1022    // Load FPRs
1023    ldp d0, d1, [x1], #16
1024    ldp d2, d3, [x1], #16
1025    ldp d4, d5, [x1], #16
1026    ldp d6, d7, [x1], #16
1027    ldp d8, d9, [x1], #16
1028    ldp d10, d11, [x1], #16
1029    ldp d12, d13, [x1], #16
1030    ldp d14, d15, [x1], #16
1031    ldp d16, d17, [x1], #16
1032    ldp d18, d19, [x1], #16
1033    ldp d20, d21, [x1], #16
1034    ldp d22, d23, [x1], #16
1035    ldp d24, d25, [x1], #16
1036    ldp d26, d27, [x1], #16
1037    ldp d28, d29, [x1], #16
1038    ldp d30, d31, [x1]
1039
1040    // Load GPRs
1041    // TODO: lots of those are smashed, could optimize.
1042    add x0, x0, #30*8
1043    ldp x30, x1, [x0], #-16          // LR & SP
1044    ldp x28, x29, [x0], #-16
1045    ldp x26, x27, [x0], #-16
1046    ldp x24, x25, [x0], #-16
1047    ldp x22, x23, [x0], #-16
1048    ldp x20, x21, [x0], #-16
1049    ldp x18, x19, [x0], #-16
1050    ldp x16, x17, [x0], #-16
1051    ldp x14, x15, [x0], #-16
1052    ldp x12, x13, [x0], #-16
1053    ldp x10, x11, [x0], #-16
1054    ldp x8, x9, [x0], #-16
1055    ldp x6, x7, [x0], #-16
1056    ldp x4, x5, [x0], #-16
1057    ldp x2, x3, [x0], #-16
1058    mov sp, x1
1059
1060    // Need to load PC, it's at the end (after the space for the unused XZR). Use x1.
1061    ldr x1, [x0, #33*8]
1062    // And the value of x0.
1063    ldr x0, [x0]
1064
1065    br  x1
1066END art_quick_do_long_jump
1067
1068    /*
1069     * Entry from managed code that calls artLockObjectFromCode, may block for GC. x0 holds the
1070     * possibly null object to lock.
1071     *
1072     * Derived from arm32 code.
1073     */
1074    .extern artLockObjectFromCode
1075ENTRY art_quick_lock_object
1076    cbz    w0, .Lslow_lock
1077    add    x4, x0, #MIRROR_OBJECT_LOCK_WORD_OFFSET  // exclusive load/store has no immediate anymore
1078.Lretry_lock:
1079    ldr    w2, [xSELF, #THREAD_ID_OFFSET] // TODO: Can the thread ID really change during the loop?
1080    ldxr   w1, [x4]
1081    mov    x3, x1
1082    and    w3, w3, #LOCK_WORD_READ_BARRIER_STATE_MASK_TOGGLED  // zero the read barrier bits
1083    cbnz   w3, .Lnot_unlocked         // already thin locked
1084    // unlocked case - x1: original lock word that's zero except for the read barrier bits.
1085    orr    x2, x1, x2                 // x2 holds thread id with count of 0 with preserved read barrier bits
1086    stxr   w3, w2, [x4]
1087    cbnz   w3, .Llock_stxr_fail       // store failed, retry
1088    dmb    ishld                      // full (LoadLoad|LoadStore) memory barrier
1089    ret
1090.Lnot_unlocked:  // x1: original lock word
1091    lsr    w3, w1, LOCK_WORD_STATE_SHIFT
1092    cbnz   w3, .Lslow_lock            // if either of the top two bits are set, go slow path
1093    eor    w2, w1, w2                 // lock_word.ThreadId() ^ self->ThreadId()
1094    uxth   w2, w2                     // zero top 16 bits
1095    cbnz   w2, .Lslow_lock            // lock word and self thread id's match -> recursive lock
1096                                      // else contention, go to slow path
1097    mov    x3, x1                     // copy the lock word to check count overflow.
1098    and    w3, w3, #LOCK_WORD_READ_BARRIER_STATE_MASK_TOGGLED  // zero the read barrier bits.
1099    add    w2, w3, #LOCK_WORD_THIN_LOCK_COUNT_ONE  // increment count in lock word placing in w2 to check overflow
1100    lsr    w3, w2, LOCK_WORD_READ_BARRIER_STATE_SHIFT  // if either of the upper two bits (28-29) are set, we overflowed.
1101    cbnz   w3, .Lslow_lock            // if we overflow the count go slow path
1102    add    w2, w1, #LOCK_WORD_THIN_LOCK_COUNT_ONE  // increment count for real
1103    stxr   w3, w2, [x4]
1104    cbnz   w3, .Llock_stxr_fail       // store failed, retry
1105    ret
1106.Llock_stxr_fail:
1107    b      .Lretry_lock               // retry
1108.Lslow_lock:
1109    SETUP_REFS_ONLY_CALLEE_SAVE_FRAME  // save callee saves in case we block
1110    mov    x1, xSELF                  // pass Thread::Current
1111    bl     artLockObjectFromCode      // (Object* obj, Thread*)
1112    RESTORE_REFS_ONLY_CALLEE_SAVE_FRAME
1113    RETURN_IF_W0_IS_ZERO_OR_DELIVER
1114END art_quick_lock_object
1115
1116    /*
1117     * Entry from managed code that calls artUnlockObjectFromCode and delivers exception on failure.
1118     * x0 holds the possibly null object to lock.
1119     *
1120     * Derived from arm32 code.
1121     */
1122    .extern artUnlockObjectFromCode
1123ENTRY art_quick_unlock_object
1124    cbz    x0, .Lslow_unlock
1125    add    x4, x0, #MIRROR_OBJECT_LOCK_WORD_OFFSET  // exclusive load/store has no immediate anymore
1126.Lretry_unlock:
1127#ifndef USE_READ_BARRIER
1128    ldr    w1, [x4]
1129#else
1130    ldxr   w1, [x4]                   // Need to use atomic instructions for read barrier
1131#endif
1132    lsr    w2, w1, LOCK_WORD_STATE_SHIFT
1133    cbnz   w2, .Lslow_unlock          // if either of the top two bits are set, go slow path
1134    ldr    w2, [xSELF, #THREAD_ID_OFFSET]
1135    mov    x3, x1                     // copy lock word to check thread id equality
1136    and    w3, w3, #LOCK_WORD_READ_BARRIER_STATE_MASK_TOGGLED  // zero the read barrier bits
1137    eor    w3, w3, w2                 // lock_word.ThreadId() ^ self->ThreadId()
1138    uxth   w3, w3                     // zero top 16 bits
1139    cbnz   w3, .Lslow_unlock          // do lock word and self thread id's match?
1140    mov    x3, x1                     // copy lock word to detect transition to unlocked
1141    and    w3, w3, #LOCK_WORD_READ_BARRIER_STATE_MASK_TOGGLED  // zero the read barrier bits
1142    cmp    w3, #LOCK_WORD_THIN_LOCK_COUNT_ONE
1143    bpl    .Lrecursive_thin_unlock
1144    // transition to unlocked
1145    mov    x3, x1
1146    and    w3, w3, #LOCK_WORD_READ_BARRIER_STATE_MASK  // w3: zero except for the preserved read barrier bits
1147    dmb    ish                        // full (LoadStore|StoreStore) memory barrier
1148#ifndef USE_READ_BARRIER
1149    str    w3, [x4]
1150#else
1151    stxr   w2, w3, [x4]               // Need to use atomic instructions for read barrier
1152    cbnz   w2, .Lunlock_stxr_fail     // store failed, retry
1153#endif
1154    ret
1155.Lrecursive_thin_unlock:  // w1: original lock word
1156    sub    w1, w1, #LOCK_WORD_THIN_LOCK_COUNT_ONE  // decrement count
1157#ifndef USE_READ_BARRIER
1158    str    w1, [x4]
1159#else
1160    stxr   w2, w1, [x4]               // Need to use atomic instructions for read barrier
1161    cbnz   w2, .Lunlock_stxr_fail     // store failed, retry
1162#endif
1163    ret
1164.Lunlock_stxr_fail:
1165    b      .Lretry_unlock               // retry
1166.Lslow_unlock:
1167    SETUP_REFS_ONLY_CALLEE_SAVE_FRAME  // save callee saves in case exception allocation triggers GC
1168    mov    x1, xSELF                  // pass Thread::Current
1169    bl     artUnlockObjectFromCode    // (Object* obj, Thread*)
1170    RESTORE_REFS_ONLY_CALLEE_SAVE_FRAME
1171    RETURN_IF_W0_IS_ZERO_OR_DELIVER
1172END art_quick_unlock_object
1173
1174    /*
1175     * Entry from managed code that calls artIsAssignableFromCode and on failure calls
1176     * artThrowClassCastException.
1177     */
1178    .extern artThrowClassCastException
1179ENTRY art_quick_check_cast
1180    // Store arguments and link register
1181    // Stack needs to be 16B aligned on calls.
1182    stp x0, x1, [sp,#-32]!
1183    .cfi_adjust_cfa_offset 32
1184    .cfi_rel_offset x0, 0
1185    .cfi_rel_offset x1, 8
1186    str xLR, [sp, #24]
1187    .cfi_rel_offset x30, 24
1188
1189    // Call runtime code
1190    bl artIsAssignableFromCode
1191
1192    // Check for exception
1193    cbz x0, .Lthrow_class_cast_exception
1194
1195    // Restore and return
1196    ldr xLR, [sp, #24]
1197    .cfi_restore x30
1198    ldp x0, x1, [sp], #32
1199    .cfi_restore x0
1200    .cfi_restore x1
1201    .cfi_adjust_cfa_offset -32
1202    ret
1203
1204    .cfi_adjust_cfa_offset 32         // Reset unwind info so following code unwinds.
1205
1206.Lthrow_class_cast_exception:
1207    // Restore
1208    ldr xLR, [sp, #24]
1209    .cfi_restore x30
1210    ldp x0, x1, [sp], #32
1211    .cfi_restore x0
1212    .cfi_restore x1
1213    .cfi_adjust_cfa_offset -32
1214
1215    SETUP_SAVE_ALL_CALLEE_SAVE_FRAME  // save all registers as basis for long jump context
1216    mov x2, xSELF                     // pass Thread::Current
1217    b artThrowClassCastException      // (Class*, Class*, Thread*)
1218    brk 0                             // We should not return here...
1219END art_quick_check_cast
1220
1221// Restore xReg's value from [sp, #offset] if xReg is not the same as xExclude.
1222.macro POP_REG_NE xReg, offset, xExclude
1223    .ifnc \xReg, \xExclude
1224        ldr \xReg, [sp, #\offset]     // restore xReg
1225        .cfi_restore \xReg
1226    .endif
1227.endm
1228
1229    /*
1230     * Macro to insert read barrier, only used in art_quick_aput_obj.
1231     * xDest, wDest and xObj are registers, offset is a defined literal such as
1232     * MIRROR_OBJECT_CLASS_OFFSET. Dest needs both x and w versions of the same register to handle
1233     * name mismatch between instructions. This macro uses the lower 32b of register when possible.
1234     * TODO: When read barrier has a fast path, add heap unpoisoning support for the fast path.
1235     */
1236.macro READ_BARRIER xDest, wDest, xObj, offset
1237#ifdef USE_READ_BARRIER
1238    // Store registers used in art_quick_aput_obj (x0-x4, LR), stack is 16B aligned.
1239    stp x0, x1, [sp, #-48]!
1240    .cfi_adjust_cfa_offset 48
1241    .cfi_rel_offset x0, 0
1242    .cfi_rel_offset x1, 8
1243    stp x2, x3, [sp, #16]
1244    .cfi_rel_offset x2, 16
1245    .cfi_rel_offset x3, 24
1246    stp x4, xLR, [sp, #32]
1247    .cfi_rel_offset x4, 32
1248    .cfi_rel_offset x30, 40
1249
1250    // mov x0, \xRef                // pass ref in x0 (no-op for now since parameter ref is unused)
1251    .ifnc \xObj, x1
1252        mov x1, \xObj               // pass xObj
1253    .endif
1254    mov w2, #\offset                // pass offset
1255    bl artReadBarrierSlow           // artReadBarrierSlow(ref, xObj, offset)
1256    // No need to unpoison return value in w0, artReadBarrierSlow() would do the unpoisoning.
1257    .ifnc \wDest, w0
1258        mov \wDest, w0              // save return value in wDest
1259    .endif
1260
1261    // Conditionally restore saved registers
1262    POP_REG_NE x0, 0, \xDest
1263    POP_REG_NE x1, 8, \xDest
1264    POP_REG_NE x2, 16, \xDest
1265    POP_REG_NE x3, 24, \xDest
1266    POP_REG_NE x4, 32, \xDest
1267    ldr xLR, [sp, #40]
1268    .cfi_restore x30
1269    add sp, sp, #48
1270    .cfi_adjust_cfa_offset -48
1271#else
1272    ldr \wDest, [\xObj, #\offset]   // Heap reference = 32b. This also zero-extends to \xDest.
1273    UNPOISON_HEAP_REF \wDest
1274#endif  // USE_READ_BARRIER
1275.endm
1276
1277    /*
1278     * Entry from managed code for array put operations of objects where the value being stored
1279     * needs to be checked for compatibility.
1280     * x0 = array, x1 = index, x2 = value
1281     *
1282     * Currently all values should fit into w0/w1/w2, and w1 always will as indices are 32b. We
1283     * assume, though, that the upper 32b are zeroed out. At least for x1/w1 we can do better by
1284     * using index-zero-extension in load/stores.
1285     *
1286     * Temporaries: x3, x4
1287     * TODO: x4 OK? ip seems wrong here.
1288     */
1289ENTRY art_quick_aput_obj_with_null_and_bound_check
1290    tst x0, x0
1291    bne art_quick_aput_obj_with_bound_check
1292    b art_quick_throw_null_pointer_exception
1293END art_quick_aput_obj_with_null_and_bound_check
1294
1295ENTRY art_quick_aput_obj_with_bound_check
1296    ldr w3, [x0, #MIRROR_ARRAY_LENGTH_OFFSET]
1297    cmp w3, w1
1298    bhi art_quick_aput_obj
1299    mov x0, x1
1300    mov x1, x3
1301    b art_quick_throw_array_bounds
1302END art_quick_aput_obj_with_bound_check
1303
1304#ifdef USE_READ_BARRIER
1305    .extern artReadBarrierSlow
1306#endif
1307ENTRY art_quick_aput_obj
1308    cbz x2, .Ldo_aput_null
1309    READ_BARRIER x3, w3, x0, MIRROR_OBJECT_CLASS_OFFSET     // Heap reference = 32b
1310                                                         // This also zero-extends to x3
1311    READ_BARRIER x4, w4, x2, MIRROR_OBJECT_CLASS_OFFSET     // Heap reference = 32b
1312                                                         // This also zero-extends to x4
1313    READ_BARRIER x3, w3, x3, MIRROR_CLASS_COMPONENT_TYPE_OFFSET // Heap reference = 32b
1314                                                         // This also zero-extends to x3
1315    cmp w3, w4  // value's type == array's component type - trivial assignability
1316    bne .Lcheck_assignability
1317.Ldo_aput:
1318    add x3, x0, #MIRROR_OBJECT_ARRAY_DATA_OFFSET
1319                                                         // "Compress" = do nothing
1320    POISON_HEAP_REF w2
1321    str w2, [x3, x1, lsl #2]                             // Heap reference = 32b
1322    ldr x3, [xSELF, #THREAD_CARD_TABLE_OFFSET]
1323    lsr x0, x0, #7
1324    strb w3, [x3, x0]
1325    ret
1326.Ldo_aput_null:
1327    add x3, x0, #MIRROR_OBJECT_ARRAY_DATA_OFFSET
1328                                                         // "Compress" = do nothing
1329    str w2, [x3, x1, lsl #2]                             // Heap reference = 32b
1330    ret
1331.Lcheck_assignability:
1332    // Store arguments and link register
1333    stp x0, x1, [sp,#-32]!
1334    .cfi_adjust_cfa_offset 32
1335    .cfi_rel_offset x0, 0
1336    .cfi_rel_offset x1, 8
1337    stp x2, xLR, [sp, #16]
1338    .cfi_rel_offset x2, 16
1339    .cfi_rel_offset x30, 24
1340
1341    // Call runtime code
1342    mov x0, x3              // Heap reference, 32b, "uncompress" = do nothing, already zero-extended
1343    mov x1, x4              // Heap reference, 32b, "uncompress" = do nothing, already zero-extended
1344    bl artIsAssignableFromCode
1345
1346    // Check for exception
1347    cbz x0, .Lthrow_array_store_exception
1348
1349    // Restore
1350    ldp x2, x30, [sp, #16]
1351    .cfi_restore x2
1352    .cfi_restore x30
1353    ldp x0, x1, [sp], #32
1354    .cfi_restore x0
1355    .cfi_restore x1
1356    .cfi_adjust_cfa_offset -32
1357
1358    add x3, x0, #MIRROR_OBJECT_ARRAY_DATA_OFFSET
1359                                                          // "Compress" = do nothing
1360    POISON_HEAP_REF w2
1361    str w2, [x3, x1, lsl #2]                              // Heap reference = 32b
1362    ldr x3, [xSELF, #THREAD_CARD_TABLE_OFFSET]
1363    lsr x0, x0, #7
1364    strb w3, [x3, x0]
1365    ret
1366    .cfi_adjust_cfa_offset 32  // 4 restores after cbz for unwinding.
1367.Lthrow_array_store_exception:
1368    ldp x2, x30, [sp, #16]
1369    .cfi_restore x2
1370    .cfi_restore x30
1371    ldp x0, x1, [sp], #32
1372    .cfi_restore x0
1373    .cfi_restore x1
1374    .cfi_adjust_cfa_offset -32
1375
1376    SETUP_SAVE_ALL_CALLEE_SAVE_FRAME
1377    mov x1, x2                    // Pass value.
1378    mov x2, xSELF                 // Pass Thread::Current.
1379    b artThrowArrayStoreException // (Object*, Object*, Thread*).
1380    brk 0                         // Unreached.
1381END art_quick_aput_obj
1382
1383// Macro to facilitate adding new allocation entrypoints.
1384.macro ONE_ARG_DOWNCALL name, entrypoint, return
1385    .extern \entrypoint
1386ENTRY \name
1387    SETUP_REFS_ONLY_CALLEE_SAVE_FRAME // save callee saves in case of GC
1388    mov    x1, xSELF                  // pass Thread::Current
1389    bl     \entrypoint                // (uint32_t type_idx, Method* method, Thread*)
1390    RESTORE_REFS_ONLY_CALLEE_SAVE_FRAME
1391    \return
1392END \name
1393.endm
1394
1395// Macro to facilitate adding new allocation entrypoints.
1396.macro TWO_ARG_DOWNCALL name, entrypoint, return
1397    .extern \entrypoint
1398ENTRY \name
1399    SETUP_REFS_ONLY_CALLEE_SAVE_FRAME // save callee saves in case of GC
1400    mov    x2, xSELF                  // pass Thread::Current
1401    bl     \entrypoint                // (uint32_t type_idx, Method* method, Thread*)
1402    RESTORE_REFS_ONLY_CALLEE_SAVE_FRAME
1403    \return
1404END \name
1405.endm
1406
1407// Macro to facilitate adding new allocation entrypoints.
1408.macro THREE_ARG_DOWNCALL name, entrypoint, return
1409    .extern \entrypoint
1410ENTRY \name
1411    SETUP_REFS_ONLY_CALLEE_SAVE_FRAME // save callee saves in case of GC
1412    mov    x3, xSELF                  // pass Thread::Current
1413    bl     \entrypoint
1414    RESTORE_REFS_ONLY_CALLEE_SAVE_FRAME
1415    \return
1416END \name
1417.endm
1418
1419// Macro to facilitate adding new allocation entrypoints.
1420.macro FOUR_ARG_DOWNCALL name, entrypoint, return
1421    .extern \entrypoint
1422ENTRY \name
1423    SETUP_REFS_ONLY_CALLEE_SAVE_FRAME // save callee saves in case of GC
1424    mov    x4, xSELF                  // pass Thread::Current
1425    bl     \entrypoint                //
1426    RESTORE_REFS_ONLY_CALLEE_SAVE_FRAME
1427    \return
1428    DELIVER_PENDING_EXCEPTION
1429END \name
1430.endm
1431
1432// Macros taking opportunity of code similarities for downcalls with referrer.
1433.macro ONE_ARG_REF_DOWNCALL name, entrypoint, return
1434    .extern \entrypoint
1435ENTRY \name
1436    SETUP_REFS_ONLY_CALLEE_SAVE_FRAME  // save callee saves in case of GC
1437    ldr    x1, [sp, #FRAME_SIZE_REFS_ONLY_CALLEE_SAVE] // Load referrer
1438    mov    x2, xSELF                  // pass Thread::Current
1439    bl     \entrypoint                // (uint32_t type_idx, Method* method, Thread*, SP)
1440    RESTORE_REFS_ONLY_CALLEE_SAVE_FRAME
1441    \return
1442END \name
1443.endm
1444
1445.macro TWO_ARG_REF_DOWNCALL name, entrypoint, return
1446    .extern \entrypoint
1447ENTRY \name
1448    SETUP_REFS_ONLY_CALLEE_SAVE_FRAME  // save callee saves in case of GC
1449    ldr    x2, [sp, #FRAME_SIZE_REFS_ONLY_CALLEE_SAVE] // Load referrer
1450    mov    x3, xSELF                  // pass Thread::Current
1451    bl     \entrypoint
1452    RESTORE_REFS_ONLY_CALLEE_SAVE_FRAME
1453    \return
1454END \name
1455.endm
1456
1457.macro THREE_ARG_REF_DOWNCALL name, entrypoint, return
1458    .extern \entrypoint
1459ENTRY \name
1460    SETUP_REFS_ONLY_CALLEE_SAVE_FRAME  // save callee saves in case of GC
1461    ldr    x3, [sp, #FRAME_SIZE_REFS_ONLY_CALLEE_SAVE] // Load referrer
1462    mov    x4, xSELF                  // pass Thread::Current
1463    bl     \entrypoint
1464    RESTORE_REFS_ONLY_CALLEE_SAVE_FRAME
1465    \return
1466END \name
1467.endm
1468
1469.macro RETURN_IF_RESULT_IS_NON_ZERO_OR_DELIVER
1470    cbz w0, 1f                 // result zero branch over
1471    ret                        // return
14721:
1473    DELIVER_PENDING_EXCEPTION
1474.endm
1475
1476    /*
1477     * Entry from managed code that calls artHandleFillArrayDataFromCode and delivers exception on
1478     * failure.
1479     */
1480TWO_ARG_REF_DOWNCALL art_quick_handle_fill_data, artHandleFillArrayDataFromCode, RETURN_IF_W0_IS_ZERO_OR_DELIVER
1481
1482    /*
1483     * Entry from managed code when uninitialized static storage, this stub will run the class
1484     * initializer and deliver the exception on error. On success the static storage base is
1485     * returned.
1486     */
1487ONE_ARG_DOWNCALL art_quick_initialize_static_storage, artInitializeStaticStorageFromCode, RETURN_IF_RESULT_IS_NON_ZERO_OR_DELIVER
1488
1489ONE_ARG_DOWNCALL art_quick_initialize_type, artInitializeTypeFromCode, RETURN_IF_RESULT_IS_NON_ZERO_OR_DELIVER
1490ONE_ARG_DOWNCALL art_quick_initialize_type_and_verify_access, artInitializeTypeAndVerifyAccessFromCode, RETURN_IF_RESULT_IS_NON_ZERO_OR_DELIVER
1491
1492ONE_ARG_REF_DOWNCALL art_quick_get_boolean_static, artGetBooleanStaticFromCode, RETURN_OR_DELIVER_PENDING_EXCEPTION_X1
1493ONE_ARG_REF_DOWNCALL art_quick_get_byte_static, artGetByteStaticFromCode, RETURN_OR_DELIVER_PENDING_EXCEPTION_X1
1494ONE_ARG_REF_DOWNCALL art_quick_get_char_static, artGetCharStaticFromCode, RETURN_OR_DELIVER_PENDING_EXCEPTION_X1
1495ONE_ARG_REF_DOWNCALL art_quick_get_short_static, artGetShortStaticFromCode, RETURN_OR_DELIVER_PENDING_EXCEPTION_X1
1496ONE_ARG_REF_DOWNCALL art_quick_get32_static, artGet32StaticFromCode, RETURN_OR_DELIVER_PENDING_EXCEPTION_X1
1497ONE_ARG_REF_DOWNCALL art_quick_get64_static, artGet64StaticFromCode, RETURN_OR_DELIVER_PENDING_EXCEPTION_X1
1498ONE_ARG_REF_DOWNCALL art_quick_get_obj_static, artGetObjStaticFromCode, RETURN_OR_DELIVER_PENDING_EXCEPTION_X1
1499
1500TWO_ARG_REF_DOWNCALL art_quick_get_boolean_instance, artGetBooleanInstanceFromCode, RETURN_OR_DELIVER_PENDING_EXCEPTION_X1
1501TWO_ARG_REF_DOWNCALL art_quick_get_byte_instance, artGetByteInstanceFromCode, RETURN_OR_DELIVER_PENDING_EXCEPTION_X1
1502TWO_ARG_REF_DOWNCALL art_quick_get_char_instance, artGetCharInstanceFromCode, RETURN_OR_DELIVER_PENDING_EXCEPTION_X1
1503TWO_ARG_REF_DOWNCALL art_quick_get_short_instance, artGetShortInstanceFromCode, RETURN_OR_DELIVER_PENDING_EXCEPTION_X1
1504TWO_ARG_REF_DOWNCALL art_quick_get32_instance, artGet32InstanceFromCode, RETURN_OR_DELIVER_PENDING_EXCEPTION_X1
1505TWO_ARG_REF_DOWNCALL art_quick_get64_instance, artGet64InstanceFromCode, RETURN_OR_DELIVER_PENDING_EXCEPTION_X1
1506TWO_ARG_REF_DOWNCALL art_quick_get_obj_instance, artGetObjInstanceFromCode, RETURN_OR_DELIVER_PENDING_EXCEPTION_X1
1507
1508TWO_ARG_REF_DOWNCALL art_quick_set8_static, artSet8StaticFromCode, RETURN_IF_W0_IS_ZERO_OR_DELIVER
1509TWO_ARG_REF_DOWNCALL art_quick_set16_static, artSet16StaticFromCode, RETURN_IF_W0_IS_ZERO_OR_DELIVER
1510TWO_ARG_REF_DOWNCALL art_quick_set32_static, artSet32StaticFromCode, RETURN_IF_W0_IS_ZERO_OR_DELIVER
1511TWO_ARG_REF_DOWNCALL art_quick_set_obj_static, artSetObjStaticFromCode, RETURN_IF_W0_IS_ZERO_OR_DELIVER
1512
1513THREE_ARG_REF_DOWNCALL art_quick_set8_instance, artSet8InstanceFromCode, RETURN_IF_W0_IS_ZERO_OR_DELIVER
1514THREE_ARG_REF_DOWNCALL art_quick_set16_instance, artSet16InstanceFromCode, RETURN_IF_W0_IS_ZERO_OR_DELIVER
1515THREE_ARG_REF_DOWNCALL art_quick_set32_instance, artSet32InstanceFromCode, RETURN_IF_W0_IS_ZERO_OR_DELIVER
1516THREE_ARG_REF_DOWNCALL art_quick_set64_instance, artSet64InstanceFromCode, RETURN_IF_W0_IS_ZERO_OR_DELIVER
1517THREE_ARG_REF_DOWNCALL art_quick_set_obj_instance, artSetObjInstanceFromCode, RETURN_IF_W0_IS_ZERO_OR_DELIVER
1518
1519// This is separated out as the argument order is different.
1520    .extern artSet64StaticFromCode
1521ENTRY art_quick_set64_static
1522    SETUP_REFS_ONLY_CALLEE_SAVE_FRAME  // save callee saves in case of GC
1523    ldr    x1, [sp, #FRAME_SIZE_REFS_ONLY_CALLEE_SAVE] // Load referrer
1524                                      // x2 contains the parameter
1525    mov    x3, xSELF                  // pass Thread::Current
1526    bl     artSet64StaticFromCode
1527    RESTORE_REFS_ONLY_CALLEE_SAVE_FRAME
1528    RETURN_IF_W0_IS_ZERO_OR_DELIVER
1529END art_quick_set64_static
1530
1531    /*
1532     * Entry from managed code to resolve a string, this stub will allocate a String and deliver an
1533     * exception on error. On success the String is returned. w0 holds the string index. The fast
1534     * path check for hit in strings cache has already been performed.
1535     */
1536ONE_ARG_DOWNCALL art_quick_resolve_string, artResolveStringFromCode, RETURN_IF_RESULT_IS_NON_ZERO_OR_DELIVER
1537
1538// Generate the allocation entrypoints for each allocator.
1539GENERATE_ALLOC_ENTRYPOINTS_FOR_EACH_ALLOCATOR
1540
1541// A hand-written override for GENERATE_ALLOC_ENTRYPOINTS_ALLOC_OBJECT(_rosalloc, RosAlloc).
1542ENTRY art_quick_alloc_object_rosalloc
1543    // Fast path rosalloc allocation.
1544    // x0: type_idx/return value, x1: ArtMethod*, xSELF(x19): Thread::Current
1545    // x2-x7: free.
1546    ldr    x2, [x1, #ART_METHOD_DEX_CACHE_TYPES_OFFSET_64]    // Load dex cache resolved types array
1547                                                              // Load the class (x2)
1548    ldr    w2, [x2, x0, lsl #COMPRESSED_REFERENCE_SIZE_SHIFT]
1549    cbz    x2, .Lart_quick_alloc_object_rosalloc_slow_path    // Check null class
1550                                                              // Check class status.
1551    ldr    w3, [x2, #MIRROR_CLASS_STATUS_OFFSET]
1552    cmp    x3, #MIRROR_CLASS_STATUS_INITIALIZED
1553    bne    .Lart_quick_alloc_object_rosalloc_slow_path
1554                                                              // Add a fake dependence from the
1555                                                              // following access flag and size
1556                                                              // loads to the status load.
1557                                                              // This is to prevent those loads
1558                                                              // from being reordered above the
1559                                                              // status load and reading wrong
1560                                                              // values (an alternative is to use
1561                                                              // a load-acquire for the status).
1562    eor    x3, x3, x3
1563    add    x2, x2, x3
1564                                                              // Check access flags has
1565                                                              // kAccClassIsFinalizable
1566    ldr    w3, [x2, #MIRROR_CLASS_ACCESS_FLAGS_OFFSET]
1567    tst    x3, #ACCESS_FLAGS_CLASS_IS_FINALIZABLE
1568    bne    .Lart_quick_alloc_object_rosalloc_slow_path
1569    ldr    x3, [xSELF, #THREAD_LOCAL_ALLOC_STACK_TOP_OFFSET]  // Check if the thread local
1570                                                              // allocation stack has room.
1571                                                              // ldp won't work due to large offset.
1572    ldr    x4, [xSELF, #THREAD_LOCAL_ALLOC_STACK_END_OFFSET]
1573    cmp    x3, x4
1574    bhs    .Lart_quick_alloc_object_rosalloc_slow_path
1575    ldr    w3, [x2, #MIRROR_CLASS_OBJECT_SIZE_OFFSET]         // Load the object size (x3)
1576    cmp    x3, #ROSALLOC_MAX_THREAD_LOCAL_BRACKET_SIZE        // Check if the size is for a thread
1577                                                              // local allocation
1578    bhs    .Lart_quick_alloc_object_rosalloc_slow_path
1579                                                              // Compute the rosalloc bracket index
1580                                                              // from the size.
1581                                                              // Align up the size by the rosalloc
1582                                                              // bracket quantum size and divide
1583                                                              // by the quantum size and subtract
1584                                                              // by 1. This code is a shorter but
1585                                                              // equivalent version.
1586    sub    x3, x3, #1
1587    lsr    x3, x3, #ROSALLOC_BRACKET_QUANTUM_SIZE_SHIFT
1588                                                              // Load the rosalloc run (x4)
1589    add    x4, xSELF, x3, lsl #POINTER_SIZE_SHIFT
1590    ldr    x4, [x4, #THREAD_ROSALLOC_RUNS_OFFSET]
1591                                                              // Load the free list head (x3). This
1592                                                              // will be the return val.
1593    ldr    x3, [x4, #(ROSALLOC_RUN_FREE_LIST_OFFSET + ROSALLOC_RUN_FREE_LIST_HEAD_OFFSET)]
1594    cbz    x3, .Lart_quick_alloc_object_rosalloc_slow_path
1595    // "Point of no slow path". Won't go to the slow path from here on. OK to clobber x0 and x1.
1596    ldr    x1, [x3, #ROSALLOC_SLOT_NEXT_OFFSET]               // Load the next pointer of the head
1597                                                              // and update the list head with the
1598                                                              // next pointer.
1599    str    x1, [x4, #(ROSALLOC_RUN_FREE_LIST_OFFSET + ROSALLOC_RUN_FREE_LIST_HEAD_OFFSET)]
1600                                                              // Store the class pointer in the
1601                                                              // header. This also overwrites the
1602                                                              // next pointer. The offsets are
1603                                                              // asserted to match.
1604#if ROSALLOC_SLOT_NEXT_OFFSET != MIRROR_OBJECT_CLASS_OFFSET
1605#error "Class pointer needs to overwrite next pointer."
1606#endif
1607    POISON_HEAP_REF w2
1608    str    w2, [x3, #MIRROR_OBJECT_CLASS_OFFSET]
1609                                                              // Push the new object onto the thread
1610                                                              // local allocation stack and
1611                                                              // increment the thread local
1612                                                              // allocation stack top.
1613    ldr    x1, [xSELF, #THREAD_LOCAL_ALLOC_STACK_TOP_OFFSET]
1614    str    w3, [x1], #COMPRESSED_REFERENCE_SIZE               // (Increment x1 as a side effect.)
1615    str    x1, [xSELF, #THREAD_LOCAL_ALLOC_STACK_TOP_OFFSET]
1616                                                              // Decrement the size of the free list
1617    ldr    w1, [x4, #(ROSALLOC_RUN_FREE_LIST_OFFSET + ROSALLOC_RUN_FREE_LIST_SIZE_OFFSET)]
1618    sub    x1, x1, #1
1619                                                              // TODO: consider combining this store
1620                                                              // and the list head store above using
1621                                                              // strd.
1622    str    w1, [x4, #(ROSALLOC_RUN_FREE_LIST_OFFSET + ROSALLOC_RUN_FREE_LIST_SIZE_OFFSET)]
1623                                                              // Fence. This is "ish" not "ishst" so
1624                                                              // that the code after this allocation
1625                                                              // site will see the right values in
1626                                                              // the fields of the class.
1627                                                              // Alternatively we could use "ishst"
1628                                                              // if we use load-acquire for the
1629                                                              // class status load.)
1630    dmb    ish
1631    mov    x0, x3                                             // Set the return value and return.
1632    ret
1633.Lart_quick_alloc_object_rosalloc_slow_path:
1634    SETUP_REFS_ONLY_CALLEE_SAVE_FRAME      // save callee saves in case of GC
1635    mov    x2, xSELF                       // pass Thread::Current
1636    bl     artAllocObjectFromCodeRosAlloc  // (uint32_t type_idx, Method* method, Thread*)
1637    RESTORE_REFS_ONLY_CALLEE_SAVE_FRAME
1638    RETURN_IF_RESULT_IS_NON_ZERO_OR_DELIVER
1639END art_quick_alloc_object_rosalloc
1640
1641// A hand-written override for GENERATE_ALLOC_ENTRYPOINTS_ALLOC_OBJECT(_tlab, TLAB).
1642ENTRY art_quick_alloc_object_tlab
1643    // Fast path tlab allocation.
1644    // x0: type_idx/return value, x1: ArtMethod*, xSELF(x19): Thread::Current
1645    // x2-x7: free.
1646#if defined(USE_READ_BARRIER)
1647    mvn    x0, xzr                                            // Read barrier not supported here.
1648    ret                                                       // Return -1.
1649#endif
1650    ldr    x2, [x1, #ART_METHOD_DEX_CACHE_TYPES_OFFSET_64]    // Load dex cache resolved types array
1651                                                              // Load the class (x2)
1652    ldr    w2, [x2, x0, lsl #COMPRESSED_REFERENCE_SIZE_SHIFT]
1653    cbz    x2, .Lart_quick_alloc_object_tlab_slow_path        // Check null class
1654                                                              // Check class status.
1655    ldr    w3, [x2, #MIRROR_CLASS_STATUS_OFFSET]
1656    cmp    x3, #MIRROR_CLASS_STATUS_INITIALIZED
1657    bne    .Lart_quick_alloc_object_tlab_slow_path
1658                                                              // Add a fake dependence from the
1659                                                              // following access flag and size
1660                                                              // loads to the status load.
1661                                                              // This is to prevent those loads
1662                                                              // from being reordered above the
1663                                                              // status load and reading wrong
1664                                                              // values (an alternative is to use
1665                                                              // a load-acquire for the status).
1666    eor    x3, x3, x3
1667    add    x2, x2, x3
1668                                                              // Check access flags has
1669                                                              // kAccClassIsFinalizable.
1670    ldr    w3, [x2, #MIRROR_CLASS_ACCESS_FLAGS_OFFSET]
1671    tbnz   x3, #ACCESS_FLAGS_CLASS_IS_FINALIZABLE_BIT, .Lart_quick_alloc_object_tlab_slow_path
1672                                                              // Load thread_local_pos (x4) and
1673                                                              // thread_local_end (x5).
1674    ldr    x4, [xSELF, #THREAD_LOCAL_POS_OFFSET]
1675    ldr    x5, [xSELF, #THREAD_LOCAL_END_OFFSET]
1676    sub    x6, x5, x4                                         // Compute the remaining buf size.
1677    ldr    w7, [x2, #MIRROR_CLASS_OBJECT_SIZE_OFFSET]         // Load the object size (x7).
1678    cmp    x7, x6                                             // Check if it fits. OK to do this
1679                                                              // before rounding up the object size
1680                                                              // assuming the buf size alignment.
1681    bhi    .Lart_quick_alloc_object_tlab_slow_path
1682    // "Point of no slow path". Won't go to the slow path from here on. OK to clobber x0 and x1.
1683                                                              // Round up the object size by the
1684                                                              // object alignment. (addr + 7) & ~7.
1685    add    x7, x7, #OBJECT_ALIGNMENT_MASK
1686    and    x7, x7, #OBJECT_ALIGNMENT_MASK_TOGGLED
1687                                                              // Move old thread_local_pos to x0
1688                                                              // for the return value.
1689    mov    x0, x4
1690    add    x5, x0, x7
1691    str    x5, [xSELF, #THREAD_LOCAL_POS_OFFSET]              // Store new thread_local_pos.
1692    ldr    x5, [xSELF, #THREAD_LOCAL_OBJECTS_OFFSET]          // Increment thread_local_objects.
1693    add    x5, x5, #1
1694    str    x5, [xSELF, #THREAD_LOCAL_OBJECTS_OFFSET]
1695    POISON_HEAP_REF w2
1696    str    w2, [x0, #MIRROR_OBJECT_CLASS_OFFSET]              // Store the class pointer.
1697                                                              // Fence. This is "ish" not "ishst" so
1698                                                              // that the code after this allocation
1699                                                              // site will see the right values in
1700                                                              // the fields of the class.
1701                                                              // Alternatively we could use "ishst"
1702                                                              // if we use load-acquire for the
1703                                                              // class status load.)
1704    dmb    ish
1705    ret
1706.Lart_quick_alloc_object_tlab_slow_path:
1707    SETUP_REFS_ONLY_CALLEE_SAVE_FRAME    // Save callee saves in case of GC.
1708    mov    x2, xSELF                     // Pass Thread::Current.
1709    bl     artAllocObjectFromCodeTLAB    // (uint32_t type_idx, Method* method, Thread*)
1710    RESTORE_REFS_ONLY_CALLEE_SAVE_FRAME
1711    RETURN_IF_RESULT_IS_NON_ZERO_OR_DELIVER
1712END art_quick_alloc_object_tlab
1713
1714GENERATE_ALLOC_ENTRYPOINTS_ALLOC_OBJECT(_region_tlab, RegionTLAB)
1715
1716    /*
1717     * Called by managed code when the thread has been asked to suspend.
1718     */
1719    .extern artTestSuspendFromCode
1720ENTRY art_quick_test_suspend
1721    ldrh   w0, [xSELF, #THREAD_FLAGS_OFFSET]  // get xSELF->state_and_flags.as_struct.flags
1722    cbnz   w0, .Lneed_suspend                 // check flags == 0
1723    ret                                       // return if flags == 0
1724.Lneed_suspend:
1725    mov    x0, xSELF
1726    SETUP_REFS_ONLY_CALLEE_SAVE_FRAME          // save callee saves for stack crawl
1727    bl     artTestSuspendFromCode             // (Thread*)
1728    RESTORE_REFS_ONLY_CALLEE_SAVE_FRAME_AND_RETURN
1729END art_quick_test_suspend
1730
1731ENTRY art_quick_implicit_suspend
1732    mov    x0, xSELF
1733    SETUP_REFS_ONLY_CALLEE_SAVE_FRAME          // save callee saves for stack crawl
1734    bl     artTestSuspendFromCode             // (Thread*)
1735    RESTORE_REFS_ONLY_CALLEE_SAVE_FRAME_AND_RETURN
1736END art_quick_implicit_suspend
1737
1738     /*
1739     * Called by managed code that is attempting to call a method on a proxy class. On entry
1740     * x0 holds the proxy method and x1 holds the receiver; The frame size of the invoked proxy
1741     * method agrees with a ref and args callee save frame.
1742     */
1743     .extern artQuickProxyInvokeHandler
1744ENTRY art_quick_proxy_invoke_handler
1745    SETUP_REFS_AND_ARGS_CALLEE_SAVE_FRAME_WITH_METHOD_IN_X0
1746    mov     x2, xSELF                   // pass Thread::Current
1747    mov     x3, sp                      // pass SP
1748    bl      artQuickProxyInvokeHandler  // (Method* proxy method, receiver, Thread*, SP)
1749    ldr     x2, [xSELF, THREAD_EXCEPTION_OFFSET]
1750    cbnz    x2, .Lexception_in_proxy    // success if no exception is pending
1751    RESTORE_REFS_AND_ARGS_CALLEE_SAVE_FRAME // Restore frame
1752    fmov    d0, x0                      // Store result in d0 in case it was float or double
1753    ret                                 // return on success
1754.Lexception_in_proxy:
1755    RESTORE_REFS_AND_ARGS_CALLEE_SAVE_FRAME
1756    DELIVER_PENDING_EXCEPTION
1757END art_quick_proxy_invoke_handler
1758
1759    /*
1760     * Called to resolve an imt conflict. xIP1 is a hidden argument that holds the target method's
1761     * dex method index.
1762     */
1763    .extern artInvokeInterfaceTrampoline
1764ENTRY art_quick_imt_conflict_trampoline
1765    mov    x0, xIP1
1766    INVOKE_TRAMPOLINE_BODY artInvokeInterfaceTrampoline
1767END art_quick_imt_conflict_trampoline
1768
1769ENTRY art_quick_resolution_trampoline
1770    SETUP_REFS_AND_ARGS_CALLEE_SAVE_FRAME
1771    mov x2, xSELF
1772    mov x3, sp
1773    bl artQuickResolutionTrampoline  // (called, receiver, Thread*, SP)
1774    cbz x0, 1f
1775    mov xIP0, x0            // Remember returned code pointer in xIP0.
1776    ldr x0, [sp, #0]        // artQuickResolutionTrampoline puts called method in *SP.
1777    RESTORE_REFS_AND_ARGS_CALLEE_SAVE_FRAME
1778    br xIP0
17791:
1780    RESTORE_REFS_AND_ARGS_CALLEE_SAVE_FRAME
1781    DELIVER_PENDING_EXCEPTION
1782END art_quick_resolution_trampoline
1783
1784/*
1785 * Generic JNI frame layout:
1786 *
1787 * #-------------------#
1788 * |                   |
1789 * | caller method...  |
1790 * #-------------------#    <--- SP on entry
1791 * | Return X30/LR     |
1792 * | X29/FP            |    callee save
1793 * | X28               |    callee save
1794 * | X27               |    callee save
1795 * | X26               |    callee save
1796 * | X25               |    callee save
1797 * | X24               |    callee save
1798 * | X23               |    callee save
1799 * | X22               |    callee save
1800 * | X21               |    callee save
1801 * | X20               |    callee save
1802 * | X19               |    callee save
1803 * | X7                |    arg7
1804 * | X6                |    arg6
1805 * | X5                |    arg5
1806 * | X4                |    arg4
1807 * | X3                |    arg3
1808 * | X2                |    arg2
1809 * | X1                |    arg1
1810 * | D7                |    float arg 8
1811 * | D6                |    float arg 7
1812 * | D5                |    float arg 6
1813 * | D4                |    float arg 5
1814 * | D3                |    float arg 4
1815 * | D2                |    float arg 3
1816 * | D1                |    float arg 2
1817 * | D0                |    float arg 1
1818 * | Method*           | <- X0
1819 * #-------------------#
1820 * | local ref cookie  | // 4B
1821 * | handle scope size | // 4B
1822 * #-------------------#
1823 * | JNI Call Stack    |
1824 * #-------------------#    <--- SP on native call
1825 * |                   |
1826 * | Stack for Regs    |    The trampoline assembly will pop these values
1827 * |                   |    into registers for native call
1828 * #-------------------#
1829 * | Native code ptr   |
1830 * #-------------------#
1831 * | Free scratch      |
1832 * #-------------------#
1833 * | Ptr to (1)        |    <--- SP
1834 * #-------------------#
1835 */
1836    /*
1837     * Called to do a generic JNI down-call
1838     */
1839ENTRY art_quick_generic_jni_trampoline
1840    SETUP_REFS_AND_ARGS_CALLEE_SAVE_FRAME_WITH_METHOD_IN_X0
1841
1842    // Save SP , so we can have static CFI info.
1843    mov x28, sp
1844    .cfi_def_cfa_register x28
1845
1846    // This looks the same, but is different: this will be updated to point to the bottom
1847    // of the frame when the handle scope is inserted.
1848    mov xFP, sp
1849
1850    mov xIP0, #5120
1851    sub sp, sp, xIP0
1852
1853    // prepare for artQuickGenericJniTrampoline call
1854    // (Thread*,  SP)
1855    //    x0      x1   <= C calling convention
1856    //   xSELF    xFP  <= where they are
1857
1858    mov x0, xSELF   // Thread*
1859    mov x1, xFP
1860    bl artQuickGenericJniTrampoline  // (Thread*, sp)
1861
1862    // The C call will have registered the complete save-frame on success.
1863    // The result of the call is:
1864    // x0: pointer to native code, 0 on error.
1865    // x1: pointer to the bottom of the used area of the alloca, can restore stack till there.
1866
1867    // Check for error = 0.
1868    cbz x0, .Lexception_in_native
1869
1870    // Release part of the alloca.
1871    mov sp, x1
1872
1873    // Save the code pointer
1874    mov xIP0, x0
1875
1876    // Load parameters from frame into registers.
1877    // TODO Check with artQuickGenericJniTrampoline.
1878    //      Also, check again APPCS64 - the stack arguments are interleaved.
1879    ldp x0, x1, [sp]
1880    ldp x2, x3, [sp, #16]
1881    ldp x4, x5, [sp, #32]
1882    ldp x6, x7, [sp, #48]
1883
1884    ldp d0, d1, [sp, #64]
1885    ldp d2, d3, [sp, #80]
1886    ldp d4, d5, [sp, #96]
1887    ldp d6, d7, [sp, #112]
1888
1889    add sp, sp, #128
1890
1891    blr xIP0        // native call.
1892
1893    // result sign extension is handled in C code
1894    // prepare for artQuickGenericJniEndTrampoline call
1895    // (Thread*, result, result_f)
1896    //    x0       x1       x2        <= C calling convention
1897    mov x1, x0      // Result (from saved).
1898    mov x0, xSELF   // Thread register.
1899    fmov x2, d0     // d0 will contain floating point result, but needs to go into x2
1900
1901    bl artQuickGenericJniEndTrampoline
1902
1903    // Pending exceptions possible.
1904    ldr x2, [xSELF, THREAD_EXCEPTION_OFFSET]
1905    cbnz x2, .Lexception_in_native
1906
1907    // Tear down the alloca.
1908    mov sp, x28
1909    .cfi_def_cfa_register sp
1910
1911    // Tear down the callee-save frame.
1912    RESTORE_REFS_AND_ARGS_CALLEE_SAVE_FRAME
1913
1914    // store into fpr, for when it's a fpr return...
1915    fmov d0, x0
1916    ret
1917
1918.Lexception_in_native:
1919    // Move to x1 then sp to please assembler.
1920    ldr x1, [xSELF, # THREAD_TOP_QUICK_FRAME_OFFSET]
1921    mov sp, x1
1922    .cfi_def_cfa_register sp
1923    # This will create a new save-all frame, required by the runtime.
1924    DELIVER_PENDING_EXCEPTION
1925END art_quick_generic_jni_trampoline
1926
1927/*
1928 * Called to bridge from the quick to interpreter ABI. On entry the arguments match those
1929 * of a quick call:
1930 * x0 = method being called/to bridge to.
1931 * x1..x7, d0..d7 = arguments to that method.
1932 */
1933ENTRY art_quick_to_interpreter_bridge
1934    SETUP_REFS_AND_ARGS_CALLEE_SAVE_FRAME   // Set up frame and save arguments.
1935
1936    //  x0 will contain mirror::ArtMethod* method.
1937    mov x1, xSELF                          // How to get Thread::Current() ???
1938    mov x2, sp
1939
1940    // uint64_t artQuickToInterpreterBridge(mirror::ArtMethod* method, Thread* self,
1941    //                                      mirror::ArtMethod** sp)
1942    bl   artQuickToInterpreterBridge
1943
1944    RESTORE_REFS_AND_ARGS_CALLEE_SAVE_FRAME  // TODO: no need to restore arguments in this case.
1945
1946    fmov d0, x0
1947
1948    RETURN_OR_DELIVER_PENDING_EXCEPTION
1949END art_quick_to_interpreter_bridge
1950
1951
1952//
1953// Instrumentation-related stubs
1954//
1955    .extern artInstrumentationMethodEntryFromCode
1956ENTRY art_quick_instrumentation_entry
1957    SETUP_REFS_AND_ARGS_CALLEE_SAVE_FRAME
1958
1959    mov   x20, x0             // Preserve method reference in a callee-save.
1960
1961    mov   x2, xSELF
1962    mov   x3, xLR
1963    bl    artInstrumentationMethodEntryFromCode  // (Method*, Object*, Thread*, LR)
1964
1965    mov   xIP0, x0            // x0 = result of call.
1966    mov   x0, x20             // Reload method reference.
1967
1968    RESTORE_REFS_AND_ARGS_CALLEE_SAVE_FRAME  // Note: will restore xSELF
1969    adr   xLR, art_quick_instrumentation_exit
1970    br    xIP0                // Tail-call method with lr set to art_quick_instrumentation_exit.
1971END art_quick_instrumentation_entry
1972
1973    .extern artInstrumentationMethodExitFromCode
1974ENTRY art_quick_instrumentation_exit
1975    mov   xLR, #0             // Clobber LR for later checks.
1976
1977    SETUP_REFS_ONLY_CALLEE_SAVE_FRAME
1978
1979    // We need to save x0 and d0. We could use a callee-save from SETUP_REF_ONLY, but then
1980    // we would need to fully restore it. As there are a lot of callee-save registers, it seems
1981    // easier to have an extra small stack area.
1982
1983    str x0, [sp, #-16]!       // Save integer result.
1984    .cfi_adjust_cfa_offset 16
1985    str d0,  [sp, #8]         // Save floating-point result.
1986
1987    add   x1, sp, #16         // Pass SP.
1988    mov   x2, x0              // Pass integer result.
1989    fmov  x3, d0              // Pass floating-point result.
1990    mov   x0, xSELF           // Pass Thread.
1991    bl   artInstrumentationMethodExitFromCode    // (Thread*, SP, gpr_res, fpr_res)
1992
1993    mov   xIP0, x0            // Return address from instrumentation call.
1994    mov   xLR, x1             // r1 is holding link register if we're to bounce to deoptimize
1995
1996    ldr   d0, [sp, #8]        // Restore floating-point result.
1997    ldr   x0, [sp], 16        // Restore integer result, and drop stack area.
1998    .cfi_adjust_cfa_offset 16
1999
2000    POP_REFS_ONLY_CALLEE_SAVE_FRAME
2001
2002    br    xIP0                // Tail-call out.
2003END art_quick_instrumentation_exit
2004
2005    /*
2006     * Instrumentation has requested that we deoptimize into the interpreter. The deoptimization
2007     * will long jump to the upcall with a special exception of -1.
2008     */
2009    .extern artDeoptimize
2010ENTRY art_quick_deoptimize
2011    SETUP_SAVE_ALL_CALLEE_SAVE_FRAME
2012    mov    x0, xSELF          // Pass thread.
2013    bl     artDeoptimize      // artDeoptimize(Thread*)
2014    brk 0
2015END art_quick_deoptimize
2016
2017    /*
2018     * Compiled code has requested that we deoptimize into the interpreter. The deoptimization
2019     * will long jump to the upcall with a special exception of -1.
2020     */
2021    .extern artDeoptimizeFromCompiledCode
2022ENTRY art_quick_deoptimize_from_compiled_code
2023    SETUP_SAVE_ALL_CALLEE_SAVE_FRAME
2024    mov    x0, xSELF                      // Pass thread.
2025    bl     artDeoptimizeFromCompiledCode  // artDeoptimizeFromCompiledCode(Thread*)
2026    brk 0
2027END art_quick_deoptimize_from_compiled_code
2028
2029
2030    /*
2031     * String's indexOf.
2032     *
2033     * TODO: Not very optimized.
2034     * On entry:
2035     *    x0:   string object (known non-null)
2036     *    w1:   char to match (known <= 0xFFFF)
2037     *    w2:   Starting offset in string data
2038     */
2039ENTRY art_quick_indexof
2040    ldr   w3, [x0, #MIRROR_STRING_COUNT_OFFSET]
2041    add   x0, x0, #MIRROR_STRING_VALUE_OFFSET
2042
2043    /* Clamp start to [0..count] */
2044    cmp   w2, #0
2045    csel  w2, wzr, w2, lt
2046    cmp   w2, w3
2047    csel  w2, w3, w2, gt
2048
2049    /* Save a copy to compute result */
2050    mov   x5, x0
2051
2052    /* Build pointer to start of data to compare and pre-bias */
2053    add   x0, x0, x2, lsl #1
2054    sub   x0, x0, #2
2055
2056    /* Compute iteration count */
2057    sub   w2, w3, w2
2058
2059    /*
2060     * At this point we have:
2061     *  x0: start of the data to test
2062     *  w1: char to compare
2063     *  w2: iteration count
2064     *  x5: original start of string data
2065     */
2066
2067    subs  w2, w2, #4
2068    b.lt  .Lindexof_remainder
2069
2070.Lindexof_loop4:
2071    ldrh  w6, [x0, #2]!
2072    ldrh  w7, [x0, #2]!
2073    ldrh  wIP0, [x0, #2]!
2074    ldrh  wIP1, [x0, #2]!
2075    cmp   w6, w1
2076    b.eq  .Lmatch_0
2077    cmp   w7, w1
2078    b.eq  .Lmatch_1
2079    cmp   wIP0, w1
2080    b.eq  .Lmatch_2
2081    cmp   wIP1, w1
2082    b.eq  .Lmatch_3
2083    subs  w2, w2, #4
2084    b.ge  .Lindexof_loop4
2085
2086.Lindexof_remainder:
2087    adds  w2, w2, #4
2088    b.eq  .Lindexof_nomatch
2089
2090.Lindexof_loop1:
2091    ldrh  w6, [x0, #2]!
2092    cmp   w6, w1
2093    b.eq  .Lmatch_3
2094    subs  w2, w2, #1
2095    b.ne  .Lindexof_loop1
2096
2097.Lindexof_nomatch:
2098    mov   x0, #-1
2099    ret
2100
2101.Lmatch_0:
2102    sub   x0, x0, #6
2103    sub   x0, x0, x5
2104    asr   x0, x0, #1
2105    ret
2106.Lmatch_1:
2107    sub   x0, x0, #4
2108    sub   x0, x0, x5
2109    asr   x0, x0, #1
2110    ret
2111.Lmatch_2:
2112    sub   x0, x0, #2
2113    sub   x0, x0, x5
2114    asr   x0, x0, #1
2115    ret
2116.Lmatch_3:
2117    sub   x0, x0, x5
2118    asr   x0, x0, #1
2119    ret
2120END art_quick_indexof
2121
2122   /*
2123     * String's compareTo.
2124     *
2125     * TODO: Not very optimized.
2126     *
2127     * On entry:
2128     *    x0:   this object pointer
2129     *    x1:   comp object pointer
2130     *
2131     */
2132    .extern __memcmp16
2133ENTRY art_quick_string_compareto
2134    mov    x2, x0         // x0 is return, use x2 for first input.
2135    sub    x0, x2, x1     // Same string object?
2136    cbnz   x0,1f
2137    ret
21381:                        // Different string objects.
2139
2140    ldr    w4, [x2, #MIRROR_STRING_COUNT_OFFSET]
2141    ldr    w3, [x1, #MIRROR_STRING_COUNT_OFFSET]
2142    add    x2, x2, #MIRROR_STRING_VALUE_OFFSET
2143    add    x1, x1, #MIRROR_STRING_VALUE_OFFSET
2144
2145    /*
2146     * Now:           Data*  Count
2147     *    first arg    x2      w4
2148     *   second arg    x1      w3
2149     */
2150
2151    // x0 := str1.length(w4) - str2.length(w3). ldr zero-extended w3/w4 into x3/x4.
2152    subs x0, x4, x3
2153    // Min(count1, count2) into w3.
2154    csel x3, x3, x4, ge
2155
2156    // TODO: Tune this value.
2157    // Check for long string, do memcmp16 for them.
2158    cmp w3, #28  // Constant from arm32.
2159    bgt .Ldo_memcmp16
2160
2161    /*
2162     * Now:
2163     *   x2: *first string data
2164     *   x1: *second string data
2165     *   w3: iteration count
2166     *   x0: return value if comparison equal
2167     *   x4, x5, x6, x7: free
2168     */
2169
2170    // Do a simple unrolled loop.
2171.Lloop:
2172    // At least two more elements?
2173    subs w3, w3, #2
2174    b.lt .Lremainder_or_done
2175
2176    ldrh w4, [x2], #2
2177    ldrh w5, [x1], #2
2178
2179    ldrh w6, [x2], #2
2180    ldrh w7, [x1], #2
2181
2182    subs w4, w4, w5
2183    b.ne .Lw4_result
2184
2185    subs w6, w6, w7
2186    b.ne .Lw6_result
2187
2188    b .Lloop
2189
2190.Lremainder_or_done:
2191    adds w3, w3, #1
2192    b.eq .Lremainder
2193    ret
2194
2195.Lremainder:
2196    ldrh w4, [x2], #2
2197    ldrh w5, [x1], #2
2198    subs w4, w4, w5
2199    b.ne .Lw4_result
2200    ret
2201
2202// Result is in w4
2203.Lw4_result:
2204    sxtw x0, w4
2205    ret
2206
2207// Result is in w6
2208.Lw6_result:
2209    sxtw x0, w6
2210    ret
2211
2212.Ldo_memcmp16:
2213    mov x14, x0                  // Save x0 and LR. __memcmp16 does not use these temps.
2214    mov x15, xLR                 //                 TODO: Codify and check that?
2215
2216    mov x0, x2
2217    uxtw x2, w3
2218    bl __memcmp16
2219
2220    mov xLR, x15                 // Restore LR.
2221
2222    cmp x0, #0                   // Check the memcmp difference.
2223    csel x0, x0, x14, ne         // x0 := x0 != 0 ? x14(prev x0=length diff) : x1.
2224    ret
2225END art_quick_string_compareto
2226