2 * tramp-arm.c: JIT trampoline code for ARM
5 * Paolo Molaro (lupus@ximian.com)
7 * (C) 2001 Ximian, Inc.
13 #include <mono/metadata/appdomain.h>
14 #include <mono/metadata/marshal.h>
15 #include <mono/metadata/tabledefs.h>
16 #include <mono/arch/arm/arm-codegen.h>
21 static guint8* nullified_class_init_trampoline;
24 * Return the instruction to jump from code to target, 0 if not
25 * reachable with a single instruction
28 branch_for_target_reachable (guint8 *branch, guint8 *target)
30 gint diff = target - branch - 8;
31 g_assert ((diff & 3) == 0);
34 return (ARMCOND_AL << ARMCOND_SHIFT) | (ARM_BR_TAG) | (diff >> 2);
36 /* diff between 0 and -33554432 */
37 if (diff >= -33554432)
38 return (ARMCOND_AL << ARMCOND_SHIFT) | (ARM_BR_TAG) | ((diff >> 2) & ~0xff000000);
44 * mono_arch_get_unbox_trampoline:
45 * @gsctx: the generic sharing context
47 * @addr: pointer to native code for @m
49 * when value type methods are called through the vtable we need to unbox the
50 * this argument. This method returns a pointer to a trampoline which does
51 * unboxing before calling the method
54 mono_arch_get_unbox_trampoline (MonoGenericSharingContext *gsctx, MonoMethod *m, gpointer addr)
58 MonoDomain *domain = mono_domain_get ();
60 if (MONO_TYPE_ISSTRUCT (mono_method_signature (m)->ret))
63 start = code = mono_domain_code_reserve (domain, 16);
65 ARM_LDR_IMM (code, ARMREG_IP, ARMREG_PC, 4);
66 ARM_ADD_REG_IMM8 (code, this_pos, this_pos, sizeof (MonoObject));
67 ARM_MOV_REG_REG (code, ARMREG_PC, ARMREG_IP);
68 *(guint32*)code = (guint32)addr;
70 mono_arch_flush_icache (start, code - start);
71 g_assert ((code - start) <= 16);
72 /*g_print ("unbox trampoline at %d for %s:%s\n", this_pos, m->klass->name, m->name);
73 g_print ("unbox code is at %p for method at %p\n", start, addr);*/
79 mono_arch_patch_callsite (guint8 *method_start, guint8 *code_ptr, guint8 *addr)
81 guint32 *code = (guint32*)code_ptr;
83 /* This is the 'bl' or the 'mov pc' instruction */
87 * Note that methods are called also with the bl opcode.
89 if ((((*code) >> 25) & 7) == 5) {
90 /*g_print ("direct patching\n");*/
91 arm_patch ((guint8*)code, addr);
92 mono_arch_flush_icache ((guint8*)code, 4);
96 if ((((*code) >> 20) & 0xFF) == 0x12) {
97 /*g_print ("patching bx\n");*/
98 arm_patch ((guint8*)code, addr);
99 mono_arch_flush_icache ((guint8*)(code - 2), 4);
103 g_assert_not_reached ();
107 mono_arch_patch_plt_entry (guint8 *code, guint8 *addr)
109 /* Patch the jump table entry used by the plt entry */
110 guint32 offset = ((guint32*)code)[3];
111 guint8 *jump_entry = code + offset + 12;
113 *(guint8**)jump_entry = addr;
117 mono_arch_nullify_class_init_trampoline (guint8 *code, gssize *regs)
119 mono_arch_patch_callsite (NULL, code, nullified_class_init_trampoline);
123 mono_arch_nullify_plt_entry (guint8 *code)
125 if (mono_aot_only && !nullified_class_init_trampoline)
126 nullified_class_init_trampoline = mono_aot_get_named_code ("nullified_class_init_trampoline");
128 mono_arch_patch_plt_entry (code, nullified_class_init_trampoline);
131 /* Stack size for trampoline function
133 #define STACK (sizeof (MonoLMF))
135 /* Method-specific trampoline code fragment size */
136 #define METHOD_TRAMPOLINE_SIZE 64
138 /* Jump-specific trampoline code fragment size */
139 #define JUMP_TRAMPOLINE_SIZE 64
141 #define GEN_TRAMP_SIZE 192
144 * Stack frame description when the generic trampoline is called.
146 * ------------------- old sp
148 * ------------------- sp
151 mono_arch_create_trampoline_code (MonoTrampolineType tramp_type)
156 GSList *unwind_ops, *l;
158 code = mono_arch_create_trampoline_code_full (tramp_type, &code_size, &ji, &unwind_ops, FALSE);
160 mono_save_trampoline_xdebug_info ("<generic_trampoline>", code, code_size, unwind_ops);
162 for (l = unwind_ops; l; l = l->next)
164 g_slist_free (unwind_ops);
170 mono_arch_create_trampoline_code_full (MonoTrampolineType tramp_type, guint32 *code_size, MonoJumpInfo **ji, GSList **out_unwind_ops, gboolean aot)
172 guint8 *buf, *code = NULL;
173 guint8 *load_get_lmf_addr, *load_trampoline;
175 GSList *unwind_ops = NULL;
180 /* Now we'll create in 'buf' the ARM trampoline code. This
181 is the trampoline code common to all methods */
183 code = buf = mono_global_codeman_reserve (GEN_TRAMP_SIZE);
186 * At this point lr points to the specific arg and sp points to the saved
187 * regs on the stack (all but PC and SP). The original LR value has been
188 * saved as sp + LR_OFFSET by the push in the specific trampoline
190 #define LR_OFFSET (sizeof (gpointer) * 13)
192 // FIXME: Finish the unwind info, the current info allows us to unwind
193 // when the trampoline is not in the epilog
195 // CFA = SP + (num registers pushed) * 4
196 cfa_offset = 14 * sizeof (gpointer);
197 mono_add_unwind_op_def_cfa (unwind_ops, code, buf, ARMREG_SP, cfa_offset);
198 // PC saved at sp+LR_OFFSET
199 mono_add_unwind_op_offset (unwind_ops, code, buf, ARMREG_LR, -4);
201 ARM_MOV_REG_REG (code, ARMREG_V1, ARMREG_SP);
202 if (aot && tramp_type != MONO_TRAMPOLINE_GENERIC_CLASS_INIT) {
204 * The trampoline contains a pc-relative offset to the got slot where the
205 * value is stored. The offset can be found at [lr + 4].
207 ARM_LDR_IMM (code, ARMREG_V2, ARMREG_LR, 4);
208 ARM_LDR_REG_REG (code, ARMREG_V2, ARMREG_V2, ARMREG_LR);
210 if (tramp_type != MONO_TRAMPOLINE_GENERIC_CLASS_INIT)
211 ARM_LDR_IMM (code, ARMREG_V2, ARMREG_LR, 0);
213 ARM_MOV_REG_REG (code, ARMREG_V2, MONO_ARCH_VTABLE_REG);
215 ARM_LDR_IMM (code, ARMREG_V3, ARMREG_SP, LR_OFFSET);
217 /* ok, now we can continue with the MonoLMF setup, mostly untouched
218 * from emit_prolog in mini-arm.c
219 * This is a synthetized call to mono_get_lmf_addr ()
222 *ji = mono_patch_info_list_prepend (*ji, code - buf, MONO_PATCH_INFO_JIT_ICALL_ADDR, "mono_get_lmf_addr");
223 ARM_LDR_IMM (code, ARMREG_R0, ARMREG_PC, 0);
225 *(gpointer*)code = NULL;
227 ARM_LDR_REG_REG (code, ARMREG_R0, ARMREG_PC, ARMREG_R0);
229 load_get_lmf_addr = code;
232 ARM_MOV_REG_REG (code, ARMREG_LR, ARMREG_PC);
233 ARM_MOV_REG_REG (code, ARMREG_PC, ARMREG_R0);
235 /* we build the MonoLMF structure on the stack - see mini-arm.h
236 * The pointer to the struct is put in r1.
237 * the iregs array is already allocated on the stack by push.
239 ARM_SUB_REG_IMM8 (code, ARMREG_SP, ARMREG_SP, sizeof (MonoLMF) - sizeof (guint) * 14);
240 cfa_offset += sizeof (MonoLMF) - sizeof (guint) * 14;
241 mono_add_unwind_op_def_cfa_offset (unwind_ops, code, buf, cfa_offset);
242 ARM_ADD_REG_IMM8 (code, ARMREG_R1, ARMREG_SP, STACK - sizeof (MonoLMF));
243 /* r0 is the result from mono_get_lmf_addr () */
244 ARM_STR_IMM (code, ARMREG_R0, ARMREG_R1, G_STRUCT_OFFSET (MonoLMF, lmf_addr));
245 /* new_lmf->previous_lmf = *lmf_addr */
246 ARM_LDR_IMM (code, ARMREG_R2, ARMREG_R0, G_STRUCT_OFFSET (MonoLMF, previous_lmf));
247 ARM_STR_IMM (code, ARMREG_R2, ARMREG_R1, G_STRUCT_OFFSET (MonoLMF, previous_lmf));
248 /* *(lmf_addr) = r1 */
249 ARM_STR_IMM (code, ARMREG_R1, ARMREG_R0, G_STRUCT_OFFSET (MonoLMF, previous_lmf));
250 /* save method info (it's in v2) */
251 if ((tramp_type == MONO_TRAMPOLINE_JIT) || (tramp_type == MONO_TRAMPOLINE_JUMP))
252 ARM_STR_IMM (code, ARMREG_V2, ARMREG_R1, G_STRUCT_OFFSET (MonoLMF, method));
253 ARM_STR_IMM (code, ARMREG_SP, ARMREG_R1, G_STRUCT_OFFSET (MonoLMF, ebp));
254 /* save the IP (caller ip) */
255 if (tramp_type == MONO_TRAMPOLINE_JUMP) {
256 ARM_MOV_REG_IMM8 (code, ARMREG_R2, 0);
258 /* assumes STACK == sizeof (MonoLMF) */
259 ARM_LDR_IMM (code, ARMREG_R2, ARMREG_SP, (G_STRUCT_OFFSET (MonoLMF, iregs) + 13*4));
261 ARM_STR_IMM (code, ARMREG_R2, ARMREG_R1, G_STRUCT_OFFSET (MonoLMF, eip));
264 * Now we're ready to call xxx_trampoline ().
266 /* Arg 1: the saved registers. It was put in v1 */
267 ARM_MOV_REG_REG (code, ARMREG_R0, ARMREG_V1);
269 /* Arg 2: code (next address to the instruction that called us) */
270 if (tramp_type == MONO_TRAMPOLINE_JUMP) {
271 ARM_MOV_REG_IMM8 (code, ARMREG_R1, 0);
273 ARM_MOV_REG_REG (code, ARMREG_R1, ARMREG_V3);
276 /* Arg 3: the specific argument, stored in v2
278 ARM_MOV_REG_REG (code, ARMREG_R2, ARMREG_V2);
281 char *icall_name = g_strdup_printf ("trampoline_func_%d", tramp_type);
282 *ji = mono_patch_info_list_prepend (*ji, code - buf, MONO_PATCH_INFO_JIT_ICALL_ADDR, icall_name);
283 ARM_LDR_IMM (code, ARMREG_IP, ARMREG_PC, 0);
285 *(gpointer*)code = NULL;
287 ARM_LDR_REG_REG (code, ARMREG_IP, ARMREG_PC, ARMREG_IP);
289 load_trampoline = code;
293 ARM_MOV_REG_REG (code, ARMREG_LR, ARMREG_PC);
294 ARM_MOV_REG_REG (code, ARMREG_PC, ARMREG_IP);
296 /* OK, code address is now on r0. Move it to the place on the stack
297 * where IP was saved (it is now no more useful to us and it can be
298 * clobbered). This way we can just restore all the regs in one inst
301 ARM_STR_IMM (code, ARMREG_R0, ARMREG_V1, (ARMREG_R12 * 4));
303 /* Check for thread interruption */
304 /* This is not perf critical code so no need to check the interrupt flag */
306 * Have to call the _force_ variant, since there could be a protected wrapper on the top of the stack.
309 *ji = mono_patch_info_list_prepend (*ji, code - buf, MONO_PATCH_INFO_JIT_ICALL_ADDR, "mono_thread_force_interruption_checkpoint");
310 ARM_LDR_IMM (code, ARMREG_IP, ARMREG_PC, 0);
312 *(gpointer*)code = NULL;
314 ARM_LDR_REG_REG (code, ARMREG_IP, ARMREG_PC, ARMREG_IP);
316 ARM_LDR_IMM (code, ARMREG_IP, ARMREG_PC, 0);
318 *(gpointer*)code = mono_thread_force_interruption_checkpoint;
321 ARM_MOV_REG_REG (code, ARMREG_LR, ARMREG_PC);
322 ARM_MOV_REG_REG (code, ARMREG_PC, ARMREG_IP);
325 * Now we restore the MonoLMF (see emit_epilogue in mini-arm.c)
326 * and the rest of the registers, so the method called will see
327 * the same state as before we executed.
328 * The pointer to MonoLMF is in r2.
330 ARM_MOV_REG_REG (code, ARMREG_R2, ARMREG_SP);
331 /* ip = previous_lmf */
332 ARM_LDR_IMM (code, ARMREG_IP, ARMREG_R2, G_STRUCT_OFFSET (MonoLMF, previous_lmf));
334 ARM_LDR_IMM (code, ARMREG_LR, ARMREG_R2, G_STRUCT_OFFSET (MonoLMF, lmf_addr));
335 /* *(lmf_addr) = previous_lmf */
336 ARM_STR_IMM (code, ARMREG_IP, ARMREG_LR, G_STRUCT_OFFSET (MonoLMF, previous_lmf));
338 /* Non-standard function epilogue. Instead of doing a proper
339 * return, we just jump to the compiled code.
341 /* Restore the registers and jump to the code:
342 * Note that IP has been conveniently set to the method addr.
344 ARM_ADD_REG_IMM8 (code, ARMREG_SP, ARMREG_SP, sizeof (MonoLMF) - sizeof (guint) * 14);
345 ARM_POP_NWB (code, 0x5fff);
346 if (tramp_type == MONO_TRAMPOLINE_RGCTX_LAZY_FETCH)
347 ARM_MOV_REG_REG (code, ARMREG_R0, ARMREG_IP);
348 /* do we need to set sp? */
349 ARM_ADD_REG_IMM8 (code, ARMREG_SP, ARMREG_SP, (14 * 4));
350 if ((tramp_type == MONO_TRAMPOLINE_CLASS_INIT) || (tramp_type == MONO_TRAMPOLINE_GENERIC_CLASS_INIT) || (tramp_type == MONO_TRAMPOLINE_RGCTX_LAZY_FETCH))
351 ARM_MOV_REG_REG (code, ARMREG_PC, ARMREG_LR);
353 ARM_MOV_REG_REG (code, ARMREG_PC, ARMREG_IP);
355 constants = (gpointer*)code;
356 constants [0] = mono_get_lmf_addr;
357 constants [1] = (gpointer)mono_get_trampoline_func (tramp_type);
360 /* backpatch by emitting the missing instructions skipped above */
361 ARM_LDR_IMM (load_get_lmf_addr, ARMREG_R0, ARMREG_PC, (code - load_get_lmf_addr - 8));
362 ARM_LDR_IMM (load_trampoline, ARMREG_IP, ARMREG_PC, (code + 4 - load_trampoline - 8));
367 /* Flush instruction cache, since we've generated code */
368 mono_arch_flush_icache (buf, code - buf);
371 g_assert ((code - buf) <= GEN_TRAMP_SIZE);
373 *code_size = code - buf;
375 if (tramp_type == MONO_TRAMPOLINE_CLASS_INIT) {
378 /* Initialize the nullified class init trampoline used in the AOT case */
379 nullified_class_init_trampoline = mono_arch_get_nullified_class_init_trampoline (&code_len);
382 *out_unwind_ops = unwind_ops;
388 mono_arch_get_nullified_class_init_trampoline (guint32 *code_len)
392 code = buf = mono_global_codeman_reserve (16);
394 ARM_MOV_REG_REG (code, ARMREG_PC, ARMREG_LR);
396 mono_arch_flush_icache (buf, code - buf);
398 *code_len = code - buf;
403 #define SPEC_TRAMP_SIZE 24
406 mono_arch_create_specific_trampoline (gpointer arg1, MonoTrampolineType tramp_type, MonoDomain *domain, guint32 *code_len)
408 guint8 *code, *buf, *tramp;
410 guint32 short_branch, size = SPEC_TRAMP_SIZE;
412 tramp = mono_get_trampoline_code (tramp_type);
414 mono_domain_lock (domain);
415 code = buf = mono_domain_code_reserve_align (domain, size, 4);
416 if ((short_branch = branch_for_target_reachable (code + 8, tramp))) {
418 mono_domain_code_commit (domain, code, SPEC_TRAMP_SIZE, size);
420 mono_domain_unlock (domain);
422 /* we could reduce this to 12 bytes if tramp is within reach:
426 * The called code can access method using the lr register
427 * A 20 byte sequence could be:
429 * ARM_MOV_REG_REG (lr, pc)
430 * ARM_LDR_IMM (pc, pc, 0)
434 /* We save all the registers, except PC and SP */
435 ARM_PUSH (code, 0x5fff);
437 constants = (gpointer*)code;
438 constants [0] = GUINT_TO_POINTER (short_branch | (1 << 24));
439 constants [1] = arg1;
442 ARM_LDR_IMM (code, ARMREG_R1, ARMREG_PC, 8); /* temp reg */
443 ARM_MOV_REG_REG (code, ARMREG_LR, ARMREG_PC);
444 ARM_MOV_REG_REG (code, ARMREG_PC, ARMREG_R1);
446 constants = (gpointer*)code;
447 constants [0] = arg1;
448 constants [1] = tramp;
452 /* Flush instruction cache, since we've generated code */
453 mono_arch_flush_icache (buf, code - buf);
455 g_assert ((code - buf) <= size);
458 *code_len = code - buf;
463 #define arm_is_imm12(v) ((int)(v) > -4096 && (int)(v) < 4096)
466 mono_arch_create_rgctx_lazy_fetch_trampoline (guint32 slot)
471 return mono_arch_create_rgctx_lazy_fetch_trampoline_full (slot, &code_size, &ji, FALSE);
475 mono_arch_create_rgctx_lazy_fetch_trampoline_full (guint32 slot, guint32 *code_size, MonoJumpInfo **ji, gboolean aot)
481 guint8 **rgctx_null_jumps;
488 mrgctx = MONO_RGCTX_SLOT_IS_MRGCTX (slot);
489 index = MONO_RGCTX_SLOT_INDEX (slot);
491 index += sizeof (MonoMethodRuntimeGenericContext) / sizeof (gpointer);
492 for (depth = 0; ; ++depth) {
493 int size = mono_class_rgctx_get_array_size (depth, mrgctx);
495 if (index < size - 1)
500 tramp_size = 64 + 16 * depth;
502 code = buf = mono_global_codeman_reserve (tramp_size);
504 rgctx_null_jumps = g_malloc (sizeof (guint8*) * (depth + 2));
507 /* The vtable/mrgctx is in R0 */
508 g_assert (MONO_ARCH_VTABLE_REG == ARMREG_R0);
512 ARM_MOV_REG_REG (code, ARMREG_R1, ARMREG_R0);
514 /* load rgctx ptr from vtable */
515 g_assert (arm_is_imm12 (G_STRUCT_OFFSET (MonoVTable, runtime_generic_context)));
516 ARM_LDR_IMM (code, ARMREG_R1, ARMREG_R0, G_STRUCT_OFFSET (MonoVTable, runtime_generic_context));
517 /* is the rgctx ptr null? */
518 ARM_CMP_REG_IMM (code, ARMREG_R1, 0, 0);
519 /* if yes, jump to actual trampoline */
520 rgctx_null_jumps [njumps ++] = code;
521 ARM_B_COND (code, ARMCOND_EQ, 0);
524 for (i = 0; i < depth; ++i) {
525 /* load ptr to next array */
526 if (mrgctx && i == 0) {
527 g_assert (arm_is_imm12 (sizeof (MonoMethodRuntimeGenericContext)));
528 ARM_LDR_IMM (code, ARMREG_R1, ARMREG_R1, sizeof (MonoMethodRuntimeGenericContext));
530 ARM_LDR_IMM (code, ARMREG_R1, ARMREG_R1, 0);
532 /* is the ptr null? */
533 ARM_CMP_REG_IMM (code, ARMREG_R1, 0, 0);
534 /* if yes, jump to actual trampoline */
535 rgctx_null_jumps [njumps ++] = code;
536 ARM_B_COND (code, ARMCOND_EQ, 0);
540 code = mono_arm_emit_load_imm (code, ARMREG_R2, sizeof (gpointer) * (index + 1));
541 ARM_LDR_REG_REG (code, ARMREG_R1, ARMREG_R1, ARMREG_R2);
542 /* is the slot null? */
543 ARM_CMP_REG_IMM (code, ARMREG_R1, 0, 0);
544 /* if yes, jump to actual trampoline */
545 rgctx_null_jumps [njumps ++] = code;
546 ARM_B_COND (code, ARMCOND_EQ, 0);
547 /* otherwise return, result is in R1 */
548 ARM_MOV_REG_REG (code, ARMREG_R0, ARMREG_R1);
549 ARM_MOV_REG_REG (code, ARMREG_PC, ARMREG_LR);
551 g_assert (njumps <= depth + 2);
552 for (i = 0; i < njumps; ++i)
553 arm_patch (rgctx_null_jumps [i], code);
555 g_free (rgctx_null_jumps);
559 /* The vtable/mrgctx is still in R0 */
562 *ji = mono_patch_info_list_prepend (*ji, code - buf, MONO_PATCH_INFO_JIT_ICALL_ADDR, g_strdup_printf ("specific_trampoline_lazy_fetch_%u", slot));
563 ARM_LDR_IMM (code, ARMREG_R1, ARMREG_PC, 0);
565 *(gpointer*)code = NULL;
567 ARM_LDR_REG_REG (code, ARMREG_PC, ARMREG_PC, ARMREG_R1);
569 tramp = mono_arch_create_specific_trampoline (GUINT_TO_POINTER (slot), MONO_TRAMPOLINE_RGCTX_LAZY_FETCH, mono_get_root_domain (), &code_len);
571 /* Jump to the actual trampoline */
572 ARM_LDR_IMM (code, ARMREG_R1, ARMREG_PC, 0); /* temp reg */
573 ARM_MOV_REG_REG (code, ARMREG_PC, ARMREG_R1);
574 *(gpointer*)code = tramp;
578 mono_arch_flush_icache (buf, code - buf);
580 g_assert (code - buf <= tramp_size);
582 *code_size = code - buf;
587 #define arm_is_imm8(v) ((v) > -256 && (v) < 256)
590 mono_arch_create_generic_class_init_trampoline (void)
595 return mono_arch_create_generic_class_init_trampoline_full (&code_size, &ji, FALSE);
599 mono_arch_create_generic_class_init_trampoline_full (guint32 *code_size, MonoJumpInfo **ji, gboolean aot)
603 static int byte_offset = -1;
604 static guint8 bitmask;
607 guint32 code_len, imm8;
614 code = buf = mono_global_codeman_reserve (tramp_size);
617 mono_marshal_find_bitfield_offset (MonoVTable, initialized, &byte_offset, &bitmask);
619 g_assert (arm_is_imm8 (byte_offset));
620 ARM_LDRSB_IMM (code, ARMREG_IP, MONO_ARCH_VTABLE_REG, byte_offset);
621 imm8 = mono_arm_is_rotated_imm8 (bitmask, &rot_amount);
622 g_assert (imm8 >= 0);
623 ARM_AND_REG_IMM (code, ARMREG_IP, ARMREG_IP, imm8, rot_amount);
624 ARM_CMP_REG_IMM (code, ARMREG_IP, 0, 0);
626 ARM_B_COND (code, ARMCOND_EQ, 0);
628 /* Initialized case */
629 ARM_MOV_REG_REG (code, ARMREG_PC, ARMREG_LR);
631 /* Uninitialized case */
632 arm_patch (jump, code);
635 *ji = mono_patch_info_list_prepend (*ji, code - buf, MONO_PATCH_INFO_JIT_ICALL_ADDR, "specific_trampoline_generic_class_init");
636 ARM_LDR_IMM (code, ARMREG_R1, ARMREG_PC, 0);
638 *(gpointer*)code = NULL;
640 ARM_LDR_REG_REG (code, ARMREG_PC, ARMREG_PC, ARMREG_R1);
642 tramp = mono_arch_create_specific_trampoline (NULL, MONO_TRAMPOLINE_GENERIC_CLASS_INIT, mono_get_root_domain (), &code_len);
644 /* Jump to the actual trampoline */
645 ARM_LDR_IMM (code, ARMREG_R1, ARMREG_PC, 0); /* temp reg */
646 ARM_MOV_REG_REG (code, ARMREG_PC, ARMREG_R1);
647 *(gpointer*)code = tramp;
651 mono_arch_flush_icache (buf, code - buf);
653 g_assert (code - buf <= tramp_size);
655 *code_size = code - buf;