Mercurial > hg > graal-compiler
annotate src/cpu/x86/vm/nativeInst_x86.cpp @ 1172:b2b6a9bf6238
6894779: Loop Predication for Loop Optimizer in C2
Summary: Loop predication implementation
Reviewed-by: never, kvn
author | cfang |
---|---|
date | Tue, 12 Jan 2010 14:37:35 -0800 |
parents | dc7f315e41f7 |
children | c18cbe5936b8 |
rev | line source |
---|---|
0 | 1 /* |
196 | 2 * Copyright 1997-2008 Sun Microsystems, Inc. All Rights Reserved. |
0 | 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
4 * | |
5 * This code is free software; you can redistribute it and/or modify it | |
6 * under the terms of the GNU General Public License version 2 only, as | |
7 * published by the Free Software Foundation. | |
8 * | |
9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
12 * version 2 for more details (a copy is included in the LICENSE file that | |
13 * accompanied this code). | |
14 * | |
15 * You should have received a copy of the GNU General Public License version | |
16 * 2 along with this work; if not, write to the Free Software Foundation, | |
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
18 * | |
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, | |
20 * CA 95054 USA or visit www.sun.com if you need additional information or | |
21 * have any questions. | |
22 * | |
23 */ | |
24 | |
25 # include "incls/_precompiled.incl" | |
26 # include "incls/_nativeInst_x86.cpp.incl" | |
27 | |
28 void NativeInstruction::wrote(int offset) { | |
29 ICache::invalidate_word(addr_at(offset)); | |
30 } | |
31 | |
32 | |
33 void NativeCall::verify() { | |
34 // Make sure code pattern is actually a call imm32 instruction. | |
35 int inst = ubyte_at(0); | |
36 if (inst != instruction_code) { | |
37 tty->print_cr("Addr: " INTPTR_FORMAT " Code: 0x%x", instruction_address(), | |
38 inst); | |
39 fatal("not a call disp32"); | |
40 } | |
41 } | |
42 | |
43 address NativeCall::destination() const { | |
44 // Getting the destination of a call isn't safe because that call can | |
45 // be getting patched while you're calling this. There's only special | |
46 // places where this can be called but not automatically verifiable by | |
47 // checking which locks are held. The solution is true atomic patching | |
48 // on x86, nyi. | |
49 return return_address() + displacement(); | |
50 } | |
51 | |
52 void NativeCall::print() { | |
53 tty->print_cr(PTR_FORMAT ": call " PTR_FORMAT, | |
54 instruction_address(), destination()); | |
55 } | |
56 | |
57 // Inserts a native call instruction at a given pc | |
58 void NativeCall::insert(address code_pos, address entry) { | |
59 intptr_t disp = (intptr_t)entry - ((intptr_t)code_pos + 1 + 4); | |
60 #ifdef AMD64 | |
61 guarantee(disp == (intptr_t)(jint)disp, "must be 32-bit offset"); | |
62 #endif // AMD64 | |
63 *code_pos = instruction_code; | |
64 *((int32_t *)(code_pos+1)) = (int32_t) disp; | |
65 ICache::invalidate_range(code_pos, instruction_size); | |
66 } | |
67 | |
68 // MT-safe patching of a call instruction. | |
69 // First patches first word of instruction to two jmp's that jmps to them | |
70 // selfs (spinlock). Then patches the last byte, and then atomicly replaces | |
71 // the jmp's with the first 4 byte of the new instruction. | |
72 void NativeCall::replace_mt_safe(address instr_addr, address code_buffer) { | |
73 assert(Patching_lock->is_locked() || | |
74 SafepointSynchronize::is_at_safepoint(), "concurrent code patching"); | |
75 assert (instr_addr != NULL, "illegal address for code patching"); | |
76 | |
77 NativeCall* n_call = nativeCall_at (instr_addr); // checking that it is a call | |
78 if (os::is_MP()) { | |
79 guarantee((intptr_t)instr_addr % BytesPerWord == 0, "must be aligned"); | |
80 } | |
81 | |
82 // First patch dummy jmp in place | |
83 unsigned char patch[4]; | |
84 assert(sizeof(patch)==sizeof(jint), "sanity check"); | |
85 patch[0] = 0xEB; // jmp rel8 | |
86 patch[1] = 0xFE; // jmp to self | |
87 patch[2] = 0xEB; | |
88 patch[3] = 0xFE; | |
89 | |
90 // First patch dummy jmp in place | |
91 *(jint*)instr_addr = *(jint *)patch; | |
92 | |
93 // Invalidate. Opteron requires a flush after every write. | |
94 n_call->wrote(0); | |
95 | |
96 // Patch 4th byte | |
97 instr_addr[4] = code_buffer[4]; | |
98 | |
99 n_call->wrote(4); | |
100 | |
101 // Patch bytes 0-3 | |
102 *(jint*)instr_addr = *(jint *)code_buffer; | |
103 | |
104 n_call->wrote(0); | |
105 | |
106 #ifdef ASSERT | |
107 // verify patching | |
108 for ( int i = 0; i < instruction_size; i++) { | |
109 address ptr = (address)((intptr_t)code_buffer + i); | |
110 int a_byte = (*ptr) & 0xFF; | |
111 assert(*((address)((intptr_t)instr_addr + i)) == a_byte, "mt safe patching failed"); | |
112 } | |
113 #endif | |
114 | |
115 } | |
116 | |
117 | |
118 // Similar to replace_mt_safe, but just changes the destination. The | |
119 // important thing is that free-running threads are able to execute this | |
120 // call instruction at all times. If the displacement field is aligned | |
121 // we can simply rely on atomicity of 32-bit writes to make sure other threads | |
122 // will see no intermediate states. Otherwise, the first two bytes of the | |
123 // call are guaranteed to be aligned, and can be atomically patched to a | |
124 // self-loop to guard the instruction while we change the other bytes. | |
125 | |
126 // We cannot rely on locks here, since the free-running threads must run at | |
127 // full speed. | |
128 // | |
129 // Used in the runtime linkage of calls; see class CompiledIC. | |
130 // (Cf. 4506997 and 4479829, where threads witnessed garbage displacements.) | |
131 void NativeCall::set_destination_mt_safe(address dest) { | |
132 debug_only(verify()); | |
133 // Make sure patching code is locked. No two threads can patch at the same | |
134 // time but one may be executing this code. | |
135 assert(Patching_lock->is_locked() || | |
136 SafepointSynchronize::is_at_safepoint(), "concurrent code patching"); | |
137 // Both C1 and C2 should now be generating code which aligns the patched address | |
138 // to be within a single cache line except that C1 does not do the alignment on | |
139 // uniprocessor systems. | |
140 bool is_aligned = ((uintptr_t)displacement_address() + 0) / cache_line_size == | |
141 ((uintptr_t)displacement_address() + 3) / cache_line_size; | |
142 | |
143 guarantee(!os::is_MP() || is_aligned, "destination must be aligned"); | |
144 | |
145 if (is_aligned) { | |
146 // Simple case: The destination lies within a single cache line. | |
147 set_destination(dest); | |
148 } else if ((uintptr_t)instruction_address() / cache_line_size == | |
149 ((uintptr_t)instruction_address()+1) / cache_line_size) { | |
150 // Tricky case: The instruction prefix lies within a single cache line. | |
151 intptr_t disp = dest - return_address(); | |
152 #ifdef AMD64 | |
153 guarantee(disp == (intptr_t)(jint)disp, "must be 32-bit offset"); | |
154 #endif // AMD64 | |
155 | |
156 int call_opcode = instruction_address()[0]; | |
157 | |
158 // First patch dummy jump in place: | |
159 { | |
160 u_char patch_jump[2]; | |
161 patch_jump[0] = 0xEB; // jmp rel8 | |
162 patch_jump[1] = 0xFE; // jmp to self | |
163 | |
164 assert(sizeof(patch_jump)==sizeof(short), "sanity check"); | |
165 *(short*)instruction_address() = *(short*)patch_jump; | |
166 } | |
167 // Invalidate. Opteron requires a flush after every write. | |
168 wrote(0); | |
169 | |
170 // (Note: We assume any reader which has already started to read | |
171 // the unpatched call will completely read the whole unpatched call | |
172 // without seeing the next writes we are about to make.) | |
173 | |
174 // Next, patch the last three bytes: | |
175 u_char patch_disp[5]; | |
176 patch_disp[0] = call_opcode; | |
177 *(int32_t*)&patch_disp[1] = (int32_t)disp; | |
178 assert(sizeof(patch_disp)==instruction_size, "sanity check"); | |
179 for (int i = sizeof(short); i < instruction_size; i++) | |
180 instruction_address()[i] = patch_disp[i]; | |
181 | |
182 // Invalidate. Opteron requires a flush after every write. | |
183 wrote(sizeof(short)); | |
184 | |
185 // (Note: We assume that any reader which reads the opcode we are | |
186 // about to repatch will also read the writes we just made.) | |
187 | |
188 // Finally, overwrite the jump: | |
189 *(short*)instruction_address() = *(short*)patch_disp; | |
190 // Invalidate. Opteron requires a flush after every write. | |
191 wrote(0); | |
192 | |
193 debug_only(verify()); | |
194 guarantee(destination() == dest, "patch succeeded"); | |
195 } else { | |
196 // Impossible: One or the other must be atomically writable. | |
197 ShouldNotReachHere(); | |
198 } | |
199 } | |
200 | |
201 | |
202 void NativeMovConstReg::verify() { | |
203 #ifdef AMD64 | |
204 // make sure code pattern is actually a mov reg64, imm64 instruction | |
205 if ((ubyte_at(0) != Assembler::REX_W && ubyte_at(0) != Assembler::REX_WB) || | |
206 (ubyte_at(1) & (0xff ^ register_mask)) != 0xB8) { | |
207 print(); | |
208 fatal("not a REX.W[B] mov reg64, imm64"); | |
209 } | |
210 #else | |
211 // make sure code pattern is actually a mov reg, imm32 instruction | |
212 u_char test_byte = *(u_char*)instruction_address(); | |
213 u_char test_byte_2 = test_byte & ( 0xff ^ register_mask); | |
214 if (test_byte_2 != instruction_code) fatal("not a mov reg, imm32"); | |
215 #endif // AMD64 | |
216 } | |
217 | |
218 | |
219 void NativeMovConstReg::print() { | |
220 tty->print_cr(PTR_FORMAT ": mov reg, " INTPTR_FORMAT, | |
221 instruction_address(), data()); | |
222 } | |
223 | |
224 //------------------------------------------------------------------- | |
225 | |
304 | 226 int NativeMovRegMem::instruction_start() const { |
227 int off = 0; | |
228 u_char instr_0 = ubyte_at(off); | |
229 | |
230 // First check to see if we have a (prefixed or not) xor | |
231 if ( instr_0 >= instruction_prefix_wide_lo && // 0x40 | |
232 instr_0 <= instruction_prefix_wide_hi) { // 0x4f | |
233 off++; | |
234 instr_0 = ubyte_at(off); | |
235 } | |
236 | |
237 if (instr_0 == instruction_code_xor) { | |
238 off += 2; | |
239 instr_0 = ubyte_at(off); | |
240 } | |
241 | |
242 // Now look for the real instruction and the many prefix/size specifiers. | |
243 | |
244 if (instr_0 == instruction_operandsize_prefix ) { // 0x66 | |
245 off++; // Not SSE instructions | |
246 instr_0 = ubyte_at(off); | |
247 } | |
0 | 248 |
304 | 249 if ( instr_0 == instruction_code_xmm_ss_prefix || // 0xf3 |
250 instr_0 == instruction_code_xmm_sd_prefix) { // 0xf2 | |
251 off++; | |
252 instr_0 = ubyte_at(off); | |
253 } | |
254 | |
255 if ( instr_0 >= instruction_prefix_wide_lo && // 0x40 | |
256 instr_0 <= instruction_prefix_wide_hi) { // 0x4f | |
257 off++; | |
258 instr_0 = ubyte_at(off); | |
259 } | |
260 | |
261 | |
262 if (instr_0 == instruction_extended_prefix ) { // 0x0f | |
263 off++; | |
264 } | |
265 | |
266 return off; | |
267 } | |
268 | |
269 address NativeMovRegMem::instruction_address() const { | |
270 return addr_at(instruction_start()); | |
271 } | |
272 | |
273 address NativeMovRegMem::next_instruction_address() const { | |
274 address ret = instruction_address() + instruction_size; | |
275 u_char instr_0 = *(u_char*) instruction_address(); | |
276 switch (instr_0) { | |
277 case instruction_operandsize_prefix: | |
278 | |
279 fatal("should have skipped instruction_operandsize_prefix"); | |
280 break; | |
0 | 281 |
304 | 282 case instruction_extended_prefix: |
283 fatal("should have skipped instruction_extended_prefix"); | |
284 break; | |
285 | |
286 case instruction_code_mem2reg_movslq: // 0x63 | |
287 case instruction_code_mem2reg_movzxb: // 0xB6 | |
288 case instruction_code_mem2reg_movsxb: // 0xBE | |
289 case instruction_code_mem2reg_movzxw: // 0xB7 | |
290 case instruction_code_mem2reg_movsxw: // 0xBF | |
291 case instruction_code_reg2mem: // 0x89 (q/l) | |
292 case instruction_code_mem2reg: // 0x8B (q/l) | |
293 case instruction_code_reg2memb: // 0x88 | |
294 case instruction_code_mem2regb: // 0x8a | |
295 | |
296 case instruction_code_float_s: // 0xd9 fld_s a | |
297 case instruction_code_float_d: // 0xdd fld_d a | |
298 | |
299 case instruction_code_xmm_load: // 0x10 | |
300 case instruction_code_xmm_store: // 0x11 | |
301 case instruction_code_xmm_lpd: // 0x12 | |
302 { | |
303 // If there is an SIB then instruction is longer than expected | |
304 u_char mod_rm = *(u_char*)(instruction_address() + 1); | |
305 if ((mod_rm & 7) == 0x4) { | |
306 ret++; | |
307 } | |
308 } | |
309 case instruction_code_xor: | |
310 fatal("should have skipped xor lead in"); | |
311 break; | |
312 | |
313 default: | |
314 fatal("not a NativeMovRegMem"); | |
0 | 315 } |
304 | 316 return ret; |
317 | |
318 } | |
0 | 319 |
304 | 320 int NativeMovRegMem::offset() const{ |
321 int off = data_offset + instruction_start(); | |
322 u_char mod_rm = *(u_char*)(instruction_address() + 1); | |
323 // nnnn(r12|rsp) isn't coded as simple mod/rm since that is | |
324 // the encoding to use an SIB byte. Which will have the nnnn | |
325 // field off by one byte | |
326 if ((mod_rm & 7) == 0x4) { | |
327 off++; | |
0 | 328 } |
304 | 329 return int_at(off); |
330 } | |
331 | |
332 void NativeMovRegMem::set_offset(int x) { | |
333 int off = data_offset + instruction_start(); | |
334 u_char mod_rm = *(u_char*)(instruction_address() + 1); | |
335 // nnnn(r12|rsp) isn't coded as simple mod/rm since that is | |
336 // the encoding to use an SIB byte. Which will have the nnnn | |
337 // field off by one byte | |
338 if ((mod_rm & 7) == 0x4) { | |
339 off++; | |
340 } | |
341 set_int_at(off, x); | |
0 | 342 } |
343 | |
344 void NativeMovRegMem::verify() { | |
345 // make sure code pattern is actually a mov [reg+offset], reg instruction | |
346 u_char test_byte = *(u_char*)instruction_address(); | |
304 | 347 switch (test_byte) { |
348 case instruction_code_reg2memb: // 0x88 movb a, r | |
349 case instruction_code_reg2mem: // 0x89 movl a, r (can be movq in 64bit) | |
350 case instruction_code_mem2regb: // 0x8a movb r, a | |
351 case instruction_code_mem2reg: // 0x8b movl r, a (can be movq in 64bit) | |
352 break; | |
353 | |
354 case instruction_code_mem2reg_movslq: // 0x63 movsql r, a | |
355 case instruction_code_mem2reg_movzxb: // 0xb6 movzbl r, a (movzxb) | |
356 case instruction_code_mem2reg_movzxw: // 0xb7 movzwl r, a (movzxw) | |
357 case instruction_code_mem2reg_movsxb: // 0xbe movsbl r, a (movsxb) | |
358 case instruction_code_mem2reg_movsxw: // 0xbf movswl r, a (movsxw) | |
359 break; | |
360 | |
361 case instruction_code_float_s: // 0xd9 fld_s a | |
362 case instruction_code_float_d: // 0xdd fld_d a | |
363 case instruction_code_xmm_load: // 0x10 movsd xmm, a | |
364 case instruction_code_xmm_store: // 0x11 movsd a, xmm | |
365 case instruction_code_xmm_lpd: // 0x12 movlpd xmm, a | |
366 break; | |
367 | |
368 default: | |
0 | 369 fatal ("not a mov [reg+offs], reg instruction"); |
370 } | |
371 } | |
372 | |
373 | |
374 void NativeMovRegMem::print() { | |
375 tty->print_cr("0x%x: mov reg, [reg + %x]", instruction_address(), offset()); | |
376 } | |
377 | |
378 //------------------------------------------------------------------- | |
379 | |
380 void NativeLoadAddress::verify() { | |
381 // make sure code pattern is actually a mov [reg+offset], reg instruction | |
382 u_char test_byte = *(u_char*)instruction_address(); | |
304 | 383 #ifdef _LP64 |
384 if ( (test_byte == instruction_prefix_wide || | |
385 test_byte == instruction_prefix_wide_extended) ) { | |
386 test_byte = *(u_char*)(instruction_address() + 1); | |
387 } | |
388 #endif // _LP64 | |
389 if ( ! ((test_byte == lea_instruction_code) | |
390 LP64_ONLY(|| (test_byte == mov64_instruction_code) ))) { | |
0 | 391 fatal ("not a lea reg, [reg+offs] instruction"); |
392 } | |
393 } | |
394 | |
395 | |
396 void NativeLoadAddress::print() { | |
397 tty->print_cr("0x%x: lea [reg + %x], reg", instruction_address(), offset()); | |
398 } | |
399 | |
400 //-------------------------------------------------------------------------------- | |
401 | |
402 void NativeJump::verify() { | |
403 if (*(u_char*)instruction_address() != instruction_code) { | |
404 fatal("not a jump instruction"); | |
405 } | |
406 } | |
407 | |
408 | |
409 void NativeJump::insert(address code_pos, address entry) { | |
410 intptr_t disp = (intptr_t)entry - ((intptr_t)code_pos + 1 + 4); | |
411 #ifdef AMD64 | |
412 guarantee(disp == (intptr_t)(int32_t)disp, "must be 32-bit offset"); | |
413 #endif // AMD64 | |
414 | |
415 *code_pos = instruction_code; | |
416 *((int32_t*)(code_pos + 1)) = (int32_t)disp; | |
417 | |
418 ICache::invalidate_range(code_pos, instruction_size); | |
419 } | |
420 | |
421 void NativeJump::check_verified_entry_alignment(address entry, address verified_entry) { | |
422 // Patching to not_entrant can happen while activations of the method are | |
423 // in use. The patching in that instance must happen only when certain | |
424 // alignment restrictions are true. These guarantees check those | |
425 // conditions. | |
426 #ifdef AMD64 | |
427 const int linesize = 64; | |
428 #else | |
429 const int linesize = 32; | |
430 #endif // AMD64 | |
431 | |
432 // Must be wordSize aligned | |
433 guarantee(((uintptr_t) verified_entry & (wordSize -1)) == 0, | |
434 "illegal address for code patching 2"); | |
435 // First 5 bytes must be within the same cache line - 4827828 | |
436 guarantee((uintptr_t) verified_entry / linesize == | |
437 ((uintptr_t) verified_entry + 4) / linesize, | |
438 "illegal address for code patching 3"); | |
439 } | |
440 | |
441 | |
442 // MT safe inserting of a jump over an unknown instruction sequence (used by nmethod::makeZombie) | |
443 // The problem: jmp <dest> is a 5-byte instruction. Atomical write can be only with 4 bytes. | |
444 // First patches the first word atomically to be a jump to itself. | |
445 // Then patches the last byte and then atomically patches the first word (4-bytes), | |
446 // thus inserting the desired jump | |
447 // This code is mt-safe with the following conditions: entry point is 4 byte aligned, | |
448 // entry point is in same cache line as unverified entry point, and the instruction being | |
449 // patched is >= 5 byte (size of patch). | |
450 // | |
451 // In C2 the 5+ byte sized instruction is enforced by code in MachPrologNode::emit. | |
452 // In C1 the restriction is enforced by CodeEmitter::method_entry | |
453 // | |
454 void NativeJump::patch_verified_entry(address entry, address verified_entry, address dest) { | |
455 // complete jump instruction (to be inserted) is in code_buffer; | |
456 unsigned char code_buffer[5]; | |
457 code_buffer[0] = instruction_code; | |
458 intptr_t disp = (intptr_t)dest - ((intptr_t)verified_entry + 1 + 4); | |
459 #ifdef AMD64 | |
460 guarantee(disp == (intptr_t)(int32_t)disp, "must be 32-bit offset"); | |
461 #endif // AMD64 | |
462 *(int32_t*)(code_buffer + 1) = (int32_t)disp; | |
463 | |
464 check_verified_entry_alignment(entry, verified_entry); | |
465 | |
466 // Can't call nativeJump_at() because it's asserts jump exists | |
467 NativeJump* n_jump = (NativeJump*) verified_entry; | |
468 | |
469 //First patch dummy jmp in place | |
470 | |
471 unsigned char patch[4]; | |
472 assert(sizeof(patch)==sizeof(int32_t), "sanity check"); | |
473 patch[0] = 0xEB; // jmp rel8 | |
474 patch[1] = 0xFE; // jmp to self | |
475 patch[2] = 0xEB; | |
476 patch[3] = 0xFE; | |
477 | |
478 // First patch dummy jmp in place | |
479 *(int32_t*)verified_entry = *(int32_t *)patch; | |
480 | |
481 n_jump->wrote(0); | |
482 | |
483 // Patch 5th byte (from jump instruction) | |
484 verified_entry[4] = code_buffer[4]; | |
485 | |
486 n_jump->wrote(4); | |
487 | |
488 // Patch bytes 0-3 (from jump instruction) | |
489 *(int32_t*)verified_entry = *(int32_t *)code_buffer; | |
490 // Invalidate. Opteron requires a flush after every write. | |
491 n_jump->wrote(0); | |
492 | |
493 } | |
494 | |
495 void NativePopReg::insert(address code_pos, Register reg) { | |
496 assert(reg->encoding() < 8, "no space for REX"); | |
497 assert(NativePopReg::instruction_size == sizeof(char), "right address unit for update"); | |
498 *code_pos = (u_char)(instruction_code | reg->encoding()); | |
499 ICache::invalidate_range(code_pos, instruction_size); | |
500 } | |
501 | |
502 | |
503 void NativeIllegalInstruction::insert(address code_pos) { | |
504 assert(NativeIllegalInstruction::instruction_size == sizeof(short), "right address unit for update"); | |
505 *(short *)code_pos = instruction_code; | |
506 ICache::invalidate_range(code_pos, instruction_size); | |
507 } | |
508 | |
509 void NativeGeneralJump::verify() { | |
510 assert(((NativeInstruction *)this)->is_jump() || | |
511 ((NativeInstruction *)this)->is_cond_jump(), "not a general jump instruction"); | |
512 } | |
513 | |
514 | |
515 void NativeGeneralJump::insert_unconditional(address code_pos, address entry) { | |
516 intptr_t disp = (intptr_t)entry - ((intptr_t)code_pos + 1 + 4); | |
517 #ifdef AMD64 | |
518 guarantee(disp == (intptr_t)(int32_t)disp, "must be 32-bit offset"); | |
519 #endif // AMD64 | |
520 | |
521 *code_pos = unconditional_long_jump; | |
522 *((int32_t *)(code_pos+1)) = (int32_t) disp; | |
523 ICache::invalidate_range(code_pos, instruction_size); | |
524 } | |
525 | |
526 | |
527 // MT-safe patching of a long jump instruction. | |
528 // First patches first word of instruction to two jmp's that jmps to them | |
529 // selfs (spinlock). Then patches the last byte, and then atomicly replaces | |
530 // the jmp's with the first 4 byte of the new instruction. | |
531 void NativeGeneralJump::replace_mt_safe(address instr_addr, address code_buffer) { | |
532 assert (instr_addr != NULL, "illegal address for code patching (4)"); | |
533 NativeGeneralJump* n_jump = nativeGeneralJump_at (instr_addr); // checking that it is a jump | |
534 | |
535 // Temporary code | |
536 unsigned char patch[4]; | |
537 assert(sizeof(patch)==sizeof(int32_t), "sanity check"); | |
538 patch[0] = 0xEB; // jmp rel8 | |
539 patch[1] = 0xFE; // jmp to self | |
540 patch[2] = 0xEB; | |
541 patch[3] = 0xFE; | |
542 | |
543 // First patch dummy jmp in place | |
544 *(int32_t*)instr_addr = *(int32_t *)patch; | |
545 n_jump->wrote(0); | |
546 | |
547 // Patch 4th byte | |
548 instr_addr[4] = code_buffer[4]; | |
549 | |
550 n_jump->wrote(4); | |
551 | |
552 // Patch bytes 0-3 | |
553 *(jint*)instr_addr = *(jint *)code_buffer; | |
554 | |
555 n_jump->wrote(0); | |
556 | |
557 #ifdef ASSERT | |
558 // verify patching | |
559 for ( int i = 0; i < instruction_size; i++) { | |
560 address ptr = (address)((intptr_t)code_buffer + i); | |
561 int a_byte = (*ptr) & 0xFF; | |
562 assert(*((address)((intptr_t)instr_addr + i)) == a_byte, "mt safe patching failed"); | |
563 } | |
564 #endif | |
565 | |
566 } | |
567 | |
568 | |
569 | |
570 address NativeGeneralJump::jump_destination() const { | |
571 int op_code = ubyte_at(0); | |
572 bool is_rel32off = (op_code == 0xE9 || op_code == 0x0F); | |
573 int offset = (op_code == 0x0F) ? 2 : 1; | |
574 int length = offset + ((is_rel32off) ? 4 : 1); | |
575 | |
576 if (is_rel32off) | |
577 return addr_at(0) + length + int_at(offset); | |
578 else | |
579 return addr_at(0) + length + sbyte_at(offset); | |
580 } | |
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581 |
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582 bool NativeInstruction::is_dtrace_trap() { |
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583 return (*(int32_t*)this & 0xff) == 0xcc; |
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584 } |