1 /*
  2  * Copyright (c) 2003, 2023, Oracle and/or its affiliates. All rights reserved.
  3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  4  *
  5  * This code is free software; you can redistribute it and/or modify it
  6  * under the terms of the GNU General Public License version 2 only, as
  7  * published by the Free Software Foundation.
  8  *
  9  * This code is distributed in the hope that it will be useful, but WITHOUT
 10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 12  * version 2 for more details (a copy is included in the LICENSE file that
 13  * accompanied this code).
 14  *
 15  * You should have received a copy of the GNU General Public License version
 16  * 2 along with this work; if not, write to the Free Software Foundation,
 17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 18  *
 19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 20  * or visit www.oracle.com if you need additional information or have any
 21  * questions.
 22  *
 23  */
 24 
 25 #ifndef CPU_X86_STUBGENERATOR_X86_64_HPP
 26 #define CPU_X86_STUBGENERATOR_X86_64_HPP
 27 
 28 #include "code/codeBlob.hpp"
 29 #include "runtime/continuation.hpp"
 30 #include "runtime/stubCodeGenerator.hpp"
 31 
 32 // Stub Code definitions
 33 
 34 class StubGenerator: public StubCodeGenerator {
 35  private:
 36 
 37   // Call stubs are used to call Java from C.
 38   address generate_call_stub(address& return_address);
 39 
 40   // Return point for a Java call if there's an exception thrown in
 41   // Java code.  The exception is caught and transformed into a
 42   // pending exception stored in JavaThread that can be tested from
 43   // within the VM.
 44   //
 45   // Note: Usually the parameters are removed by the callee. In case
 46   // of an exception crossing an activation frame boundary, that is
 47   // not the case if the callee is compiled code => need to setup the
 48   // rsp.
 49   //
 50   // rax: exception oop
 51 
 52   address generate_catch_exception();
 53 
 54   // Continuation point for runtime calls returning with a pending
 55   // exception.  The pending exception check happened in the runtime
 56   // or native call stub.  The pending exception in Thread is
 57   // converted into a Java-level exception.
 58   //
 59   // Contract with Java-level exception handlers:
 60   // rax: exception
 61   // rdx: throwing pc
 62   //
 63   // NOTE: At entry of this stub, exception-pc must be on stack !!
 64 
 65   address generate_forward_exception();
 66 
 67   // Support for intptr_t OrderAccess::fence()
 68   address generate_orderaccess_fence();
 69 
 70   // Support for intptr_t get_previous_sp()
 71   //
 72   // This routine is used to find the previous stack pointer for the
 73   // caller.
 74   address generate_get_previous_sp();
 75 
 76   //----------------------------------------------------------------------------------------------------
 77   // Support for void verify_mxcsr()
 78   //
 79   // This routine is used with -Xcheck:jni to verify that native
 80   // JNI code does not return to Java code without restoring the
 81   // MXCSR register to our expected state.
 82 
 83   address generate_verify_mxcsr();
 84 
 85   address generate_f2i_fixup();
 86   address generate_f2l_fixup();
 87   address generate_d2i_fixup();
 88   address generate_d2l_fixup();
 89 
 90   address generate_count_leading_zeros_lut(const char *stub_name);
 91   address generate_popcount_avx_lut(const char *stub_name);
 92   address generate_iota_indices(const char *stub_name);
 93   address generate_vector_reverse_bit_lut(const char *stub_name);
 94 
 95   address generate_vector_reverse_byte_perm_mask_long(const char *stub_name);
 96   address generate_vector_reverse_byte_perm_mask_int(const char *stub_name);
 97   address generate_vector_reverse_byte_perm_mask_short(const char *stub_name);
 98   address generate_vector_byte_shuffle_mask(const char *stub_name);
 99 
100   address generate_fp_mask(const char *stub_name, int64_t mask);
101 
102   address generate_vector_mask(const char *stub_name, int64_t mask);
103 
104   address generate_vector_byte_perm_mask(const char *stub_name);
105 
106   address generate_vector_fp_mask(const char *stub_name, int64_t mask);
107 
108   address generate_vector_custom_i32(const char *stub_name, Assembler::AvxVectorLen len,
109                                      int32_t val0, int32_t val1, int32_t val2, int32_t val3,
110                                      int32_t val4 = 0, int32_t val5 = 0, int32_t val6 = 0, int32_t val7 = 0,
111                                      int32_t val8 = 0, int32_t val9 = 0, int32_t val10 = 0, int32_t val11 = 0,
112                                      int32_t val12 = 0, int32_t val13 = 0, int32_t val14 = 0, int32_t val15 = 0);
113 
114   // Non-destructive plausibility checks for oops
115   address generate_verify_oop();
116 
117   // Verify that a register contains clean 32-bits positive value
118   // (high 32-bits are 0) so it could be used in 64-bits shifts.
119   void assert_clean_int(Register Rint, Register Rtmp);
120 
121   //  Generate overlap test for array copy stubs
122   void array_overlap_test(address no_overlap_target, Label* NOLp, Address::ScaleFactor sf);
123 
124   void array_overlap_test(address no_overlap_target, Address::ScaleFactor sf) {
125     assert(no_overlap_target != nullptr, "must be generated");
126     array_overlap_test(no_overlap_target, nullptr, sf);
127   }
128   void array_overlap_test(Label& L_no_overlap, Address::ScaleFactor sf) {
129     array_overlap_test(nullptr, &L_no_overlap, sf);
130   }
131 
132 
133   // Shuffle first three arg regs on Windows into Linux/Solaris locations.
134   void setup_arg_regs(int nargs = 3);
135   void restore_arg_regs();
136 
137 #ifdef ASSERT
138   bool _regs_in_thread;
139 #endif
140 
141   // This is used in places where r10 is a scratch register, and can
142   // be adapted if r9 is needed also.
143   void setup_arg_regs_using_thread(int nargs = 3);
144 
145   void restore_arg_regs_using_thread();
146 
147   // Copy big chunks forward
148   void copy_bytes_forward(Register end_from, Register end_to,
149                           Register qword_count, Register tmp1,
150                           Register tmp2, Label& L_copy_bytes,
151                           Label& L_copy_8_bytes, DecoratorSet decorators,
152                           BasicType type);
153 
154   // Copy big chunks backward
155   void copy_bytes_backward(Register from, Register dest,
156                            Register qword_count, Register tmp1,
157                            Register tmp2, Label& L_copy_bytes,
158                            Label& L_copy_8_bytes, DecoratorSet decorators,
159                            BasicType type);
160 
161   void setup_argument_regs(BasicType type);
162 
163   void restore_argument_regs(BasicType type);
164 
165 #if COMPILER2_OR_JVMCI
166   // Following rules apply to AVX3 optimized arraycopy stubs:
167   // - If target supports AVX3 features (BW+VL+F) then implementation uses 32 byte vectors (YMMs)
168   //   for both special cases (various small block sizes) and aligned copy loop. This is the
169   //   default configuration.
170   // - If copy length is above AVX3Threshold, then implementation use 64 byte vectors (ZMMs)
171   //   for main copy loop (and subsequent tail) since bulk of the cycles will be consumed in it.
172   // - If user forces MaxVectorSize=32 then above 4096 bytes its seen that REP MOVs shows a
173   //   better performance for disjoint copies. For conjoint/backward copy vector based
174   //   copy performs better.
175   // - If user sets AVX3Threshold=0, then special cases for small blocks sizes operate over
176   //   64 byte vector registers (ZMMs).
177 
178   address generate_disjoint_copy_avx3_masked(address* entry, const char *name, int shift,
179                                              bool aligned, bool is_oop, bool dest_uninitialized);
180 
181   address generate_conjoint_copy_avx3_masked(address* entry, const char *name, int shift,
182                                              address nooverlap_target, bool aligned, bool is_oop,
183                                              bool dest_uninitialized);
184 
185   void arraycopy_avx3_special_cases(XMMRegister xmm, KRegister mask, Register from,
186                                     Register to, Register count, int shift,
187                                     Register index, Register temp,
188                                     bool use64byteVector, Label& L_entry, Label& L_exit);
189 
190   void arraycopy_avx3_special_cases_conjoint(XMMRegister xmm, KRegister mask, Register from,
191                                              Register to, Register start_index, Register end_index,
192                                              Register count, int shift, Register temp,
193                                              bool use64byteVector, Label& L_entry, Label& L_exit);
194 
195   void copy32_avx(Register dst, Register src, Register index, XMMRegister xmm,
196                   int shift = Address::times_1, int offset = 0);
197 
198   void copy64_avx(Register dst, Register src, Register index, XMMRegister xmm,
199                   bool conjoint, int shift = Address::times_1, int offset = 0,
200                   bool use64byteVector = false);
201 
202   void copy64_masked_avx(Register dst, Register src, XMMRegister xmm,
203                          KRegister mask, Register length, Register index,
204                          Register temp, int shift = Address::times_1, int offset = 0,
205                          bool use64byteVector = false);
206 
207   void copy32_masked_avx(Register dst, Register src, XMMRegister xmm,
208                          KRegister mask, Register length, Register index,
209                          Register temp, int shift = Address::times_1, int offset = 0);
210 #endif // COMPILER2_OR_JVMCI
211 
212   address generate_disjoint_byte_copy(bool aligned, address* entry, const char *name);
213 
214   address generate_conjoint_byte_copy(bool aligned, address nooverlap_target,
215                                       address* entry, const char *name);
216 
217   address generate_disjoint_short_copy(bool aligned, address *entry, const char *name);
218 
219   address generate_fill(BasicType t, bool aligned, const char *name);
220 
221   address generate_conjoint_short_copy(bool aligned, address nooverlap_target,
222                                        address *entry, const char *name);
223   address generate_disjoint_int_oop_copy(bool aligned, bool is_oop, address* entry,
224                                          const char *name, bool dest_uninitialized = false);
225   address generate_conjoint_int_oop_copy(bool aligned, bool is_oop, address nooverlap_target,
226                                          address *entry, const char *name,
227                                          bool dest_uninitialized = false);
228   address generate_disjoint_long_oop_copy(bool aligned, bool is_oop, address *entry,
229                                           const char *name, bool dest_uninitialized = false);
230   address generate_conjoint_long_oop_copy(bool aligned, bool is_oop,
231                                           address nooverlap_target, address *entry,
232                                           const char *name, bool dest_uninitialized = false);
233 
234   // Helper for generating a dynamic type check.
235   // Smashes no registers.
236   void generate_type_check(Register sub_klass,
237                            Register super_check_offset,
238                            Register super_klass,
239                            Label& L_success);
240 
241   // Generate checkcasting array copy stub
242   address generate_checkcast_copy(const char *name, address *entry,
243                                   bool dest_uninitialized = false);
244 
245   // Generate 'unsafe' array copy stub
246   // Though just as safe as the other stubs, it takes an unscaled
247   // size_t argument instead of an element count.
248   //
249   // Examines the alignment of the operands and dispatches
250   // to a long, int, short, or byte copy loop.
251   address generate_unsafe_copy(const char *name,
252                                address byte_copy_entry, address short_copy_entry,
253                                address int_copy_entry, address long_copy_entry);
254 
255   // Perform range checks on the proposed arraycopy.
256   // Kills temp, but nothing else.
257   // Also, clean the sign bits of src_pos and dst_pos.
258   void arraycopy_range_checks(Register src,     // source array oop (c_rarg0)
259                               Register src_pos, // source position (c_rarg1)
260                               Register dst,     // destination array oo (c_rarg2)
261                               Register dst_pos, // destination position (c_rarg3)
262                               Register length,
263                               Register temp,
264                               Label& L_failed);
265 
266   // Generate generic array copy stubs
267   address generate_generic_copy(const char *name,
268                                 address byte_copy_entry, address short_copy_entry,
269                                 address int_copy_entry, address oop_copy_entry,
270                                 address long_copy_entry, address checkcast_copy_entry);
271 
272   address generate_data_cache_writeback();
273 
274   address generate_data_cache_writeback_sync();
275 
276   void generate_arraycopy_stubs();
277 
278 
279   // MD5 stubs
280 
281   // ofs and limit are use for multi-block byte array.
282   // int com.sun.security.provider.MD5.implCompress(byte[] b, int ofs)
283   address generate_md5_implCompress(bool multi_block, const char *name);
284 
285 
286   // SHA stubs
287 
288   // ofs and limit are use for multi-block byte array.
289   // int com.sun.security.provider.DigestBase.implCompressMultiBlock(byte[] b, int ofs, int limit)
290   address generate_sha1_implCompress(bool multi_block, const char *name);
291 
292   // ofs and limit are use for multi-block byte array.
293   // int com.sun.security.provider.DigestBase.implCompressMultiBlock(byte[] b, int ofs, int limit)
294   address generate_sha256_implCompress(bool multi_block, const char *name);
295   address generate_sha512_implCompress(bool multi_block, const char *name);
296 
297   // Mask for byte-swapping a couple of qwords in an XMM register using (v)pshufb.
298   address generate_pshuffle_byte_flip_mask_sha512();
299 
300   address generate_upper_word_mask();
301   address generate_shuffle_byte_flip_mask();
302   address generate_pshuffle_byte_flip_mask();
303 
304 
305   // AES intrinsic stubs
306 
307   address generate_aescrypt_encryptBlock();
308 
309   address generate_aescrypt_decryptBlock();
310 
311   address generate_cipherBlockChaining_encryptAESCrypt();
312 
313   // A version of CBC/AES Decrypt which does 4 blocks in a loop at a time
314   // to hide instruction latency
315   address generate_cipherBlockChaining_decryptAESCrypt_Parallel();
316 
317   address generate_electronicCodeBook_encryptAESCrypt();
318 
319   void aesecb_encrypt(Register source_addr, Register dest_addr, Register key, Register len);
320 
321   address generate_electronicCodeBook_decryptAESCrypt();
322 
323   void aesecb_decrypt(Register source_addr, Register dest_addr, Register key, Register len);
324 
325   // Vector AES Galois Counter Mode implementation
326   address generate_galoisCounterMode_AESCrypt();
327   void aesgcm_encrypt(Register in, Register len, Register ct, Register out, Register key,
328                       Register state, Register subkeyHtbl, Register avx512_subkeyHtbl, Register counter);
329 
330 
331  // Vector AES Counter implementation
332   address generate_counterMode_VectorAESCrypt();
333   void aesctr_encrypt(Register src_addr, Register dest_addr, Register key, Register counter,
334                       Register len_reg, Register used, Register used_addr, Register saved_encCounter_start);
335 
336   // This is a version of CTR/AES crypt which does 6 blocks in a loop at a time
337   // to hide instruction latency
338   address generate_counterMode_AESCrypt_Parallel();
339 
340   address generate_cipherBlockChaining_decryptVectorAESCrypt();
341 
342   address generate_key_shuffle_mask();
343 
344   void roundDec(XMMRegister xmm_reg);
345   void roundDeclast(XMMRegister xmm_reg);
346   void roundEnc(XMMRegister key, int rnum);
347   void lastroundEnc(XMMRegister key, int rnum);
348   void roundDec(XMMRegister key, int rnum);
349   void lastroundDec(XMMRegister key, int rnum);
350   void gfmul_avx512(XMMRegister ghash, XMMRegister hkey);
351   void generateHtbl_48_block_zmm(Register htbl, Register avx512_subkeyHtbl, Register rscratch);
352   void ghash16_encrypt16_parallel(Register key, Register subkeyHtbl, XMMRegister ctr_blockx,
353                                   XMMRegister aad_hashx, Register in, Register out, Register data, Register pos, bool reduction,
354                                   XMMRegister addmask, bool no_ghash_input, Register rounds, Register ghash_pos,
355                                   bool final_reduction, int index, XMMRegister counter_inc_mask);
356   // Load key and shuffle operation
357   void ev_load_key(XMMRegister xmmdst, Register key, int offset, XMMRegister xmm_shuf_mask);
358   void ev_load_key(XMMRegister xmmdst, Register key, int offset, Register rscratch);
359 
360   // Utility routine for loading a 128-bit key word in little endian format
361   // can optionally specify that the shuffle mask is already in an xmmregister
362   void load_key(XMMRegister xmmdst, Register key, int offset, XMMRegister xmm_shuf_mask);
363   void load_key(XMMRegister xmmdst, Register key, int offset, Register rscratch);
364 
365   // Utility routine for increase 128bit counter (iv in CTR mode)
366   void inc_counter(Register reg, XMMRegister xmmdst, int inc_delta, Label& next_block);
367 
368   void generate_aes_stubs();
369 
370 
371   // GHASH stubs
372 
373   void generate_ghash_stubs();
374 
375   void schoolbookAAD(int i, Register subkeyH, XMMRegister data, XMMRegister tmp0,
376                      XMMRegister tmp1, XMMRegister tmp2, XMMRegister tmp3);
377   void gfmul(XMMRegister tmp0, XMMRegister t);
378   void generateHtbl_one_block(Register htbl, Register rscratch);
379   void generateHtbl_eight_blocks(Register htbl);
380   void avx_ghash(Register state, Register htbl, Register data, Register blocks);
381 
382   // Used by GHASH and AES stubs.
383   address ghash_polynomial_addr();
384   address ghash_shufflemask_addr();
385   address ghash_long_swap_mask_addr(); // byte swap x86 long
386   address ghash_byte_swap_mask_addr(); // byte swap x86 byte array
387 
388   // Single and multi-block ghash operations
389   address generate_ghash_processBlocks();
390 
391   // Ghash single and multi block operations using AVX instructions
392   address generate_avx_ghash_processBlocks();
393 
394   // ChaCha20 stubs and helper functions
395   void generate_chacha_stubs();
396   address generate_chacha20Block_avx();
397   address generate_chacha20Block_avx512();
398   void cc20_quarter_round_avx(XMMRegister aVec, XMMRegister bVec,
399     XMMRegister cVec, XMMRegister dVec, XMMRegister scratch,
400     XMMRegister lrot8, XMMRegister lrot16, int vector_len);
401   void cc20_shift_lane_org(XMMRegister bVec, XMMRegister cVec,
402     XMMRegister dVec, int vector_len, bool colToDiag);
403   void cc20_keystream_collate_avx512(XMMRegister aVec, XMMRegister bVec,
404     XMMRegister cVec, XMMRegister dVec, Register baseAddr, int baseOffset);
405 
406   // Poly1305 multiblock using IFMA instructions
407   address generate_poly1305_processBlocks();
408   void poly1305_process_blocks_avx512(const Register input, const Register length,
409                                       const Register A0, const Register A1, const Register A2,
410                                       const Register R0, const Register R1, const Register C1);
411   void poly1305_multiply_scalar(const Register a0, const Register a1, const Register a2,
412                                 const Register r0, const Register r1, const Register c1, bool only128,
413                                 const Register t0, const Register t1, const Register t2,
414                                 const Register mulql, const Register mulqh);
415   void poly1305_multiply8_avx512(const XMMRegister A0, const XMMRegister A1, const XMMRegister A2,
416                                  const XMMRegister R0, const XMMRegister R1, const XMMRegister R2, const XMMRegister R1P, const XMMRegister R2P,
417                                  const XMMRegister P0L, const XMMRegister P0H, const XMMRegister P1L, const XMMRegister P1H, const XMMRegister P2L, const XMMRegister P2H,
418                                  const XMMRegister TMP, const Register rscratch);
419   void poly1305_limbs(const Register limbs, const Register a0, const Register a1, const Register a2, const Register t0, const Register t1);
420   void poly1305_limbs_out(const Register a0, const Register a1, const Register a2, const Register limbs, const Register t0, const Register t1);
421   void poly1305_limbs_avx512(const XMMRegister D0, const XMMRegister D1,
422                              const XMMRegister L0, const XMMRegister L1, const XMMRegister L2, bool padMSG,
423                              const XMMRegister TMP, const Register rscratch);
424 
425   // BASE64 stubs
426 
427   address base64_shuffle_addr();
428   address base64_avx2_shuffle_addr();
429   address base64_avx2_input_mask_addr();
430   address base64_avx2_lut_addr();
431   address base64_encoding_table_addr();
432 
433   // Code for generating Base64 encoding.
434   // Intrinsic function prototype in Base64.java:
435   // private void encodeBlock(byte[] src, int sp, int sl, byte[] dst, int dp, boolean isURL)
436   address generate_base64_encodeBlock();
437 
438   // base64 AVX512vbmi tables
439   address base64_vbmi_lookup_lo_addr();
440   address base64_vbmi_lookup_hi_addr();
441   address base64_vbmi_lookup_lo_url_addr();
442   address base64_vbmi_lookup_hi_url_addr();
443   address base64_vbmi_pack_vec_addr();
444   address base64_vbmi_join_0_1_addr();
445   address base64_vbmi_join_1_2_addr();
446   address base64_vbmi_join_2_3_addr();
447   address base64_decoding_table_addr();
448   address base64_AVX2_decode_tables_addr();
449   address base64_AVX2_decode_LUT_tables_addr();
450 
451   // Code for generating Base64 decoding.
452   //
453   // Based on the article (and associated code) from https://arxiv.org/abs/1910.05109.
454   //
455   // Intrinsic function prototype in Base64.java:
456   // private void decodeBlock(byte[] src, int sp, int sl, byte[] dst, int dp, boolean isURL, isMIME);
457   address generate_base64_decodeBlock();
458 
459   address generate_updateBytesCRC32();
460   address generate_updateBytesCRC32C(bool is_pclmulqdq_supported);
461 
462   address generate_updateBytesAdler32();
463 
464   address generate_multiplyToLen();
465 
466   address generate_vectorizedMismatch();
467 
468   address generate_squareToLen();
469 
470   address generate_method_entry_barrier();
471 
472   address generate_mulAdd();
473 
474   address generate_bigIntegerRightShift();
475   address generate_bigIntegerLeftShift();
476 
477   address generate_float16ToFloat();
478   address generate_floatToFloat16();
479 
480   // Libm trigonometric stubs
481 
482   address generate_libmSin();
483   address generate_libmCos();
484   address generate_libmTan();
485   address generate_libmExp();
486   address generate_libmPow();
487   address generate_libmLog();
488   address generate_libmLog10();
489 
490   // Shared constants
491   static address ZERO;
492   static address NEG_ZERO;
493   static address ONE;
494   static address ONEHALF;
495   static address SIGN_MASK;
496   static address TWO_POW_55;
497   static address TWO_POW_M55;
498   static address SHIFTER;
499   static address PI32INV;
500   static address PI_INV_TABLE;
501   static address Ctable;
502   static address SC_1;
503   static address SC_2;
504   static address SC_3;
505   static address SC_4;
506   static address PI_4;
507   static address P_1;
508   static address P_3;
509   static address P_2;
510 
511   void generate_libm_stubs();
512 
513 
514   address generate_cont_thaw(const char* label, Continuation::thaw_kind kind);
515   address generate_cont_thaw();
516 
517   // TODO: will probably need multiple return barriers depending on return type
518   address generate_cont_returnBarrier();
519   address generate_cont_returnBarrier_exception();
520 
521 #if INCLUDE_JFR
522 
523   // For c2: c_rarg0 is junk, call to runtime to write a checkpoint.
524   // It returns a jobject handle to the event writer.
525   // The handle is dereferenced and the return value is the event writer oop.
526   RuntimeStub* generate_jfr_write_checkpoint();
527 
528 #endif // INCLUDE_JFR
529 
530   // Continuation point for throwing of implicit exceptions that are
531   // not handled in the current activation. Fabricates an exception
532   // oop and initiates normal exception dispatching in this
533   // frame. Since we need to preserve callee-saved values (currently
534   // only for C2, but done for C1 as well) we need a callee-saved oop
535   // map and therefore have to make these stubs into RuntimeStubs
536   // rather than BufferBlobs.  If the compiler needs all registers to
537   // be preserved between the fault point and the exception handler
538   // then it must assume responsibility for that in
539   // AbstractCompiler::continuation_for_implicit_null_exception or
540   // continuation_for_implicit_division_by_zero_exception. All other
541   // implicit exceptions (e.g., NullPointerException or
542   // AbstractMethodError on entry) are either at call sites or
543   // otherwise assume that stack unwinding will be initiated, so
544   // caller saved registers were assumed volatile in the compiler.
545   address generate_throw_exception(const char* name,
546                                    address runtime_entry,
547                                    Register arg1 = noreg,
548                                    Register arg2 = noreg);
549 
550   // interpreter or compiled code marshalling registers to/from inline type instance
551   address generate_return_value_stub(address destination, const char* name, bool has_res);
552 
553   void create_control_words();
554 
555   // Initialization
556   void generate_initial_stubs();
557   void generate_continuation_stubs();
558   void generate_compiler_stubs();
559   void generate_final_stubs();
560 
561  public:
562   StubGenerator(CodeBuffer* code, StubsKind kind);
563 };
564 
565 #endif // CPU_X86_STUBGENERATOR_X86_64_HPP