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GeezerVison is showing github.com — cpython/Python/jit.c at main · python/cpython Expand file tree/ Copy pathjit.cMore file actions 756 lines (690 loc) · 25.1 KB / Copy pathjit.cFile metadata and controls756 lines (690 loc) · 25.1 KB 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 #ifdef _Py_JIT #include "Python.h" #include "pycore_abstract.h" #include "pycore_bitutils.h" #include "pycore_call.h" #include "pycore_ceval.h" #include "pycore_critical_section.h" #include "pycore_dict.h" #include "pycore_floatobject.h" #include "pycore_frame.h" #include "pycore_function.h" #include "pycore_genobject.h" #include "pycore_import.h" #include "pycore_interpframe.h" #include "pycore_interpolation.h" #include "pycore_intrinsics.h" #include "pycore_jit_publish.h" #include "pycore_lazyimportobject.h" #include "pycore_list.h" #include "pycore_long.h" #include "pycore_mmap.h" #include "pycore_opcode_metadata.h" #include "pycore_opcode_utils.h" #include "pycore_optimizer.h" #include "pycore_pyerrors.h" #include "pycore_setobject.h" #include "pycore_sliceobject.h" #include "pycore_template.h" #include "pycore_tuple.h" #include "pycore_unicodeobject.h" #include "pycore_jit.h" // Memory management stuff: /////////////////////////////////////////////////// #ifndef MS_WINDOWS #include <sys/mman.h> #endif static size_t get_page_size(void) { #ifdef MS_WINDOWS SYSTEM_INFO si; GetSystemInfo(&si); return si.dwPageSize; #else return sysconf(_SC_PAGESIZE); #endif } static void jit_error(const char *message) { #ifdef MS_WINDOWS int hint = GetLastError(); #else int hint = errno; #endif PyErr_Format(PyExc_RuntimeWarning, "JIT %s (%d)", message, hint); } static int address_in_executor_array(_PyExecutorObject **ptrs, size_t count, uintptr_t addr) { for (size_t i = 0; i < count; i++) { _PyExecutorObject *exec = ptrs[i]; if (exec->jit_code == NULL || exec->jit_size == 0) { continue; } uintptr_t start = (uintptr_t)exec->jit_code; uintptr_t end = start + exec->jit_size; if (addr >= start && addr < end) { return 1; } } return 0; } static int address_in_executor_list(_PyExecutorObject *head, uintptr_t addr) { for (_PyExecutorObject *exec = head; exec != NULL; exec = exec->vm_data.links.next) { if (exec->jit_code == NULL || exec->jit_size == 0) { continue; } uintptr_t start = (uintptr_t)exec->jit_code; uintptr_t end = start + exec->jit_size; if (addr >= start && addr < end) { return 1; } } return 0; } PyAPI_FUNC(int) _PyJIT_AddressInJitCode(PyInterpreterState *interp, uintptr_t addr) { if (interp == NULL) { return 0; } if (address_in_executor_array(interp->executor_ptrs, interp->executor_count, addr)) { return 1; } if (address_in_executor_list(interp->executor_deletion_list_head, addr)) { return 1; } return 0; } static unsigned char * jit_alloc(size_t size) { if (size > PY_MAX_JIT_CODE_SIZE) { jit_error("code too big; refactor bytecodes.c to keep uop size down, or reduce maximum trace length."); return NULL; } assert(size); assert(size % get_page_size() == 0); #ifdef MS_WINDOWS int flags = MEM_COMMIT | MEM_RESERVE; unsigned char *memory = VirtualAlloc(NULL, size, flags, PAGE_READWRITE); int failed = memory == NULL; #else int flags = MAP_ANONYMOUS | MAP_PRIVATE; int prot = PROT_READ | PROT_WRITE; unsigned char *memory = mmap(NULL, size, prot, flags, -1, 0); int failed = memory == MAP_FAILED; if (!failed) { (void)_PyAnnotateMemoryMap(memory, size, "cpython:jit"); } #endif if (failed) { jit_error("unable to allocate memory"); return NULL; } return memory; } static int jit_free(unsigned char *memory, size_t size) { assert(size); assert(size % get_page_size() == 0); #ifdef MS_WINDOWS int failed = !VirtualFree(memory, 0, MEM_RELEASE); #else int failed = munmap(memory, size); #endif if (failed) { jit_error("unable to free memory"); return -1; } OPT_STAT_ADD(jit_freed_memory_size, size); return 0; } static int mark_executable(unsigned char *memory, size_t size) { if (size == 0) { return 0; } assert(size % get_page_size() == 0); // Do NOT ever leave the memory writable! Also, don't forget to flush the // i-cache (I cannot begin to tell you how horrible that is to debug): #ifdef MS_WINDOWS if (!FlushInstructionCache(GetCurrentProcess(), memory, size)) { jit_error("unable to flush instruction cache"); return -1; } DWORD old; int failed = !VirtualProtect(memory, size, PAGE_EXECUTE_READ, &old); #else __builtin___clear_cache((char *)memory, (char *)memory + size); int failed = mprotect(memory, size, PROT_EXEC | PROT_READ); #endif if (failed) { jit_error("unable to protect executable memory"); return -1; } return 0; } // JIT compiler stuff: ///////////////////////////////////////////////////////// #define GOT_SLOT_SIZE sizeof(uintptr_t) #define SYMBOL_MASK_WORDS 8 typedef uint32_t symbol_mask[SYMBOL_MASK_WORDS]; typedef struct { unsigned char *mem; symbol_mask mask; size_t size; } symbol_state; typedef struct { symbol_state trampolines; symbol_state got_symbols; uintptr_t instruction_starts[UOP_MAX_TRACE_LENGTH]; } jit_state; // Warning! AArch64 requires you to get your hands dirty. These are your gloves: // value[value_start : value_start + len] static uint32_t get_bits(uint64_t value, uint8_t value_start, uint8_t width) { assert(width <= 32); return (value >> value_start) & ((1ULL << width) - 1); } // *loc[loc_start : loc_start + width] = value[value_start : value_start + width] static void set_bits(uint32_t *loc, uint8_t loc_start, uint64_t value, uint8_t value_start, uint8_t width) { assert(loc_start + width <= 32); uint32_t temp_val; // Use memcpy to safely read the value, avoiding potential alignment // issues and strict aliasing violations. memcpy(&temp_val, loc, sizeof(temp_val)); // Clear the bits we're about to patch: temp_val &= ~(((1ULL << width) - 1) << loc_start); assert(get_bits(temp_val, loc_start, width) == 0); // Patch the bits: temp_val |= get_bits(value, value_start, width) << loc_start; assert(get_bits(temp_val, loc_start, width) == get_bits(value, value_start, width)); // Safely write the modified value back to memory. memcpy(loc, &temp_val, sizeof(temp_val)); } // See https://developer.arm.com/documentation/ddi0602/2023-09/Base-Instructions // for instruction encodings: #define IS_AARCH64_ADD_OR_SUB(I) (((I) & 0x11C00000) == 0x11000000) #define IS_AARCH64_ADRP(I) (((I) & 0x9F000000) == 0x90000000) #define IS_AARCH64_BRANCH(I) (((I) & 0x7C000000) == 0x14000000) #define IS_AARCH64_BRANCH_COND(I) (((I) & 0x7C000000) == 0x54000000) #define IS_AARCH64_BRANCH_ZERO(I) (((I) & 0x7E000000) == 0x34000000) #define IS_AARCH64_TEST_AND_BRANCH(I) (((I) & 0x7E000000) == 0x36000000) #define IS_AARCH64_LDR_OR_STR(I) (((I) & 0x3B000000) == 0x39000000) #define IS_AARCH64_MOV(I) (((I) & 0x9F800000) == 0x92800000) // LLD is a great reference for performing relocations... just keep in // mind that Tools/jit/build.py does filtering and preprocessing for us! // Here's a good place to start for each platform: // - aarch64-apple-darwin: // - https://github.com/llvm/llvm-project/blob/main/lld/MachO/Arch/ARM64.cpp // - https://github.com/llvm/llvm-project/blob/main/lld/MachO/Arch/ARM64Common.cpp // - https://github.com/llvm/llvm-project/blob/main/lld/MachO/Arch/ARM64Common.h // - aarch64-pc-windows-msvc: // - https://github.com/llvm/llvm-project/blob/main/lld/COFF/Chunks.cpp // - aarch64-unknown-linux-gnu: // - https://github.com/llvm/llvm-project/blob/main/lld/ELF/Arch/AArch64.cpp // - i686-pc-windows-msvc: // - https://github.com/llvm/llvm-project/blob/main/lld/COFF/Chunks.cpp // - x86_64-apple-darwin: // - https://github.com/llvm/llvm-project/blob/main/lld/MachO/Arch/X86_64.cpp // - x86_64-pc-windows-msvc: // - https://github.com/llvm/llvm-project/blob/main/lld/COFF/Chunks.cpp // - x86_64-unknown-linux-gnu: // - https://github.com/llvm/llvm-project/blob/main/lld/ELF/Arch/X86_64.cpp // Get the symbol slot memory location for a given symbol ordinal. static unsigned char * get_symbol_slot(int ordinal, symbol_state *state, int size) { const uint32_t symbol_mask = 1U << (ordinal % 32); const uint32_t state_mask = state->mask[ordinal / 32]; assert(symbol_mask & state_mask); // Count the number of set bits in the symbol mask lower than ordinal size_t index = _Py_popcount32(state_mask & (symbol_mask - 1)); for (int i = 0; i < ordinal / 32; i++) { index += _Py_popcount32(state->mask[i]); } unsigned char *slot = state->mem + index * size; assert((size_t)(index + 1) * size <= state->size); return slot; } // Return the address of the GOT slot for the requested symbol ordinal. static uintptr_t got_symbol_address(int ordinal, jit_state *state) { return (uintptr_t)get_symbol_slot(ordinal, &state->got_symbols, GOT_SLOT_SIZE); } // Many of these patches are "relaxing", meaning that they can rewrite the // code they're patching to be more efficient (like turning a 64-bit memory // load into a 32-bit immediate load). These patches have an "x" in their name. // Relative patches have an "r" in their name. // 32-bit absolute address. void patch_32(unsigned char *location, uint64_t value) { // Check that we're not out of range of 32 unsigned bits: assert(value < (1ULL << 32)); uint32_t final_value = (uint32_t)value; memcpy(location, &final_value, sizeof(final_value)); } // 32-bit relative address. void patch_32r(unsigned char *location, uint64_t value) { value -= (uintptr_t)location; // Check that we're not out of range of 32 signed bits: assert((int64_t)value >= -(1LL << 31)); assert((int64_t)value < (1LL << 31)); uint32_t final_value = (uint32_t)value; memcpy(location, &final_value, sizeof(final_value)); } // 64-bit absolute address. void patch_64(unsigned char *location, uint64_t value) { memcpy(location, &value, sizeof(value)); } // 12-bit low part of an absolute address. Pairs nicely with patch_aarch64_21r // (below). void patch_aarch64_12(unsigned char *location, uint64_t value) { uint32_t *loc32 = (uint32_t *)location; assert(IS_AARCH64_LDR_OR_STR(*loc32) || IS_AARCH64_ADD_OR_SUB(*loc32)); // There might be an implicit shift encoded in the instruction: uint8_t shift = 0; if (IS_AARCH64_LDR_OR_STR(*loc32)) { shift = (uint8_t)get_bits(*loc32, 30, 2); // If both of these are set, the shift is supposed to be 4. // That's pretty weird, and it's never actually been observed... assert(get_bits(*loc32, 23, 1) == 0 || get_bits(*loc32, 26, 1) == 0); } value = get_bits(value, 0, 12); assert(get_bits(value, 0, shift) == 0); set_bits(loc32, 10, value, shift, 12); } // Relaxable 12-bit low part of an absolute address. // Usually paired with patch_aarch64_21rx (below). void patch_aarch64_12x(unsigned char *location, uint64_t value) { patch_aarch64_12(location, value); } // 16-bit low part of an absolute address. void patch_aarch64_16a(unsigned char *location, uint64_t value) { uint32_t *loc32 = (uint32_t *)location; assert(IS_AARCH64_MOV(*loc32)); // Check the implicit shift (this is "part 0 of 3"): assert(get_bits(*loc32, 21, 2) == 0); set_bits(loc32, 5, value, 0, 16); } // 16-bit middle-low part of an absolute address. void patch_aarch64_16b(unsigned char *location, uint64_t value) { uint32_t *loc32 = (uint32_t *)location; assert(IS_AARCH64_MOV(*loc32)); // Check the implicit shift (this is "part 1 of 3"): assert(get_bits(*loc32, 21, 2) == 1); set_bits(loc32, 5, value, 16, 16); } // 16-bit middle-high part of an absolute address. void patch_aarch64_16c(unsigned char *location, uint64_t value) { uint32_t *loc32 = (uint32_t *)location; assert(IS_AARCH64_MOV(*loc32)); // Check the implicit shift (this is "part 2 of 3"): assert(get_bits(*loc32, 21, 2) == 2); set_bits(loc32, 5, value, 32, 16); } // 16-bit high part of an absolute address. void patch_aarch64_16d(unsigned char *location, uint64_t value) { uint32_t *loc32 = (uint32_t *)location; assert(IS_AARCH64_MOV(*loc32)); // Check the implicit shift (this is "part 3 of 3"): assert(get_bits(*loc32, 21, 2) == 3); set_bits(loc32, 5, value, 48, 16); } // 21-bit count of pages between this page and an absolute address's page... I // know, I know, it's weird. Pairs nicely with patch_aarch64_12 (above). void patch_aarch64_21r(unsigned char *location, uint64_t value) { uint32_t *loc32 = (uint32_t *)location; value = (value >> 12) - ((uintptr_t)location >> 12); // Check that we're not out of range of 21 signed bits: assert((int64_t)value >= -(1 << 20)); assert((int64_t)value < (1 << 20)); // value[0:2] goes in loc[29:31]: set_bits(loc32, 29, value, 0, 2); // value[2:21] goes in loc[5:26]: set_bits(loc32, 5, value, 2, 19); } // Relaxable 21-bit count of pages between this page and an absolute address's // page. Usually paired with patch_aarch64_12x (above). void patch_aarch64_21rx(unsigned char *location, uint64_t value) { patch_aarch64_21r(location, value); } // 21-bit relative branch. void patch_aarch64_19r(unsigned char *location, uint64_t value) { uint32_t *loc32 = (uint32_t *)location; assert(IS_AARCH64_BRANCH_COND(*loc32) || IS_AARCH64_BRANCH_ZERO(*loc32)); value -= (uintptr_t)location; // Check that we're not out of range of 21 signed bits: assert((int64_t)value >= -(1 << 20)); assert((int64_t)value < (1 << 20)); // Since instructions are 4-byte aligned, only use 19 bits: assert(get_bits(value, 0, 2) == 0); set_bits(loc32, 5, value, 2, 19); } // 28-bit relative branch. void patch_aarch64_26r(unsigned char *location, uint64_t value) { uint32_t *loc32 = (uint32_t *)location; assert(IS_AARCH64_BRANCH(*loc32)); value -= (uintptr_t)location; // Check that we're not out of range of 28 signed bits: assert((int64_t)value >= -(1 << 27)); assert((int64_t)value < (1 << 27)); // Since instructions are 4-byte aligned, only use 26 bits: assert(get_bits(value, 0, 2) == 0); set_bits(loc32, 0, value, 2, 26); } // A pair of patch_aarch64_21rx and patch_aarch64_12x. void patch_aarch64_33rx(unsigned char *location_a, unsigned char *location_b, uint64_t value) { uint32_t *loc32_a = (uint32_t *)location_a; uint32_t *loc32_b = (uint32_t *)location_b; // Try to relax the pair of GOT loads into an immediate value: assert(IS_AARCH64_ADRP(*loc32_a)); assert(IS_AARCH64_LDR_OR_STR(*loc32_b)); unsigned char reg = get_bits(*loc32_a, 0, 5); // There should be only one register involved: assert(reg == get_bits(*loc32_a, 0, 5)); // ldr's output register. assert(reg == get_bits(*loc32_b, 5, 5)); // ldr's input register. uint64_t relaxed = *(uint64_t *)value; if (relaxed < (1UL << 16)) { // adrp reg, AAA; ldr reg, [reg + BBB] -> movz reg, XXX; nop *loc32_a = 0xD2800000 | (get_bits(relaxed, 0, 16) << 5) | reg; *loc32_b = 0xD503201F; return; } if (relaxed < (1ULL << 32)) { // adrp reg, AAA; ldr reg, [reg + BBB] -> movz reg, XXX; movk reg, YYY *loc32_a = 0xD2800000 | (get_bits(relaxed, 0, 16) << 5) | reg; *loc32_b = 0xF2A00000 | (get_bits(relaxed, 16, 16) << 5) | reg; return; } int64_t page_delta = (relaxed >> 12) - ((uintptr_t)location_a >> 12); if (page_delta >= -(1L << 20) && page_delta < (1L << 20)) { // adrp reg, AAA; ldr reg, [reg + BBB] -> adrp reg, AAA; add reg, reg, BBB patch_aarch64_21rx(location_a, relaxed); *loc32_b = 0x91000000 | get_bits(relaxed, 0, 12) << 10 | reg << 5 | reg; return; } relaxed = value - (uintptr_t)location_a; if ((relaxed & 0x3) == 0 && (int64_t)relaxed >= -(1L << 19) && (int64_t)relaxed < (1L << 19)) { // adrp reg, AAA; ldr reg, [reg + BBB] -> ldr reg, XXX; nop *loc32_a = 0x58000000 | (get_bits(relaxed, 2, 19) << 5) | reg; *loc32_b = 0xD503201F; return; } // Couldn't do it. Just patch the two instructions normally: patch_aarch64_21rx(location_a, value); patch_aarch64_12x(location_b, value); } // Relaxable 32-bit relative address. void patch_x86_64_32rx(unsigned char *location, uint64_t value) { uint8_t *loc8 = (uint8_t *)location; // Try to relax the GOT load into an immediate value: uint64_t relaxed; memcpy(&relaxed, (void *)(value + 4), sizeof(relaxed)); relaxed -= 4; if ((int64_t)relaxed - (int64_t)location >= -(1LL << 31) && (int64_t)relaxed - (int64_t)location + 1 < (1LL << 31)) { if (loc8[-2] == 0x8B) { // mov reg, dword ptr [rip + AAA] -> lea reg, [rip + XXX] loc8[-2] = 0x8D; value = relaxed; } else if (loc8[-2] == 0xFF && loc8[-1] == 0x15) { // call qword ptr [rip + AAA] -> nop; call XXX loc8[-2] = 0x90; loc8[-1] = 0xE8; value = relaxed; } else if (loc8[-2] == 0xFF && loc8[-1] == 0x25) { // jmp qword ptr [rip + AAA] -> nop; jmp XXX loc8[-2] = 0x90; loc8[-1] = 0xE9; value = relaxed; } } patch_32r(location, value); } void patch_got_symbol(jit_state *state, int ordinal); void patch_aarch64_trampoline(unsigned char *location, int ordinal, jit_state *state); void patch_x86_64_trampoline(unsigned char *location, int ordinal, jit_state *state); #include "jit_stencils.h" #if defined(__aarch64__) || defined(_M_ARM64) #define TRAMPOLINE_SIZE 16 #define DATA_ALIGN 8 #elif defined(__x86_64__) && defined(__APPLE__) // LLVM 20 on macOS x86_64 debug builds: GOT entries may exceed ±2GB PC-relative // range. #define TRAMPOLINE_SIZE 16 // 14 bytes + 2 bytes padding for alignment #define DATA_ALIGN 8 #else #define TRAMPOLINE_SIZE 0 #define DATA_ALIGN 1 #endif // Populate the GOT entry for the given symbol ordinal with its resolved address. void patch_got_symbol(jit_state *state, int ordinal) { uint64_t value = (uintptr_t)symbols_map[ordinal]; unsigned char *location = (unsigned char *)get_symbol_slot(ordinal, &state->got_symbols, GOT_SLOT_SIZE); patch_64(location, value); } // Generate and patch AArch64 trampolines. The symbols to jump to are stored // in the jit_stencils.h in the symbols_map. void patch_aarch64_trampoline(unsigned char *location, int ordinal, jit_state *state) { uint64_t value = (uintptr_t)symbols_map[ordinal]; int64_t range = value - (uintptr_t)location; // If we are in range of 28 signed bits, we patch the instruction with // the address of the symbol. if (range >= -(1 << 27) && range < (1 << 27)) { patch_aarch64_26r(location, (uintptr_t)value); return; } // Out of range - need a trampoline uint32_t *p = (uint32_t *)get_symbol_slot(ordinal, &state->trampolines, TRAMPOLINE_SIZE); /* Generate the trampoline 0: 58000048 ldr x8, 8 4: d61f0100 br x8 8: 00000000 // The next two words contain the 64-bit address to jump to. c: 00000000 */ p[0] = 0x58000048; p[1] = 0xD61F0100; p[2] = value & 0xffffffff; p[3] = value >> 32; patch_aarch64_26r(location, (uintptr_t)p); } // Generate and patch x86_64 trampolines. void patch_x86_64_trampoline(unsigned char *location, int ordinal, jit_state *state) { uint64_t value = (uintptr_t)symbols_map[ordinal]; int64_t range = (int64_t)value - 4 - (int64_t)location; // If we are in range of 32 signed bits, we can patch directly if (range >= -(1LL << 31) && range < (1LL << 31)) { patch_32r(location, value - 4); return; } // Out of range - need a trampoline unsigned char *trampoline = get_symbol_slot(ordinal, &state->trampolines, TRAMPOLINE_SIZE); /* Generate the trampoline (14 bytes, padded to 16): 0: ff 25 00 00 00 00 jmp *(%rip) 6: XX XX XX XX XX XX XX XX (64-bit target address) Reference: https://wiki.osdev.org/X86-64_Instruction_Encoding#FF (JMP r/m64) */ trampoline[0] = 0xFF; trampoline[1] = 0x25; memset(trampoline + 2, 0, 4); memcpy(trampoline + 6, &value, 8); // Patch the call site to call the trampoline instead patch_32r(location, (uintptr_t)trampoline - 4); } static void combine_symbol_mask(const symbol_mask src, symbol_mask dest) { // Calculate the union of the trampolines required by each StencilGroup for (size_t i = 0; i < SYMBOL_MASK_WORDS; i++) { dest[i] |= src[i]; } } // Compiles executor in-place. Don't forget to call _PyJIT_Free later! int _PyJIT_Compile(_PyExecutorObject *executor, const _PyUOpInstruction trace[], size_t length) { const StencilGroup *group; // Loop once to find the total compiled size: size_t code_size = 0; size_t data_size = 0; jit_state state = {0}; for (size_t i = 0; i < length; i++) { const _PyUOpInstruction *instruction = &trace[i]; group = &stencil_groups[instruction->opcode]; state.instruction_starts[i] = code_size; code_size += group->code_size; data_size += group->data_size; combine_symbol_mask(group->trampoline_mask, state.trampolines.mask); combine_symbol_mask(group->got_mask, state.got_symbols.mask); } group = &stencil_groups[_FATAL_ERROR_r00]; code_size += group->code_size; data_size += group->data_size; combine_symbol_mask(group->trampoline_mask, state.trampolines.mask); combine_symbol_mask(group->got_mask, state.got_symbols.mask); // Calculate the size of the trampolines required by the whole trace for (size_t i = 0; i < Py_ARRAY_LENGTH(state.trampolines.mask); i++) { state.trampolines.size += _Py_popcount32(state.trampolines.mask[i]) * TRAMPOLINE_SIZE; } for (size_t i = 0; i < Py_ARRAY_LENGTH(state.got_symbols.mask); i++) { state.got_symbols.size += _Py_popcount32(state.got_symbols.mask[i]) * GOT_SLOT_SIZE; } // Round up to the nearest page: size_t page_size = get_page_size(); assert((page_size & (page_size - 1)) == 0); size_t code_padding = DATA_ALIGN - ((code_size + state.trampolines.size) & (DATA_ALIGN - 1)); size_t padding = page_size - ((code_size + state.trampolines.size + code_padding + data_size + state.got_symbols.size) & (page_size - 1)); size_t total_size = code_size + state.trampolines.size + code_padding + data_size + state.got_symbols.size + padding; unsigned char *memory = jit_alloc(total_size); if (memory == NULL) { return -1; } // Collect memory stats OPT_STAT_ADD(jit_total_memory_size, total_size); OPT_STAT_ADD(jit_code_size, code_size); OPT_STAT_ADD(jit_trampoline_size, state.trampolines.size); OPT_STAT_ADD(jit_data_size, data_size); OPT_STAT_ADD(jit_got_size, state.got_symbols.size); OPT_STAT_ADD(jit_padding_size, padding); OPT_HIST(total_size, trace_total_memory_hist); // Update the offsets of each instruction: for (size_t i = 0; i < length; i++) { state.instruction_starts[i] += (uintptr_t)memory; } // Loop again to emit the code: unsigned char *code = memory; state.trampolines.mem = memory + code_size; unsigned char *data = memory + code_size + state.trampolines.size + code_padding; assert(trace[0].opcode == _START_EXECUTOR_r00 || trace[0].opcode == _COLD_EXIT_r00 || trace[0].opcode == _COLD_DYNAMIC_EXIT_r00); state.got_symbols.mem = data + data_size; for (size_t i = 0; i < length; i++) { const _PyUOpInstruction *instruction = &trace[i]; group = &stencil_groups[instruction->opcode]; group->emit(code, data, executor, instruction, &state); code += group->code_size; data += group->data_size; } // Protect against accidental buffer overrun into data: group = &stencil_groups[_FATAL_ERROR_r00]; group->emit(code, data, executor, NULL, &state); code += group->code_size; data += group->data_size; assert(code == memory + code_size); assert(data == memory + code_size + state.trampolines.size + code_padding + data_size); if (mark_executable(memory, total_size)) { jit_free(memory, total_size); return -1; } executor->jit_code = memory; executor->jit_size = total_size; executor->jit_registration = _PyJit_RegisterCode( memory, code_size + state.trampolines.size, "jit", "executor"); return 0; } // Free executor's memory allocated with _PyJIT_Compile void _PyJIT_Free(_PyExecutorObject *executor) { unsigned char *memory = (unsigned char *)executor->jit_code; size_t size = executor->jit_size; if (memory) { executor->jit_code = NULL; executor->jit_size = 0; _PyJit_UnregisterCode(executor->jit_registration); executor->jit_registration = NULL; if (jit_free(memory, size)) { PyErr_FormatUnraisable("Exception ignored while " "freeing JIT memory"); } } } // Avoid excessive bloat due to asserts in stencils int _Py_jit_assertion_failure(int line) { printf("Assertion failure at line %d of executor_cases.c.h", line); fflush(stdout); abort(); return 0; } #endif // _Py_JIT |
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