#ifdef _Py_JIT

#include "Python.h"

#include "pycore_abstract.h"

#include "pycore_call.h"

#include "pycore_ceval.h"

#include "pycore_dict.h"

#include "pycore_intrinsics.h"

#include "pycore_long.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_jit.h"

#include "jit_stencils.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 char *

jit_alloc(size_t size)

{

assert(size);

assert(size % get_page_size() == 0);

#ifdef MS_WINDOWS

int flags = MEM_COMMIT | MEM_RESERVE;

char *memory = VirtualAlloc(NULL, size, flags, PAGE_READWRITE);

int failed = memory == NULL;

#else

int flags = MAP_ANONYMOUS | MAP_PRIVATE;

char *memory = mmap(NULL, size, PROT_READ | PROT_WRITE, flags, -1, 0);

int failed = memory == MAP_FAILED;

#endif

if (failed) {

jit_error("unable to allocate memory");

return NULL;

}

return memory;

}

static int

jit_free(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;

}

return 0;

}

static int

mark_executable(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;

}

int 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;

}

static int

mark_readable(char *memory, size_t size)

{

if (size == 0) {

return 0;

}

assert(size % get_page_size() == 0);

#ifdef MS_WINDOWS

DWORD old;

int failed = !VirtualProtect(memory, size, PAGE_READONLY, &old);

#else

int failed = mprotect(memory, size, PROT_READ);

#endif

if (failed) {

jit_error("unable to protect readable memory");

return -1;

}

return 0;

}

// JIT compiler stuff: /////////////////////////////////////////////////////////

// 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);

// Clear the bits we're about to patch:

*loc &= ~(((1ULL << width) - 1) << loc_start);

assert(get_bits(*loc, loc_start, width) == 0);

// Patch the bits:

*loc |= get_bits(value, value_start, width) << loc_start;

assert(get_bits(*loc, loc_start, width) == get_bits(value, value_start, width));

}

// 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_LDR_OR_STR(I) (((I) & 0x3B000000) == 0x39000000)

#define IS_AARCH64_MOV(I) (((I) & 0x9F800000) == 0x92800000)

// Fill all of stencil's holes in the memory pointed to by base, using the

// values in patches.

static void

patch(char *base, const Stencil *stencil, uint64_t *patches)

{

for (uint64_t i = 0; i < stencil->holes_size; i++) {

const Hole *hole = &stencil->holes[i];

void *location = base + hole->offset;

uint64_t value = patches[hole->value] + (uint64_t)hole->symbol + hole->addend;

uint32_t *loc32 = (uint32_t *)location;

uint64_t *loc64 = (uint64_t *)location;

// 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/ARM64Common.cpp

// - https://github.com/llvm/llvm-project/blob/main/lld/MachO/Arch/ARM64Common.h

// - 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

switch (hole->kind) {

case HoleKind_IMAGE_REL_I386_DIR32:

// 32-bit absolute address.

// Check that we're not out of range of 32 unsigned bits:

assert(value < (1ULL << 32));

*loc32 = (uint32_t)value;

continue;

case HoleKind_ARM64_RELOC_UNSIGNED:

case HoleKind_IMAGE_REL_AMD64_ADDR64:

case HoleKind_R_AARCH64_ABS64:

case HoleKind_X86_64_RELOC_UNSIGNED:

case HoleKind_R_X86_64_64:

// 64-bit absolute address.

*loc64 = value;

continue;

case HoleKind_R_AARCH64_CALL26:

case HoleKind_R_AARCH64_JUMP26:

// 28-bit relative branch.

assert(IS_AARCH64_BRANCH(*loc32));

value -= (uint64_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);

continue;

case HoleKind_R_AARCH64_MOVW_UABS_G0_NC:

// 16-bit low part of an absolute address.

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);

continue;

case HoleKind_R_AARCH64_MOVW_UABS_G1_NC:

// 16-bit middle-low part of an absolute address.

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);

continue;

case HoleKind_R_AARCH64_MOVW_UABS_G2_NC:

// 16-bit middle-high part of an absolute address.

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);

continue;

case HoleKind_R_AARCH64_MOVW_UABS_G3:

// 16-bit high part of an absolute address.

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);

continue;

case HoleKind_ARM64_RELOC_GOT_LOAD_PAGE21:

// 21-bit count of pages between this page and an absolute address's

// page... I know, I know, it's weird. Pairs nicely with

// ARM64_RELOC_GOT_LOAD_PAGEOFF12 (below).

assert(IS_AARCH64_ADRP(*loc32));

// Number of pages between this page and the value's page:

value = (value >> 12) - ((uint64_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);

continue;

case HoleKind_ARM64_RELOC_GOT_LOAD_PAGEOFF12:

// 12-bit low part of an absolute address. Pairs nicely with

// ARM64_RELOC_GOT_LOAD_PAGE21 (above).

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);

continue;

}

Py_UNREACHABLE();

}

}

static void

copy_and_patch(char *base, const Stencil *stencil, uint64_t *patches)

{

memcpy(base, stencil->body, stencil->body_size);

patch(base, stencil, patches);

}

static void

emit(const StencilGroup *group, uint64_t patches[])

{

copy_and_patch((char *)patches[HoleValue_CODE], &group->code, patches);

copy_and_patch((char *)patches[HoleValue_DATA], &group->data, patches);

}

// Compiles executor in-place. Don't forget to call _PyJIT_Free later!

int

_PyJIT_Compile(_PyExecutorObject *executor, const _PyUOpInstruction *trace, size_t length)

{

// Loop once to find the total compiled size:

size_t code_size = 0;

size_t data_size = 0;

for (size_t i = 0; i < length; i++) {

_PyUOpInstruction *instruction = (_PyUOpInstruction *)&trace[i];

const StencilGroup *group = &stencil_groups[instruction->opcode];

code_size += group->code.body_size;

data_size += group->data.body_size;

}

// Round up to the nearest page (code and data need separate pages):

size_t page_size = get_page_size();

assert((page_size & (page_size - 1)) == 0);

code_size += page_size - (code_size & (page_size - 1));

data_size += page_size - (data_size & (page_size - 1));

char *memory = jit_alloc(code_size + data_size);

if (memory == NULL) {

return -1;

}

// Loop again to emit the code:

char *code = memory;

char *data = memory + code_size;

char *top = code;

if (trace[0].opcode == _START_EXECUTOR) {

// Don't want to execute this more than once:

top += stencil_groups[_START_EXECUTOR].code.body_size;

}

for (size_t i = 0; i < length; i++) {

_PyUOpInstruction *instruction = (_PyUOpInstruction *)&trace[i];

const StencilGroup *group = &stencil_groups[instruction->opcode];

// Think of patches as a dictionary mapping HoleValue to uint64_t:

uint64_t patches[] = GET_PATCHES();

patches[HoleValue_CODE] = (uint64_t)code;

patches[HoleValue_CONTINUE] = (uint64_t)code + group->code.body_size;

patches[HoleValue_DATA] = (uint64_t)data;

patches[HoleValue_EXECUTOR] = (uint64_t)executor;

patches[HoleValue_OPARG] = instruction->oparg;

patches[HoleValue_OPERAND] = instruction->operand;

patches[HoleValue_TARGET] = instruction->target;

patches[HoleValue_TOP] = (uint64_t)top;

patches[HoleValue_ZERO] = 0;

emit(group, patches);

code += group->code.body_size;

data += group->data.body_size;

}

if (mark_executable(memory, code_size) ||

mark_readable(memory + code_size, data_size))

{

jit_free(memory, code_size + data_size);

return -1;

}

executor->jit_code = memory;

executor->jit_size = code_size + data_size;

return 0;

}

void

_PyJIT_Free(_PyExecutorObject *executor)

{

char *memory = (char *)executor->jit_code;

size_t size = executor->jit_size;

if (memory) {

executor->jit_code = NULL;

executor->jit_size = 0;

if (jit_free(memory, size)) {

PyErr_WriteUnraisable(NULL);

}

}

}

#endif // _Py_JIT