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GH-129231: Group executable JIT code in memory (GH-129232)

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Diego Russo 2025-02-02 23:19:55 +00:00 • committed by GitHub
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commit a29a9c0f38
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2 changed files with 6 additions and 5 deletions
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Misc/NEWS.d/next/Core_and_Builtins/2025-01-24-11-37-22.gh-issue-129231.ZsAP9v.rst Normal file
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@ -0,0 +1 @@
Improve memory layout of JIT traces. Patch by Diego Russo

10
Python/jit.c
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@ -502,8 +502,8 @@ _PyJIT_Compile(_PyExecutorObject *executor, const _PyUOpInstruction trace[], siz
// Round up to the nearest page: // Round up to the nearest page:
size_t page_size = get_page_size(); size_t page_size = get_page_size();
assert((page_size & (page_size - 1)) == 0); assert((page_size & (page_size - 1)) == 0);
size_t padding = page_size - ((code_size + data_size + state.trampolines.size) & (page_size - 1)); size_t padding = page_size - ((code_size + state.trampolines.size + data_size) & (page_size - 1));
size_t total_size = code_size + data_size + state.trampolines.size + padding; size_t total_size = code_size + state.trampolines.size + data_size + padding;
unsigned char *memory = jit_alloc(total_size); unsigned char *memory = jit_alloc(total_size);
if (memory == NULL) { if (memory == NULL) {
return -1; return -1;
@ -524,8 +524,8 @@ _PyJIT_Compile(_PyExecutorObject *executor, const _PyUOpInstruction trace[], siz
} }
// Loop again to emit the code: // Loop again to emit the code:
unsigned char *code = memory; unsigned char *code = memory;
unsigned char *data = memory + code_size; state.trampolines.mem = memory + code_size;
state.trampolines.mem = memory + code_size + data_size; unsigned char *data = memory + code_size + state.trampolines.size;
// Compile the shim, which handles converting between the native // Compile the shim, which handles converting between the native
// calling convention and the calling convention used by jitted code // calling convention and the calling convention used by jitted code
// (which may be different for efficiency reasons). // (which may be different for efficiency reasons).
@ -547,7 +547,7 @@ _PyJIT_Compile(_PyExecutorObject *executor, const _PyUOpInstruction trace[], siz
code += group->code_size; code += group->code_size;
data += group->data_size; data += group->data_size;
assert(code == memory + code_size); assert(code == memory + code_size);
assert(data == memory + code_size + data_size); assert(data == memory + code_size + state.trampolines.size + data_size);
#ifdef MAP_JIT #ifdef MAP_JIT
pthread_jit_write_protect_np(1); pthread_jit_write_protect_np(1);
#endif #endif