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GH-95113: Don't use EXTENDED_ARG_QUICK in unquickened code #95121

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Merged
merged 3 commits into from
Jul 22, 2022
+20 −200
Merged

GH-95113: Don't use EXTENDED_ARG_QUICK in unquickened code #95121

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23e358a
Don't use EXTENDED_ARG_QUICK in unquickened code
brandtbucher Jul 22, 2022
b0c44b5
blurb add
brandtbucher Jul 22, 2022
e3b0adc
Add some comments and an assert to EXTENDED_ARG
brandtbucher Jul 22, 2022
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188 changes: 0 additions & 188 deletions Include/internal/pycore_opcode.h
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2 changes: 1 addition & 1 deletion Lib/test/test_dis.py
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Original file line number Diff line number Diff line change
Expand Up @@ -744,7 +744,7 @@ def extended_arg_quick():
%3d 0 RESUME 0

%3d 2 LOAD_CONST 1 (Ellipsis)
4 EXTENDED_ARG_QUICK 1
4 EXTENDED_ARG 1
6 UNPACK_EX 256
8 STORE_FAST 0 (_)
10 STORE_FAST 0 (_)
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4 changes: 4 additions & 0 deletions Misc/NEWS.d/next/Core and Builtins/2022-07-21-17-54-52.gh-issue-95113.NnSLpT.rst
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@@ -0,0 +1,4 @@
Replace all ``EXTENDED_ARG_QUICK`` instructions with basic
:opcode:`EXTENDED_ARG` instructions in unquickened code. Consumers of
non-adaptive bytecode should be able to handle extended arguments the same
way they were handled in CPython 3.10 and older.
2 changes: 1 addition & 1 deletion Objects/codeobject.c
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Expand Up @@ -1418,7 +1418,7 @@ deopt_code(_Py_CODEUNIT *instructions, Py_ssize_t len)
{
for (int i = 0; i < len; i++) {
_Py_CODEUNIT instruction = instructions[i];
int opcode = _PyOpcode_Original[_Py_OPCODE(instruction)];
int opcode = _PyOpcode_Deopt[_Py_OPCODE(instruction)];
int caches = _PyOpcode_Caches[opcode];
instructions[i] = _Py_MAKECODEUNIT(opcode, _Py_OPARG(instruction));
while (caches--) {
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8 changes: 8 additions & 0 deletions Python/ceval.c
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Expand Up @@ -5631,8 +5631,16 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, _PyInterpreterFrame *frame, int
assert(oparg);
oparg <<= 8;
oparg |= _Py_OPARG(*next_instr);
// We might be tracing. To avoid breaking tracing guarantees in
// quickened instructions, always deoptimize the next opcode:
opcode = _PyOpcode_Deopt[_Py_OPCODE(*next_instr)];
PRE_DISPATCH_GOTO();
// CPython hasn't traced the following instruction historically
// (DO_TRACING would clobber our extended oparg anyways), so just
// skip our usual cframe.use_tracing check before dispatch. Also,
// make sure the next instruction isn't a RESUME, since that needs
// to trace properly (and shouldn't have an extended arg anyways):
assert(opcode != RESUME);
DISPATCH_GOTO();
}

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6 changes: 3 additions & 3 deletions Python/compile.c
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Original file line number Diff line number Diff line change
Expand Up @@ -211,13 +211,13 @@ write_instr(_Py_CODEUNIT *codestr, struct instr *instruction, int ilen)
int caches = _PyOpcode_Caches[opcode];
switch (ilen - caches) {
case 4:
*codestr++ = _Py_MAKECODEUNIT(EXTENDED_ARG_QUICK, (oparg >> 24) & 0xFF);
*codestr++ = _Py_MAKECODEUNIT(EXTENDED_ARG, (oparg >> 24) & 0xFF);
/* fall through */
case 3:
*codestr++ = _Py_MAKECODEUNIT(EXTENDED_ARG_QUICK, (oparg >> 16) & 0xFF);
*codestr++ = _Py_MAKECODEUNIT(EXTENDED_ARG, (oparg >> 16) & 0xFF);
/* fall through */
case 2:
*codestr++ = _Py_MAKECODEUNIT(EXTENDED_ARG_QUICK, (oparg >> 8) & 0xFF);
*codestr++ = _Py_MAKECODEUNIT(EXTENDED_ARG, (oparg >> 8) & 0xFF);
/* fall through */
case 1:
*codestr++ = _Py_MAKECODEUNIT(opcode, oparg & 0xFF);
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3 changes: 3 additions & 0 deletions Python/specialize.c
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Original file line number Diff line number Diff line change
Expand Up @@ -295,6 +295,9 @@ _PyCode_Quicken(PyCodeObject *code)
else {
assert(!_PyOpcode_Caches[opcode]);
switch (opcode) {
case EXTENDED_ARG:
_Py_SET_OPCODE(instructions[i], EXTENDED_ARG_QUICK);
break;
case JUMP_BACKWARD:
_Py_SET_OPCODE(instructions[i], JUMP_BACKWARD_QUICK);
break;
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7 changes: 0 additions & 7 deletions Tools/scripts/generate_opcode_h.py
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Expand Up @@ -131,7 +131,6 @@ def main(opcode_py, outfile='Include/opcode.h', internaloutfile='Include/interna

iobj.write("\nextern const uint8_t _PyOpcode_Caches[256];\n")
iobj.write("\nextern const uint8_t _PyOpcode_Deopt[256];\n")
iobj.write("\nextern const uint8_t _PyOpcode_Original[256];\n")
iobj.write("\n#ifdef NEED_OPCODE_TABLES\n")
write_int_array_from_ops("_PyOpcode_RelativeJump", opcode['hasjrel'], iobj)
write_int_array_from_ops("_PyOpcode_Jump", opcode['hasjrel'] + opcode['hasjabs'], iobj)
Expand All @@ -153,12 +152,6 @@ def main(opcode_py, outfile='Include/opcode.h', internaloutfile='Include/interna
for opt, deopt in sorted(deoptcodes.items()):
iobj.write(f" [{opt}] = {deopt},\n")
iobj.write("};\n")
iobj.write("\nconst uint8_t _PyOpcode_Original[256] = {\n")
for opt, deopt in sorted(deoptcodes.items()):
if opt.startswith("EXTENDED_ARG"):
deopt = "EXTENDED_ARG_QUICK"
iobj.write(f" [{opt}] = {deopt},\n")
iobj.write("};\n")
iobj.write("#endif // NEED_OPCODE_TABLES\n")

fobj.write("\n")
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