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gh-116168: Remove extra _CHECK_STACK_SPACE uops (#117242)

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This merges all `_CHECK_STACK_SPACE` uops in a trace into a single `_CHECK_STACK_SPACE_OPERAND` uop that checks whether there is enough stack space for all calls included in the entire trace.
This commit is contained in:
Peter Lazorchak 2024-04-03 10:14:18 -07:00 • committed by GitHub
parent 976bcb2379
commit 1c43468886
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GPG key ID: B5690EEEBB952194
8 changed files with 493 additions and 125 deletions
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101
Python/optimizer_analysis.c
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@ -529,14 +529,41 @@ remove_unneeded_uops(_PyUOpInstruction *buffer, int buffer_size)
}
}
}
Py_FatalError("No terminating instruction");
Py_UNREACHABLE();
}
/* _PUSH_FRAME/_POP_FRAME's operand can be 0, a PyFunctionObject *, or a
* PyCodeObject *. Retrieve the code object if possible.
*/
static PyCodeObject *
get_co(_PyUOpInstruction *op)
{
assert(op->opcode == _PUSH_FRAME || op->opcode == _POP_FRAME);
PyCodeObject *co = NULL;
uint64_t operand = op->operand;
if (operand == 0) {
return NULL;
}
if (operand & 1) {
co = (PyCodeObject *)(operand & ~1);
}
else {
PyFunctionObject *func = (PyFunctionObject *)operand;
assert(PyFunction_Check(func));
co = (PyCodeObject *)func->func_code;
}
assert(PyCode_Check(co));
return co;
}
static void
peephole_opt(_PyInterpreterFrame *frame, _PyUOpInstruction *buffer, int buffer_size)
{
PyCodeObject *co = _PyFrame_GetCode(frame);
int curr_space = 0;
int max_space = 0;
_PyUOpInstruction *first_valid_check_stack = NULL;
_PyUOpInstruction *corresponding_check_stack = NULL;
for (int pc = 0; pc < buffer_size; pc++) {
int opcode = buffer[pc].opcode;
switch(opcode) {
@ -547,8 +574,7 @@ peephole_opt(_PyInterpreterFrame *frame, _PyUOpInstruction *buffer, int buffer_s
buffer[pc].operand = (uintptr_t)val;
break;
}
case _CHECK_PEP_523:
{
case _CHECK_PEP_523: {
/* Setting the eval frame function invalidates
* all executors, so no need to check dynamically */
if (_PyInterpreterState_GET()->eval_frame == NULL) {
@ -556,29 +582,72 @@ peephole_opt(_PyInterpreterFrame *frame, _PyUOpInstruction *buffer, int buffer_s
}
break;
}
case _PUSH_FRAME:
case _POP_FRAME:
{
uint64_t operand = buffer[pc].operand;
if (operand & 1) {
co = (PyCodeObject *)(operand & ~1);
assert(PyCode_Check(co));
case _CHECK_STACK_SPACE: {
assert(corresponding_check_stack == NULL);
corresponding_check_stack = &buffer[pc];
break;
}
case _PUSH_FRAME: {
assert(corresponding_check_stack != NULL);
co = get_co(&buffer[pc]);
if (co == NULL) {
// should be about to _EXIT_TRACE anyway
goto finish;
}
else if (operand == 0) {
co = NULL;
int framesize = co->co_framesize;
assert(framesize > 0);
curr_space += framesize;
if (curr_space < 0 || curr_space > INT32_MAX) {
// won't fit in signed 32-bit int
goto finish;
}
max_space = curr_space > max_space ? curr_space : max_space;
if (first_valid_check_stack == NULL) {
first_valid_check_stack = corresponding_check_stack;
}
else {
PyFunctionObject *func = (PyFunctionObject *)operand;
assert(PyFunction_Check(func));
co = (PyCodeObject *)func->func_code;
// delete all but the first valid _CHECK_STACK_SPACE
corresponding_check_stack->opcode = _NOP;
}
corresponding_check_stack = NULL;
break;
}
case _POP_FRAME: {
assert(corresponding_check_stack == NULL);
assert(co != NULL);
int framesize = co->co_framesize;
assert(framesize > 0);
assert(framesize <= curr_space);
curr_space -= framesize;
co = get_co(&buffer[pc]);
if (co == NULL) {
// might be impossible, but bailing is still safe
goto finish;
}
break;
}
case _JUMP_TO_TOP:
case _EXIT_TRACE:
return;
goto finish;
#ifdef Py_DEBUG
case _CHECK_STACK_SPACE_OPERAND: {
/* We should never see _CHECK_STACK_SPACE_OPERANDs.
* They are only created at the end of this pass. */
Py_UNREACHABLE();
}
#endif
}
}
Py_UNREACHABLE();
finish:
if (first_valid_check_stack != NULL) {
assert(first_valid_check_stack->opcode == _CHECK_STACK_SPACE);
assert(max_space > 0);
assert(max_space <= INT_MAX);
assert(max_space <= INT32_MAX);
first_valid_check_stack->opcode = _CHECK_STACK_SPACE_OPERAND;
first_valid_check_stack->operand = max_space;
}
}
// 0 - failure, no error raised, just fall back to Tier 1