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gh-106149: Simplify stack depth calculation. Replace asserts by exceptions. (#107255)

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Irit Katriel 2023-07-26 13:32:47 +01:00 • committed by GitHub
parent 14d074e1fb
commit b0202a4e5d
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4 changed files with 91 additions and 42 deletions
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61
Python/flowgraph.c
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@ -615,23 +615,28 @@ make_cfg_traversal_stack(basicblock *entryblock) {
return stack;
}
Py_LOCAL_INLINE(void)
Py_LOCAL_INLINE(int)
stackdepth_push(basicblock ***sp, basicblock *b, int depth)
{
assert(b->b_startdepth < 0 || b->b_startdepth == depth);
if (!(b->b_startdepth < 0 || b->b_startdepth == depth)) {
PyErr_Format(PyExc_ValueError, "Invalid CFG, inconsistent stackdepth");
return ERROR;
}
if (b->b_startdepth < depth && b->b_startdepth < 100) {
assert(b->b_startdepth < 0);
b->b_startdepth = depth;
*(*sp)++ = b;
}
return SUCCESS;
}
/* Find the flow path that needs the largest stack. We assume that
* cycles in the flow graph have no net effect on the stack depth.
*/
int
_PyCfg_Stackdepth(basicblock *entryblock, int code_flags)
_PyCfg_Stackdepth(cfg_builder *g)
{
basicblock *entryblock = g->g_entryblock;
for (basicblock *b = entryblock; b != NULL; b = b->b_next) {
b->b_startdepth = INT_MIN;
}
@ -640,14 +645,13 @@ _PyCfg_Stackdepth(basicblock *entryblock, int code_flags)
return ERROR;
}
int stackdepth = -1;
int maxdepth = 0;
basicblock **sp = stack;
if (code_flags & (CO_GENERATOR | CO_COROUTINE | CO_ASYNC_GENERATOR)) {
stackdepth_push(&sp, entryblock, 1);
} else {
stackdepth_push(&sp, entryblock, 0);
if (stackdepth_push(&sp, entryblock, 0) < 0) {
goto error;
}
while (sp != stack) {
basicblock *b = *--sp;
int depth = b->b_startdepth;
@ -655,27 +659,40 @@ _PyCfg_Stackdepth(basicblock *entryblock, int code_flags)
basicblock *next = b->b_next;
for (int i = 0; i < b->b_iused; i++) {
cfg_instr *instr = &b->b_instr[i];
int effect = PyCompile_OpcodeStackEffectWithJump(instr->i_opcode, instr->i_oparg, 0);
int effect = PyCompile_OpcodeStackEffectWithJump(
instr->i_opcode, instr->i_oparg, 0);
if (effect == PY_INVALID_STACK_EFFECT) {
PyErr_Format(PyExc_SystemError,
"compiler PyCompile_OpcodeStackEffectWithJump(opcode=%d, arg=%i) failed",
"Invalid stack effect for opcode=%d, arg=%i",
instr->i_opcode, instr->i_oparg);
return ERROR;
goto error;
}
int new_depth = depth + effect;
assert(new_depth >= 0); /* invalid code or bug in stackdepth() */
if (new_depth < 0) {
PyErr_Format(PyExc_ValueError,
"Invalid CFG, stack underflow");
goto error;
}
if (new_depth > maxdepth) {
maxdepth = new_depth;
}
if (HAS_TARGET(instr->i_opcode)) {
effect = PyCompile_OpcodeStackEffectWithJump(instr->i_opcode, instr->i_oparg, 1);
assert(effect != PY_INVALID_STACK_EFFECT);
effect = PyCompile_OpcodeStackEffectWithJump(
instr->i_opcode, instr->i_oparg, 1);
if (effect == PY_INVALID_STACK_EFFECT) {
PyErr_Format(PyExc_SystemError,
"Invalid stack effect for opcode=%d, arg=%i",
instr->i_opcode, instr->i_oparg);
goto error;
}
int target_depth = depth + effect;
assert(target_depth >= 0); /* invalid code or bug in stackdepth() */
if (target_depth > maxdepth) {
maxdepth = target_depth;
}
stackdepth_push(&sp, instr->i_target, target_depth);
if (stackdepth_push(&sp, instr->i_target, target_depth) < 0) {
goto error;
}
}
depth = new_depth;
assert(!IS_ASSEMBLER_OPCODE(instr->i_opcode));
@ -689,11 +706,15 @@ _PyCfg_Stackdepth(basicblock *entryblock, int code_flags)
}
if (next != NULL) {
assert(BB_HAS_FALLTHROUGH(b));
stackdepth_push(&sp, next, depth);
if (stackdepth_push(&sp, next, depth) < 0) {
goto error;
}
}
}
stackdepth = maxdepth;
error:
PyMem_Free(stack);
return maxdepth;
return stackdepth;
}
static int
@ -2009,7 +2030,7 @@ mark_cold(basicblock *entryblock) {
static int
push_cold_blocks_to_end(cfg_builder *g, int code_flags) {
push_cold_blocks_to_end(cfg_builder *g) {
basicblock *entryblock = g->g_entryblock;
if (entryblock->b_next == NULL) {
/* single basicblock, no need to reorder */
@ -2251,7 +2272,7 @@ resolve_line_numbers(cfg_builder *g, int firstlineno)
int
_PyCfg_OptimizeCodeUnit(cfg_builder *g, PyObject *consts, PyObject *const_cache,
int code_flags, int nlocals, int nparams, int firstlineno)
int nlocals, int nparams, int firstlineno)
{
assert(cfg_builder_check(g));
/** Preprocessing **/
@ -2268,7 +2289,7 @@ _PyCfg_OptimizeCodeUnit(cfg_builder *g, PyObject *consts, PyObject *const_cache,
g->g_entryblock, nlocals, nparams));
insert_superinstructions(g);
RETURN_IF_ERROR(push_cold_blocks_to_end(g, code_flags));
RETURN_IF_ERROR(push_cold_blocks_to_end(g));
RETURN_IF_ERROR(resolve_line_numbers(g, firstlineno));
return SUCCESS;
}