1berry/cpython
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

gh-92782: unify the style of CFG traversal algorithms in the compiler (GH-92784)

Browse Source
This commit is contained in:
Irit Katriel 2022-05-17 13:00:11 +01:00 committed by GitHub
parent 93fc14933b
commit 8781a041a0
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 45 additions and 38 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

83
Python/compile.c
View File

@ -7061,7 +7061,6 @@ struct assembler {
PyObject *a_except_table; /* bytes containing exception table */ PyObject *a_except_table; /* bytes containing exception table */
basicblock *a_entry; basicblock *a_entry;
int a_offset; /* offset into bytecode */ int a_offset; /* offset into bytecode */
int a_nblocks; /* number of reachable blocks */
int a_except_table_off; /* offset into exception table */ int a_except_table_off; /* offset into exception table */
int a_prevlineno; /* lineno of last emitted line in line table */ int a_prevlineno; /* lineno of last emitted line in line table */
int a_prev_end_lineno; /* end_lineno of last emitted line in line table */ int a_prev_end_lineno; /* end_lineno of last emitted line in line table */
@ -7074,6 +7073,20 @@ struct assembler {
int a_location_off; /* offset of last written location info frame */ int a_location_off; /* offset of last written location info frame */
}; };
static basicblock**
make_cfg_traversal_stack(basicblock *entry) {
int nblocks = 0;
for (basicblock *b = entry; b != NULL; b = b->b_next) {
b->b_visited = 0;
nblocks++;
}
basicblock **stack = (basicblock **)PyMem_Malloc(sizeof(basicblock *) * nblocks);
if (!stack) {
PyErr_NoMemory();
}
return stack;
}
Py_LOCAL_INLINE(void) Py_LOCAL_INLINE(void)
stackdepth_push(basicblock ***sp, basicblock *b, int depth) stackdepth_push(basicblock ***sp, basicblock *b, int depth)
{ {
@ -7089,31 +7102,26 @@ stackdepth_push(basicblock ***sp, basicblock *b, int depth)
* cycles in the flow graph have no net effect on the stack depth. * cycles in the flow graph have no net effect on the stack depth.
*/ */
static int static int
stackdepth(struct compiler *c) stackdepth(struct compiler *c, basicblock *entry)
{ {
basicblock *b, *entryblock = NULL; for (basicblock *b = entry; b != NULL; b = b->b_next) {
basicblock **stack, **sp;
int nblocks = 0, maxdepth = 0;
for (b = c->u->u_blocks; b != NULL; b = b->b_list) {
b->b_startdepth = INT_MIN; b->b_startdepth = INT_MIN;
entryblock = b;
nblocks++;
} }
assert(entryblock!= NULL); basicblock **stack = make_cfg_traversal_stack(entry);
stack = (basicblock **)PyObject_Malloc(sizeof(basicblock *) * nblocks);
if (!stack) { if (!stack) {
PyErr_NoMemory();
return -1; return -1;
} }
sp = stack; int maxdepth = 0;
basicblock **sp = stack;
if (c->u->u_ste->ste_generator || c->u->u_ste->ste_coroutine) { if (c->u->u_ste->ste_generator || c->u->u_ste->ste_coroutine) {
stackdepth_push(&sp, entryblock, 1); stackdepth_push(&sp, entry, 1);
} else { } else {
stackdepth_push(&sp, entryblock, 0); stackdepth_push(&sp, entry, 0);
} }
while (sp != stack) { while (sp != stack) {
b = *--sp; basicblock *b = *--sp;
int depth = b->b_startdepth; int depth = b->b_startdepth;
assert(depth >= 0); assert(depth >= 0);
basicblock *next = b->b_next; basicblock *next = b->b_next;
@ -7159,7 +7167,7 @@ stackdepth(struct compiler *c)
stackdepth_push(&sp, next, depth); stackdepth_push(&sp, next, depth);
} }
} }
PyObject_Free(stack); PyMem_Free(stack);
return maxdepth; return maxdepth;
} }
@ -7264,14 +7272,8 @@ copy_except_stack(ExceptStack *stack) {
static int static int
label_exception_targets(basicblock *entry) { label_exception_targets(basicblock *entry) {
int nblocks = 0; basicblock **todo_stack = make_cfg_traversal_stack(entry);
for (basicblock *b = entry; b != NULL; b = b->b_next) {
b->b_visited = 0;
nblocks++;
}
basicblock **todo_stack = PyMem_Malloc(sizeof(basicblock *)*nblocks);
if (todo_stack == NULL) { if (todo_stack == NULL) {
PyErr_NoMemory();
return -1; return -1;
} }
ExceptStack *except_stack = make_except_stack(); ExceptStack *except_stack = make_except_stack();
@ -8051,7 +8053,7 @@ static int
optimize_cfg(struct compiler *c, struct assembler *a, PyObject *consts); optimize_cfg(struct compiler *c, struct assembler *a, PyObject *consts);
static int static int
trim_unused_consts(struct compiler *c, struct assembler *a, PyObject *consts); trim_unused_consts(struct assembler *a, PyObject *consts);
/* Duplicates exit BBs, so that line numbers can be propagated to them */ /* Duplicates exit BBs, so that line numbers can be propagated to them */
static int static int
@ -8347,7 +8349,6 @@ assemble(struct compiler *c, int addNone)
if (!assemble_init(&a, nblocks, c->u->u_firstlineno)) if (!assemble_init(&a, nblocks, c->u->u_firstlineno))
goto error; goto error;
a.a_entry = entryblock; a.a_entry = entryblock;
a.a_nblocks = nblocks;
int numdropped = fix_cell_offsets(c, entryblock, cellfixedoffsets); int numdropped = fix_cell_offsets(c, entryblock, cellfixedoffsets);
PyMem_Free(cellfixedoffsets); // At this point we're done with it. PyMem_Free(cellfixedoffsets); // At this point we're done with it.
@ -8368,12 +8369,12 @@ assemble(struct compiler *c, int addNone)
if (duplicate_exits_without_lineno(c)) { if (duplicate_exits_without_lineno(c)) {
return NULL; return NULL;
} }
if (trim_unused_consts(c, &a, consts)) { if (trim_unused_consts(&a, consts)) {
goto error; goto error;
} }
propagate_line_numbers(&a); propagate_line_numbers(&a);
guarantee_lineno_for_exits(&a, c->u->u_firstlineno); guarantee_lineno_for_exits(&a, c->u->u_firstlineno);
int maxdepth = stackdepth(c); int maxdepth = stackdepth(c, entryblock);
if (maxdepth < 0) { if (maxdepth < 0) {
goto error; goto error;
} }
@ -9081,17 +9082,19 @@ normalize_basic_block(basicblock *bb) {
static int static int
mark_reachable(struct assembler *a) { mark_reachable(struct assembler *a) {
basicblock **stack, **sp; basicblock **stack = make_cfg_traversal_stack(a->a_entry);
sp = stack = (basicblock **)PyObject_Malloc(sizeof(basicblock *) * a->a_nblocks);
if (stack == NULL) { if (stack == NULL) {
return -1; return -1;
} }
basicblock **sp = stack;
a->a_entry->b_predecessors = 1; a->a_entry->b_predecessors = 1;
*sp++ = a->a_entry; *sp++ = a->a_entry;
while (sp > stack) { while (sp > stack) {
basicblock *b = *(--sp); basicblock *b = *(--sp);
b->b_visited = 1;
if (b->b_next && !b->b_nofallthrough) { if (b->b_next && !b->b_nofallthrough) {
if (b->b_next->b_predecessors == 0) { if (!b->b_next->b_visited) {
assert(b->b_next->b_predecessors == 0);
*sp++ = b->b_next; *sp++ = b->b_next;
} }
b->b_next->b_predecessors++; b->b_next->b_predecessors++;
@ -9101,14 +9104,15 @@ mark_reachable(struct assembler *a) {
struct instr *instr = &b->b_instr[i]; struct instr *instr = &b->b_instr[i];
if (is_jump(instr) || is_block_push(instr)) { if (is_jump(instr) || is_block_push(instr)) {
target = instr->i_target; target = instr->i_target;
if (target->b_predecessors == 0) { if (!target->b_visited) {
assert(target->b_predecessors == 0 || target == b->b_next);
*sp++ = target; *sp++ = target;
} }
target->b_predecessors++; target->b_predecessors++;
} }
} }
} }
PyObject_Free(stack); PyMem_Free(stack);
return 0; return 0;
} }
@ -9128,12 +9132,15 @@ eliminate_empty_basic_blocks(basicblock *entry) {
if (b->b_iused == 0) { if (b->b_iused == 0) {
continue; continue;
} }
if (is_jump(&b->b_instr[b->b_iused-1])) { for (int i = 0; i < b->b_iused; i++) {
basicblock *target = b->b_instr[b->b_iused-1].i_target; struct instr *instr = &b->b_instr[i];
while (target->b_iused == 0) { if (is_jump(instr) || is_block_push(instr)) {
target = target->b_next; basicblock *target = instr->i_target;
while (target->b_iused == 0) {
target = target->b_next;
}
instr->i_target = target;
} }
b->b_instr[b->b_iused-1].i_target = target;
} }
} }
} }
@ -9253,7 +9260,7 @@ optimize_cfg(struct compiler *c, struct assembler *a, PyObject *consts)
// Remove trailing unused constants. // Remove trailing unused constants.
static int static int
trim_unused_consts(struct compiler *c, struct assembler *a, PyObject *consts) trim_unused_consts(struct assembler *a, PyObject *consts)
{ {
assert(PyList_CheckExact(consts)); assert(PyList_CheckExact(consts));