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[3.10] bpo-45773: Stop "optimizing" certain jump patterns (GH-29526)

This commit is contained in:
Brandt Bucher 2021-11-11 13:52:43 -08:00 committed by GitHub
parent c5bfb88eb6
commit a89bbde83f
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GPG Key ID: 4AEE18F83AFDEB23
6 changed files with 60 additions and 81 deletions
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7
Lib/test/test_peepholer.py
View File

@ -514,5 +514,12 @@ def test_bpo_42057(self):
except Exception or Exception:
pass
def test_bpo_45773_pop_jump_if_true(self):
compile("while True or spam: pass", "<test>", "exec")
def test_bpo_45773_pop_jump_if_false(self):
compile("while True or not spam: pass", "<test>", "exec")
if __name__ == "__main__":
unittest.main()

1
Misc/NEWS.d/next/Core and Builtins/2021-11-09-13-01-35.bpo-45773.POU8A4.rst Normal file
View File

@ -0,0 +1 @@
Fix a compiler hang when attempting to optimize certain jump patterns.

115
Python/compile.c
View File

@ -21,6 +21,8 @@
* objects.
*/
#include <stdbool.h>
#include "Python.h"
#include "pycore_ast.h" // _PyAST_GetDocString()
#include "pycore_compile.h" // _PyFuture_FromAST()
@ -7264,25 +7266,24 @@ fold_rotations(struct instr *inst, int n)
}
}
static int
eliminate_jump_to_jump(basicblock *bb, int opcode) {
assert (bb->b_iused > 0);
struct instr *inst = &bb->b_instr[bb->b_iused-1];
assert (is_jump(inst));
assert (inst->i_target->b_iused > 0);
struct instr *target = &inst->i_target->b_instr[0];
if (inst->i_target == target->i_target) {
/* Nothing to do */
return 0;
// Attempt to eliminate jumps to jumps by updating inst to jump to
// target->i_target using the provided opcode. Return whether or not the
// optimization was successful.
static bool
jump_thread(struct instr *inst, struct instr *target, int opcode)
{
assert(is_jump(inst));
assert(is_jump(target));
// bpo-45773: If inst->i_target == target->i_target, then nothing actually
// changes (and we fall into an infinite loop):
if (inst->i_lineno == target->i_lineno &&
inst->i_target != target->i_target)
{
inst->i_target = target->i_target;
inst->i_opcode = opcode;
return true;
}
int lineno = target->i_lineno;
if (add_jump_to_block(bb, opcode, lineno, target->i_target) == 0) {
return -1;
}
assert (bb->b_iused >= 2);
bb->b_instr[bb->b_iused-2].i_opcode = NOP;
return 0;
return false;
}
/* Maximum size of basic block that should be copied in optimizer */
@ -7399,25 +7400,21 @@ optimize_basic_block(struct compiler *c, basicblock *bb, PyObject *consts)
where y+1 is the instruction following the second test.
*/
case JUMP_IF_FALSE_OR_POP:
switch(target->i_opcode) {
switch (target->i_opcode) {
case POP_JUMP_IF_FALSE:
if (inst->i_lineno == target->i_lineno) {
*inst = *target;
i--;
}
i -= jump_thread(inst, target, POP_JUMP_IF_FALSE);
break;
case JUMP_ABSOLUTE:
case JUMP_FORWARD:
case JUMP_IF_FALSE_OR_POP:
if (inst->i_lineno == target->i_lineno &&
inst->i_target != target->i_target) {
inst->i_target = target->i_target;
i--;
}
i -= jump_thread(inst, target, JUMP_IF_FALSE_OR_POP);
break;
case JUMP_IF_TRUE_OR_POP:
assert (inst->i_target->b_iused == 1);
case POP_JUMP_IF_TRUE:
if (inst->i_lineno == target->i_lineno) {
// We don't need to bother checking for loops here,
// since a block's b_next cannot point to itself:
assert(inst->i_target != inst->i_target->b_next);
inst->i_opcode = POP_JUMP_IF_FALSE;
inst->i_target = inst->i_target->b_next;
--i;
@ -7425,27 +7422,22 @@ optimize_basic_block(struct compiler *c, basicblock *bb, PyObject *consts)
break;
}
break;
case JUMP_IF_TRUE_OR_POP:
switch(target->i_opcode) {
switch (target->i_opcode) {
case POP_JUMP_IF_TRUE:
if (inst->i_lineno == target->i_lineno) {
*inst = *target;
i--;
}
i -= jump_thread(inst, target, POP_JUMP_IF_TRUE);
break;
case JUMP_ABSOLUTE:
case JUMP_FORWARD:
case JUMP_IF_TRUE_OR_POP:
if (inst->i_lineno == target->i_lineno &&
inst->i_target != target->i_target) {
inst->i_target = target->i_target;
i--;
}
i -= jump_thread(inst, target, JUMP_IF_TRUE_OR_POP);
break;
case JUMP_IF_FALSE_OR_POP:
assert (inst->i_target->b_iused == 1);
case POP_JUMP_IF_FALSE:
if (inst->i_lineno == target->i_lineno) {
// We don't need to bother checking for loops here,
// since a block's b_next cannot point to itself:
assert(inst->i_target != inst->i_target->b_next);
inst->i_opcode = POP_JUMP_IF_TRUE;
inst->i_target = inst->i_target->b_next;
--i;
@ -7453,54 +7445,33 @@ optimize_basic_block(struct compiler *c, basicblock *bb, PyObject *consts)
break;
}
break;
case POP_JUMP_IF_FALSE:
switch(target->i_opcode) {
switch (target->i_opcode) {
case JUMP_ABSOLUTE:
case JUMP_FORWARD:
if (inst->i_lineno == target->i_lineno) {
inst->i_target = target->i_target;
i--;
}
break;
case JUMP_IF_FALSE_OR_POP:
i -= jump_thread(inst, target, POP_JUMP_IF_FALSE);
}
break;
case POP_JUMP_IF_TRUE:
switch(target->i_opcode) {
switch (target->i_opcode) {
case JUMP_ABSOLUTE:
case JUMP_FORWARD:
if (inst->i_lineno == target->i_lineno) {
inst->i_target = target->i_target;
i--;
}
break;
case JUMP_IF_TRUE_OR_POP:
i -= jump_thread(inst, target, POP_JUMP_IF_TRUE);
}
break;
case JUMP_ABSOLUTE:
case JUMP_FORWARD:
assert (i == bb->b_iused-1);
switch(target->i_opcode) {
case JUMP_FORWARD:
if (eliminate_jump_to_jump(bb, inst->i_opcode)) {
goto error;
}
break;
switch (target->i_opcode) {
case JUMP_ABSOLUTE:
if (eliminate_jump_to_jump(bb, JUMP_ABSOLUTE)) {
goto error;
}
break;
case JUMP_FORWARD:
i -= jump_thread(inst, target, JUMP_ABSOLUTE);
}
break;
case FOR_ITER:
assert (i == bb->b_iused-1);
if (target->i_opcode == JUMP_FORWARD) {
if (eliminate_jump_to_jump(bb, inst->i_opcode)) {
goto error;
}
i -= jump_thread(inst, target, FOR_ITER);
}
break;
case ROT_N:

8
Python/importlib.h generated
View File

@ -782,8 +782,8 @@ const unsigned char _Py_M__importlib_bootstrap[] = {
103,0,110,1,100,2,125,5,124,4,124,0,124,1,124,5,
100,4,141,3,83,0,124,3,100,2,117,0,114,67,116,0,
124,1,100,5,131,2,114,65,122,7,124,1,160,4,124,0,
161,1,125,3,87,0,110,13,4,0,116,5,121,64,1,0,
1,0,1,0,100,2,125,3,89,0,110,3,119,0,100,6,
161,1,125,3,87,0,113,67,4,0,116,5,121,64,1,0,
1,0,1,0,100,2,125,3,89,0,113,67,119,0,100,6,
125,3,116,6,124,0,124,1,124,2,124,3,100,7,141,4,
83,0,41,8,122,53,82,101,116,117,114,110,32,97,32,109,
111,100,117,108,101,32,115,112,101,99,32,98,97,115,101,100,
@ -812,9 +812,9 @@ const unsigned char _Py_M__importlib_bootstrap[] = {
122,5,124,0,106,4,125,5,87,0,110,11,4,0,116,1,
121,59,1,0,1,0,1,0,100,0,125,5,89,0,110,1,
119,0,124,2,100,0,117,0,114,87,124,5,100,0,117,0,
114,85,122,5,124,1,106,5,125,2,87,0,110,13,4,0,
114,85,122,5,124,1,106,5,125,2,87,0,113,87,4,0,
116,1,121,84,1,0,1,0,1,0,100,0,125,2,89,0,
110,3,119,0,124,5,125,2,122,5,124,0,106,6,125,6,
113,87,119,0,124,5,125,2,122,5,124,0,106,6,125,6,
87,0,110,11,4,0,116,1,121,103,1,0,1,0,1,0,
100,0,125,6,89,0,110,1,119,0,122,7,116,7,124,0,
106,8,131,1,125,7,87,0,110,11,4,0,116,1,121,122,

6
Python/importlib_external.h generated
View File

@ -977,8 +977,8 @@ const unsigned char _Py_M__importlib_bootstrap_external[] = {
8,0,0,0,67,0,0,0,115,54,1,0,0,124,1,100,
1,117,0,114,29,100,2,125,1,116,0,124,2,100,3,131,
2,114,28,122,7,124,2,160,1,124,0,161,1,125,1,87,
0,110,38,4,0,116,2,121,27,1,0,1,0,1,0,89,
0,110,30,119,0,110,28,116,3,160,4,124,1,161,1,125,
0,113,57,4,0,116,2,121,27,1,0,1,0,1,0,89,
0,113,57,119,0,110,28,116,3,160,4,124,1,161,1,125,
1,116,5,124,1,131,1,115,57,122,9,116,6,116,3,160,
7,161,0,124,1,131,2,125,1,87,0,110,9,4,0,116,
8,121,56,1,0,1,0,1,0,89,0,110,1,119,0,116,
@ -990,7 +990,7 @@ const unsigned char _Py_M__importlib_bootstrap_external[] = {
1,83,0,124,3,116,16,117,0,114,131,116,0,124,2,100,
6,131,2,114,130,122,7,124,2,160,17,124,0,161,1,125,
7,87,0,110,9,4,0,116,2,121,124,1,0,1,0,1,
0,89,0,110,10,119,0,124,7,114,130,103,0,124,4,95,
0,89,0,113,134,119,0,124,7,114,130,103,0,124,4,95,
18,110,3,124,3,124,4,95,18,124,4,106,18,103,0,107,
2,114,153,124,1,114,153,116,19,124,1,131,1,100,7,25,
0,125,8,124,4,106,18,160,20,124,8,161,1,1,0,124,

4
Python/importlib_zipimport.h
View File

@ -1004,9 +1004,9 @@ const unsigned char _Py_M__zipimport[] = {
1,0,1,0,89,0,113,9,119,0,124,8,100,4,25,0,
125,9,116,8,124,0,106,4,124,8,131,2,125,10,100,0,
125,11,124,5,114,91,122,10,116,9,124,0,124,9,124,7,
124,1,124,10,131,5,125,11,87,0,110,25,4,0,116,10,
124,1,124,10,131,5,125,11,87,0,113,96,4,0,116,10,
121,90,1,0,125,12,1,0,122,8,124,12,125,3,87,0,
89,0,100,0,125,12,126,12,110,10,100,0,125,12,126,12,
89,0,100,0,125,12,126,12,113,96,100,0,125,12,126,12,
119,1,119,0,116,11,124,9,124,10,131,2,125,11,124,11,
100,0,117,0,114,101,113,9,124,8,100,4,25,0,125,9,
124,11,124,6,124,9,102,3,2,0,1,0,83,0,124,3,