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bpo-1875: Raise SyntaxError in invalid blocks that will be optimised away (GH-13332)

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Move the check for dead conditionals (if 0) to the peephole optimizer
and make sure that the code block is still compiled to report any
existing syntax errors within.
This commit is contained in:
Pablo Galindo 2019-05-17 11:37:08 +01:00 • committed by GitHub
parent a8b46944d7
commit af8646c805
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GPG key ID: 4AEE18F83AFDEB23
4 changed files with 33 additions and 9 deletions
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9
Python/compile.c
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@ -2546,13 +2546,12 @@ compiler_if(struct compiler *c, stmt_ty s)
return 0;
constant = expr_constant(s->v.If.test);
/* constant = 0: "if 0"
/* constant = 0: "if 0" Leave the optimizations to
* the pephole optimizer to check for syntax errors
* in the block.
* constant = 1: "if 1", "if 2", ...
* constant = -1: rest */
if (constant == 0) {
if (s->v.If.orelse)
VISIT_SEQ(c, stmt, s->v.If.orelse);
} else if (constant == 1) {
if (constant == 1) {
VISIT_SEQ(c, stmt, s->v.If.body);
} else {
if (asdl_seq_LEN(s->v.If.orelse)) {

16
Python/peephole.c
View file

@ -302,11 +302,19 @@ PyCode_Optimize(PyObject *code, PyObject* consts, PyObject *names,
case LOAD_CONST:
cumlc = lastlc + 1;
if (nextop != POP_JUMP_IF_FALSE ||
!ISBASICBLOCK(blocks, op_start, i + 1) ||
!PyObject_IsTrue(PyList_GET_ITEM(consts, get_arg(codestr, i))))
!ISBASICBLOCK(blocks, op_start, i + 1)) {
break;
fill_nops(codestr, op_start, nexti + 1);
cumlc = 0;
}
PyObject* cnt = PyList_GET_ITEM(consts, get_arg(codestr, i));
int is_true = PyObject_IsTrue(cnt);
if (is_true == 1) {
fill_nops(codestr, op_start, nexti + 1);
cumlc = 0;
} else if (is_true == 0) {
h = get_arg(codestr, nexti) / sizeof(_Py_CODEUNIT);
tgt = find_op(codestr, codelen, h);
fill_nops(codestr, op_start, tgt);
}
break;
/* Try to fold tuples of constants.