SF bug #1053819: Segfault in tuple_of_constants
Peepholer could be fooled into misidentifying a tuple_of_constants.
Added code to count consecutive occurrences of LOAD_CONST.
Use the count to weed out the misidentified cases.
Added a unittest.
diff --git a/Lib/test/test_peepholer.py b/Lib/test/test_peepholer.py
index 913f805..934b57c 100644
--- a/Lib/test/test_peepholer.py
+++ b/Lib/test/test_peepholer.py
@@ -83,6 +83,23 @@
self.assert_(elem in asm)
self.assert_('BUILD_TUPLE' not in asm)
+ # Bug 1053819: Tuple of constants misidentified when presented with:
+ # . . . opcode_with_arg 100 unary_opcode BUILD_TUPLE 1 . . .
+ # The following would segfault upon compilation
+ def crater():
+ (~[
+ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
+ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
+ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
+ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
+ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
+ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
+ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
+ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
+ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
+ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
+ ],)
+
def test_elim_extra_return(self):
# RETURN LOAD_CONST None RETURN --> RETURN
def f(x):
diff --git a/Python/compile.c b/Python/compile.c
index dfb94d3..37793ca 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -419,15 +419,16 @@
newconst = PyTuple_New(n);
if (newconst == NULL)
return 0;
+ len_consts = PyList_GET_SIZE(consts);
for (i=0 ; i<n ; i++) {
arg = GETARG(codestr, (i*3));
+ assert(arg < len_consts);
constant = PyList_GET_ITEM(consts, arg);
Py_INCREF(constant);
PyTuple_SET_ITEM(newconst, i, constant);
}
/* Append folded constant onto consts */
- len_consts = PyList_GET_SIZE(consts);
if (PyList_Append(consts, newconst)) {
Py_DECREF(newconst);
return 0;
@@ -501,6 +502,7 @@
unsigned char *lineno;
int *addrmap = NULL;
int new_line, cum_orig_line, last_line, tabsiz;
+ int cumlc=0, lastlc=0; /* Count runs of consecutive LOAD_CONST codes */
unsigned int *blocks;
char *name;
@@ -536,6 +538,10 @@
for (i=0, nops=0 ; i<codelen ; i += CODESIZE(codestr[i])) {
addrmap[i] = i - nops;
opcode = codestr[i];
+
+ lastlc = cumlc;
+ cumlc = 0;
+
switch (opcode) {
/* Replace UNARY_NOT JUMP_IF_FALSE POP_TOP with
@@ -589,6 +595,7 @@
/* Skip over LOAD_CONST trueconst JUMP_IF_FALSE xx POP_TOP */
case LOAD_CONST:
+ cumlc = lastlc + 1;
j = GETARG(codestr, i);
if (codestr[i+3] != JUMP_IF_FALSE ||
codestr[i+6] != POP_TOP ||
@@ -607,6 +614,7 @@
j = GETARG(codestr, i);
h = i - 3 * j;
if (h >= 0 &&
+ j == lastlc &&
codestr[h] == LOAD_CONST &&
ISBASICBLOCK(blocks, h, 3*(j+1)) &&
tuple_of_constants(&codestr[h], j, consts)) {