Author: Carl Friedrich Bolz-Tereick <[email protected]>
Branch: py3.6
Changeset: r97491:cedd17bf511f
Date: 2019-09-16 13:50 +0200
http://bitbucket.org/pypy/pypy/changeset/cedd17bf511f/
Log: don't fold too huge left shift either
diff --git a/pypy/interpreter/astcompiler/optimize.py
b/pypy/interpreter/astcompiler/optimize.py
--- a/pypy/interpreter/astcompiler/optimize.py
+++ b/pypy/interpreter/astcompiler/optimize.py
@@ -142,6 +142,16 @@
""")
return space.pow(w_left, w_right, space.w_None)
+def _fold_lshift(space, w_left, w_right):
+ # don't constant-fold if "w_left" and "w_right" are integers and
+ # the estimated bit length of the result is unreasonably large
+ space.appexec([w_left, w_right], """(left, right):
+ if isinstance(left, int) and isinstance(right, int):
+ if left.bit_length() + right > 1000:
+ raise OverflowError
+ """)
+ return space.lshift(w_left, w_right)
+
def _fold_not(space, operand):
return space.newbool(not space.is_true(operand))
@@ -154,7 +164,7 @@
ast.FloorDiv : _binary_fold("floordiv"),
ast.Mod : _binary_fold("mod"),
ast.Pow : _fold_pow,
- ast.LShift : _binary_fold("lshift"),
+ ast.LShift : _fold_lshift,
ast.RShift : _binary_fold("rshift"),
ast.BitOr : _binary_fold("or_"),
ast.BitXor : _binary_fold("xor"),
diff --git a/pypy/interpreter/astcompiler/test/test_compiler.py
b/pypy/interpreter/astcompiler/test/test_compiler.py
--- a/pypy/interpreter/astcompiler/test/test_compiler.py
+++ b/pypy/interpreter/astcompiler/test/test_compiler.py
@@ -1474,13 +1474,14 @@
assert ops.LOAD_CONST in counts
def test_dont_fold_huge_powers(self):
- for source in (
- "2 ** 3000", # not constant-folded: too big
- "(-2) ** 3000",
+ for source, op in (
+ ("2 ** 3000", ops.BINARY_POWER), # not constant-folded: too
big
+ ("(-2) ** 3000", ops.BINARY_POWER),
+ ("5 << 1000", ops.BINARY_LSHIFT),
):
source = 'def f(): %s' % source
counts = self.count_instructions(source)
- assert ops.BINARY_POWER in counts
+ assert op in counts
for source in (
"2 ** 2000", # constant-folded
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