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| author | Yu Feng <rainwoodman@gmail.com> | 2017-04-10 10:38:58 -0700 |
|---|---|---|
| committer | Yu Feng <rainwoodman@gmail.com> | 2017-04-10 10:38:58 -0700 |
| commit | 44f2a623e177606a2d5c27b7b26d5d8d3af8a0da (patch) | |
| tree | 7b6c14f066a597b1c9e4efc5ddc30b8c2fbb9980 /numpy/random | |
| parent | 32776774fd6d7f0e62e68ff191b8f834a77932a4 (diff) | |
| download | python-numpy-44f2a623e177606a2d5c27b7b26d5d8d3af8a0da.tar.gz python-numpy-44f2a623e177606a2d5c27b7b26d5d8d3af8a0da.tar.bz2 python-numpy-44f2a623e177606a2d5c27b7b26d5d8d3af8a0da.zip | |
MAINT: avoid memcpy when i == j
Valgrind complains about memcpy with overlapping address in mtrand.c
It happens when i == j in this loop.
Closer inspection the i == j iteration is not needed (it is a swap).
So, skip it and avoid depending on undefined behavior of memcpy.
related read:
https://sourceware.org/bugzilla/show_bug.cgi?id=12518
Diffstat (limited to 'numpy/random')
| -rw-r--r-- | numpy/random/mtrand/mtrand.pyx | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/numpy/random/mtrand/mtrand.pyx b/numpy/random/mtrand/mtrand.pyx index bf3a385a9..ee5749d14 100644 --- a/numpy/random/mtrand/mtrand.pyx +++ b/numpy/random/mtrand/mtrand.pyx @@ -4828,6 +4828,7 @@ cdef class RandomState: cdef npy_intp i, j for i in reversed(range(1, n)): j = rk_interval(i, self.internal_state) + if i == j : continue # i == j is not needed and memcpy is undefined. string.memcpy(buf, data + j * stride, itemsize) string.memcpy(data + j * stride, data + i * stride, itemsize) string.memcpy(data + i * stride, buf, itemsize) |