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Diffstat (limited to 'mailinglist/output_launchpad/1655700')
| -rw-r--r-- | mailinglist/output_launchpad/1655700 | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/mailinglist/output_launchpad/1655700 b/mailinglist/output_launchpad/1655700 new file mode 100644 index 00000000..a371703c --- /dev/null +++ b/mailinglist/output_launchpad/1655700 @@ -0,0 +1,31 @@ +disas/libvixl/vixl/invalset.h: possible dodgy code in binary search ? + + +[qemu/disas/libvixl/vixl/invalset.h:442]: (style) Array index 'low' is used before limits check. + +Source code is + + while (!IsValid(elements[low]) && (low < high)) ++low; + +Also: + +qemu/disas/libvixl/vixl/invalset.h:450]: (style) Array index 'middle' is used before limits check. + +The source code is + + while (!IsValid(elements[high]) && (low < high)) --high; + +Mind you, these lines of code look similar but didn't get reported: + + while (!IsValid(elements[middle]) && (middle < high - 1)) ++middle; + while (!IsValid(elements[middle]) && (low + 1 < middle)) --middle; + +Given that binary search is notoriously tricky to get correct and a standard C library routine +I am puzzled as to why the standard library routine didn't get used, with of course a custom +comparison function. + +That doesn't look like a bounds check to me, so I think your checker is producing false positives. + +libvixl is third-party code in any case, so stylistic questions are better directed to them upstream. But I think the difference between this code and a standard binary search is (as the comment says) that it ignores invalid elements in the array. + + |