[Bug libdw/22546] New: dwarf_aggregate_size() doesn't work for multi-dimensional arrays
https://sourceware.org/bugzilla/show_bug.cgi?id=22546 Bug ID: 22546 Summary: dwarf_aggregate_size() doesn't work for multi-dimensional arrays Product: elfutils Version: unspecified Status: UNCONFIRMED Severity: normal Priority: P2 Component: libdw Assignee: unassigned at sourceware dot org Reporter: sourceware at dima dot secretsauce.net CC: elfutils-devel at sourceware dot org Target Milestone: --- Hi. I'm observing that dwarf_aggregate_size() returns bogus results when looking at double-dimensional arrays. For instance, looking at double dd[3][5]; It says the aggregate is 64-bytes long instead of 120. The bug is that it ends up computing (3+5)*8 instead of 3*5*8. I'm attaching a simple test case. It loads the current process's debug information, and prints out the size of dd, defined as above. It shows the failure: dima@fatty:/tmp$ gcc -g -ldw -lelf dwarf_aggregate_size_bug.c -o dwarf_aggregate_size_bug dima@fatty:/tmp$ ./dwarf_aggregate_size_bug Found DIE for 'dd'. size: 64 I'm using libelf1 0.168-1 on Debian/sid, although at least version 0.170 has the bug too. I'm attaching a proof-of-concept patch to solve this. Note that this patch isn't final: previously we would compute a separate stride for each dimension, while the patch only computes the stride once. I don't know what case specifically that is meant to handle. Tests pass before and after. If for some reason dwarf_aggregate_size() isn't meant to be used this way, then it should still be changed to fail in a more obvious way. Answering 64 here is NEVER the right answer. -- You are receiving this mail because: You are on the CC list for the bug.
[Bug libdw/22546] dwarf_aggregate_size() doesn't work for multi-dimensional arrays
https://sourceware.org/bugzilla/show_bug.cgi?id=22546 --- Comment #1 from dima kogan --- Created attachment 10662 --> https://sourceware.org/bugzilla/attachment.cgi?id=10662&action=edit Prototype fix -- You are receiving this mail because: You are on the CC list for the bug.
[Bug libdw/22546] dwarf_aggregate_size() doesn't work for multi-dimensional arrays
https://sourceware.org/bugzilla/show_bug.cgi?id=22546 --- Comment #2 from dima kogan --- Created attachment 10663 --> https://sourceware.org/bugzilla/attachment.cgi?id=10663&action=edit Demo program -- You are receiving this mail because: You are on the CC list for the bug.
[Bug libdw/22546] dwarf_aggregate_size() doesn't work for multi-dimensional arrays
https://sourceware.org/bugzilla/show_bug.cgi?id=22546 --- Comment #3 from dima kogan --- Created attachment 10672 --> https://sourceware.org/bugzilla/attachment.cgi?id=10672&action=edit Update to the test suite to show this problem -- You are receiving this mail because: You are on the CC list for the bug.
[Bug libdw/22546] dwarf_aggregate_size() doesn't work for multi-dimensional arrays
https://sourceware.org/bugzilla/show_bug.cgi?id=22546 --- Comment #4 from dima kogan --- Here's a patch to add the failing case to the test suite. This test update fails in the stock sources, but succeeds with my patch applied. Note that this patch contains a diff to a binary file (that's how the test suite works), and this binary piece will be recognized by 'git am' only. -- You are receiving this mail because: You are on the CC list for the bug.
[Bug libdw/22546] dwarf_aggregate_size() doesn't work for multi-dimensional arrays
https://sourceware.org/bugzilla/show_bug.cgi?id=22546 --- Comment #7 from dima kogan --- Thanks for looking at it. I submitted the patch. -- You are receiving this mail because: You are on the CC list for the bug.
