https://sourceware.org/bugzilla/show_bug.cgi?id=32161
--- Comment #2 from Sourceware Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Nick Alcock <[email protected]>: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=e135b989412ca9421331f5c32611a7340fbb5430 commit e135b989412ca9421331f5c32611a7340fbb5430 Author: Bruce McCulloch <[email protected]> Date: Fri Nov 1 12:31:46 2024 -0400 libctf: dump CTF array dimensions in the right order Before GCC PR114186, all looked good in the land of multidimensional arrays: you wrote int a[5][10]; and ctf_type_aname() et al would print it as int [5][10] Unfortunately this was two bugs in one. GCC was emitting the array as if it were int a[10][5], i.e. as this: a -> [10] -> [5] -> int rather than a -> [5] -> [10] -> int as it should be. libctf was hiding this by printing them in the wrong order, concealing the bug from anyone using objdump --ctf or anything but actual type graph traversal. Once this was fixed for GCC, the bug was visible in libctf: multidimensional arrays were printed backwards! (But this is just a print-time bug: the underlying bug, that something traversing the type graph would see the array in backwards order, was fixed by the fix to GCC.) Fix this libctf bug, printing the arrays the right way round. In a possibly futile attempt to retain some vestige of backwards compatibility, introduce a new bug-compat flag CTF_F_ARRNELEMS, which, if on, indicates that PR114186 is fixed and GCC is emitting array elements the right way round. (Unfortunately, the fix went in without this flag, so some GCCs will still emit CTF that will cause libctf to print them wrong, even with this fix -- but it's no wronger than it was before, and new GCC and new binutils, as well as GCC older than any fix for PR114186 and new binutils, will print things properly. Someone traversing the type graph will see things right after the GCC fix, wrong before it, and there isn't really any reliable way to tell which you have, though if CTF_F_ARRNELEMS is set, you definitely have a fixed GCC. The test checks for this, but it's not something we expect actual users to ever do -- CTF dict flags are an internal implementation detail with no user-visible API for a reason.) [nca: log message, test compat with older compilers] include/ * ctf.h (CTF_F_ARRNELEMS): New bug-compat flag. (CTF_F_MAX): Adjust. libctf/ PR libctf/32161 * ctf-decl.c (ctf_decl_push): Prepend if this is an array and the bug-compat flag is set. * ctf-dump.c (ctf_dump_header): Dump the new bug-compat flag. * testsuite/libctf-lookup/multidim-array*: New test. -- You are receiving this mail because: You are on the CC list for the bug.
