clayborg added a comment. In D106837#3207676 <https://reviews.llvm.org/D106837#3207676>, @rZhBoYao wrote:
> Hi all, I found this patch causing PR52702 <https://llvm.org/PR52702> in that > the parent of this commit > <https://github.com/llvm/llvm-project/commit/ec1a4917> and LLDB 12 worked > fine. > When disassembling a hello world C program on Linux, LLDB used to show > `callq 0x401030 ; symbol stub for: puts` > instead of > `callq 0x401030 ; symbol stub for: > ___lldb_unnamed_symbol36`. > Examining the symbol table by running `lldb -b -o 'image dump symtab' a.out` > used to show: > > [ 18] 20 X Undefined 0x0000000000000000 > 0x0000000000000000 0x00000012 puts@GLIBC_2.2.5 > ........ > [ 33] 35 X Code 0x0000000000401000 > 0x000000000000001b 0x00000212 _init > [ 34] 36 S Trampoline 0x0000000000401030 > 0x0000000000000010 0x00000000 puts > [ 35] 37 SX Code 0x0000000000401020 > 0x0000000000000010 0x00000000 ___lldb_unnamed_symbol1$$a.out > > and now (ToT and LLDB 13) it's: > > [ 18] 20 X Undefined 0x0000000000000000 > 0x0000000000000000 0x00000012 puts@GLIBC_2.2.5 > ........ > [ 33] 35 X Code 0x0000000000401000 > 0x000000000000001b 0x00000212 _init > [ 34] 36 S Trampoline 0x0000000000401030 > 0x0000000000000010 0x00000000 ___lldb_unnamed_symbol36 > [ 35] 37 SX Code 0x0000000000401020 > 0x0000000000000010 0x00000000 ___lldb_unnamed_symbol37 > > `image dump symtab libc.so.6` gives similar result. > Before ec1a4917 <https://github.com/llvm/llvm-project/commit/ec1a4917> : > > [ 2366] 2367 S Trampoline 0x0000000000025010 0x00007ffff7df2010 > 0x0000000000000010 0x00000000 realloc > [ 2367] 2368 S Trampoline 0x0000000000025020 0x00007ffff7df2020 > 0x0000000000000010 0x00000000 __tls_get_addr > [ 2368] 2369 S Trampoline 0x0000000000025030 0x00007ffff7df2030 > 0x0000000000000010 0x00000000 memalign > [ 2369] 2370 S Trampoline 0x0000000000025040 0x00007ffff7df2040 > 0x0000000000000010 0x00000000 _dl_exception_create > [ 2370] 2371 S Trampoline 0x0000000000025050 0x00007ffff7df2050 > 0x0000000000000010 0x00000000 __tunable_get_val > [ 2371] 2372 S Trampoline 0x0000000000025060 0x00007ffff7df2060 > 0x0000000000000010 0x00000000 _dl_find_dso_for_object > [ 2372] 2373 S Trampoline 0x0000000000025070 0x00007ffff7df2070 > 0x0000000000000010 0x00000000 calloc > [ 2373] 2373 SX Code 0x0000000000025000 0x00007ffff7df2000 > 0x0000000000000010 0x00000000 ___lldb_unnamed_symbol1$$libc.so.6 > [ 2374] 2373 SX Code 0x0000000000025300 0x00007ffff7df2300 > 0x0000000000000040 0x00000000 ___lldb_unnamed_symbol2$$libc.so.6 > [ 2375] 2373 SX Code 0x0000000000025340 0x00007ffff7df2340 > 0x00000000000002f0 0x00000000 ___lldb_unnamed_symbol3$$libc.so.6 > [ 2376] 2373 SX Code 0x0000000000025630 0x00007ffff7df2630 > 0x000000000000000c 0x00000000 ___lldb_unnamed_symbol4$$libc.so.6 > > After: > > [ 2366] 2367 S Trampoline 0x0000000000025010 0x00007ffff7df2010 > 0x0000000000000010 0x00000000 ___lldb_unnamed_symbol2367 > [ 2367] 2368 S Trampoline 0x0000000000025020 0x00007ffff7df2020 > 0x0000000000000010 0x00000000 ___lldb_unnamed_symbol2368 > [ 2368] 2369 S Trampoline 0x0000000000025030 0x00007ffff7df2030 > 0x0000000000000010 0x00000000 ___lldb_unnamed_symbol2369 > [ 2369] 2370 S Trampoline 0x0000000000025040 0x00007ffff7df2040 > 0x0000000000000010 0x00000000 ___lldb_unnamed_symbol2370 > [ 2370] 2371 S Trampoline 0x0000000000025050 0x00007ffff7df2050 > 0x0000000000000010 0x00000000 ___lldb_unnamed_symbol2371 > [ 2371] 2372 S Trampoline 0x0000000000025060 0x00007ffff7df2060 > 0x0000000000000010 0x00000000 ___lldb_unnamed_symbol2372 > [ 2372] 2373 S Trampoline 0x0000000000025070 0x00007ffff7df2070 > 0x0000000000000010 0x00000000 ___lldb_unnamed_symbol2373 > [ 2373] 2374 SX Code 0x0000000000025000 0x00007ffff7df2000 > 0x0000000000000010 0x00000000 ___lldb_unnamed_symbol2374 > [ 2374] 2375 SX Code 0x0000000000025300 0x00007ffff7df2300 > 0x0000000000000040 0x00000000 ___lldb_unnamed_symbol2375 > [ 2375] 2376 SX Code 0x0000000000025340 0x00007ffff7df2340 > 0x00000000000002f0 0x00000000 ___lldb_unnamed_symbol2376 > [ 2376] 2377 SX Code 0x0000000000025630 0x00007ffff7df2630 > 0x000000000000000c 0x00000000 ___lldb_unnamed_symbol2377 > > Is this intended for the performance boost? It seems to me that "`S > Trampoline`" symbols should be handled differently. It is a huge performance boost for Darwin binaries that are stripped because we end up with many symbols with no names due to the fact that mach-o binaries have a LC_FUNCTION_STARTS load command that details the start of all functions even that won't have symbols in the symbol tables. > FWIW, I also found that this doesn't affect macOS tho as `puts` is not even a > synthetic symbol: > > Index UserID DSX Type File Address/Value Load Address > Size Flags Name > ------- ------ --- --------------- ------------------ ------------------ > ------------------ ---------- ---------------------------------- > [ 0] 0 Data 0x0000000100008008 > 0x0000000000000008 0x000e0000 _dyld_private > [ 1] 1 X Data 0x0000000100000000 > 0x0000000000003f70 0x000f0010 _mh_execute_header > [ 2] 2 X Code 0x0000000100003f70 > 0x0000000000000014 0x000f0000 main > [ 3] 3 Trampoline 0x0000000100003f84 > 0x0000000000000006 0x00010100 puts > [ 4] 4 X Undefined 0x0000000000000000 > 0x0000000000000000 0x00010100 dyld_stub_binder > > callq 0x100003f84 ; symbol stub for: puts Looks like you found the underlying issue in https://reviews.llvm.org/D116217. Thanks for finding this issue! Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D106837/new/ https://reviews.llvm.org/D106837 _______________________________________________ lldb-commits mailing list lldb-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
