llvm dev - Dec 2017 - [LLD] Slow callstacks in gdb

Martin Richtarsky <s at martinien.de> writes:
> Rafael Avila de Espindola wrote:
>>> I will retry with clang trunk, when it reproduces I will build some
>>> other
>>> large project (that has DSOs) using our compile/link options (they
are
>>> not
>>> that special, I think).
>>
>> If you can try lld trunk too that would be awesome.
>
> I meant lld trunk :)
>
> The problem goes away when building with clang 4.0 and linking with lld (a
> version from trunk maybe 6 weeks before the 5.0.0 release). However the
> compile options are different in that case, e.g. with respect to -Ox and
> -gx, so it's perhaps a bit apples to oranges.
>
> When building with gcc 6.2.1 and linking with lld trunk, I get a link
error:
>
> bin-lld/ld: error: lib/libse.a(file1.cpp.o): unaligned data
That means that file1.cpp.o has an invalid sh_offset. Can you post a
readelf -SW of it? How is it being created?

The error is from ELF.h: ELFFile<ELFT>::getSectionContentsAsArray.

Cheers,
Rafael

>> When building with gcc 6.2.1 and linking with lld trunk, I get a link
>> error:
>>
>> bin-lld/ld: error: lib/libse.a(file1.cpp.o): unaligned data
>
> That means that file1.cpp.o has an invalid sh_offset. Can you post a
> readelf -SW of it? How is it being created?
>
> The error is from ELF.h: ELFFile<ELFT>::getSectionContentsAsArray.
Output looks as follows [1] Seems sh_offset is missing?

The object file was created with ICC (not sure which version)

Best regards,
Martin

[1]
There are 25 section headers, starting at offset 0xd5e50:

Section Headers:
  [Nr] Name              Type            Address          Off    Size   ES
Flg Lk Inf Al
  [ 0]                   NULL            0000000000000000 000000 000000 00
     0   0  0
  [ 1] .symtab           SYMTAB          0000000000000000 000040 000228 18
    16  17  4
  [ 2] .data             PROGBITS        0000000000000000 000268 000000 00
 WA  0   0  4
  [ 3] .bss              NOBITS          0000000000000000 000268 000000 00
 WA  0   0  4
  [ 4] .text             PROGBITS        0000000000000000 000268 010330 00
 AX  0   0 16
  [ 5] .rodata           PROGBITS        0000000000000000 010598 001460 00
  A  0   0 32
  [ 6] .debug_opt_report PROGBITS        0000000000000000 0119f8 002d52 00
     0   0  1
  [ 7] .note.GNU-stack   NOTE            0000000000000000 01474a 000000 00
     0   0  1
  [ 8] .debug_info       PROGBITS        0000000000000000 01474a 020d66 00
     0   0  1
  [ 9] .debug_line       PROGBITS        0000000000000000 0354b0 00968b 00
     0   0  1
  [10] .debug_abbrev     PROGBITS        0000000000000000 03eb3b 0003ea 00
     0   0  1
  [11] .debug_frame      PROGBITS        0000000000000000 03ef25 001220 00
     0   0  1
  [12] .debug_str        PROGBITS        0000000000000000 040145 018b94 01
 MS  0   0  1
  [13] .eh_frame         PROGBITS        0000000000000000 058cd9 001220 00
  A  0   0  8
  [14] .debug_ranges     PROGBITS        0000000000000000 059ef9 016000 00
     0   0  1
  [15] .gnu.linkonce.d.DW.ref.__gxx_personality_v0 PROGBITS       
0000000000000000 06fef9 000008 00   A  0   0  1
  [16] .strtab           STRTAB          0000000000000000 06ff01 001522 00
     0   0  1
  [17] .rela.text        RELA            0000000000000000 071423 001728 18
     1   4  8
  [18] .rela.debug_opt_report RELA            0000000000000000 072b4b
001fb0 18      1   6  8
  [19] .rela.debug_info  RELA            0000000000000000 074afb 028680 18
     1   8  8
  [20] .rela.debug_line  RELA            0000000000000000 09d17b 000048 18
     1   9  8
  [21] .rela.debug_frame RELA            0000000000000000 09d1c3 000090 18
     1  11  8
  [22] .rela.eh_frame    RELA            0000000000000000 09d253 000060 18
     1  13  8
  [23] .rela.debug_ranges RELA            0000000000000000 09d2b3 038b80
18      1  14  8
  [24] .rela.gnu.linkonce.d.DW.ref.__gxx_personality_v0 RELA           
0000000000000000 0d5e33 000018 18      1  15  8
Key to Flags:
  W (write), A (alloc), X (execute), M (merge), S (strings), l (large)
  I (info), L (link order), G (group), T (TLS), E (exclude), x (unknown)
  O (extra OS processing required) o (OS specific), p (processor specific)


-- 
http://www.productive-cpp.com/

Martin Richtarsky <s at martinien.de> writes:
> Output looks as follows [1] Seems sh_offset is missing?
That is what readelf prints as Off
>   [17] .rela.text        RELA            0000000000000000 071423 001728 18
>      1   4  8
The offset of rela text should have been aligned, but it is not. Can you
report a bug on icc? As a work around using the gnu assembler if
possible should fix this.

Cheers,
Rafael