https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=228753
Bug ID: 228753
Summary: [i386] lld emits malformed DWARF info for crt1.o
Product: Base System
Version: CURRENT
Hardware: i386
OS: Any
Status: New
Severity: Affects Only Me
Priority: ---
Component: bin
Assignee: b...@freebsd.org
Reporter: ma...@freebsd.org
With an lld-linked i386 world, ld.bfd hangs when linking the following program:
$ cat conftest.c
int k; int foo () { __builtin_alloca (k); }
$
During the link, ld emits a warning referencing _start1; it looks like ld from
binutils 2.18.5 gets into an infinite loop when performing a lookup in the
DWARF info:
(gdb) bt
#0 0x000d0c1c in add_line_info (table=0x207d4548, address=<optimized out>,
filename=0x201a80c0 "\001/usr/home/markj/src/freebsd-dev/lib/csu/i386", line=1,
column=0, end_sequence=0) at
/usr/home/markj/src/freebsd-dev/gnu/usr.bin/binutils/libbfd/../../../../contrib/binutils/bfd/dwarf2.c:849
#1 0x000cfd1e in decode_line_info (unit=<optimized out>, stash=<optimized
out>)
at
/usr/home/markj/src/freebsd-dev/gnu/usr.bin/binutils/libbfd/../../../../contrib/binutils/bfd/dwarf2.c:1169
#2 0x000cf693 in comp_unit_find_nearest_line (unit=0x207d44bc, addr=<optimized
out>, filename_ptr=0xffbfe5d0, functionname_ptr=0xffbfe5cc,
linenumber_ptr=0xffbfe5c8, stash=0x20469e30)
at
/usr/home/markj/src/freebsd-dev/gnu/usr.bin/binutils/libbfd/../../../../contrib/binutils/bfd/dwarf2.c:2103
#3 0x000ced29 in find_line (abfd=0x201d50c0, section=<optimized out>,
offset=160, symbol=0x0, symbols=0x20480000, filename_ptr=0xffbfe5d0,
functionname_ptr=0xffbfe5cc, linenumber_ptr=0xffbfe5c8, addr_size=0,
pinfo=0x20197344)
at
/usr/home/markj/src/freebsd-dev/gnu/usr.bin/binutils/libbfd/../../../../contrib/binutils/bfd/dwarf2.c:2575
#4 0x000ce063 in _bfd_dwarf2_find_nearest_line (abfd=0x201d50c0,
section=0x201990d0, symbols=0x20480000, offset=160, filename_ptr=0xffbfe5d0,
functionname_ptr=0xffbfe5cc, linenumber_ptr=0xffbfe5c8, addr_size=0,
pinfo=0x20197344)
at
/usr/home/markj/src/freebsd-dev/gnu/usr.bin/binutils/libbfd/../../../../contrib/binutils/bfd/dwarf2.c:2607
#5 0x000ac37e in _bfd_elf_find_nearest_line (abfd=0x201d50c0,
section=0x201990d0, symbols=0x20480000, offset=160, filename_ptr=0xffbfe5d0,
functionname_ptr=0xffbfe5cc, line_ptr=0xffbfe5c8)
at
/usr/home/markj/src/freebsd-dev/gnu/usr.bin/binutils/libbfd/../../../../contrib/binutils/bfd/elf.c:7198
#6 0x0007c3a9 in vfinfo (fp=0x181bac <__sF+472>, fmt=0x250e8 " undefined
reference to `%T'\n", arg=0xffbfe668 "\300P\035 \320\220\031 \240",
is_warning=1)
at
/usr/home/markj/src/freebsd-dev/gnu/usr.bin/binutils/ld/../../../../contrib/binutils/ld/ldmisc.c:324
#7 0x0007c82d in einfo (fmt=0x250e3 "%X%C: undefined reference to `%T'\n")
at
/usr/home/markj/src/freebsd-dev/gnu/usr.bin/binutils/ld/../../../../contrib/binutils/ld/ldmisc.c:465
#8 0x0007b838 in undefined_symbol (info=0x1831d0 <link_info>, name=0x201bf6c8
"main", abfd=0x201d50c0, section=0x201990d0, address=160, error=1)
at
/usr/home/markj/src/freebsd-dev/gnu/usr.bin/binutils/ld/../../../../contrib/binutils/ld/ldmain.c:1397
#9 0x0008f1d6 in elf_i386_relocate_section (output_bfd=0x201d5000,
info=0x1831d0 <link_info>, input_bfd=0x201d50c0, input_section=0x201990d0,
contents=0x206d5000
"1\355U\211\345\203\344\360\215E\b\203\354\004P\377u\004R\350\b",
relocs=0x201d8288, local_syms=0x2046be00,
local_sections=0x201ff400) at
/usr/home/markj/src/freebsd-dev/gnu/usr.bin/binutils/libbfd/../../../../contrib/binutils/bfd/elf32-i386.c:2346
#10 0x000bb38d in elf_link_input_bfd (input_bfd=<optimized out>,
finfo=<optimized out>)
at
/usr/home/markj/src/freebsd-dev/gnu/usr.bin/binutils/libbfd/../../../../contrib/binutils/bfd/elflink.c:8706
#11 bfd_elf_final_link (abfd=0x201d5000, info=0x1831d0 <link_info>)
at
/usr/home/markj/src/freebsd-dev/gnu/usr.bin/binutils/libbfd/../../../../contrib/binutils/bfd/elflink.c:9843
#12 0x0007cf35 in ldwrite () at
/usr/home/markj/src/freebsd-dev/gnu/usr.bin/binutils/ld/../../../../contrib/binutils/ld/ldwrite.c:557
#13 0x0007a728 in main (argc=<optimized out>, argv=<optimized out>)
at
/usr/home/markj/src/freebsd-dev/gnu/usr.bin/binutils/ld/../../../../contrib/binutils/ld/ldmain.c:468
The problem seems to occur only if crt1.o, which is a partial link of crt1_c.o
and crt1_s.o, is linked using lld. That is, if I link everything under lib/csu
using lld and just link crt1.o using ld.bfd, the infinite loop doesn't occur.
If I try to link conftest.c using ld from binutils 2.30, I get an internal
warning instead of a hang:
$ clang conftest.c
conftest.c:1:43: warning: control reaches end of non-void function
[-Wreturn-type]
int k; int foo () { __builtin_alloca (k); }
^
1 warning generated.
/usr/bin/ld: Dwarf Error: Line info data is bigger (0xefb0101) than the space
remaining in the section (0x23f)
/usr/lib/crt1.o: In function `_start1':
(.text+0xa0): undefined reference to `main'
clang: error: linker command failed with exit code 1 (use -v to see invocation)
$
So it looks like lld is somehow messing up the DWARF info when merging crt1_c.o
and crt1_s.o.
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