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Bug 2119380 - binutils not working correctly with "clang -flto"
Summary: binutils not working correctly with "clang -flto"
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 8
Classification: Red Hat
Component: binutils
Version: 8.7
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: rc
: ---
Assignee: Nick Clifton
QA Contact: Miloš Prchlík
Jacob Taylor Valdez
URL:
Whiteboard:
Depends On:
Blocks: 2119383 2120959
TreeView+ depends on / blocked
 
Reported: 2022-08-18 13:43 UTC by Jesus Checa
Modified: 2023-05-16 10:16 UTC (History)
5 users (show)

Fixed In Version: binutils-2.30-119.el8
Doc Type: No Doc Update
Doc Text:
Clone Of:
: 2119383 2120959 (view as bug list)
Environment:
Last Closed: 2023-05-16 08:45:00 UTC
Type: Bug
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Issue Tracker RHELPLAN-131415 0 None None None 2022-08-18 13:50:14 UTC
Red Hat Product Errata RHBA-2023:2949 0 None None None 2023-05-16 08:45:05 UTC

Description Jesus Checa 2022-08-18 13:43:53 UTC 
Description of problem:
binutils are not able to correctly read objects and binaries compiled with "clang -flto".

I tested this in RHEL-9.0 and Fedora 34+. In those environments the output is as expected.

This is reproducible in every supported arch.

How reproducible:
100%

Steps to Reproduce:
1. echo "void lto_function(){}" | clang -flto -O2 -c -x c -o foo.o -
2. nm foo.o
3. ar crs foo.a foo.o
4. readelf -c foo.a

Actual results:
[root@hpe-apollo-cn99xx-14-vm-25 ~]# echo "void lto_function(){}" | clang -flto -O2 -c -x c -o foo.o -
[root@hpe-apollo-cn99xx-14-vm-25 ~]# nm foo.o
nm: foo.o: file format not recognized
[root@hpe-apollo-cn99xx-14-vm-25 ~]# ar crs foo.a foo.o
[root@hpe-apollo-cn99xx-14-vm-25 ~]# readelf -c foo.a
foo.a has no archive index
readelf: foo.a: Error: foo.a: unable to dump the index as none was found

Expected results:
$  echo "void lto_function(){}" | clang -flto -O2 -c -x c -o foo.o -
$ nm foo.o
00000000 T lto_function
$ ranlib foo.a foo.o
ranlib: foo.o: file format not recognized
$ ar crs foo.a foo.o
$ readelf -c foo.a
Index of archive foo.a: (1 entries, 0xe bytes in the symbol table)
Contents of binary foo.a(foo.o) at offset 0x5a
        lto_function
Comment 1 Nick Clifton 2022-08-19 12:31:04 UTC 
Right - I have found the problem.  There is a bug in the BFD library.  It does automatically load a plugin when needed, but it looks in the wrong place for it:

  # strace nm foo.o |& grep plugin
  openat(AT_FDCWD, "/usr/bin/../bin/../lib/bfd-plugins", O_RDONLY|O_NONBLOCK|O_CLOEXEC|O_DIRECTORY) = -1 ENOENT (No such file or directory)

The LLVMgold.so plugin is in the /usr/lib64/bfd-plugins directory not the /usr/lib/bfd-plugins directory.
Comment 6 Nick Clifton 2022-09-05 11:14:25 UTC 
Fixed in binutils-2.30-119.el8
Comment 7 Miloš Prchlík 2022-09-19 06:50:42 UTC 
[root@ci-vm-10-0-139-112 ~]# rpm -q binutils
binutils-2.30-119.el8.x86_64
[root@ci-vm-10-0-139-112 ~]# echo "void lto_function(){}" | clang -flto -O2 -c -x c -o foo.o -
[root@ci-vm-10-0-139-112 ~]# nm foo.o
00000000 T lto_function
[root@ci-vm-10-0-139-112 ~]# ar crs foo.a foo.o
[root@ci-vm-10-0-139-112 ~]# readelf -c foo.a
Index of archive foo.a: (1 entries, 0xe bytes in the symbol table)
Contents of binary foo.a(foo.o) at offset 0x5a
        lto_function
[root@ci-vm-10-0-139-112 ~]#
Comment 11 Miloš Prchlík 2022-09-19 06:53:20 UTC 
Verified with binutils-2.30-119.el8
Comment 13 errata-xmlrpc 2023-05-16 08:45:00 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (binutils bug fix and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2023:2949
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