https://sourceware.org/bugzilla/show_bug.cgi?id=32846
Bug ID: 32846
Summary: LTO link failures in various packages since
2707d55e539ef323dd14a1293e762bf3d9739ee7
Product: binutils
Version: 2.45 (HEAD)
Status: NEW
Severity: normal
Priority: P2
Component: ld
Assignee: unassigned at sourceware dot org
Reporter: sam at gentoo dot org
CC: hjl.tools at gmail dot com, matz at suse dot de
Target Milestone: ---
Hi!
Since ...
commit 2707d55e539ef323dd14a1293e762bf3d9739ee7
Author: Michael Matz <[email protected]>
Date: Mon Mar 31 15:57:08 2025 +0200
[lto] Fix symlookup in archives vs shared
when a shared library defines 'foo@@FOO' (default version),
a static archive defines 'foo', the shared lib comes in front
of the archive and under effect of --as-needed, and the requesting
object file uses LTO, then the link editor was wrongly including
the definition from the static archive. It must use the one
from the shared lib, like in the non-LTO or the --no-as-needed case.
See the added testcase that would wrongly print "FAIL" before
this patch.
The problem stems from several connected problems:
(1) only the decorated symbol was entered into first_hash (the hash
table designed to handle definition order in the pre-LTO-plugin
phase of the symbol table walks)
(2) in the archive symbol walk only the undecorated name would be
looked up in first_hash (and hence not found due to (1))
(3) in the archive symbol walk first_hash would only be consulted
when the linker hash table had a defined symbol. In pre-LTO
phase shared lib symbols aren't entered into the linker symbol
table.
So: add also the undecorated name into first_hash when it stems from
a default version and consult first_hash in the archive walker also
for currently undefined symbols. If it has an entry which doesn't
point to the archive, then it comes from an earlier library (shared or
static), and so _this_ archive won't provide the definition.
... I see a bunch of link failures when using LTO in various packages.
Attached a reduction based on kmod.
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