[Bug ld/26806] New: Suspected linker bug with LTO

[jakub at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=26806

            Bug ID: 26806
           Summary: Suspected linker bug with LTO
           Product: binutils
           Version: 2.35
            Status: NEW
          Severity: normal
          Priority: P2
         Component: ld
          Assignee: unassigned at sourceware dot org
          Reporter: jakub at redhat dot com
  Target Milestone: ---

#include <unistd.h>
int foo (int x) { if (__builtin_constant_p (x)) return getpid (); return 0; }

compiled with
gcc -shared -fpic -O2 -flto -o testpid.so testpid.c
nm testpid.so | grep getpid; nm -D testpid.so | grep getpid
shows getpid@@GLIBC_2.2.5 in both symbol tables when linked with binutils 2.35
and none when linked with binutils 2.31.1.
As the ltrans assembly file lto1 emits doesn't contain any references to
getpid,
i.e. getpid as undefined symbol is there before IPA optimizations and later
optimized away, it doesn't seem like a GCC bug (unless it is a linker plugin
bug, but then, the same linker plugin works fine against older linker).
https://bugzilla.redhat.com/show_bug.cgi?id=1889763
contains another testcase (even more important one, where because of this the
link is rejected, as the symbol kept in symbol table that really shouldn't be
there gets an linker error (__open*_missing_mode).

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