Hi:
  The issue is described in the bugzilla.
  Bootstrap is ok, regression test for i386/x86-64 backend is ok.
  Ok for trunk?

ChangeLog
gcc/
        PR target/96350
        * config/i386/i386.c (ix86_legitimate_constant_p): Return
        false for ENDBR immediate.
        (ix86_legitimate_address_p): Ditto.
        * config/i386/predicated.md
        (x86_64_immediate_operand): Exclude ENDBR immediate.
        (x86_64_zext_immediate_operand): Ditto.
        (x86_64_dwzext_immediate_operand): Ditto.
        (ix86_not_endbr_immediate_operand): New predicate.

gcc/testsuite
        * gcc.target/i386/endbr_immediate.c: New test.

-- 
BR,
Hongtao