It's as old as we have -mavx512vl (since GCC 5.1.0): $ gfortran /home/marxin/Programming/gcc/gcc/testsuite/gfortran.dg/deferred_character_23.f90 -Os -mavx512vl -fno-rerun-cse-after-loop -c during RTL pass: ira /home/marxin/Programming/gcc/gcc/testsuite/gfortran.dg/deferred_character_23.f90:27:0: 27 | END MODULE TN4 | internal compiler error: in elimination_costs_in_insn, at reload1.c:3547 0x6b68b6 elimination_costs_in_insn /home/marxin/Programming/gcc/gcc/reload1.c:3547 0xdad05d calculate_elim_costs_all_insns() /home/marxin/Programming/gcc/gcc/reload1.c:1609 0xc5d45d ira_costs() /home/marxin/Programming/gcc/gcc/ira-costs.c:2305 0xc56b79 ira_build() /home/marxin/Programming/gcc/gcc/ira-build.c:3432 0xc4db07 ira /home/marxin/Programming/gcc/gcc/ira.c:5352 0xc4db07 execute /home/marxin/Programming/gcc/gcc/ira.c:5663
Are you sure? It compiles OK with gcc-9 for me.
Latest SVN creates the following RTX in _.ira dump: (insn 144 12 145 2 (set (subreg:V2DI (reg:DI 161) 0) (vec_merge:V2DI (vec_duplicate:V2DI (reg:DI 111 [ ubound.0 ])) (const_vector:V2DI [ (const_int 0 [0]) repeated x2 ]) (const_int 1 [0x1]))) "deferred_character_23.f90":27:0 -1 (nil)) This is suspiciously close to PR91454. "-1" hints at unknown insn.
Fixed by r274535. *** This bug has been marked as a duplicate of bug 91454 ***