https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91568
Martin Liška <marxin at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |marxin at gcc dot gnu.org Known to work| |10.0 Target Milestone|--- |9.3 Known to fail| |9.2.0 --- Comment #3 from Martin Liška <marxin at gcc dot gnu.org> --- Reduced test-case: $ cat pr91568.f90 subroutine h3dall(z,hvec,hder) complex *16 hvec(1),hder(0:1) complex *16 z,zinv,ztmp/1.0/ if (abs0ifder.eq.1) then zinv=1.0/z do i=1,nterms dtmp=i ztmp=zinv*dtmp hder(i)=hvec(i-1)-ztmp*hvec(i) enddo endif end $ gcc-9 pr91568.f90 -Ofast pr91568.f90:9:18: 6 | do i=1,nterms | 2 ...... 9 | hder(i)=hvec(i-1)-ztmp*hvec(i) | 1 Warning: Array reference at (1) out of bounds (0 < 1) in loop beginning at (2) during GIMPLE pass: vect pr91568.f90:1:0: 1 | subroutine h3dall(z,hvec,hder) | internal compiler error: in vect_schedule_slp_instance, at tree-vect-slp.c:3922 0x7fa337825bca __libc_start_main ../csu/libc-start.c:308 Please submit a full bug report, with preprocessed source if appropriate. Please include the complete backtrace with any bug report. See <https://bugs.opensuse.org/> for instructions. I can reproduce that only on 9-branch.