Hi All, I ran the polyhedron testsuite with the patched gfortran-13.0.1 and 7.4(as used in the posted Linux test). The timings are comparable except for rnflow.f90. As noted below, rnflow.f90 hangs with the unpatched mainline at -O3 but runs successfully at -O2. I presume that this is a serious regression since it involves optimization? Which component should I post it against? Regards Paul gfortran 13.0.1 with patch Benchmark Compile Executable Ave Run Number Estim Name (secs) (bytes) (secs) Repeats Err % --------- ------- ---------- ------- ------- ------ ac 0.00 55904 7.28 2 0.0550 aermod 0.00 1149032 10.32 2 0.0242 air 0.00 120224 3.57 2 0.3083 capacita 0.00 110872 20.27 2 0.0765 channel2 0.00 43928 98.23 2 0.2703 doduc 0.00 190296 13.86 2 0.2453 gas_dyn2 0.00 108176 96.77 2 0.1364 fatigue2 0.00 90752 61.44 2 0.0618 induct2 0.00 224992 57.71 2 0.0572 linpk 0.00 47672 5.54 2 0.1806 mp_prop_desi 0.00 52640 94.50 2 0.0079 nf 0.00 64480 9.25 2 0.4053 protein 0.00 136496 20.83 2 0.9096 rnflow 0.00 181320 3417.15 2 99.8270**** test_fpu2 0.00 126752 52.35 2 0.1691 tfft2 0.00 60280 37.61 2 0.9387 Geometric Mean Execution Time = 32.72 seconds ****rnflow hangs without patch as well. Seems to be a rather serious regression. gets stuck with -O3 in the loop starting at line 3566 in subroutine cptrf2 ================================================================================ gfortran7.4 Benchmark Compile Executable Ave Run Number Estim Name (secs) (bytes) (secs) Repeats Err % --------- ------- ---------- ------- ------- ------ ac 0.00 3612576 7.30 2 0.0205 aermod 0.00 5204760 10.21 2 0.0784 air 0.00 3829736 4.05 2 0.0988 capacita 0.00 3672512 22.25 2 0.1506 channel2 0.00 3663368 87.22 2 0.5767 doduc 0.00 3840336 13.60 2 0.0221 gas_dyn2 0.00 3673920 89.54 2 0.1106 fatigue2 0.00 3691256 74.34 2 0.0921 induct2 0.00 4062312 57.87 2 0.1348 linpk 0.00 3591984 5.59 2 0.0358 mp_prop_desi 0.00 3966920 93.99 2 0.0654 nf 0.00 3622112 9.27 2 0.0324 protein 0.00 3832280 22.10 2 0.1289 rnflow 0.00 4129984 23.49 2 0.7449 test_fpu2 0.00 3940944 53.29 2 0.2561 tfft2 0.00 3622040 36.56 2 0.1026 Geometric Mean Execution Time = 24.33 seconds