https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80859
--- Comment #15 from Thorsten Kurth <thorstenkurth at me dot com> --- The code I care about definitely has optimization enabled. For the fortran stuff it does (for example): ftn -g -O3 -ffree-line-length-none -fno-range-check -fno-second-underscore -Jo/3d.gnu.MPI.OMP.EXE -I o/3d.gnu.MPI.OMP.EXE -fimplicit-none -fopenmp -I. -I../../Src/C_BoundaryLib -I../../Src/LinearSolvers/C_CellMG -I../../Src/LinearSolvers/C_CellMG4 -I../../Src/C_BaseLib -I../../Src/C_BoundaryLib -I../../Src/C_BaseLib -I../../Src/LinearSolvers/C_CellMG -I../../Src/LinearSolvers/C_CellMG4 -I/opt/intel/vtune_amplifier_xe_2017.2.0.499904/include -I../../Src/LinearSolvers/C_to_F_MG -I../../Src/LinearSolvers/C_to_F_MG -I../../Src/LinearSolvers/F_MG -I../../Src/LinearSolvers/F_MG -I../../Src/F_BaseLib -I../../Src/F_BaseLib -c ../../Src/LinearSolvers/F_MG/itsol.f90 -o o/3d.gnu.MPI.OMP.EXE/itsol.o Compiling cc_mg_tower_smoother.f90 ... and for the C++ stuff it does CC -g -O3 -std=c++14 -fopenmp -g -DCG_USE_OLD_CONVERGENCE_CRITERIA -DBL_OMP_FABS -DDEVID=0 -DNUM_TEAMS=1 -DNUM_THREADS_PER_BOX=1 -march=knl -DNDEBUG -DBL_USE_MPI -DBL_USE_OMP -DBL_GCC_VERSION='6.3.0' -DBL_GCC_MAJOR_VERSION=6 -DBL_GCC_MINOR_VERSION=3 -DBL_SPACEDIM=3 -DBL_FORT_USE_UNDERSCORE -DBL_Linux -DMG_USE_FBOXLIB -DBL_USE_F_BASELIB -DBL_USE_FORTRAN_MPI -DUSE_F90_SOLVERS -I. -I../../Src/C_BoundaryLib -I../../Src/LinearSolvers/C_CellMG -I../../Src/LinearSolvers/C_CellMG4 -I../../Src/C_BaseLib -I../../Src/C_BoundaryLib -I../../Src/C_BaseLib -I../../Src/LinearSolvers/C_CellMG -I../../Src/LinearSolvers/C_CellMG4 -I/opt/intel/vtune_amplifier_xe_2017.2.0.499904/include -I../../Src/LinearSolvers/C_to_F_MG -I../../Src/LinearSolvers/C_to_F_MG -I../../Src/LinearSolvers/F_MG -I../../Src/LinearSolvers/F_MG -I../../Src/F_BaseLib -I../../Src/F_BaseLib -c ../../Src/C_BaseLib/FPC.cpp -o o/3d.gnu.MPI.OMP.EXE/FPC.o Compiling Box.cpp ... But the kernels I care about are in C++.
