please check if you have set the prefix for gcc:
and VLE_TOOLCHAIN_DIR/bin points points to folder with cross tools binaries. Also check if the binaries are physically present on the hard drive.
I have checked the settings you mentioned above,but they don't work.
I find If I delete the optimization info in .cproject file and then built,the Program "gcc" not found in PATH error message will be removed,but the optimization level of lib_mem.c will be changed from O3(what optimization level I want) to none automatically.
I tried reproduce the issue - but no success. Can you please share the .args file for your lib_mem project with Level 3 optimization enabled?
Are you able use the current S32DS Power version - v2017.R1?