NEC machines are special, because they use vector processors. Compiling code always means cross compiling for this type of hardware. The SX-Series uses SUPER-UX, an unix-base operating systems. On the basis of our experience with our former supercomputer (SX6) the following settings might be usefull
CFLAGS="-O -Onooverlap,restrict=all -pvctl,fullmsg,noassume,loopcnt=1000000"
Depending on the cross compiler, you should also set
CC=sxcc AR=sxar or
CC=escc AR=esar. This example is taken from our collection of machine dependent presets for local installations: source:/config/default