U Options

u (Linux* OS and Mac OS* X)
This is an alternate option name for option -warn declarations.
u (Windows* OS)
Undefines all previously defined preprocessor values.
U
Undefines any definition currently in effect for the specified symbol.
undefine
This is an alternate option name for option U.
unroll, Qunroll
Tells the compiler the maximum number of times to unroll loops.
unroll-aggressive, Qunroll-aggressive
Determines whether the compiler uses more aggressive unrolling for certain loops.
uppercase, Quppercase
This is a deprecated option.
us
This is a deprecated option.
use-asm, Quse-asm
Tells the compiler to produce objects through the assembler.