Set the optimization level of a single c function in gcc

single_function.c

// You can use a Function Attribute called optimize to do this. 
// I got the info on Function Attributes from this link:
// https://gcc.gnu.org/onlinedocs/gcc-4.5.4/gcc/Function-Attributes.html#Function-Attributes
// To set the optimization level to -O0 for a function:
void __attribute__ ((optimize("-O0"))) foo() {}