Treats the specified register names as fixed registers, and prevents the compiler from generating code that uses these registers.
NoteTry to avoid using this option, because it restricts the compiler in terms of register allocation and can potentially give a negative effect on code generation and performance.
is the AAPCS name of the register,
denoted by an integer value in the range
8 map sequentially onto registers
is unspecified, the compiler faults use of
This option has the same restrictions as the
__global_reg storage class