RISC-V Registers

Registers

Hardwired Zero (zero - x0) (read-only)

• Used in various operations that require the value 0.
• Instead of explicitly specifying 0, using x0 allows for a shorter bit representation.
• If there are 32 registers in total, only 5 bits are needed to represent the address.

Return Address (ra - x1)

• Stores the return address.
• Return address : The location in the code where the program should return after a function call is completed.

Stack pointer (sp - x2)

• Points to the top of the current stack frame
• Used for managing function calls and local variables.

Global pointer (gp - x3)

• Points to a fixed region in memory that holds global variables accessible throughout the program.

Thread pointer (tp - x4)

• Points to thread-specific data, allowing each thread to access its own set of variables.

Temporary (t0-t6 - x5-x7, x28-x31)

• Caller-save registers

Saved Registers (s0-s11 - x8-x9, x18-x27)

• Callee-save registers

Frame pointer (fp - x8)

• Points to the base of the current stack frame
• Used for accessing function parameters and local variables within that frame.

Function Arguments (a0-a7 - x10-x17)

• Used to pass arguments to functions and return values from functions.

pc

• Program counter
• Hidden register