Calling Convention

The questions below are due on Sunday November 01, 2026; 11:59:00 PM.

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RISC-V Assembly 2

Load and store operations

For the following questions assume that the registers have been initialized as follows:

x1 = 0x00000001 x2 = 0x00000002 x3 = 0x00000003 x4 = 0x00000004 x5 = 0x00000005

Also assume that you are told the contents of a few locations in main memory beginning at address 0x2000. The following notation implies that the value stored at address 0x2000 is 0x0F00FF00, the value stored at address 0x2004 is 0xA0A0A0A0, and the value stored at address 0x2008 is 0x11111111.

    . = 0x2000
    .word 0x0F00FF00
    .word 0xA0A0A0A0
    .word 0x11111111

Consider the following sequence of instructions:

     lui x1, 2
     lw x2, 4(x1)
     sw x3, 8(x1)

What value is written into register x2 after executing the instruction lw x2, 4(x1)?

0x00002004

0x0F00FF00

0xA0A0A0A0

0x11111111

0xA0A0A0A4

0x0F00FF04

Which memory location (which address) is written to by the sw x3, 8(x1) instruction?

0x00002000

0x00002004

0x00002008

0x0000200C

What value is written to that memory location (provide your answer as a 32-bit hexadecimal)? 0x

Which registers are modified by this sequence of instructions? Include all modified registers in your answer.

x1, x2

x1, x3

x2, x3

x1, x2, x3

Sign-Extension

Consider the following sequence of instructions:

     addi x2, zero, 0xF2
     addi x3, zero, 0xFF4

What value is left in register x2 after execution of this code segment?

0x000000F2

0x00000FF2

0xFFFFFFF2

0x00000FF4

0xFFFFFFF4

What value is left in register x3 after execution of this code segment?

0x000000F2

0x00000FF2

0xFFFFFFF2

0x00000FF4

0xFFFFFFF4

RISC-V Calling Convention

What set of registers are used to pass arguments to a procedure?

a0-a7

t0-t6

s0-s11

zero

Which register is used to remember the return address from a procedure call?

zero

The s0-s11 registers are callee-saved registers. This means that: (select all correct answers)

Prior to making a procedure call, all s registers must be saved on the stack.

At the beginning of each procedure, all s registers must be saved to the stack.

All s registers that are overwritten within a procedure must first be saved to the stack.

At the end of each procedure, all s registers must be restored from the stack.

At the end of each procedure, all modified s registers must be restored from the stack.

Which of the following statements are True in code that follows the RISC-V calling convention?

Since a registers are caller-saved, you never need to save them onto the stack in your procedure implementation.

All a registers must be saved to the stack prior to making a procedure call.

Only the a registers whose value you will need after returning from a procedure must be saved onto the stack.

The ra register must be saved to the stack at the beginning of every procedure.

The ra register must be saved to the stack prior to making a procedure call.

The s registers must be saved to the stack prior to making a procedure call.

The t registers never need to be saved on the stack.

The s registers are guaranteed to be returned from a procedure call with their values unchanged.

A procedure may modify the stack without restoring it to its original state.

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