One extension of the MIPS instruction set architecture has two new instructions

Question

One extension of the MIPS instruction set architecture has two new instructions called movn (move if not zero) and movz (move if zero). For example, the instruction

movn $8, $11, $4

copies the contents of register 11 into register 8, provided that the value in register 4 is nonzero (otherwise it does nothing). The movz instruction is similar but copying takes place only if the register’s value is zero. Show how to use the new instructions to put whichever is larger, register 8’s value or register 9’s value, into register 10. If the values are equal, copy either into register 10. You may use register 1 as an extra register for temporary use. Do not use any conditional branches.

Explanation / Answer

$LFB1024 = .
greatest(int, int):
addiu $sp,$sp,-24
sw $fp,20($sp)
move $fp,$sp
sw $4,24($fp)
sw $5,28($fp)
lw $3,24($fp)
lw $2,28($fp)
nop
slt $2,$2,$3
movz $2,$0,$L2
nop

lw $2,24($fp)
b $L3
nop

lw $2,28($fp)
nop
sw $2,8($fp)
lw $2,8($fp)
move $sp,$fp
lw $fp,20($sp)
addiu $sp,$sp,24
j $31
nop

$LFB1025 = .
main:
addiu $sp,$sp,-48
sw $31,44($sp)
sw $fp,40($sp)
sw $16,36($sp)
move $fp,$sp
lui $2,%hi($LC0)
addiu $5,$2,%lo($LC0)
lui $2,%hi(std::cout)
addiu $4,$2,%lo(std::cout)
jal std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)
nop

addiu $2,$fp,24
move $5,$2
lui $2,%hi(std::cin)
addiu $4,$2,%lo(std::cin)
jal std::basic_istream<char, std::char_traits<char> >::operator>>(int&)
nop

move $3,$2
addiu $2,$fp,28
move $5,$2
move $4,$3
jal std::basic_istream<char, std::char_traits<char> >::operator>>(int&)
nop

lui $2,%hi($LC1)
addiu $5,$2,%lo($LC1)
lui $2,%hi(std::cout)
addiu $4,$2,%lo(std::cout)
jal std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)
nop

move $16,$2
lw $2,24($fp)
lw $3,28($fp)
nop
move $5,$3
move $4,$2
jal greatest(int, int)
nop

move $5,$2
move $4,$16
jal std::basic_ostream<char, std::char_traits<char> >::operator<<(int)
nop

move $2,$0
move $sp,$fp
lw $31,44($sp)
lw $fp,40($sp)
lw $16,36($sp)
addiu $sp,$sp,48
j $31
nop

$LFB1029 = .
__static_initialization_and_destruction_0(int, int):
addiu $sp,$sp,-32
sw $31,28($sp)
sw $fp,24($sp)
move $fp,$sp
sw $4,32($fp)
sw $5,36($fp)
lw $3,32($fp)
li $2,1 # 0x1
bne $3,$2,$L9
nop

lw $3,36($fp)
li $2,65535 # 0xffff
movn $3,$2,$L9
nop

lui $2,%hi(std::__ioinit)
addiu $4,$2,%lo(std::__ioinit)
jal std::ios_base::Init::Init()
nop

lui $2,%hi(__dso_handle)
addiu $6,$2,%lo(__dso_handle)
lui $2,%hi(std::__ioinit)
addiu $5,$2,%lo(std::__ioinit)
lui $2,%hi(std::ios_base::Init::~Init())
addiu $4,$2,%lo(std::ios_base::Init::~Init())
jal __cxa_atexit
nop

nop
move $sp,$fp
lw $31,28($sp)
lw $fp,24($sp)
addiu $sp,$sp,32
j $31
nop

$LFB1030 = .
_GLOBAL__sub_I_main:
addiu $sp,$sp,-32
sw $31,28($sp)
sw $fp,24($sp)
move $fp,$sp
li $5,65535 # 0xffff
li $4,1 # 0x1
jal __static_initialization_and_destruction_0(int, int)
nop

move $sp,$fp
lw $31,28($sp)
lw $fp,24($sp)
addiu $sp,$sp,32
j $31
nop

Related Questions

Navigate

• Browse (All)
• Browse O
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.