Yes — the fragment makes no assumptions about what is in temp registers after the subroutine call.
The registers are grouped into those used
as variables and arguments in subroutines
($0, $v0-$v1,
$a0-$a3, $t0-$t9,
$s0-$s7),
and those used for other purposes.
Subroutines are discussed in a future chapter.
The other uses are discussed as the topic arises.
The most fundamental part
of an operating system is
the kernel.
The rest of the OS is mostly implemented
using the functions provided by the kernel.
Two registers, $k0 and $k1,
are reserved for
the kernel.
Applications programs (and most OS subroutines)
should not touch them.
SPIM does not come with an OS.
But it loads a trap handler, if requested,
which uses $k0 and $k1
as well as several of the temporary registers.
The registers $gp, $sp,
and $fp are
used as base registers to
access to various parts of memory.
What does the following assembly language instruction do?
addu $t5,$zero,$t7
It the contents of register into register .