### Description
Sets the current stack pointer to source register a.
When stackrestore is used with operand a written by a prior stacksave instruction, it
will effectively restore the state of stack as it was before stacksave was executed. Note that
if stackrestore is used with an arbitrary value of a, it may cause corruption of stack
pointer. This implies that the correct use of this feature requires that stackrestore.type a is
used after stacksave.type a without redefining the value of a between them.
Operand a has the same type as the instruction type.
### Syntax
```
stackrestore.type a;
.type = { .u32, .u64 };
```
### Semantics
```
stackptr = a;
```
### Examples
```
.reg .u32 ra;
stacksave.u32 ra;
// Code that may modify stack pointer
...
stackrestore.u32 ra;
```