1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
use crate::RegId;
/// Describes an error handler stored during IR evaluation.
#[derive(Debug, Clone, Copy)]
pub struct ErrorHandler {
/// Instruction index within the block that will handle the error
pub handler_index: usize,
/// Register to put the error information into, when an error occurs
pub error_register: Option<RegId>,
}
/// Keeps track of error handlers pushed during evaluation of an IR block.
#[derive(Debug, Clone, Default)]
pub struct ErrorHandlerStack {
handlers: Vec<ErrorHandler>,
}
impl ErrorHandlerStack {
pub const fn new() -> ErrorHandlerStack {
ErrorHandlerStack { handlers: vec![] }
}
/// Get the current base of the stack, which establishes a frame.
pub fn get_base(&self) -> usize {
self.handlers.len()
}
/// Push a new error handler onto the stack.
pub fn push(&mut self, handler: ErrorHandler) {
self.handlers.push(handler);
}
/// Try to pop an error handler from the stack. Won't go below `base`, to avoid retrieving a
/// handler belonging to a parent frame.
pub fn pop(&mut self, base: usize) -> Option<ErrorHandler> {
if self.handlers.len() > base {
self.handlers.pop()
} else {
None
}
}
/// Reset the stack to the state it was in at the beginning of the frame, in preparation to
/// return control to the parent frame.
pub fn leave_frame(&mut self, base: usize) {
if self.handlers.len() >= base {
self.handlers.truncate(base);
} else {
panic!(
"ErrorHandlerStack bug: tried to leave frame at {base}, but current base is {}",
self.get_base()
)
}
}
}