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[ares] fix a couple bugs in unifying equality

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East/West typo, also we were setting the frame pointer to the stack
pointer while chasing up the stack.

This also refactors the conditionals in a way that I think is easier to
read.  We always have to do both calculations anyway.
This commit is contained in:
Philip Monk 2023-02-13 18:43:43 -07:00
parent 5edfc1a801
commit 43f3622f63
1 changed files with 11 additions and 18 deletions
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29
rust/ares/src/mem.rs
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@ -777,21 +777,14 @@ unsafe fn senior_pointer_first<T>(
),
};
loop {
if a < high_pointer && a >= low_pointer {
// a is in the current frame
if b < high_pointer && b >= low_pointer {
// so is b, pick arbitrarily
break (a, b);
} else {
// b is not, so b must be further up, b is senior
break (b, a);
}
} else {
// a is not in the current frame
if b < high_pointer && b >= low_pointer {
// b is, a is senior
break (a, b);
} else {
match (
a < high_pointer && a >= low_pointer,
b < high_pointer && b >= low_pointer,
) {
(true, true) => break (a, b), // both pointers are in the same frame, pick arbitrarily
(true, false) => break (b, a), // a is in the frame, b is not, so b is senior
(false, true) => break (a, b), // b is in the frame, a is not, so a is senior
(false, false) => {
// chase up the stack
if (frame_pointer as *const u64) == stack.start {
// we found the top of the stack!
@ -801,15 +794,15 @@ unsafe fn senior_pointer_first<T>(
Polarity::East => {
high_pointer = *(frame_pointer.sub(2)) as *const T;
low_pointer = *(frame_pointer.sub(1)) as *const T;
frame_pointer = *(frame_pointer.sub(1)) as *const u64;
frame_pointer = *(frame_pointer.sub(2)) as *const u64;
polarity = Polarity::West;
continue;
}
Polarity::West => {
high_pointer = *frame_pointer as *const T;
low_pointer = *(frame_pointer.add(1)) as *const T;
frame_pointer = *frame_pointer as *const u64;
polarity = Polarity::West;
frame_pointer = *(frame_pointer.add(1)) as *const u64;
polarity = Polarity::East;
continue;
}
}