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miri: helper methods for max values of machine's usize/isize #66410

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Merged
merged 1 commit into from
Nov 15, 2019
Merged

miri: helper methods for max values of machine's usize/isize #66410

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13 changes: 13 additions & 0 deletions src/librustc/mir/interpret/pointer.rs
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Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
use std::fmt::{self, Display};
use std::convert::TryFrom;

use crate::mir;
use crate::ty::layout::{self, HasDataLayout, Size};
Expand Down Expand Up @@ -40,6 +41,18 @@ pub trait PointerArithmetic: layout::HasDataLayout {
self.data_layout().pointer_size
}

#[inline]
fn usize_max(&self) -> u64 {
let max_usize_plus_1 = 1u128 << self.pointer_size().bits();
u64::try_from(max_usize_plus_1-1).unwrap()
}

#[inline]
fn isize_max(&self) -> i64 {
let max_isize_plus_1 = 1u128 << (self.pointer_size().bits()-1);
i64::try_from(max_isize_plus_1-1).unwrap()
}

/// Helper function: truncate given value-"overflowed flag" pair to pointer size and
/// update "overflowed flag" if there was an overflow.
/// This should be called by all the other methods before returning!
Expand Down