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Auto merge of #149 - rust-lang-nursery:gh148, r=alexcrichton

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fix debug assertion in divdi3

fixes #148

r? @alexcrichton
This commit is contained in:
bors 2017-03-07 00:38:33 +00:00
commit 9681358dc5
1 changed files with 6 additions and 2 deletions
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8
src/int/sdiv.rs
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@ -10,8 +10,12 @@ macro_rules! div {
pub extern "C" fn $intrinsic(a: $ty, b: $ty) -> $tyret {
let s_a = a >> (<$ty>::bits() - 1);
let s_b = b >> (<$ty>::bits() - 1);
let a = (a ^ s_a) - s_a;
let b = (b ^ s_b) - s_b;
// NOTE it's OK to overflow here because of the `as $uty` cast below
// This whole operation is computing the absolute value of the inputs
// So some overflow will happen when dealing with e.g. `i64::MIN`
// where the absolute value is `(-i64::MIN) as u64`
let a = (a ^ s_a).wrapping_sub(s_a);
let b = (b ^ s_b).wrapping_sub(s_b);
let s = s_a ^ s_b;
let r = udiv!(a as $uty, b as $uty);