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Using better subtraction when optimizations are enabled

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This commit is contained in:
Tomasz Drwięga 2016-03-08 12:09:04 +01:00
parent 9ae2341ba9
commit c47209e9bf
1 changed files with 7 additions and 3 deletions
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10
util/bigint/src/uint.rs
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@ -165,6 +165,12 @@ macro_rules! uint_overflowing_add {
#[cfg(not(all(asm_available, target_arch="x86_64")))] #[cfg(not(all(asm_available, target_arch="x86_64")))]
macro_rules! uint_overflowing_sub { macro_rules! uint_overflowing_sub {
($name:ident, $n_words: expr, $self_expr: expr, $other: expr) => ({
uint_overflowing_sub_reg!($name, $n_words, $self_expr, $other)
})
}
macro_rules! uint_overflowing_sub_reg {
($name:ident, $n_words: expr, $self_expr: expr, $other: expr) => ({ ($name:ident, $n_words: expr, $self_expr: expr, $other: expr) => ({
let $name(ref me) = $self_expr; let $name(ref me) = $self_expr;
let $name(ref you) = $other; let $name(ref you) = $other;
@ -255,9 +261,7 @@ macro_rules! uint_overflowing_sub {
(U512(result), overflow != 0) (U512(result), overflow != 0)
}); });
($name:ident, $n_words: expr, $self_expr: expr, $other: expr) => ({ ($name:ident, $n_words: expr, $self_expr: expr, $other: expr) => ({
let res = overflowing!((!$other).overflowing_add(From::from(1u64))); uint_overflowing_sub_reg!($name, $n_words, $self_expr, $other)
let res = overflowing!($self_expr.overflowing_add(res));
(res, $self_expr < $other)
}) })
} }