diff options
| -rw-r--r-- | library/core/src/num/int_macros.rs | 61 | ||||
| -rw-r--r-- | library/core/src/num/uint_macros.rs | 64 |
2 files changed, 52 insertions, 73 deletions
diff --git a/library/core/src/num/int_macros.rs b/library/core/src/num/int_macros.rs index d40e02352a1..6ed0eb07e48 100644 --- a/library/core/src/num/int_macros.rs +++ b/library/core/src/num/int_macros.rs @@ -1495,18 +1495,17 @@ macro_rules! int_impl { let mut base = self; let mut acc: Self = 1; - while exp > 1 { + loop { if (exp & 1) == 1 { acc = try_opt!(acc.checked_mul(base)); + // since exp!=0, finally the exp must be 1. + if exp == 1 { + return Some(acc); + } } exp /= 2; base = try_opt!(base.checked_mul(base)); } - // since exp!=0, finally the exp must be 1. - // Deal with the final bit of the exponent separately, since - // squaring the base afterwards is not necessary and may cause a - // needless overflow. - acc.checked_mul(base) } /// Strict exponentiation. Computes `self.pow(exp)`, panicking if @@ -1546,18 +1545,17 @@ macro_rules! int_impl { let mut base = self; let mut acc: Self = 1; - while exp > 1 { + loop { if (exp & 1) == 1 { acc = acc.strict_mul(base); + // since exp!=0, finally the exp must be 1. + if exp == 1 { + return acc; + } } exp /= 2; base = base.strict_mul(base); } - // since exp!=0, finally the exp must be 1. - // Deal with the final bit of the exponent separately, since - // squaring the base afterwards is not necessary and may cause a - // needless overflow. - acc.strict_mul(base) } /// Returns the square root of the number, rounded down. @@ -2181,19 +2179,17 @@ macro_rules! int_impl { let mut base = self; let mut acc: Self = 1; - while exp > 1 { + loop { if (exp & 1) == 1 { acc = acc.wrapping_mul(base); + // since exp!=0, finally the exp must be 1. + if exp == 1 { + return acc; + } } exp /= 2; base = base.wrapping_mul(base); } - - // since exp!=0, finally the exp must be 1. - // Deal with the final bit of the exponent separately, since - // squaring the base afterwards is not necessary and may cause a - // needless overflow. - acc.wrapping_mul(base) } /// Calculates `self` + `rhs` @@ -2687,9 +2683,14 @@ macro_rules! int_impl { // Scratch space for storing results of overflowing_mul. let mut r; - while exp > 1 { + loop { if (exp & 1) == 1 { r = acc.overflowing_mul(base); + // since exp!=0, finally the exp must be 1. + if exp == 1 { + r.1 |= overflown; + return r; + } acc = r.0; overflown |= r.1; } @@ -2698,14 +2699,6 @@ macro_rules! int_impl { base = r.0; overflown |= r.1; } - - // since exp!=0, finally the exp must be 1. - // Deal with the final bit of the exponent separately, since - // squaring the base afterwards is not necessary and may cause a - // needless overflow. - r = acc.overflowing_mul(base); - r.1 |= overflown; - r } /// Raises self to the power of `exp`, using exponentiation by squaring. @@ -2732,19 +2725,17 @@ macro_rules! int_impl { let mut base = self; let mut acc = 1; - while exp > 1 { + loop { if (exp & 1) == 1 { acc = acc * base; + // since exp!=0, finally the exp must be 1. + if exp == 1 { + return acc; + } } exp /= 2; base = base * base; } - - // since exp!=0, finally the exp must be 1. - // Deal with the final bit of the exponent separately, since - // squaring the base afterwards is not necessary and may cause a - // needless overflow. - acc * base } /// Returns the square root of the number, rounded down. diff --git a/library/core/src/num/uint_macros.rs b/library/core/src/num/uint_macros.rs index ad72c29758b..b272a9d901b 100644 --- a/library/core/src/num/uint_macros.rs +++ b/library/core/src/num/uint_macros.rs @@ -1534,20 +1534,17 @@ macro_rules! uint_impl { let mut base = self; let mut acc: Self = 1; - while exp > 1 { + loop { if (exp & 1) == 1 { acc = try_opt!(acc.checked_mul(base)); + // since exp!=0, finally the exp must be 1. + if exp == 1 { + return Some(acc); + } } exp /= 2; base = try_opt!(base.checked_mul(base)); } - - // since exp!=0, finally the exp must be 1. - // Deal with the final bit of the exponent separately, since - // squaring the base afterwards is not necessary and may cause a - // needless overflow. - - acc.checked_mul(base) } /// Strict exponentiation. Computes `self.pow(exp)`, panicking if @@ -1587,18 +1584,17 @@ macro_rules! uint_impl { let mut base = self; let mut acc: Self = 1; - while exp > 1 { + loop { if (exp & 1) == 1 { acc = acc.strict_mul(base); + // since exp!=0, finally the exp must be 1. + if exp == 1 { + return acc; + } } exp /= 2; base = base.strict_mul(base); } - // since exp!=0, finally the exp must be 1. - // Deal with the final bit of the exponent separately, since - // squaring the base afterwards is not necessary and may cause a - // needless overflow. - acc.strict_mul(base) } /// Saturating integer addition. Computes `self + rhs`, saturating at @@ -2059,19 +2055,17 @@ macro_rules! uint_impl { let mut base = self; let mut acc: Self = 1; - while exp > 1 { + loop { if (exp & 1) == 1 { acc = acc.wrapping_mul(base); + // since exp!=0, finally the exp must be 1. + if exp == 1 { + return acc; + } } exp /= 2; base = base.wrapping_mul(base); } - - // since exp!=0, finally the exp must be 1. - // Deal with the final bit of the exponent separately, since - // squaring the base afterwards is not necessary and may cause a - // needless overflow. - acc.wrapping_mul(base) } /// Calculates `self` + `rhs` @@ -2516,9 +2510,14 @@ macro_rules! uint_impl { // Scratch space for storing results of overflowing_mul. let mut r; - while exp > 1 { + loop { if (exp & 1) == 1 { r = acc.overflowing_mul(base); + // since exp!=0, finally the exp must be 1. + if exp == 1 { + r.1 |= overflown; + return r; + } acc = r.0; overflown |= r.1; } @@ -2527,15 +2526,6 @@ macro_rules! uint_impl { base = r.0; overflown |= r.1; } - - // since exp!=0, finally the exp must be 1. - // Deal with the final bit of the exponent separately, since - // squaring the base afterwards is not necessary and may cause a - // needless overflow. - r = acc.overflowing_mul(base); - r.1 |= overflown; - - r } /// Raises self to the power of `exp`, using exponentiation by squaring. @@ -2560,19 +2550,17 @@ macro_rules! uint_impl { let mut base = self; let mut acc = 1; - while exp > 1 { + loop { if (exp & 1) == 1 { acc = acc * base; + // since exp!=0, finally the exp must be 1. + if exp == 1 { + return acc; + } } exp /= 2; base = base * base; } - - // since exp!=0, finally the exp must be 1. - // Deal with the final bit of the exponent separately, since - // squaring the base afterwards is not necessary and may cause a - // needless overflow. - acc * base } /// Returns the square root of the number, rounded down. |