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Remove all instances of static_cast<size_t>(1).

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In preparation for removing magic numbers, simplify code that is
computing masks with a single bit set.
This commit is contained in:
David Chisnall
2019-04-30 11:49:00 +01:00
parent 95c23b1a00
commit 8bd136c224
7 changed files with 32 additions and 23 deletions
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32
src/ds/bits.h
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@@ -85,6 +85,16 @@ namespace snmalloc
return BITS == 64;
}
/**
* Returns a value of type T that has a single bit set,
*/
template<typename T = size_t>
constexpr T one_at_bit(size_t shift)
{
static_assert(std::is_integral_v<T>, "Type must be integral");
return (static_cast<T>(1)) << shift;
}
static constexpr size_t ADDRESS_BITS = is64() ? 48 : 32;
inline void pause()
@@ -225,7 +235,7 @@ namespace snmalloc
for (int i = BITS - 1; i >= 0; i--)
{
size_t mask = static_cast<size_t>(1) << i;
size_t mask = one_at_bit(i);
if ((x & mask) == mask)
return n;
@@ -255,7 +265,7 @@ namespace snmalloc
for (size_t i = 0; i < BITS; i++)
{
size_t mask = static_cast<size_t>(1) << i;
size_t mask = one_at_bit(i);
if ((x & mask) == mask)
return n;
@@ -296,7 +306,7 @@ namespace snmalloc
if (x <= 2)
return x;
return static_cast<size_t>(1) << (BITS - clz(x - 1));
return one_at_bit(BITS - clz(x - 1));
}
inline size_t next_pow2_bits(size_t x)
@@ -311,7 +321,7 @@ namespace snmalloc
if (x <= 2)
return x;
return static_cast<size_t>(1) << (BITS - clz_const(x - 1));
return one_at_bit(BITS - clz_const(x - 1));
}
constexpr size_t next_pow2_bits_const(size_t x)
@@ -419,9 +429,8 @@ namespace snmalloc
template<size_t MANTISSA_BITS, size_t LOW_BITS = 0>
static size_t to_exp_mant(size_t value)
{
size_t LEADING_BIT =
(static_cast<size_t>(1) << (MANTISSA_BITS + LOW_BITS)) >> 1;
size_t MANTISSA_MASK = (static_cast<size_t>(1) << MANTISSA_BITS) - 1;
size_t LEADING_BIT = one_at_bit(MANTISSA_BITS + LOW_BITS) >> 1;
size_t MANTISSA_MASK = one_at_bit(MANTISSA_BITS) - 1;
value = value - 1;
@@ -436,9 +445,8 @@ namespace snmalloc
template<size_t MANTISSA_BITS, size_t LOW_BITS = 0>
constexpr static size_t to_exp_mant_const(size_t value)
{
size_t LEADING_BIT =
(static_cast<size_t>(1) << (MANTISSA_BITS + LOW_BITS)) >> 1;
size_t MANTISSA_MASK = (static_cast<size_t>(1) << MANTISSA_BITS) - 1;
size_t LEADING_BIT = one_at_bit(MANTISSA_BITS + LOW_BITS) >> 1;
size_t MANTISSA_MASK = one_at_bit(MANTISSA_BITS) - 1;
value = value - 1;
@@ -456,7 +464,7 @@ namespace snmalloc
if (MANTISSA_BITS > 0)
{
m_e = m_e + 1;
size_t MANTISSA_MASK = (static_cast<size_t>(1) << MANTISSA_BITS) - 1;
size_t MANTISSA_MASK = one_at_bit(MANTISSA_BITS) - 1;
size_t m = m_e & MANTISSA_MASK;
size_t e = m_e >> MANTISSA_BITS;
size_t b = e == 0 ? 0 : 1;
@@ -465,7 +473,7 @@ namespace snmalloc
return extended_m << (shifted_e + LOW_BITS);
}
return static_cast<size_t>(1) << (m_e + LOW_BITS);
return one_at_bit(m_e + LOW_BITS);
}
/**