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Userland: static vs non-static constexpr variables

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Problem:
- `static` variables consume memory and sometimes are less
  optimizable.
- `static const` variables can be `constexpr`, usually.
- `static` function-local variables require an initialization check
  every time the function is run.

Solution:
- If a global `static` variable is only used in a single function then
  move it into the function and make it non-`static` and `constexpr`.
- Make all global `static` variables `constexpr` instead of `const`.
- Change function-local `static const[expr]` variables to be just
  `constexpr`.
This commit is contained in:
Lenny Maiorani 2021-05-19 09:32:07 -06:00 • committed by Linus Groh
parent 17ff895e1c
commit 800ea8ea96
38 changed files with 192 additions and 184 deletions
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30
Userland/Libraries/LibM/math.cpp
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@ -56,11 +56,11 @@ union FloatExtractor;
// This assumes long double is 80 bits, which is true with GCC on Intel platforms
template<>
union FloatExtractor<long double> {
static const int mantissa_bits = 64;
static const unsigned long long mantissa_max = ~0u;
static const int exponent_bias = 16383;
static const int exponent_bits = 15;
static const unsigned exponent_max = 32767;
static constexpr int mantissa_bits = 64;
static constexpr unsigned long long mantissa_max = ~0u;
static constexpr int exponent_bias = 16383;
static constexpr int exponent_bits = 15;
static constexpr unsigned exponent_max = 32767;
struct {
unsigned long long mantissa;
unsigned exponent : 15;
@ -72,11 +72,11 @@ union FloatExtractor<long double> {
template<>
union FloatExtractor<double> {
static const int mantissa_bits = 52;
static const unsigned long long mantissa_max = (1ull << 52) - 1;
static const int exponent_bias = 1023;
static const int exponent_bits = 11;
static const unsigned exponent_max = 2047;
static constexpr int mantissa_bits = 52;
static constexpr unsigned long long mantissa_max = (1ull << 52) - 1;
static constexpr int exponent_bias = 1023;
static constexpr int exponent_bits = 11;
static constexpr unsigned exponent_max = 2047;
struct {
unsigned long long mantissa : 52;
unsigned exponent : 11;
@ -87,11 +87,11 @@ union FloatExtractor<double> {
template<>
union FloatExtractor<float> {
static const int mantissa_bits = 23;
static const unsigned mantissa_max = (1 << 23) - 1;
static const int exponent_bias = 127;
static const int exponent_bits = 8;
static const unsigned exponent_max = 255;
static constexpr int mantissa_bits = 23;
static constexpr unsigned mantissa_max = (1 << 23) - 1;
static constexpr int exponent_bias = 127;
static constexpr int exponent_bits = 8;
static constexpr unsigned exponent_max = 255;
struct {
unsigned long long mantissa : 23;
unsigned exponent : 8;