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Kernel: 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 08:35:09 -06:00 • committed by Linus Groh
parent 2b64d163cd
commit 5751327195
15 changed files with 30 additions and 37 deletions
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6
Kernel/VM/PageDirectory.cpp
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@ -13,9 +13,6 @@
namespace Kernel {
static const FlatPtr userspace_range_base = 0x00800000;
static const FlatPtr userspace_range_ceiling = 0xbe000000;
static AK::Singleton<HashMap<u32, PageDirectory*>> s_cr3_map;
static HashMap<u32, PageDirectory*>& cr3_map()
@ -53,6 +50,9 @@ UNMAP_AFTER_INIT PageDirectory::PageDirectory()
PageDirectory::PageDirectory(const RangeAllocator* parent_range_allocator)
{
constexpr FlatPtr userspace_range_base = 0x00800000;
constexpr FlatPtr userspace_range_ceiling = 0xbe000000;
ScopedSpinLock lock(s_mm_lock);
if (parent_range_allocator) {
m_range_allocator.initialize_from_parent(*parent_range_allocator);