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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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16
Userland/Libraries/LibGfx/PNGLoader.cpp
View file

@ -25,7 +25,7 @@
namespace Gfx {
static const u8 png_header[8] = { 0x89, 'P', 'N', 'G', 13, 10, 26, 10 };
static constexpr Array png_header = { 0x89, 'P', 'N', 'G', 13, 10, 26, 10 };
struct PNG_IHDR {
NetworkOrdered<u32> width;
@ -512,7 +512,7 @@ static bool decode_png_header(PNGLoadingContext& context)
return false;
}
if (memcmp(context.data, png_header, sizeof(png_header)) != 0) {
if (memcmp(context.data, png_header.data(), sizeof(png_header)) != 0) {
dbgln_if(PNG_DEBUG, "Invalid PNG header");
context.state = PNGLoadingContext::State::Error;
return false;
@ -661,14 +661,14 @@ static int adam7_width(PNGLoadingContext& context, int pass)
}
}
// Index 0 unused (non-interlaced case)
static int adam7_starty[8] = { 0, 0, 0, 4, 0, 2, 0, 1 };
static int adam7_startx[8] = { 0, 0, 4, 0, 2, 0, 1, 0 };
static int adam7_stepy[8] = { 1, 8, 8, 8, 4, 4, 2, 2 };
static int adam7_stepx[8] = { 1, 8, 8, 4, 4, 2, 2, 1 };
static bool decode_adam7_pass(PNGLoadingContext& context, Streamer& streamer, int pass)
{
// Index 0 unused (non-interlaced case)
constexpr Array adam7_starty = { 0, 0, 0, 4, 0, 2, 0, 1 };
constexpr Array adam7_startx = { 0, 0, 4, 0, 2, 0, 1, 0 };
constexpr Array adam7_stepy = { 1, 8, 8, 8, 4, 4, 2, 2 };
constexpr Array adam7_stepx = { 1, 8, 8, 4, 4, 2, 2, 1 };
PNGLoadingContext subimage_context;
subimage_context.width = adam7_width(context, pass);
subimage_context.height = adam7_height(context, pass);