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/ test_uint8.c
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May 15, 2026 11:41
8-bit math using -O3, compared to -O2, gives different results.
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| /* 8-bit math using -O3, compared to -O2, gives different results. | |
| * Using both `gcc` and `clang` and both -Ox, i've see three (four) | |
| * different values. Which one is correct? | |
| * | |
| * NOTE code is extremely fragile: Even uncomment printf() | |
| * below, hides the "bug", makes all results same. Same is when | |
| * trying shrink the code even a bit. | |
| * | |
| * gcc -O2 ./test_uint8.c # prints ... ffffd565 | |
| * gcc -O3 ./test_uint8.c # prints ... ff80d565 |
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| // jpka, 2025: Q&D example to make glBars transparent, | |
| // this is impossible with glut. And make it pure C. | |
| // Note, there will be no MSAA using integrated GPU. | |
| // The fun fact is all colors were already made correctly | |
| // using alpha, as if it was already transparent years ago. | |
| // Tested w/ Archlinux. | |
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