是什么东西的优化让 run5 的浮点数运算跟 run6 的整数运算速度差别不大的？

【 在 haha103 的大作中提到: 】
: 楼上的代码，稍微改了一下openmp线程数=16
: $ g++ -DNTHREADS=16 -std=c++20 -Wall -O3 -ffast-math -fopenmp -mavx2 -o out-avx2 test.cxx
: $ ./out-avx2
: OpenMP init.
: Run0 resut is 4999999950000000.00, done in 0.347654 s!
: Run1 resut is 4999999950000000.00, done in 0.022820 s!
: Run2 resut is 4999999950000000.00, done in 0.022877 s!
: Run3 resut is 4999999950000000.00, done in 0.022880 s!
: Run4 resut is 4999999950000000.00, done in 0.024044 s!
: Run5 resut is 4999999950000000.00, done in 0.001822 s!
: Run6 resut is 4999999950000000.00, done in 0.001357 s!
--
FROM 58.48.87.*