Strange assembly from array 0-initialization

Question

Inspired by the question Difference in initalizing and zeroing an array in c/c++ ?, I decided to actually examine the assembly of, in my case, an optimized release build for

Answer 1

Both bits of code are bugfree. The two lines mentioned aren't smart, but you're just proving that this compiler is emitting suboptimal code.

Padding bytes are usually only initialized if that simplifies the assembly or speeds up the code. E.g if you have padding between two zero-filled members, it's often easier to zero-fill the padding as well. Also, if you have padding at the end and your memset() is optimized for multi-byte writes, it may be faster to overwrite that padding too.