Close. Sign extension. But this is a C puzzle, so I'd get away with "undefined b... | Hacker News

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		mfukar on Nov 10, 2016 \| parent \| context \| favorite \| on: C puzzles Close. Sign extension. But this is a C puzzle, so I'd get away with "undefined behaviour".

mikeash on Nov 10, 2016 [–]

Where does sign extension occur here?

asamy45 on Nov 10, 2016 | [–]

The movslq instruction will sign extend the upper 32 bits.

mikeash on Nov 10, 2016 | | [–]

Right you are! Thanks. I tried to check, but didn't realize my test case had produced a zero bit in that position so didn't expose sign extension.

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