[Assist] GCC extreme bit-shift by constant vs. by variable

Rudolf Dovičín rudolf.dovicin at gmail.com
Tue Oct 14 19:30:19 BST 2014


In GCC (version 4.9.1 20140903 on x86_64) when I write
1u << 32u;
I will get correct result 0u.

But if I write
unsigned thirty_two_unsigned = 32u;
1u << thirty_two_unsigned;
I will get incorrect result 1u.

(It is the same in the right-shift.)

I do not know if it is an error or regular behaviour (i. e. undefined
Rudolf Dovičín
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