What is the performance implication of converting to bool in C++?

Question

[This question is related to but not the same as this one.]

My compiler warns about implicitly converting or casting certain types to bool whereas explicit

Answer 1

The performance is identical across the board. It involves a couple of instructions on x86, maybe 3 on some other architectures.

On x86 / VC++, they all do

cmp DWORD PTR [whatever], 0
setne al

GCC generates the same thing, but without the warnings (at any warning-level).