Roland Dreier wrote:
In this case the code is basically

        u32 x;

        for (n = 0; cond; ++n) {
                ...
                if (!n)
                        x = something;
                ...
        }

        if (n) {
                ...
                use(x);
                ...
        }

and gcc still warns...


Interestingly, the above accurately describes a common code pattern matching code which caused gcc to emit the uninit'd-var warnings.

For the record I think initializating 'f0' to zero is safer for the reasons Linus gave, and in addition, f0 is or'd with a value written to a hardware register, which means things should go awry (if they go) in a semi-predictable manner.

According to the assembly language produced, sure it is larger -- by one (per function) MOV that is adjacent to other initializations, making it highly likely the initializations are all streamed together. I doubt one MOV per function will make a huge difference, considering the peace of mind it buys.

        Jeff


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