3 ms·

The switch-to-if thing is pretty inelegant. It seems like you could fix this by mapping to a platform-neutral set of constants, so you could dereference the run

The switch-to-if thing is pretty inelegant. It seems like you could fix this by mapping to a platform-neutral set of constants, so you could dereference the runtime symbol with a function -- `switch(CosmoMappErrno(EINVAL))` and `case COSMO_EINVAL:` and so avoid turning the code into goto mush.

outworlder 3y ago
Do we even care if the replacement is done automatically?
jsmith45 3y ago
But that won't help with compiling unmodified code. Nobody should worry about gotos being created inside the compiler. It is doing that all over the place anyway. Unless of course you mean that the compiler should be recognizing switches like this, and instead of rewriting them to if trees, it should be rewriting them to switches, changing the labels to use special cosmo specific constants for each of the values, and wraping the input value to the switch with a call to a function that maps the current runtimes platform's values for these over to corresponding cosmo specific constants (and letting other values pass though unchanged). That... actually might be a simpler compiler transformation to implement. There would be complexity in needing to recognize which of the multiple sets of of constants are being used, and applying the right call or calls to the switch input to map them. It also require complexity on the library side though (creating these ). Not sure if the author would want to implement it, given they have a working implementation of the other transformation. Lastly such a mapping approach would have risks of inappropriately mapping, or trickiness like having to invert the input before mapping for code that does the negative errno value thing.
ahgamut 3y ago
Dereferencing the runtime symbol with a function sounds interesting! If you can show me an example of where it works, I'd be happy to try it out. I like the if-else-goto arrangement because it fit in perfectly with the other parts of gcc -- if you look at my patch[1], you will find that I had to change very little of gcc's existing code to add this capability. [1]: https://github.com/ahgamut/gcc/tree/portcosmo-11.2 https://github.com/ahgamut/gcc/tree/portcosmo-11.2

outworlder 3y ago

Do we even care if the replacement is done automatically?

jsmith45 3y ago

But that won't help with compiling unmodified code. Nobody should worry about gotos being created inside the compiler. It is doing that all over the place anyway. Unless of course you mean that the compiler should be recognizing switches like this, and instead of rewriting them to if trees, it should be rewriting them to switches, changing the labels to use special cosmo specific constants for each of the values, and wraping the input value to the switch with a call to a function that maps the current runtimes platform's values for these over to corresponding cosmo specific constants (and letting other values pass though unchanged). That... actually might be a simpler compiler transformation to implement. There would be complexity in needing to recognize which of the multiple sets of of constants are being used, and applying the right call or calls to the switch input to map them. It also require complexity on the library side though (creating these ). Not sure if the author would want to implement it, given they have a working implementation of the other transformation. Lastly such a mapping approach would have risks of inappropriately mapping, or trickiness like having to invert the input before mapping for code that does the negative errno value thing.

ahgamut 3y ago

Dereferencing the runtime symbol with a function sounds interesting! If you can show me an example of where it works, I'd be happy to try it out. I like the if-else-goto arrangement because it fit in perfectly with the other parts of gcc -- if you look at my patch[1], you will find that I had to change very little of gcc's existing code to add this capability. [1]: https://github.com/ahgamut/gcc/tree/portcosmo-11.2 https://github.com/ahgamut/gcc/tree/portcosmo-11.2