On Fri, 23 Feb 2018, Michael Matz wrote:
> Hi, > > On Thu, 22 Feb 2018, Mikulas Patocka wrote: > > > I think that that nodata_wanted misoptimization should be removed at all > > - in the C language, you can jump to any location in the function with > > goto or switch-case statement - thus reasoning such as "all the > > variables behind if (0) are unreachable" is incorrect. > > > > If you wanted to do that optimization correctly, you'd need to build > > control flow graph, and tcc is just too simple to do that. > > You're right that as implemented the non-allocation of variables is wrong. > But a full CFG isn't needed to fix this, the allocation merely needs to be > postponed to the first real use. Unfortunately that is somewhat > complicated when there are initializers (which matter only for static vars > in this case, but still). > > So, yeah, the easy fix is to remove it, but with more work the > optimization (or parts of it) could be retained, grischka? > > > Ciao, > Michael. I think tcc is too simple to do such optimizations as holding variables and allocating them when they are used. If I need an optimizing compiler, I use gcc, if I need something fast and simple, I use tcc. Mikulas _______________________________________________ Tinycc-devel mailing list Tinycc-devel@nongnu.org https://lists.nongnu.org/mailman/listinfo/tinycc-devel
