The interesting thing about the peephole superoptimizer paper that he linked is that the actual peephole optimization process is not necessarily slower than a r

The interesting thing about the peephole superoptimizer paper that he linked is that the actual peephole optimization process is not necessarily slower than a regular peephole optimizer, as all it is doing is looking up faster equivalent instructions in a database. The difficult (compute intensive) part is training the database, and you only have to do that once for each optimization... I am a little confused by why he stated that the results of the super optimizer were not very impressive. Presumably, man-years have been invested in defining optimizations for compilers like GCC and the intel C compiler, by human experts... To have a machine that even gets close to those results is impressive to me. If the technique were used for an actual compiler, it would mean that no one would have to write peephole optimizations, instead, the compiler would just get better and better as it ages. Combined with aggressive in-lining (or maybe dynamic recompilation? e.x. lisp style function compilation rather than C), it seems to me that this sort of technology could be incredibly powerful. Am I wrong?