On Nov 7, 2006, at 11:47 AM, Douglas Gregor wrote:
I just read Nathan's discussion [1] on changing GCC's type system to use canonical type nodes, where the comparison between two types requires only a pointer comparison. Right now, we use "comptypes", which typically needs to do deep structural checks to determine if two types are equivalent, because we often clone _TYPE nodes.
One difficulty is that compatibility of types in C is not transitive, especially when you're compiling more than one translation unit at a time. See the thread "IMA vs tree-ssa" in Feb-Mar 2004. Geoff Keating and Joseph Myers give good examples.
