* Fix DerivedType::dropAllTypeUses to not change the number of types in a
type when it gets refined. This allows us to hash on this crucial value.
* Fix several issues in TypeMap::RefineAbstractType that prevent it from
handling hash values that change correctly.
* Define hashTypeStructure to not always return 0. :)
This last part (which depends on the first two) speeds up gccld time on eon
from 3.78s to 2.75s with a release build (a 28% speedup!). This resolves
PR474.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@24372
91177308-0d34-0410-b5e6-
96231b3b80d8