The only part of ASTContext.h that requires most AST types to be
complete is the parent map. Nothing in Clang proper uses the ParentMap,
so split it out into its own class. Make ASTContext own the
ParentMapContext so there is still a one-to-one relationship.
After this change, 562 fewer files depend on ASTTypeTraits.h, and 66
fewer depend on TypeLoc.h:
$ diff -u deps-before.txt deps-after.txt | \ grep '^[-+] ' | sort | uniq -c | sort -nr | less 562 - ../clang/include/clang/AST/ASTTypeTraits.h 340 + ../clang/include/clang/AST/ParentMapContext.h 66 - ../clang/include/clang/AST/TypeLocNodes.def 66 - ../clang/include/clang/AST/TypeLoc.h 15 - ../clang/include/clang/AST/TemplateBase.h ...
I computed deps-before.txt and deps-after.txt with ninja -t deps.
This removes a common and key dependency on TemplateBase.h and
This also has the effect of breaking the ParentMap RecursiveASTVisitor
instantiation into its own file, which roughly halves the compilation
time of ASTContext.cpp (29.75s -> 17.66s). The new file takes 13.8s to
I left behind forwarding methods for getParents(), but clients will need
to include a new header to make them work:
I noticed that this parent map functionality is unfortunately duplicated
in ParentMap.h, which only works for Stmt nodes.