[PATCH] D28845: Prototype of modules codegen

[David Blaikie via Phabricator via cfe-commits]

dblaikie created this revision.

First pass at generating weak definitions of inline functions from module files
(& currently skipping definitions of those functions in uses)

I've done some manual testing (haven't delved into the preferred testing
strategy for modules). Seems to work for simplest cases, including transitive
modules.

Also doesn't have an actual flag plumbed through, yet. I can submit that ahead
of this in a separate patch (open to ideas, etc). Is there a goal for how
explicit modules should be used via the driver (rather than cc1)? Otherwise
this would be a cc1 option to match.

One quandry: What to do with non-inline definitions in headers? Currently this
prototype moves their emission (while keeping their linkage) to the module
object. This would remove ODR violations and actually make it 'correct' to
define a non-inline function in a header, which may or may not be desirable. It
could be kept in all the users as it is today.

I'm sure I don't know nearly enough about linkage and about how linkage is
handled in Clang & LLVM. So I'm certainly open to ideas about how this
implementation isn't ideal or correct - or the myriad of interesting linkage
cases I should test/consider.

Perhaps we could chat about this in person/over the shoulder if a faster
iteration would be worthwhile.


https://reviews.llvm.org/D28845

Files:
  include/clang/AST/ASTContext.h
  include/clang/AST/ExternalASTSource.h
  include/clang/Basic/LangOptions.def
  include/clang/Basic/Module.h
  include/clang/Serialization/ASTBitCodes.h
  include/clang/Serialization/ASTReader.h
  include/clang/Serialization/ASTWriter.h
  lib/AST/ASTContext.cpp
  lib/AST/ExternalASTSource.cpp
  lib/Basic/Module.cpp
  lib/CodeGen/CodeGenModule.cpp
  lib/Lex/ModuleMap.cpp
  lib/Serialization/ASTReader.cpp
  lib/Serialization/ASTWriter.cpp
  lib/Serialization/ASTWriterDecl.cpp

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