[PATCH] D11958: Add a -gmodules option to the clang driver.

[David Blaikie via cfe-commits]

On Tue, Aug 11, 2015 at 1:49 PM, Adrian Prantl <aprantl at apple.com> wrote:

> aprantl created this revision.
> aprantl added reviewers: dblaikie, echristo.
> aprantl added a subscriber: cfe-commits.
> aprantl set the repository for this revision to rL LLVM.
>
> This patch adds a -gmodules option to the driver and a -dwarf-ext-refs to
> cc1 to enable the use of external type references in the debug info (a.k.a.
> module debugging).
>
> The driver expands -gmodules to "-g -fmodule-format=obj -dwarf-ext-refs"
> and passes that to cc1.
> Most options that start with -g (e.g., -gdwarf-2) also turn on -g, and
> module requires object-container-wrapped modules, "-dwarf-ext-refs" been
> the actual low-level option for turning on external type references.
>
> Rationale for the choice of names (and this is really all there is to
> review in this patch):
> "-gmodules": is meant to pair nicely with "-fmodules"
> "-dwarf-ext-refs": Fits into the naming scheme of similar options like
> "-dwarf-column-info" and "-dwarf-debug-flags". Spelling out the option
> "-dwarf-external-type-references" seemed to be overkill.
>

Sounds reasonable - and the flag will be for more than just types
eventually anyway (specifically references to members (functions, etc) of
types too).


> All this does at the moment is set a flag codegenopts. Having this flag in
> place is a prerequisite for emitting debug info into modules: The debug
> info for a module needs to use external type references for types defined
> in (other) modules or we would violate the minimal deserialization
> requirements (cf. test/PCH/check-deserializations.cpp).
>

Could you explain what you mean by "violate the minimal deserialization
requirements"

Mechanically, the patch looks fine/exactly what you'd expect. Feel free to
commit whenever you're ready.


>
> Repository:
>   rL LLVM
>
> http://reviews.llvm.org/D11958
>
> Files:
>   docs/CommandGuide/clang.rst
>   include/clang/Driver/CC1Options.td
>   include/clang/Driver/Options.td
>   include/clang/Frontend/CodeGenOptions.def
>   lib/CodeGen/CGDebugInfo.cpp
>   lib/CodeGen/CGDebugInfo.h
>   lib/CodeGen/ObjectFilePCHContainerOperations.cpp
>   lib/Driver/Tools.cpp
>   lib/Frontend/CompilerInvocation.cpp
>   test/Driver/debug-options.c
>
>
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