> On Aug 19, 2015, at 1:12 PM, David Blaikie <dblai...@gmail.com> wrote:
>
>
>
> On Tue, Aug 11, 2015 at 1:49 PM, Adrian Prantl <apra...@apple.com
> <mailto:apra...@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”
There are tests in the testsuite to ensure that when deserializing a type from
a module, only the bare minimum is actually deserialized. For example:
a.h
class A {};
b.h
class B { A a; };
When emitting debug info for B we need to emit an external reference for A
instead of recursively emitting A (and thus “illegally” deserializing A from
a.pcm).
>
> Mechanically, the patch looks fine/exactly what you'd expect. Feel free to
> commit whenever you're ready.
thanks,
adrian
>
>
> Repository:
> rL LLVM
>
> http://reviews.llvm.org/D11958
> <https://urldefense.proofpoint.com/v2/url?u=http-3A__reviews.llvm.org_D11958&d=BQMFaQ&c=eEvniauFctOgLOKGJOplqw&r=cTx6f1tAfqPeajYunFWp7_8ot79RnHyNteqzig4fXmA&m=OYlTn71sx_aJ_kkl6dcJDmmGe2SZ2AOMtPSiptwqe3M&s=9Oww56T9mtLMfzpO0B3gFzdboCnRX1kVMs8QUq18Tpw&e=>
>
> 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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