[llvm-dev] Implications of Module SourceFileName

Rarrum via llvm-dev
Tue, 26 May 2020 19:14:39 -0000

There's currently a 1-1 mapping between my language's concept of a
module
and an llvm module.  This language doesn't have a concept of forward
declarations or header files.  One of the early steps of the compiler is to
search across all of the module files and figure out what types are
available, so that we can resolve them later without depending on
declaration order.  This does mean that all of the files that make up a
language module do need to be compiled together.  The end result is an llvm
module where almost everything has internal linkage, except for a few
things that are specifically defined to be exported.

On Tue, May 26, 2020 at 11:42 AM David Blaikie <dblaikie at gmail.com>
wrote:

> Does your source language's concept of Module have to/have any bearing
on
> the llvm concept of a Module? (ie: do all the source files need to be
> compiled in one go/together into one file? C++'s concept of a module
> doesn't have this, for instance... I /think/ at least that each
fragment of
> a module can be compiled separately - which is good for build parallelism,
> etc)
>
> On Mon, May 25, 2020 at 3:23 PM Rarrum via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
>> In the language I'm working on, a module (which does have a
user-defined
>> name in source) may be comprised of several files.  I'm considering
passing
>> the (user-defined) name to llvm::Module's setModuleIdentifier, then
a
>> semicolon separated list of file names to setSourceFileName.  Is this
going
>> to cause unforeseen problems?
>>
>> https://releases.llvm.org/10.0.0/docs/LangRef.html#source-filename
seems
>> to imply that it only needs to be a "consistent unique global
identifier",
>> but then also shows a unix-style path as the syntax.  I don't see
anything
>> crazy being done with it from a quick source of llvm's source.
>> _______________________________________________
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>> llvm-dev at lists.llvm.org
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>>
>
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