[llvm-dev] LLVM + MASM (llvm-ml)

[Nico Weber via llvm-dev]

On Fri, Oct 23, 2020 at 3:24 PM Martin Storsjö <martin at martin.st> wrote:

> Hi,
>
> On Fri, 23 Oct 2020, Eric Astor via llvm-dev wrote:
>
> > Just a quick update on the llvm-ml project. As a refresher, this was a
> > proposal to add native [MASM][1] support to LLVM's assembly
> capabilities, as
> > part of supporting cross-platform Windows compilation.
> >
> >    [1]:
> https://docs.microsoft.com/en-us/cpp/assembler/masm/microsoft-macro-as
> > sembler-reference?view=vs-2019
> >
> > A large set of directives are now supported, with a growing suite of
> tests.
> > After the next outstanding chain of commits ([tip][2]) adds macro
> procedures
> > and macro functions (including local symbols), this will include most of
> the
> > headline features for the language. (STRUCTs have been in place for some
> > time now, including type inference for size-checking.) Features not yet
> in
> > place include:
> >  *  RECORDs,
> >  *  ASSUME,
> >  *  the ALIGN/ORG/EVEN directives,
> >  *  the GOTO directive (within macros),
> >  *  anonymous labels, and
> >  *  built-in macros (and the string-manipulation directives).
> >     [2]: https://reviews.llvm.org/D89741
> >
> > Anyone else interested in reviewing some of the commits around this
> project?
>
> I just recently got an interest in this project, when I tried building the
> OpenMP runtimes for windows - and they contain one source file in MASM
> format.
>
> From very brief attempts at assembling the source file [1] with llvm-ml
> noticed that it lacked some sort of preprocessing that the source used,
> among a few other issues.
>
> CMake also ends up adding a few parameters using forward slashes, while it
> seems like llvm-ml currently only accepts parameters with dashes. Handling
> both (like clang-cl and lld/COFF do, among others) probably would require
> rewriting the option handling using the llvm/Option framework, like those
> tools do.
>

Yes, this is a known TODO :)


>
> An example command for building it looks like this (in
> llvm-project/openmp/build):
>
> <tool> -Domp_EXPORTS -Iruntime/src -I../runtime/src -I../runtime/src/i18n
> -I../runtime/src/include -I../runtime/src/thirdparty/ittnotify -D
> _CRT_SECURE_NO_WARNINGS -D _CRT_SECURE_NO_DEPRECATE -D _WINDOWS -D _WINNT
> -D _WIN32_WINNT=0x0501 -D _USRDLL -win64 -D_M_AMD64 -DOMPT_SUPPORT=0 /c
> /Fo runtime/src/CMakeFiles/omp.dir/z_Windows_NT-586_asm.asm.obj
> ../runtime/src/z_Windows_NT-586_asm.asm
>
> When building for i386, you'd also see the parameters "/coff" and
> "/safeseh" added on the command line [2].
>
> [1]
> https://github.com/llvm/llvm-project/blob/master/openmp/runtime/src/z_Windows_NT-586_asm.asm
>
> [2]
> https://github.com/llvm/llvm-project/blob/master/openmp/runtime/cmake/LibompHandleFlags.cmake#L74-L82
>
> // Martin
>
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