llvm dev - Nov 2015 - llvm, new language and inline assembly.

Hello,

I am creating a very small language which needs inline assembly, with llvm as a
compiler framework.

On x86, I am interested in the
"out","in","mfence","lfence".. and other
specific sse operations.

How may I tell llvm about them in my language?

-> I read that "module asm" should be my companion but I am not
sure how it works (the doc about it, is only a few lines of not so complete
information. What is the syntax when the final register the value comes from or
goes in doesn't matter? so no explicit %%rax or %%rdx but rather something
like %%r?x; here the question mark let the compiler to choose the best register
for the value);

I need the same functionalities as "asm" in C but in my language
basically.

Thanks
-- 
Alex

On 14 November 2015 at 13:09, AlexandreFressange via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> -> I read that "module asm" should be my companion but I am
not sure how it works (the doc about it, is only a few lines of not so complete
information.
The documentation is unfortunately lacking. But you almost certainly
don't want module-level inline asm; you probably want a "%res = call
TYPE asm ..." type thing instead.
> What is the syntax when the final register the value comes from or goes in
doesn't matter? so no explicit %%rax or %%rdx but rather something like
%%r?x; here the question mark let the compiler to choose the best register for
the value);
Our inline asm is based heavily on GCC style syntax. The main change
is that a "%N" or "%[whatever]" argument to reference an
in/out value
becomes $N. Operand modifiers are written "${N:mod}" rather than
"%modN".

The best way to get familiar with it is probably to write what you
want in GCC asm and run "clang -S -o- -emit-llvm" to see what IR gets
produced.

Cheers.

Tim.

Will do that Tim,

Thanks a lot :)

-- 
Alex


15.11.2015, 03:57, "Tim Northover" <t.p.northover at
gmail.com>:
> On 14 November 2015 at 13:09, AlexandreFressange via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
>>  -> I read that "module asm" should be my companion but I
am not sure how it works (the doc about it, is only a few lines of not so
complete information.
>
> The documentation is unfortunately lacking. But you almost certainly
> don't want module-level inline asm; you probably want a "%res =
call
> TYPE asm ..." type thing instead.
>
>>  What is the syntax when the final register the value comes from or
goes in doesn't matter? so no explicit %%rax or %%rdx but rather something
like %%r?x; here the question mark let the compiler to choose the best register
for the value);
>
> Our inline asm is based heavily on GCC style syntax. The main change
> is that a "%N" or "%[whatever]" argument to reference
an in/out value
> becomes $N. Operand modifiers are written "${N:mod}" rather than
> "%modN".
>
> The best way to get familiar with it is probably to write what you
> want in GCC asm and run "clang -S -o- -emit-llvm" to see what IR
gets
> produced.
>
> Cheers.
>
> Tim.