Cross-module inlining in gdc

[Mike Farnsworth]

So, as I've been working on getting the gcc builtins available to D code (somewhat successfully as of last night, I might add), I've run into a fairly significant inlining problem.

Given a function definition in D, where I want to force inlining:

// Assume __v4sf is defined by the compiler
pragma(set_attribute, _mm_add_ps, always_inline, artificial);
__v4sf _mm_add_ps (__v4sf __A, __v4sf __B)
{
    return __builtin_ia32_addps(__A, __B);
}

When this occurs in the module I care about, it works dandy.  It gets inlined, the generated code is pretty optimal, etc.  When it is defined in another module, and I call the function, I get messages like "sorry, unimplemented: inlining failed" where it states it doesn't have the body of the function.

I was compiling each file as a separate module, one at a time, so I used -combine to give it multiple source files at once and allow it to link it right away.  That didn't make any difference.  If I take away the pragma, it will then compile, but it never inlines.

When doing -combine, is there a way to get gdc to feed all of the source to the frontend all at once, such that all the definitions/bodies/etc. are all present so that inlining can occur?  I would imagine even this strategy falls apart when linking against a library; is there any way we can support something like -flto so that at codegen time gcc has more opportunity to do inlining?

Intrinsic wrappers defined in a different module, and then never getting inlined kinda defeats the purpose of the intrinsics.  It'd be nice if we can find a way to get cross-module inlining to work, even if it means using link-time optimization.

-Mike