- I'm writing a HIP (amd gpu kernels) linker in my job and the calling convention is contained in a metadata section in the object file.
Whether the array is passed in registers or pointers can be chosen by the compiler based on factors like profile guided optimization. That the ABI isn't stable doesn't matter because the linker handles it for the programmer.
This is all publicly documented in the llvm docs too so you can write your own loader.
- This reads like word games. The article basically argues for optimizing the calling discipline on a per-function basis, using the function body to guide the optimization. That's not a calling convention and definitely not a standard ABI. What they're arguing for is a kind of static optimization mid-way between targeting a calling convention and inlining. That's not a bad idea on its face, but has nothing at all to do with the C ABI. As to whether it would actually improve anything, frankly, I'm half-surprised compilers don't already do this, i.e. for functions where it's deemed too costly to inline, but which aren't externally visible, and the fact that they don't suggests that maybe there's not much to gain here.
I've yet to read an article criticizing the so-called C ABI that doesn't end up effectively changing the problem statement (in this case, into something utterly incomparable), as opposed to providing a better solution to the same problem. Changing the problem statement is often how you arrive at better solutions overall, but don't try to sell it as something it isn't, insinuating that the pre-existing solution is stupid.
- Can someone explain the part about Diana's $89 dress?
- > Another reason is compilation time. The more complicated the function signatures, the more prologue/epilogue code we have to generate that LLVM has to chew on. [...]
I know that LLVM completely dominates compilation time, but maybe the improvements from this could make the other bits (i.e. compiling rustc with callconv=fast) fast enough to make up the difference?
by jauntywundrkind
1 subcomments
- What was the interval of time for Rust having green threads, out of curiosity? How if at all had that affected layout and calling?
- Previously:
The Rust calling convention we deserve - https://news.ycombinator.com/item?id=40081314 - April 2024 (137 comments)
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