[PATCH] D75903: [AArch64][CodeGen] Fixing stack alignment of HFA arguments on AArch64 PCS

Momchil Velikov via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Fri Feb 5 01:49:04 PST 2021


chill added inline comments.


================
Comment at: llvm/docs/LangRef.rst:1220
+``alignstack(<n>)``
+    This indicates the alignment that should be considered by the backend when
+    assigning this parameter to a stack slot during calling convention
----------------
rnk wrote:
> This seems like you are introducing a new meaning to `alignstack`, which according to the comments, only affects function SP alignment, not parameter alignment.
> 
> I'm assuming the reason you can't use the regular `align` attribute is that it is overloaded to mean two things: the alignment of the pointer when applied to a pointer, and the alignment of the argument memory when that pointer argument is marked `byval`. If you want to resolve this ambiguity, it seems like something that should be discussed on llvm-dev with a wider audience.
Sorry, I couldn't quite get it, do you suggest we should be using the `align` attribute instead of `alignstack`, if there  are no
(major) objections on the llvm-dev list?

It certainly makes sense to me to use `align` as it already pertains to individual argument alignment (even though it's for pointers only now).



Repository:
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  https://reviews.llvm.org/D75903/new/

https://reviews.llvm.org/D75903



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