[PATCH] D70157: Align branches within 32-Byte boundary(NOP padding)

Tue Dec 17 13:08:56 PST 2019

jyknight added a comment.

In D70157#1788418 <https://reviews.llvm.org/D70157#1788418>, @reames wrote:

> In D70157#1788025 <https://reviews.llvm.org/D70157#1788025>, @jyknight wrote:
>
> > > .push_align_branch_boundary [N,] [instruction,]*
> >
> > I'd like to raise again the possibility of using a more general region directive to denote "It is allowable to add prefixes/nops before instructions in this region if the assembler wants to", as I'd started discussing in https://reviews.llvm.org/D71238#1786885 (but let's move the discussion here).
>
>
> James, I think this proposal is increasing the scope of this proposal too much.  It also ignores some of the use cases identified and described in the writeup (i.e. the scoped semantics).  I'm open to discussing such a feature more generally, but I'd prefer to see a more narrowly focused feature immediately.

I do not intend that we expand the scope of the project to include any of the other features.

All I want is to slightly consider surrounding features when adding the new assembly syntax. The situations where we want to avoid modifying a certain block of code are extremely likely to apply to //any// nop-or-prefix-introducing code modifications -- not just modifications resulting from branch alignment. So if we can make the directives annotating where such changes are allowable (and conversely, where they are not) generally-applicable, with a very minimal amount of work, that would be nice.

I also don't understand what you mean by "it ignores [...] scoped semantics"?

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D70157/new/

https://reviews.llvm.org/D70157