[PATCH] D149246: [RISCV] Relax rules for ordering s/z/x prefixed extensions in ISA naming strings

[Conor Dooley via Phabricator via cfe-commits]

ConchuOD added a comment.

Perhaps redundant now that Palmer has commented, an opinion was solicited from me so here I am, pretty much copy-pasting from elsewhere:

IMO, alignment with gcc is helpful, permissiveness is better.
Given "canonical order" can, and has, change(d) in the past I think it's good to insulate against it happening again.
Conjuring up march is bad enough as things stand w/ availability with given toolchain versions, especially in situations where different toolchain components are mixed between various versions llvm and gnu stuff. 
Having to do special handing of different versions of gcc/clang whenever we do actually need to add Sfoo or Xfoo sounds like another layer of misery I would love to avoid.
Although it looks like we'll probably have to do some Makefile dance around older gcc/clang versions but at least going forward it'd be the same.


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  https://reviews.llvm.org/D149246/new/

https://reviews.llvm.org/D149246