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Re: [PATCH] Add "riscv" as an alias for "riscv32"

From: John Ericson
Subject: Re: [PATCH] Add "riscv" as an alias for "riscv32"
Date: Fri, 22 Jun 2018 12:48:06 -0400
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1

DJ's and Karsten's concerns match my config-for-target vs config-for-toolchain distinction.

arm*- riscv-* and x86-* do make sense as compiler prefixes that indicate toolchain support for a set of targets. But when we think of a toolchain + a set of standard libraries (without multilib), only a single target makes sense, so those 3 are all bad.

On the other hand riscv32 is bad because, as I just learned, there are *3* base ISAs, not *2*, and riscv32e and riscv32i are totally incompatible. So for targets we need riscv32e-* riscv32i-* riscv64e-*. riscv{32,64} may be what uname does, but uname's output is the most harmful of here: it's too vague for actual targets, and too specific for stdlib-less embedded compiler prefixes, so both camps are left wanting.

As to riscv-* I see the exact-target and toolchain use-cases as fundamentally irreconcilable, so GNU config should just learn the difference so as to satisfy everyone *without* compromise. If we can agree on this I volunteer to immediately do all the work---I now have enough information from this thread.

And finally, the original patch is no good in my mind even as a first incremental step, as the unconditional riscv- to riscv32- desugar is also wrong for embedded and desktop/distro alike.


P.S. Sorry to be basically repeating myself, but I think I was too wordy the first time / lost within the fast pace of the thread the first time around

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