Misleading error message for unimplemented instructions

[chazy]

Consider the following example used with the aarch64.cat model:

{
0:X1=x; 0:X3=y;
1:X1=y; 1:X3=x;
}
 P0                     | P1          ;
 STLXP W0, X1, X2, [X3] |             ;

exists (0:X0=1)

herd7 will complain because the STLXP instruction is not implemented, but the error message given is:
File "unknown-instr.litmus", line 7, characters 7-9: unexpected 'W0' (in prog) (User error)

If possible, it would improve usability in this scenario if the tool could report "Unrecognized statement 'STLXP'" or something like that instead.

[maranget]

Hi, I see your point,

However, I have no idea of how to get better error messages here. This probably means quite a lot of work and many tasks on herd7 are urgent. Hence this issue is not a high priority one,

[chazy]

Ok, that’s fair enough. Perhaps we can meet this issue around and either try to fix later or document somewhere that an error message like this can simply mean that some construct is not known.

…

On Wed, 9 Sep 2020 at 14.26, Luc Maranget ***@***.***> wrote: Hi, I see your point, However, I have no idea of how to get better error messages here. This probably means quite a lot of work and many tasks on herd7 are urgent. Hence this issue is not a high priority one, — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#46 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAIE24DZM2DKDIPDHG5VJ4LSE5YAVANCNFSM4QL7HD5Q> .

[lukeg101]

one thought is that we could implement the parsing for instructions like this (I have implemented stlxp on my branch), and then add a 'not implemented' pattern in AArch64Sem:

somewhere around?

herdtools7/herd/AArch64Sem.ml

Line 640 in 82816da

(* Cannot handle *)

of course it's up to us to add all the instruction variants, but this might work?

[jalglave]

hi Luke, if you've got an idea, please prepare a PR and we'll review then.
Thanks,
Jade

[Jichao]

same problem on test for arch x86_64.