[PATCH] sim: tighten up generated decode tables

[Mike Frysinger]

On 22 Dec 2023 11:55, Jose E. Marchesi wrote:
> > The use of /* fall through */ with consective case statements doesn't
> > really add any value, and when generating large files, can take up a
> > lot of space.  In the case of cris, it alone adds ~20k, or ~10%.
> 
> I am a little concern this change may trigger implicit-fallthrough
> warnings when compiling the generated code.  Not sure this is a problem
> in practice though, since nor binutils nor sim uses
> -Wimplicit-fallthrough for building as far as I can see.

pretty sure compilers don't warn about consecutive case statements that
don't have any non-case code inbetween.  so we're talking about:
          case 11:
          case 12:
          case 13:
          case 14: itype = CRISV10F_INSN_ADDOQ; goto extract_sfmt_addoq;

since this is a very common scenario, compilers accept it without warning.
if you did something like:
          case 13:
            printf("");
          case 14: itype = CRISV10F_INSN_ADDOQ; goto extract_sfmt_addoq;
then it'd warn.

i'm actually enabling -Wimplicit-fallthrough in sim now and none of these
trigger warnings.
-mike
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