RE: [PATCH v8 29/35] Hexagon (target/hexagon) translation

[Taylor Simpson]

> -----Original Message-----
> From: Richard Henderson <richard.henderson@linaro.org>
> Sent: Saturday, March 13, 2021 7:44 PM
> To: Taylor Simpson <tsimpson@quicinc.com>; qemu-devel@nongnu.org
> Cc: philmd@redhat.com; alex.bennee@linaro.org; laurent@vivier.eu;
> ale@rev.ng; Brian Cain <bcain@quicinc.com>
> Subject: Re: [PATCH v8 29/35] Hexagon (target/hexagon) translation
>
> >> -----Original Message-----
> >> From: Richard Henderson <richard.henderson@linaro.org>
> >> Sent: Sunday, February 14, 2021 7:04 PM
> >> To: Taylor Simpson <tsimpson@quicinc.com>; qemu-devel@nongnu.org
> >> Cc: philmd@redhat.com; alex.bennee@linaro.org; laurent@vivier.eu;
> >> ale@rev.ng; Brian Cain <bcain@quicinc.com>
> >> Subject: Re: [PATCH v8 29/35] Hexagon (target/hexagon) translation
> >>
> >> On 2/7/21 9:46 PM, Taylor Simpson wrote:
> >>> +    case DISAS_NORETURN:
> >>> +        gen_exec_counters(ctx);
> >>> +        tcg_gen_mov_tl(hex_gpr[HEX_REG_PC], hex_next_PC);
> >>> +        if (ctx->base.singlestep_enabled) {
> >>> +            gen_exception_debug();
> >>> +        } else {
> >>> +            tcg_gen_exit_tb(NULL, 0);
> >>> +        }
> >>
> >> DISAS_NORETURN says that we have *already* exited the TB.  None of the 
> >> code you emit here will be reachable.
> >
> > Isn't this called before the TB ends?
>
> Yes, but DISAS_NORETURN still means we've already exited.
>
> Just like calling abort() in C means that we won't reach any following return 
> statement.

Then I'm missing something because the code emitted here does get executed.  I 
thought the tb_stop function is a place for the target to add code.  Should I 
push this up to all the places where we set ctx->base.is_jmp to DISAS_NORETURN?


Taylor