Re: [PATCH] target/ppc: fix unreachable code in do_ldst_quad()

[Richard Henderson]

On 7/20/22 19:27, Daniel Henrique Barboza wrote:
> Coverity reports that commit fc34e81acd51 ("target/ppc: add macros to
> check privilege level") turned the following code unreachable:
>
> if (!prefixed && !(ctx->insns_flags2 & PPC2_LSQ_ISA207)) {
>      /* lq and stq were privileged prior to V. 2.07 */
>      REQUIRE_SV(ctx);
>
> > > >      CID 1490757:  Control flow issues  (UNREACHABLE)
> > > >      This code cannot be reached: "if (ctx->le_mode) {
>      if (ctx->le_mode) {
>          gen_align_no_le(ctx);
>          return true;
>      }
> }
>
> This happens because the macro REQUIRE_SV(), in CONFIG_USER_MODE, will
> always result in a 'return true' statement.

I think adding ifdefs isn't fantastic.  This isn't actually fix a bug, so we *could* just 
mark this as ignore in Coverity.

If you wanted to clean this up, remove the implicit control flow from REQUIRE_* and turn 
the macros into pure predicates, so that you get

    if (REQUIRE_SV(ctx)) {
        return true;
    }
    if (ctx->le_mode) {
        ...
    }


r~