Re: [PATCH] target/rx: Fix compiler errors for build with sanitizers

[Laurent Vivier]

Le 28/01/2021 à 18:21, Stefan Weil a écrit :
> gcc (Debian 10.2.1-6) 10.2.1 20210110 aborts builds with enabled sanitizers:
> 
> ../../../target/rx/op_helper.c: In function ‘helper_scmpu’:
> ../../../target/rx/op_helper.c:213:24: error: ‘tmp1’ may be used 
> uninitialized in this function [-Werror=maybe-uninitialized]
>   213 |     env->psw_c = (tmp0 >= tmp1);
>       |                  ~~~~~~^~~~~~~~
> ../../../target/rx/op_helper.c:213:24: error: ‘tmp0’ may be used 
> uninitialized in this function [-Werror=maybe-uninitialized]
> ../../../target/rx/op_helper.c: In function ‘helper_suntil’:
> ../../../target/rx/op_helper.c:299:23: error: ‘tmp’ may be used uninitialized 
> in this function [-Werror=maybe-uninitialized]
>   299 |     env->psw_c = (tmp <= env->regs[2]);
>       |                  ~~~~~^~~~~~~~~~~~~~~~
> ../../../target/rx/op_helper.c: In function ‘helper_swhile’:
> ../../../target/rx/op_helper.c:318:23: error: ‘tmp’ may be used uninitialized 
> in this function [-Werror=maybe-uninitialized]
>   318 |     env->psw_c = (tmp <= env->regs[2]);
>       |                  ~~~~~^~~~~~~~~~~~~~~~
> 
> Rewriting the code fixes those errors.
> 
> Signed-off-by: Stefan Weil <sw@weilnetz.de>
> ---
> 
> Those error are false positives, but simple code changes help the
> compiler (and perhaps reviewers) to understand it better.
> 
> Stefan
> 
> 
>  target/rx/op_helper.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/target/rx/op_helper.c b/target/rx/op_helper.c
> index 59389f4992..4d315b4449 100644
> --- a/target/rx/op_helper.c
> +++ b/target/rx/op_helper.c
> @@ -201,14 +201,14 @@ void helper_scmpu(CPURXState *env)
>      if (env->regs[3] == 0) {
>          return;
>      }
> -    while (env->regs[3] != 0) {
> +    do {
>          tmp0 = cpu_ldub_data_ra(env, env->regs[1]++, GETPC());
>          tmp1 = cpu_ldub_data_ra(env, env->regs[2]++, GETPC());
>          env->regs[3]--;
>          if (tmp0 != tmp1 || tmp0 == '\0') {
>              break;
>          }
> -    }
> +    } while (env->regs[3] != 0);
>      env->psw_z = tmp0 - tmp1;
>      env->psw_c = (tmp0 >= tmp1);
>  }
> @@ -287,14 +287,14 @@ void helper_suntil(CPURXState *env, uint32_t sz)
>      if (env->regs[3] == 0) {
>          return ;
>      }
> -    while (env->regs[3] != 0) {
> +    do {
>          tmp = cpu_ldufn[sz](env, env->regs[1], GETPC());
>          env->regs[1] += 1 << sz;
>          env->regs[3]--;
>          if (tmp == env->regs[2]) {
>              break;
>          }
> -    }
> +    } while (env->regs[3] != 0);
>      env->psw_z = tmp - env->regs[2];
>      env->psw_c = (tmp <= env->regs[2]);
>  }
> @@ -306,14 +306,14 @@ void helper_swhile(CPURXState *env, uint32_t sz)
>      if (env->regs[3] == 0) {
>          return ;
>      }
> -    while (env->regs[3] != 0) {
> +    do {
>          tmp = cpu_ldufn[sz](env, env->regs[1], GETPC());
>          env->regs[1] += 1 << sz;
>          env->regs[3]--;
>          if (tmp != env->regs[2]) {
>              break;
>          }
> -    }
> +    } while (env->regs[3] != 0);
>      env->psw_z = env->regs[3];
>      env->psw_c = (tmp <= env->regs[2]);
>  }
> 

Applied to my trivial-patches branch.

Thanks,
Laurent