Re: [PATCH 2/3] target/arm: Make IT insn undef when not present

On 8/21/26 06:25, Peter Maydell wrote:
> The IT insn is introduced for A-profile starting in v6T2; for
> M-profile it is present when the Main Extension is implemented (which
> includes v7M and excludes v6M).  We were missing the feature-check,
> so fail to UNDEF on earlier cores.
> 
> Add the missing check.
> 
> Cc: [email protected]
> Fixes: 9ee6e8bb853bde ("ARMv7 support.")
> Signed-off-by: Peter Maydell <[email protected]>
> ---
>   target/arm/tcg/translate.c | 10 ++++++++++
>   1 file changed, 10 insertions(+)
> 
> diff --git a/target/arm/tcg/translate.c b/target/arm/tcg/translate.c
> index df98dc2e34d..103e2fe7c73 100644
> --- a/target/arm/tcg/translate.c
> +++ b/target/arm/tcg/translate.c
> @@ -6038,6 +6038,16 @@ static bool trans_IT(DisasContext *s, arg_IT *a)
>   {
>       int cond_mask = a->cond_mask;
>   
> +    /*
> +     * IT insn introduced in v6T2 for A-profile; it is only present
> +     * on M-profile if the Main Extension is implemented.
> +     */
> +    if (!arm_dc_feature(s, ARM_FEATURE_THUMB2) ||
> +        (arm_dc_feature(s, ARM_FEATURE_M) &&
> +         !arm_dc_feature(s, ARM_FEATURE_M_MAIN))) {
> +        return false;
> +    }
In practice this is going to be the same as just thumb2, because v7M has v7 which implies 
thumb2, and all v7M have m_main.

Is it clearer as

	!(arm_dc_feature(s, ARM_FEATURE_M)
           ? arm_dc_feature(s, ARM_FEATURE_M_MAIN)
           : arm_dc_feature(s, ARM_FEATURE_THUMB2))

?

r~