Re: [PATCH] target/arm: Fix accidental write to TCG constant

[Peter Maydell <peter.maydell@linaro.org>]

On Thu, 6 Nov 2025 at 14:49, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> Currently an unpredictable movw such as
>
>   movw pc, 0x123
>
> results in the tinycode
>
>    and_i32 $0x123,$0x123,$0xfffffffc
>    mov_i32 pc,$0x123
>    exit_tb $0x0
>
> which is clearly a bug, writing to a constant is incorrect and discards
> the result of the mask.  Fix this by adding a temporary in store_reg().
>
> Signed-off-by: Anton Johansson <anjo@rev.ng>
> [rth: Avoid an extra temp and extra move.]
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---


Applied to target-arm.next, thanks; tweaked the commit
message to match the code:

    which is clearly a bug: writing to a constant is incorrect and
    discards the result of the mask.  Fix this by always doing an and_i32
    and trusting the optimizer to turn this into a simple move when the
    mask is zero.


-- PMM