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Re: [Qemu-devel] [PATCH v2 01/11] target-arm: Share all common TCG tempo
From: |
Peter Maydell |
Subject: |
Re: [Qemu-devel] [PATCH v2 01/11] target-arm: Share all common TCG temporaries |
Date: |
Mon, 7 Sep 2015 17:57:23 +0100 |
On 2 September 2015 at 18:57, Richard Henderson <address@hidden> wrote:
> This is a bug fix for aarch64. At present, we have branches using
> the 32-bit (translate.c) versions of cpu_[NZCV]F, but we set the flags
> using the 64-bit (translate-a64.c) versions of cpu_[NZCV]F. From
> the view of the TCG code generator, these are unrelated variables.
>
> The bug is hard to see because we currently only read these variables
> from branches, and upon reaching a branch TCG will first spill live
> variables and then reload the arguments of the branch. Since the
> 32-bit versions were never live until reaching the branch, we'd re-read
> the data that had just been spilled from the 64-bit versions.
>
> There is currently no such problem with the cpu_exclusive_* variables,
> but there's no point in tempting fate.
>
> Signed-off-by: Richard Henderson <address@hidden>
Reviewed-by: Peter Maydell <address@hidden>
Should this be cc:address@hidden ?
thanks
-- PMM