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Re: [qemu-s390x] [PATCH v2] s390x/tcg: Don't model FP registers as globa

From: Cornelia Huck
Subject: Re: [qemu-s390x] [PATCH v2] s390x/tcg: Don't model FP registers as globals
Date: Mon, 4 Feb 2019 18:47:41 +0100

On Mon,  4 Feb 2019 16:44:06 +0100
David Hildenbrand <address@hidden> wrote:

> As floating point registers overlay some vector registers and we want
> to make use of the general tcg_gvec infrastructure that assumes vectors
> are not stored in globals but in memory, don't model flaoting point
> registers as globals anymore. This is than similar to how arm handles
> it.
> Reading/writing a floating point register means reading/writing memory now.
> Break up ugly in2_x2() handling that modifies both, in1 and in2 into
> in1_x2l and in2_x2h. This makes things more readable. Also, in1_x1() is
> ugly as it touches out/out2, get rid of that and use prep_x1() instead.
> As we are no longer able to use the original global variables for
> out/out2, we have to use new temporary variables and write from them to
> the target registers using wout_ helpers.
> E.g. an instruction that reads and writes x1 will use
> - prep_x1 to get the values into out/out2
> - wout_x1 to write the values from out/out2
> This special handling is needed for x1 as it is often used along with
> other inputs, so in1/in2 is already used.
> Reviewed-by: Richard Henderson <address@hidden>
> Signed-off-by: David Hildenbrand <address@hidden>
> ---
> v1 -> v2:
> - renamed x2h -> x2l and x2l -> x2h to match the actual meaning
>   ("high" on s390x is where the smaller bit numbers are ;) )
> - did another quick sniff test
>  target/s390x/insn-data.def | 150 ++++++++++++++++++-------------------
>  target/s390x/translate.c   | 135 ++++++++++++++++++++-------------
>  2 files changed, 160 insertions(+), 125 deletions(-)

Thanks, applied.

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