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Re: [qemu-s390x] [Qemu-devel] [PATCH v1] s390x/tcg: Don't model FP regis

From: Richard Henderson
Subject: Re: [qemu-s390x] [Qemu-devel] [PATCH v1] s390x/tcg: Don't model FP registers as globals
Date: Mon, 4 Feb 2019 13:27:31 +0000
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0

On 1/31/19 2:37 PM, David Hildenbrand 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.
> Signed-off-by: David Hildenbrand <address@hidden>
> ---
>  target/s390x/insn-data.def | 150 ++++++++++++++++++-------------------
>  target/s390x/translate.c   | 133 +++++++++++++++++++-------------
>  2 files changed, 158 insertions(+), 125 deletions(-)

Reviewed-by: Richard Henderson <address@hidden>


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