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Re: [PATCH v3] target/s390x: Fix CC set by CONVERT TO FIXED/LOGICAL

From: Cornelia Huck
Subject: Re: [PATCH v3] target/s390x: Fix CC set by CONVERT TO FIXED/LOGICAL
Date: Thu, 01 Jul 2021 15:56:36 +0200
User-agent: Notmuch/0.32.1 (https://notmuchmail.org)

On Wed, Jun 30 2021, Ulrich Weigand <ulrich.weigand@de.ibm.com> wrote:

> The FP-to-integer conversion instructions need to set CC 3 whenever
> a "special case" occurs; this is the case whenever the instruction
> also signals the IEEE invalid exception.  (See e.g. figure 19-18
> in the Principles of Operation.)
> However, qemu currently will set CC 3 only in the case where the
> input was a NaN.  This is indeed one of the special cases, but
> there are others, most notably the case where the input is out
> of range of the target data type.
> This patch fixes the problem by switching these instructions to
> the "static" CC method and computing the correct result directly
> in the helper.  (It cannot be re-computed later as the information
> about the invalid exception is no longer available.)
> This fixes a bug observed when running the wasmtime test suite
> under the s390x-linux-user target.
> Signed-off-by: Ulrich Weigand <ulrich.weigand@de.ibm.com>
> ---
>  target/s390x/fpu_helper.c | 63 
> ++++++++++++++++++++++++++++++++++++++++++++---
>  target/s390x/helper.h     | 24 +++++++++---------
>  target/s390x/translate.c  | 39 +++++++++--------------------
>  3 files changed, 83 insertions(+), 43 deletions(-)

Thanks, applied.

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