From: "Alex Bennée" <alex.bennee@linaro.org>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: qemu-devel@nongnu.org, qemu-arm@nongnu.org
Subject: Re: [PATCH 3/4] target/arm: Implement FPST_STD_F16 fpstatus
Date: Thu, 06 Aug 2020 12:47:40 +0100 [thread overview]
Message-ID: <87ft90knc3.fsf@linaro.org> (raw)
In-Reply-To: <20200806104453.30393-4-peter.maydell@linaro.org>
Peter Maydell <peter.maydell@linaro.org> writes:
> Architecturally, Neon FP16 operations use the "standard FPSCR" like
> all other Neon operations. However, this is defined in the Arm ARM
> pseudocode as "a fixed value, except that FZ16 (and AHP) follow the
> FPSCR bits". In QEMU, the softfloat float_status doesn't include
> separate flush-to-zero for FP16 operations, so we must keep separate
> fp_status for "Neon non-FP16" and "Neon fp16" operations, in the
> same way we do already for the non-Neon "fp_status" vs "fp_status_f16".
>
> Add the extra float_status field to the CPU state structure,
> ensure it is correctly initialized and updated on FPSCR writes,
> and make fpstatus_ptr(FPST_STD_F16) return a pointer to it.
>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
--
Alex Bennée
WARNING: multiple messages have this Message-ID (diff)
From: "Alex Bennée" <alex.bennee@linaro.org>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: qemu-arm@nongnu.org, qemu-devel@nongnu.org
Subject: Re: [PATCH 3/4] target/arm: Implement FPST_STD_F16 fpstatus
Date: Thu, 06 Aug 2020 12:47:40 +0100 [thread overview]
Message-ID: <87ft90knc3.fsf@linaro.org> (raw)
In-Reply-To: <20200806104453.30393-4-peter.maydell@linaro.org>
Peter Maydell <peter.maydell@linaro.org> writes:
> Architecturally, Neon FP16 operations use the "standard FPSCR" like
> all other Neon operations. However, this is defined in the Arm ARM
> pseudocode as "a fixed value, except that FZ16 (and AHP) follow the
> FPSCR bits". In QEMU, the softfloat float_status doesn't include
> separate flush-to-zero for FP16 operations, so we must keep separate
> fp_status for "Neon non-FP16" and "Neon fp16" operations, in the
> same way we do already for the non-Neon "fp_status" vs "fp_status_f16".
>
> Add the extra float_status field to the CPU state structure,
> ensure it is correctly initialized and updated on FPSCR writes,
> and make fpstatus_ptr(FPST_STD_F16) return a pointer to it.
>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
--
Alex Bennée
next prev parent reply other threads:[~2020-08-06 11:47 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-06 10:44 [PATCH 0/4] Refactor get_fpstatus_ptr() ready for AArch32 fp16 Peter Maydell
2020-08-06 10:44 ` [PATCH 1/4] target/arm: Replace A64 get_fpstatus_ptr() with generic fpstatus_ptr() Peter Maydell
2020-08-06 11:44 ` Alex Bennée
2020-08-06 10:44 ` [PATCH 2/4] target/arm: Make A32/T32 use new fpstatus_ptr() API Peter Maydell
2020-08-06 11:46 ` Alex Bennée
2020-08-06 11:46 ` Alex Bennée
2020-08-06 10:44 ` [PATCH 3/4] target/arm: Implement FPST_STD_F16 fpstatus Peter Maydell
2020-08-06 11:47 ` Alex Bennée [this message]
2020-08-06 11:47 ` Alex Bennée
2020-08-06 10:44 ` [PATCH 4/4] target/arm: Use correct FPST for VCMLA, VCADD on fp16 Peter Maydell
2020-08-06 11:50 ` Alex Bennée
2020-08-06 11:50 ` Alex Bennée
2020-08-06 21:08 ` [PATCH 0/4] Refactor get_fpstatus_ptr() ready for AArch32 fp16 Richard Henderson
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