In AArch32, the floating point control and status bits are all in a
single register, FPSCR. In AArch64, these were split into separate
FPCR and FPSR registers, but the bit layouts remained the same, with
no overlaps, so that you could construct an FPSCR value by ORing FPCR
and FPSR, or equivalently could produce FPSR and FPCR by masking an
FPSCR value. For QEMU's implementation, we opted to use masking to
produce FPSR and FPCR, because we started with an AArch32
implementation of FPSCR.
The addition of the (AArch64-only) FEAT_AFP adds new bits to the FPCR
which overlap with some bits in the FPSR. This means we'll no longer
be able to consider the FPSCR-encoded value as the primary one, but
instead need to treat FPSR/FPCR as the primary encoding and construct
the FPSCR from those. (This remains possible because the FEAT_AFP
bits in FPCR don't appear in the FPSCR.)
As the first step in this refactoring, make vfp_get_fpscr() call
vfp_get_fpcr() and vfp_get_fpsr(), instead of the other way around.
Note that vfp_get_fpcsr_from_host() returns only bits in the FPSR
(for the cumulative fp exception bits), so we can simply rename
it without needing to add a new function for getting FPCR bits.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20240628142347.1283015-3-peter.maydell@linaro.org
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