Commit graph

88 commits

Author SHA1 Message Date
Richard Henderson
d75f680476 target/arm: Simplify DO_VFP_cmp in vfp_helper.c
Pass ARMFPStatusFlavour index instead of fp_status[FOO].

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20250129013857.135256-17-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2025-02-11 16:22:08 +00:00
Richard Henderson
54afbf6632 target/arm: Remove fp_status_a32
Replace with fp_status[FPST_A32].  As this was the last of the
old structures, we can remove the anonymous union and struct.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20250129013857.135256-15-richard.henderson@linaro.org
[PMM: tweak to account for change to is_ebf()]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2025-02-11 16:22:07 +00:00
Richard Henderson
1c349f43b1 target/arm: Remove fp_status_a64
Replace with fp_status[FPST_A64].

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20250129013857.135256-14-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2025-02-11 16:22:07 +00:00
Richard Henderson
828def800e target/arm: Remove fp_status_f16_a32
Replace with fp_status[FPST_A32_F16].

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20250129013857.135256-13-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2025-02-11 16:22:07 +00:00
Richard Henderson
c71296565c target/arm: Remove fp_status_f16_a64
Replace with fp_status[FPST_A64_F16].

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20250129013857.135256-12-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2025-02-11 16:22:07 +00:00
Richard Henderson
ee4316f65b target/arm: Remove ah_fp_status
Replace with fp_status[FPST_AH].

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20250129013857.135256-11-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2025-02-11 16:22:07 +00:00
Richard Henderson
fc25b174d5 target/arm: Remove ah_fp_status_f16
Replace with fp_status[FPST_AH_F16].

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20250129013857.135256-10-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2025-02-11 16:22:07 +00:00
Richard Henderson
f069b26b8e target/arm: Remove standard_fp_status
Replace with fp_status[FPST_STD].

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20250129013857.135256-9-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2025-02-11 16:22:07 +00:00
Richard Henderson
7678859152 target/arm: Remove standard_fp_status_f16
Replace with fp_status[FPST_STD_F16].

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20250129013857.135256-8-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2025-02-11 16:22:07 +00:00
Peter Maydell
22330d2b0f target/arm: Implement increased precision FRSQRTE
Implement the increased precision variation of FRSQRTE.  In the
pseudocode this corresponds to the handling of the
"increasedprecision" boolean in the FPRSqrtEstimate() and
RecipSqrtEstimate() functions.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
2025-02-11 16:22:07 +00:00
Peter Maydell
c1567205e0 target/arm: Implement increased precision FRECPE
Implement the increased precision variation of FRECPE.  In the
pseudocode this corresponds to the handling of the
"increasedprecision" boolean in the FPRecipEstimate() and
RecipEstimate() functions.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
2025-02-11 16:22:07 +00:00
Peter Maydell
0ff5c021f0 target/arm: Plumb FEAT_RPRES frecpe and frsqrte through to new helper
FEAT_RPRES implements an "increased precision" variant of the single
precision FRECPE and FRSQRTE instructions from an 8 bit to a 12
bit mantissa. This applies only when FPCR.AH == 1. Note that the
halfprec and double versions of these insns retain the 8 bit
precision regardless.

In this commit we add all the plumbing to make these instructions
call a new helper function when the increased-precision is in
effect. In the following commit we will provide the actual change
in behaviour in the helpers.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
2025-02-11 16:22:07 +00:00
Peter Maydell
1828053990 target/arm: Set up float_status to use for FPCR.AH=1 behaviour
When FPCR.AH is 1, the behaviour of some instructions changes:
 * AdvSIMD BFCVT, BFCVTN, BFCVTN2, BFMLALB, BFMLALT
 * SVE BFCVT, BFCVTNT, BFMLALB, BFMLALT, BFMLSLB, BFMLSLT
 * SME BFCVT, BFCVTN, BFMLAL, BFMLSL (these are all in SME2 which
   QEMU does not yet implement)
 * FRECPE, FRECPS, FRECPX, FRSQRTE, FRSQRTS

The behaviour change is:
 * the instructions do not update the FPSR cumulative exception flags
 * trapped floating point exceptions are disabled (a no-op for QEMU,
   which doesn't implement FPCR.{IDE,IXE,UFE,OFE,DZE,IOE})
 * rounding is always round-to-nearest-even regardless of FPCR.RMode
 * denormalized inputs and outputs are always flushed to zero, as if
   FPCR.{FZ,FIZ} is {1,1}
 * FPCR.FZ16 is still honoured for half-precision inputs

(See the Arm ARM DDI0487L.a section A1.5.9.)

We can provide all these behaviours with another pair of float_status fields
which we use only for these insns, when FPCR.AH is 1. These float_status
fields will always have:
 * flush_to_zero and flush_inputs_to_zero set for the non-F16 field
 * rounding mode set to round-to-nearest-even
and so the only FPCR fields they need to honour are DN and FZ16.

In this commit we only define the new fp_status fields and give them
the required behaviour when FPSR is updated.  In subsequent commits
we will arrange to use this new fp_status field for the instructions
that should be affected by FPCR.AH in this way.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
2025-02-11 16:22:07 +00:00
Peter Maydell
a4550b7be9 target/arm: Adjust exception flag handling for AH = 1
When FPCR.AH = 1, some of the cumulative exception flags in the FPSR
behave slightly differently for A64 operations:
 * IDC is set when a denormal input is used without flushing
 * IXC (Inexact) is set when an output denormal is flushed to zero

Update vfp_get_fpsr_from_host() to do this.

Note that because half-precision operations never set IDC, we now
need to add float_flag_input_denormal_used to the set we mask out of
fp_status_f16_a64.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
2025-02-11 16:22:07 +00:00
Peter Maydell
b3d00d0a44 target/arm: Adjust FP behaviour for FPCR.AH = 1
When FPCR.AH is set, various behaviours of AArch64 floating point
operations which are controlled by softfloat config settings change:
 * tininess and ftz detection before/after rounding
 * NaN propagation order
 * result of 0 * Inf + NaN
 * default NaN value

When the guest changes the value of the AH bit, switch these config
settings on the fp_status_a64 and fp_status_f16_a64 float_status
fields.

This requires us to make the arm_set_default_fp_behaviours() function
global, since we now need to call it from cpu.c and vfp_helper.c; we
move it to vfp_helper.c so it can be next to the new
arm_set_ah_fp_behaviours().

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
2025-02-11 16:22:07 +00:00
Peter Maydell
c2e6020477 target/arm: Implement FPCR.FIZ handling
Part of FEAT_AFP is the new control bit FPCR.FIZ.  This bit affects
flushing of single and double precision denormal inputs to zero for
AArch64 floating point instructions.  (For half-precision, the
existing FPCR.FZ16 control remains the only one.)

FPCR.FIZ differs from FPCR.FZ in that if we flush an input denormal
only because of FPCR.FIZ then we should *not* set the cumulative
exception bit FPSR.IDC.

FEAT_AFP also defines that in AArch64 the existing FPCR.FZ only
applies when FPCR.AH is 0.

We can implement this by setting the "flush inputs to zero" state
appropriately when FPCR is written, and by not reflecting the
float_flag_input_denormal status flag into FPSR reads when it is the
result only of FPSR.FIZ.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
2025-02-11 16:22:07 +00:00
Peter Maydell
7ea2b119f9 target/arm: Define FPCR AH, FIZ, NEP bits
The Armv8.7 FEAT_AFP feature defines three new control bits in
the FPCR:
 * FPCR.AH: "alternate floating point mode"; this changes floating
   point behaviour in a variety of ways, including:
    - the sign of a default NaN is 1, not 0
    - if FPCR.FZ is also 1, denormals detected after rounding
      with an unbounded exponent has been applied are flushed to zero
    - FPCR.FZ does not cause denormalized inputs to be flushed to zero
    - miscellaneous other corner-case behaviour changes
 * FPCR.FIZ: flush denormalized numbers to zero on input for
   most instructions
 * FPCR.NEP: makes scalar SIMD operations merge the result with
   higher vector elements in one of the source registers, instead
   of zeroing the higher elements of the destination

This commit defines the new bits in the FPCR, and allows them to be
read or written when FEAT_AFP is implemented.  Actual behaviour
changes will be implemented in subsequent commits.

Note that these are the first FPCR bits which don't appear in the
AArch32 FPSCR view of the register, and which share bit positions
with FPSR bits.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
2025-02-11 16:22:07 +00:00
Peter Maydell
7af64d103d fpu: Rename float_flag_output_denormal to float_flag_output_denormal_flushed
Our float_flag_output_denormal exception flag is set when
the fpu code flushes an output denormal to zero. Rename
it to float_flag_output_denormal_flushed:
 * this keeps it parallel with the flag for flushing
   input denormals, which we just renamed
 * it makes it clearer that it doesn't mean "set when
   the output is a denormal"

Commit created with
 for f in `git grep -l float_flag_output_denormal`; do sed -i -e 's/float_flag_output_denormal/float_flag_output_denormal_flushed/' $f; done

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20250124162836.2332150-21-peter.maydell@linaro.org
2025-01-28 18:40:19 +00:00
Peter Maydell
584b7aec81 fpu: Rename float_flag_input_denormal to float_flag_input_denormal_flushed
Our float_flag_input_denormal exception flag is set when the fpu code
flushes an input denormal to zero.  This is what many guest
architectures (eg classic Arm behaviour) require, but it is not the
only donarmal-related reason we might want to set an exception flag.
The x86 behaviour (which we do not currently model correctly) wants
to see an exception flag when a denormal input is *not* flushed to
zero and is actually used in an arithmetic operation. Arm's FEAT_AFP
also wants these semantics.

Rename float_flag_input_denormal to float_flag_input_denormal_flushed
to make it clearer when it is set and to allow us to add a new
float_flag_input_denormal_used next to it for the x86/FEAT_AFP
semantics.

Commit created with
 for f in `git grep -l float_flag_input_denormal`; do sed -i -e 's/float_flag_input_denormal/float_flag_input_denormal_flushed/' $f; done

and manual editing of softfloat-types.h and softfloat.c to clean
up the indentation afterwards and to fix a comment which wasn't
using the full name of the flag.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20250124162836.2332150-20-peter.maydell@linaro.org
2025-01-28 18:40:19 +00:00
Peter Maydell
3847b5b1fb target/arm: Remove now-unused vfp.fp_status_f16 and FPST_FPCR_F16
Now we have moved all the uses of vfp.fp_status_f16 and FPST_FPCR_F16
to the new A32 or A64 fields, we can remove these.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20250124162836.2332150-19-peter.maydell@linaro.org
2025-01-28 18:40:19 +00:00
Peter Maydell
85fffc1085 target/arm: Use fp_status_f16_a32 in AArch32-only helpers
We directly use fp_status_f16 in a handful of helpers that
are AArch32-specific; switch to fp_status_f16_a32 for these.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20250124162836.2332150-15-peter.maydell@linaro.org
2025-01-28 18:40:19 +00:00
Peter Maydell
5f4ed6da85 target/arm: Define new fp_status_f16_a32 and fp_status_f16_a64
As the first part of splitting the existing fp_status_f16
into separate float_status fields for AArch32 and AArch64
(so that we can make FEAT_AFP control bits apply only
for AArch64), define the two new fp_status_f16_a32 and
fp_status_f16_a64 fields, but don't use them yet.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20250124162836.2332150-14-peter.maydell@linaro.org
2025-01-28 18:40:19 +00:00
Peter Maydell
2aa9656ebc target/arm: Remove now-unused vfp.fp_status and FPST_FPCR
Now we have moved all the uses of vfp.fp_status and FPST_FPCR
to either the A32 or A64 fields, we can remove these.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20250124162836.2332150-13-peter.maydell@linaro.org
2025-01-28 18:40:19 +00:00
Peter Maydell
d1ce6db3b1 target/arm: Use fp_status_a32 in vfp_cmp helpers
The helpers vfp_cmps, vfp_cmpes, vfp_cmpd, vfp_cmped are used only from
the A32 decoder; the A64 decoder uses separate vfp_cmps_a64 etc helpers
(because for A64 we update the main NZCV flags and for A32 we update
the FPSCR NZCV flags). So we can make these helpers use the fp_status_a32
field instead of fp_status.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20250124162836.2332150-10-peter.maydell@linaro.org
2025-01-28 18:40:19 +00:00
Peter Maydell
1069d8ab30 target/arm: Use fp_status_a32 in vjvct helper
Use fp_status_a32 in the vjcvt helper function; this is called only
from the A32/T32 decoder and is not used inside a
set_rmode/restore_rmode sequence.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20250124162836.2332150-9-peter.maydell@linaro.org
2025-01-28 18:40:19 +00:00
Peter Maydell
2208cb46e6 target/arm: Define new fp_status_a32 and fp_status_a64
We want to split the existing fp_status in the Arm CPUState into
separate float_status fields for AArch32 and AArch64.  (This is
because new control bits defined by FEAT_AFP only have an effect for
AArch64, not AArch32.) To make this split we will:
 * define new fp_status_a32 and fp_status_a64 which have
   identical behaviour to the existing fp_status
 * move existing uses of fp_status to fp_status_a32 or
   fp_status_a64 as appropriate
 * delete the old fp_status when it has no uses left

In this patch we add the new float_status fields.

We will also need to split fp_status_f16, but we will do that
as a separate series of patches.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20250124162836.2332150-7-peter.maydell@linaro.org
2025-01-28 18:40:19 +00:00
Peter Maydell
eda8d53083 target/arm: Use uint32_t in vfp_exceptbits_from_host()
In vfp_exceptbits_from_host(), we accumulate the FPSR flags in
an "int", and our return type is also "int". However, the only
callsite returns the same information as a uint32_t, and
more generally we handle FPSR values in the code as uint32_t,
not int. Bring this function in to line with that convention.

There is no behaviour change because none of the FPSR bits
we set in this function are bit 31. The input argument to
the function remains 'int' because that is the return type
of the softfloat get_float_exception_flags().

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20250124162836.2332150-6-peter.maydell@linaro.org
2025-01-28 18:40:19 +00:00
Peter Maydell
f10dee833f target/arm: Use FPSR_ constants in vfp_exceptbits_from_host()
Use the FPSR_ named constants in vfp_exceptbits_from_host(),
rather than hardcoded magic numbers.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20250124162836.2332150-5-peter.maydell@linaro.org
2025-01-28 18:40:19 +00:00
Richard Henderson
1660866e2c target/arm: Use float_status in helper_vfp_fcvt{ds,sd}
Pass float_status not env to match other functions.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20241206031952.78776-3-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2024-12-17 15:05:42 +00:00
Richard Henderson
cca8b4f2a1 target/arm: Convert vfp_helper.c to fpst alias
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20241206031224.78525-3-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2024-12-17 15:05:39 +00:00
Denis Rastyogin
30c78658aa target/arm: remove redundant code
This call is redundant as it only retrieves a value that is not used further.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Denis Rastyogin <gerben@altlinux.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20241212120618.518369-1-gerben@altlinux.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2024-12-17 15:05:39 +00:00
Richard Henderson
9a93223c86 target/arm: Convert FCVTZ[SU] (vector, fixed-point) to decodetree
Remove handle_simd_shift_fpint_conv and disas_simd_shift_imm
as these were the last insns decoded by those functions.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20241211163036.2297116-64-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2024-12-13 13:39:24 +00:00
Richard Henderson
cf866d81b8 target/arm: Pass fpstatus to vfp_sqrt*
Pass fpstatus not env, like most other fp helpers.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20241211163036.2297116-26-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2024-12-13 13:39:23 +00:00
Peter Maydell
d9c7adb601 target/arm: Store FPSR cumulative exception bits in env->vfp.fpsr
Currently we store the FPSR cumulative exception bits in the
float_status fields, and use env->vfp.fpsr only for the NZCV bits.
(The QC bit is stored in env->vfp.qc[].)

This works for TCG, but if QEMU was built without CONFIG_TCG (i.e.
with KVM support only) then we use the stub versions of
vfp_get_fpsr_from_host() and vfp_set_fpsr_to_host() which do nothing,
throwing away the cumulative exception bit state.  The effect is that
if the FPSR state is round-tripped from KVM to QEMU then we lose the
cumulative exception bits.  In particular, this will happen if the VM
is migrated.  There is no user-visible bug when using KVM with a QEMU
binary that was built with CONFIG_TCG.

Fix this by always storing the cumulative exception bits in
env->vfp.fpsr.  If we are using TCG then we may also keep pending
cumulative exception information in the float_status fields, so we
continue to fold that in on reads.

This change will also be helpful for implementing FEAT_AFP later,
because that includes a feature where in some situations we want to
cause input denormals to be flushed to zero without affecting the
existing state of the FPSR.IDC bit, so we need a place to store IDC
which is distinct from the various float_status fields.

(Note for stable backports: the bug goes back to 4a15527c9f but
this code was refactored in commits ea8618382aba..a8ab8706d4cc461, so
fixing it in branches without those refactorings will mean either
backporting the refactor or else implementing a conceptually similar
fix for the old code.)

Cc: qemu-stable@nongnu.org
Fixes: 4a15527c9f ("target/arm/vfp_helper: Restrict the SoftFloat use to TCG")
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20241011162401.3672735-1-peter.maydell@linaro.org
2024-10-29 15:04:46 +00:00
Peter Maydell
8b0898f8dd target/arm: Allow setting the FPCR.EBF bit for FEAT_EBF16
FEAT_EBF16 adds one new bit to the FPCR floating point control
register.  Allow this bit to be read and written when the ID
registers indicate the presence of the feature.

Note that because this new bit is not in FPSCR_FPCR_MASK the bit is
not visible in the AArch32 FPSCR, and FPSCR writes do not affect it.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
2024-09-05 13:12:35 +01:00
Peter Maydell
a8ab8706d4 target/arm: Allow FPCR bits that aren't in FPSCR
In order to allow FPCR bits that aren't in the FPSCR (like the new
bits that are defined for FEAT_AFP), we need to make sure that writes
to the FPSCR only write to the bits of FPCR that are architecturally
mapped, and not the others.

Implement this with a new function vfp_set_fpcr_masked() which
takes a mask of which bits to update.

(We could do the same for FPSR, but we leave that until we actually
are likely to need it.)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20240628142347.1283015-10-peter.maydell@linaro.org
2024-07-11 11:41:33 +01:00
Peter Maydell
db397a81ee target/arm: Rename FPSR_MASK and FPCR_MASK and define them symbolically
Now that we store FPSR and FPCR separately, the FPSR_MASK and
FPCR_MASK macros are slightly confusingly named and the comment
describing them is out of date.  Rename them to FPSCR_FPSR_MASK and
FPSCR_FPCR_MASK, document that they are the mask of which FPSCR bits
are architecturally mapped to which AArch64 register, and define them
symbolically rather than as hex values.  (This latter requires
defining some extra macros for bits which we haven't previously
defined.)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20240628142347.1283015-9-peter.maydell@linaro.org
2024-07-11 11:41:33 +01:00
Peter Maydell
a26db547b7 target/arm: Rename FPCR_ QC, NZCV macros to FPSR_
The QC, N, Z, C, V bits live in the FPSR, not the FPCR. Rename the
macros that define these bits accordingly.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20240628142347.1283015-8-peter.maydell@linaro.org
2024-07-11 11:41:33 +01:00
Peter Maydell
ce07ea61ed target/arm: Store FPSR and FPCR in separate CPU state fields
Now that we have refactored the set/get functions so that the FPSCR
format is no longer the authoritative one, we can keep FPSR and FPCR
in separate CPU state fields.

As well as the get and set functions, we also have a scattering of
places in the code which directly access vfp.xregs[ARM_VFP_FPSCR] to
extract single fields which are stored there.  These all change to
directly access either vfp.fpsr or vfp.fpcr, depending on the
location of the field.  (Most commonly, this is the NZCV flags.)

We make the field in the CPU state struct 64 bits, because
architecturally FPSR and FPCR are 64 bits.  However we leave the
types of the arguments and return values of the get/set functions as
32 bits, since we don't need to make that change with the current
architecture and various callsites would be unable to handle
set bits in the high half (for instance the gdbstub protocol
assumes they're only 32 bit registers).

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20240628142347.1283015-7-peter.maydell@linaro.org
2024-07-11 11:41:33 +01:00
Peter Maydell
b167325e93 target/arm: Make vfp_set_fpscr() call vfp_set_{fpcr, fpsr}
Make vfp_set_fpscr() call vfp_set_fpsr() and vfp_set_fpcr()
instead of the other way around.

The masking we do when getting and setting vfp.xregs[ARM_VFP_FPSCR]
is a little awkward, but we are going to change where we store the
underlying FPSR and FPCR information in a later commit, so it will
go away then.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20240628142347.1283015-4-peter.maydell@linaro.org
2024-07-11 11:41:33 +01:00
Peter Maydell
2de7cf9e05 target/arm: Make vfp_get_fpscr() call vfp_get_{fpcr, fpsr}
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
2024-07-11 11:41:33 +01:00
Peter Maydell
ea8618382a target/arm: Correct comments about M-profile FPSCR
The M-profile FPSCR LTPSIZE is bits [18:16]; this is the same
field as A-profile FPSCR Len, not Stride. Correct the comment
in vfp_get_fpscr().

We also implemented M-profile FPSCR.QC, but forgot to delete
a TODO comment from vfp_set_fpscr(); remove it now.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20240628142347.1283015-2-peter.maydell@linaro.org
2024-07-11 11:41:33 +01:00
Richard Henderson
7619129f0d target/arm: Fix FJCVTZS vs flush-to-zero
Input denormals cause the Javascript inexact bit
(output to Z) to be set.

Cc: qemu-stable@nongnu.org
Fixes: 6c1f6f2733 ("target/arm: Implement ARMv8.3-JSConv")
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2375
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20240625183536.1672454-4-richard.henderson@linaro.org
[PMM: fixed hardcoded tab in test case]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2024-07-01 12:48:55 +01:00
Richard Henderson
21e885aff4 target/arm: Expand vfp neg and abs inline
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20240524232121.284515-23-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2024-05-28 14:29:01 +01:00
Peter Maydell
5a534314a8 target/arm: Move feature test functions to their own header
The feature test functions isar_feature_*() now take up nearly
a thousand lines in target/arm/cpu.h. This header file is included
by a lot of source files, most of which don't need these functions.
Move the feature test functions to their own header file.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20231024163510.2972081-2-peter.maydell@linaro.org
2023-10-27 11:44:32 +01:00
Richard Henderson
34d03ad963 target/arm: Use float64_to_int32_modulo for FJCVTZS
The standard floating point results are provided by the generic routine.
We only need handle the extra Z flag result afterward.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20230527141910.1885950-5-richard.henderson@linaro.org>
2023-07-01 08:26:54 +02:00
Richard Henderson
6ce21abd40 target/arm: Improve arm_rmode_to_sf
Use proper enumeration types for input and output.
Use a const array to perform the mapping, with an
assert that the input is valid.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2023-03-13 06:44:38 -07:00
Richard Henderson
ab9ced73fa target/arm: Handle FPROUNDING_ODD in arm_rmode_to_sf
While this enumerator has been present since the first commit,
it isn't ever used.  The first actual use of round-to-odd came
with SVE, which currently uses float_round_to_odd instead of
the arm-specific enumerator.

Amusingly, the comment about unhandled TIEAWAY has been
out of date since the initial commit of translate-a64.c.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2023-03-13 06:44:38 -07:00
Joe Komlodi
103e7579dd target/arm: Check NaN mode before silencing NaN
If the CPU is running in default NaN mode (FPCR.DN == 1) and we execute
FRSQRTE, FRECPE, or FRECPX with a signaling NaN, parts_silence_nan_frac() will
assert due to fpst->default_nan_mode being set.

To avoid this, we check to see what NaN mode we're running in before we call
floatxx_silence_nan().

Signed-off-by: Joe Komlodi <joe.komlodi@xilinx.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 1624662174-175828-2-git-send-email-joe.komlodi@xilinx.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2021-07-02 11:48:36 +01:00
Peter Maydell
c485ce2c49 target/arm: Enable FPSCR.QC bit for MVE
MVE has an FPSCR.QC bit similar to the A-profile Neon one; when MVE
is implemented make the bit writeable, both in the generic "load and
store FPSCR" helper functions and in the code for handling the NZCVQC
sysreg which we had previously left as "TODO when we implement MVE".

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210614151007.4545-3-peter.maydell@linaro.org
2021-06-16 14:33:52 +01:00