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Our current codegen for MVE always calls out to helper functions,
because some byte lanes might be predicated. The common case is that
in fact there is no predication active and all lanes should be
updated together, so we can produce better code by detecting that and
using the TCG generic vector infrastructure.
Add a TB flag that is set when we can guarantee that there is no
active MVE predication, and a bool in the DisasContext. Subsequent
patches will use this flag to generate improved code for some
instructions.
In most cases when the predication state changes we simply end the TB
after that instruction. For the code called from vfp_access_check()
that handles lazy state preservation and creating a new FP context,
we can usually avoid having to try to end the TB because luckily the
new value of the flag following the register changes in those
sequences doesn't depend on any runtime decisions. We do have to end
the TB if the guest has enabled lazy FP state preservation but not
automatic state preservation, but this is an odd corner case that is
not going to be common in real-world code.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210913095440.13462-4-peter.maydell@linaro.org
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Implement the MVE VMOV forms that move data between 2 general-purpose
registers and 2 32-bit lanes in a vector register.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
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In a CPU with MVE, the VMOV (vector lane to general-purpose register)
and VMOV (general-purpose register to vector lane) insns are not
predicated, but they are subject to beatwise execution if they
are not in an IT block.
Since our implementation always executes all 4 beats in one tick,
this means only that we need to handle PSR.ECI:
* we must do the usual check for bad ECI state
* we must advance ECI state if the insn succeeds
* if ECI says we should not be executing the beat corresponding
to the lane of the vector register being accessed then we
should skip performing the move
Note that if PSR.ECI is non-zero then we cannot be in an IT block.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210617121628.20116-45-peter.maydell@linaro.org
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Instead of open-coding the "take NOCP exception if FPU disabled,
otherwise call gen_preserve_fp_state()" code in the accessors for
FPCXT_NS, add an argument to vfp_access_check_m() which tells it to
skip the gen_update_fp_context() call, so we can use it for the
FPCXT_NS case.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210618141019.10671-8-peter.maydell@linaro.org
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vfp_access_check and its helper routine full_vfp_access_check() has
gradually grown and is now an awkward mix of A-profile only and
M-profile only pieces. Refactor it into an A-profile only and an
M-profile only version, taking advantage of the fact that now the
only direct call to full_vfp_access_check() is in A-profile-only
code.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210618141019.10671-7-peter.maydell@linaro.org
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Factor the code in full_vfp_access_check() which updates the
ownership of the FP context and creates a new FP context
out into its own function.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210618141019.10671-6-peter.maydell@linaro.org
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The M-profile architecture requires that accesses to FPCXT_NS when
there is no active FP state must not take a NOCP fault even if the
FPU is disabled. We were not implementing this correctly, because
in our decode we catch the NOCP faults early in m-nocp.decode.
Fix this bug by moving all the handling of M-profile FP system
register accesses from vfp.decode into m-nocp.decode and putting
it above the NOCP blocks. This provides the correct behaviour:
* for accesses other than FPCXT_NS the trans functions call
vfp_access_check(), which will check for FPU disabled and
raise a NOCP exception if necessary
* for FPCXT_NS we have the special case code that doesn't
call vfp_access_check()
* when these trans functions want to raise an UNDEF they return
false, so the decoder will fall through into the NOCP blocks.
This means that NOCP correctly takes precedence over UNDEF
for these insns. (This is a difference from the other insns
handled by m-nocp.decode, where UNDEF takes precedence and
which we implement by having those trans functions call
unallocated_encoding() in the appropriate places.)
[Note for backport to stable: this commit has a semantic dependency
on commit 9a486856e9173af, which was not marked as cc-stable because
we didn't know we'd need it for a for-stable bugfix.]
Cc: qemu-stable@nongnu.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210618141019.10671-4-peter.maydell@linaro.org
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If the guest makes an FPCXT_NS access when the FPU is disabled,
one of two things happens:
* if there is no active FP context, then the insn behaves the
same way as if the FPU was enabled: writes ignored, reads
same value as FPDSCR_NS
* if there is an active FP context, then we take a NOCP
exception
Add code to the sysreg read/write functions which emits
code to take the NOCP exception in the latter case.
At the moment this will never be used, because the NOCP checks in
m-nocp.decode happen first, and so the trans functions are never
called when the FPU is disabled. The code will be needed when we
move the sysreg access insns to before the NOCP patterns in the
following commit.
Cc: qemu-stable@nongnu.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210618141019.10671-3-peter.maydell@linaro.org
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In the code for handling VFP system register accesses there is some
stray whitespace after a unary '-' operator, and also some incorrect
indent in a couple of function prototypes. We're about to move this
code to another file, so fix the code style issues first so
checkpatch doesn't complain about the code-movement patch.
Cc: qemu-stable@nongnu.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210618141019.10671-2-peter.maydell@linaro.org
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In commit a3494d4671797c we reworked the M-profile handling of its
checks for when the NOCP exception should be raised because the FPU
is disabled, so that (in line with the architecture) the NOCP check
is done early over a large range of the encoding space, and takes
precedence over UNDEF exceptions. As part of this, we removed the
code from full_vfp_access_check() which raised an exception there for
M-profile with the FPU disabled, because it was no longer reachable.
For MVE, some instructions which are outside the "coprocessor space"
region of the encoding space must nonetheless do "is the FPU enabled"
checks and possibly raise a NOCP exception. (In particular this
covers the MVE-specific low-overhead branch insns LCTP, DLSTP and
WLSTP.) To support these insns, reinstate the code in
full_vfp_access_check(), so that their trans functions can call
vfp_access_check() and get the correct behaviour.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210614151007.4545-6-peter.maydell@linaro.org
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On A-profile, PSR bits [15:10][26:25] are always the IT state bits.
On M-profile, some of the reserved encodings of the IT state are used
to instead indicate partial progress through instructions that were
interrupted partway through by an exception and can be resumed.
These resumable instructions fall into two categories:
(1) load/store multiple instructions, where these bits are called
"ICI" and specify the register in the ldm/stm list where execution
should resume. (Specifically: LDM, STM, VLDM, VSTM, VLLDM, VLSTM,
CLRM, VSCCLRM.)
(2) MVE instructions subject to beatwise execution, where these bits
are called "ECI" and specify which beats in this and possibly also
the following MVE insn have been executed.
There are also a few insns (LE, LETP, and BKPT) which do not use the
ICI/ECI bits but must leave them alone.
Otherwise, we should raise an INVSTATE UsageFault for any attempt to
execute an insn with non-zero ICI/ECI bits.
So far we have been able to ignore ECI/ICI, because the architecture
allows the IMPDEF choice of "always restart load/store multiple from
the beginning regardless of ICI state", so the only thing we have
been missing is that we don't raise the INVSTATE fault for bad guest
code. However, MVE requires that we honour ECI bits and do not
rexecute beats of an insn that have already been executed.
Add the support in the decoder for handling ECI/ICI:
* identify the ECI/ICI case in the CONDEXEC TB flags
* when a load/store multiple insn succeeds, it updates the ECI/ICI
state (both in DisasContext and in the CPU state), and sets a flag
to say that the ECI/ICI state was handled
* if we find that the insn we just decoded did not handle the
ECI/ICI state, we delete all the code that we just generated for
it and instead emit the code to raise the INVFAULT. This allows
us to avoid having to update every non-MVE non-LDM/STM insn to
make it check for "is ECI/ICI set?".
We continue with our existing IMPDEF choice of not caring about the
ICI state for the load/store multiples and simply restarting them
from the beginning. Because we don't allow interrupts in the middle
of an insn, the only way we would see this state is if the guest set
ICI manually on return from an exception handler, so it's a corner
case which doesn't merit optimisation.
ICI update for LDM/STM is simple -- it always zeroes the state. ECI
update for MVE beatwise insns will be a little more complex, since
the ECI state may include information for the following insn.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210614151007.4545-5-peter.maydell@linaro.org
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When MVE is supported, the VPR register has a place on the exception
stack frame in a previously reserved slot just above the FPSCR.
It must also be zeroed in various situations when we invalidate
FPU context.
Update the code which handles the stack frames (exception entry and
exit code, VLLDM, and VLSTM) to save/restore VPR.
Update code which invalidates FP registers (mostly also exception
entry and exit code, but also VSCCLRM and the code in
full_vfp_access_check() that corresponds to the ExecuteFPCheck()
pseudocode) to zero VPR.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210614151007.4545-4-peter.maydell@linaro.org
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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
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This is the 64-bit BFCVT and the 32-bit VCVT{B,T}.BF16.F32.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210525225817.400336-4-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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If MVE is implemented for an M-profile CPU then it has a VPR
register, which tracks predication information.
Implement the read and write handling of this register, and
the migration of its state.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210520152840.24453-7-peter.maydell@linaro.org
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The fp_sysreg_checks() function is supposed to be returning an
FPSysRegCheckResult, which is an enum with three possible values.
However, three places in the function "return false" (a hangover from
a previous iteration of the design where the function just returned a
bool). Make these return FPSysRegCheckFailed instead (for no
functional change, since both false and FPSysRegCheckFailed are
zero).
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210520152840.24453-6-peter.maydell@linaro.org
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Split out the handling of VMOV_reg_sp and VMOV_reg_dp so that we can
permit the insns if either FP or MVE are present.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210520152840.24453-5-peter.maydell@linaro.org
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The do_vfp_2op_sp() and do_vfp_2op_dp() functions currently check
whether floating point is supported via the aa32_fpdp_v2 and
aa32_fpsp_v2 isar checks. For v8.1M MVE support, the VMOV_reg trans
functions (but not any of the others) need to update this to also
allow the insn if MVE is implemented. Move the check out of the do_
function and into its callsites (which are all implemented via the
DO_VFP_2OP macro), so we have a place to change the check for the
VMOV insns.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210520152840.24453-4-peter.maydell@linaro.org
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Some v8M instructions are present if either the floating point
extension or MVE is implemented. Update our implementation of them
to check for MVE as well as for FP.
This is all the insns which use CheckDecodeFaults(ExtType_MveOrFp) or
CheckDecodeFaults(ExtType_MveOrDpFp) in their pseudocode, which are
essentially the loads and stores, moves and sysreg accesses, except
for VMOV_reg_sp and VMOV_reg_dp, which we handle in subsequent
patches because they need a refactor to provide a place to put the
new MVE check.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210520152840.24453-3-peter.maydell@linaro.org
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Switch translate-vfp.c.inc from being #included into translate.c
to being its own compilation unit.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210430132740.10391-9-peter.maydell@linaro.org
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