The ISA manual documents the output is undefined if the input was zero.
However, we document in target-i386 that the behavior of real silicon
is to preserve the contents of the output register. We also mention
that there are real applications that depend on this. That this is
baked into silicon is mentioned as a potential cause for some false
sharing behaviour wrt lzcnt/tzcnt.
Taking advantage of this allows us to save 2 insns in the normal case,
and 4 insns for i686 emulating a 64-bit clz.
Signed-off-by: Richard Henderson <rth@twiddle.net>
Previously we could not have different constraints for different ISA levels,
which prevented us from eliding the matching constraint for shifts.
We do now have to make sure that the operands match for constant shifts.
We can also handle some small left shifts via lea.
Signed-off-by: Richard Henderson <rth@twiddle.net>
Use a switch instead of searching a table. Share constraints between
32-bit and 64-bit, when at all possible.
Signed-off-by: Richard Henderson <rth@twiddle.net>
This allows an output operand to match an input operand
only when the input operand needs a register.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>
This will let us choose how to interpret a given constraint
depending on whether the opcode is 32- or 64-bit. Which will
let us share more constraint combinations between opcodes.
At the same time, change the interface to return the advanced
pointer instead of passing it in/out by reference.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>
This will allow the target to tailor the constraints to the
auto-detected ISA extensions.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>
This is the same concept as, and same markup as, the
early clobber markup in gcc.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>
Use the new primitives for RDWINM and RLDICL.
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Richard Henderson <rth@twiddle.net>
A couple of places where it was easy to identify a right-shift
followed by an extract or and-with-immediate, and the obvious
sign-extract from a high byte register.
Acked-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Richard Henderson <rth@twiddle.net>
Since we can no longer use matching constraints, this does
mean we must handle that data movement by hand.
Signed-off-by: Richard Henderson <rth@twiddle.net>
This lets us expose facilities to TCG_TARGET_HAS_* defines
directly, rather than hiding behind function calls.
Signed-off-by: Richard Henderson <rth@twiddle.net>
This allows us to use this detection within the TCG_TARGET_HAS_*
macros, instead of requiring a function call into tcg-target.inc.c.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>
While we don't require a new opcode, it is handy to have an expander
that knows the first source is zero.
Signed-off-by: Richard Henderson <rth@twiddle.net>
Assert that len is not 0.
Since we have asserted that ofs + len <= N, a later
check for len == N implies that ofs == 0.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>
Adds tcg_gen_extract_* and tcg_gen_sextract_* for extraction of
fixed position bitfields, much like we already have for deposit.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>
beginnings of iotlb support for vhost
acpi hotplug rework
vhost net tx flush on link down
passing mtu to guests
hotplug for virtio crypto
fixes and cleanups all over the place
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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Merge remote-tracking branch 'remotes/mst/tags/for_upstream' into staging
virtio, vhost, pc: fixes, features
beginnings of iotlb support for vhost
acpi hotplug rework
vhost net tx flush on link down
passing mtu to guests
hotplug for virtio crypto
fixes and cleanups all over the place
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
# gpg: Signature made Tue 10 Jan 2017 05:37:48 GMT
# gpg: using RSA key 0x281F0DB8D28D5469
# gpg: Good signature from "Michael S. Tsirkin <mst@kernel.org>"
# gpg: aka "Michael S. Tsirkin <mst@redhat.com>"
# Primary key fingerprint: 0270 606B 6F3C DF3D 0B17 0970 C350 3912 AFBE 8E67
# Subkey fingerprint: 5D09 FD08 71C8 F85B 94CA 8A0D 281F 0DB8 D28D 5469
* remotes/mst/tags/for_upstream: (41 commits)
acpi-test: update expected files
memhp: move DIMM devices into dedicated scope with related common methods
memhp: don't generate memory hotplug AML if it's not enabled/supported
memhp: move memory hotplug only defines to memory_hotplug.c
memhp: move GPE handler_E03 into build_memory_hotplug_aml()
memhp: merge build_memory_devices() into build_memory_hotplug_aml()
memhp: consolidate scattered MHPD device declaration
memhp: move build_memory_devices() into memory_hotplug.c
memhp: move build_memory_hotplug_aml() into memory_hotplug.c
tests: pc: add memory hotplug acpi tables tests
virtio-net: Add MTU feature support
vhost-net: Notify the backend about the host MTU
vhost-user: Add MTU protocol feature and op
net: virtio-net discards TX data after link down
virtio: Introduce virtqueue_drop_all procedure
net: vhost stop updates virtio queue state
net: Add virtio queue interface to update used index from vring state
balloon: Don't balloon roms
virtio: fix vq->inuse recalc after migr
pcie_aer: support configurable AER capa version
...
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Richard Henderson
Peter Maydell