The new placement of the TB means that we can use one insn
to load the goto_tb destination directly from the TB.
Signed-off-by: Richard Henderson <rth@twiddle.net>
The new placement of the TB means that we can use one insn
to load the return value for exit_tb returning the TB pointer.
Tested-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>
Allocating an arbitrarily-sized array of tbs results in either
(a) a lot of memory wasted or (b) unnecessary flushes of the code
cache when we run out of TB structs in the array.
An obvious solution would be to just malloc a TB struct when needed,
and keep the TB array as an array of pointers (recall that tb_find_pc()
needs the TB array to run in O(log n)).
Perhaps a better solution, which is implemented in this patch, is to
allocate TB's right before the translated code they describe. This
results in some memory waste due to padding to have code and TBs in
separate cache lines--for instance, I measured 4.7% of padding in the
used portion of code_gen_buffer when booting aarch64 Linux on a
host with 64-byte cache lines. However, it can allow for optimizations
in some host architectures, since TCG backends could safely assume that
the TB and the corresponding translated code are very close to each
other in memory. See this message by rth for a detailed explanation:
https://lists.gnu.org/archive/html/qemu-devel/2017-03/msg05172.html
Subject: Re: GSoC 2017 Proposal: TCG performance enhancements
Message-ID: <1e67644b-4b30-887e-d329-1848e94c9484@twiddle.net>
Suggested-by: Richard Henderson <rth@twiddle.net>
Reviewed-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-Id: <1496790745-314-3-git-send-email-cota@braap.org>
[rth: Simplify the arithmetic in tcg_tb_alloc]
Signed-off-by: Richard Henderson <rth@twiddle.net>
Add helpers to gather cache info from the host at init-time.
For now, only export the host's I/D cache line sizes, which we
will use to improve cache locality to avoid false sharing.
Suggested-by: Richard Henderson <rth@twiddle.net>
Suggested-by: Geert Martin Ijewski <gm.ijewski@web.de>
Tested-by: Geert Martin Ijewski <gm.ijewski@web.de>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-Id: <1496794624-4083-1-git-send-email-cota@braap.org>
[rth: Move all implementations from tcg/ppc/]
Signed-off-by: Richard Henderson <rth@twiddle.net>
move tcg-runtime.c, translate-all.(ch) and translate-common.c into
accel/tcg/ subdirectory and updated related trace-events file.
Signed-off-by: Yang Zhong <yang.zhong@intel.com>
Message-Id: <1496383606-18060-4-git-send-email-yang.zhong@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
In theory this would re-enable usage of QEMU on an armv4 host.
Whether this is worthwhile is debatable -- we've been unconditionally
issuing the armv5t BX instruction in the prologue since 2011 without
complaint. Possibly we should simply require an armv6 host.
Signed-off-by: Richard Henderson <rth@twiddle.net>
Instead of exporting goto_ptr directly to TCG frontends, export
tcg_gen_lookup_and_goto_ptr(), which calls goto_ptr with the pointer
returned by the lookup_tb_ptr() helper. This is the only use case
we have for goto_ptr and lookup_tb_ptr, so having this function is
very convenient. Furthermore, it trivially allows us to avoid calling
the lookup helper if goto_ptr is not implemented by the backend.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-Id: <1493263764-18657-2-git-send-email-cota@braap.org>
Message-Id: <1493263764-18657-3-git-send-email-cota@braap.org>
Message-Id: <1493263764-18657-4-git-send-email-cota@braap.org>
Message-Id: <1493263764-18657-5-git-send-email-cota@braap.org>
[rth: Squashed 4 related commits.]
Signed-off-by: Richard Henderson <rth@twiddle.net>
Users of tcg_gen_atomic_cmpxchg and do_atomic_op rightfully utilize
the output. Even though this code is dead, it gets translated, and
without the initialization we encounter a tcg_error.
Reported-by: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
Tested-by: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
Tested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>
We already require gcc 4.1 or newer (for the atomic
support), so the fallback codepaths for older gcc
versions than that are now dead code and we can
just delete them.
NB: clang reports itself as gcc 4.2 (regardless of
clang version), so clang won't be using the fallbacks
either.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
The C store helper functions take the address argument as a
target_ulong type; if this is 32 bit but the host is 64 bit
then the SPARC calling convention requires that the caller
must zero extend the value. We weren't doing this, which
meant we could pass values to the caller with high bits set
and QEMU would crash if it was compiled with optimizations.
In particular, the i386 BIOS would not start.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1490871151-29029-3-git-send-email-peter.maydell@linaro.org
Reviewed-by: Richard Henderson <rth@twiddle.net>
The C store helper functions take the data argument as a uint8_t,
uint16_t, etc depending on the store size. The SPARC calling
convention requires that data types smaller than the register
size must be extended by the caller. We weren't doing this,
which meant that if QEMU was compiled with optimizations enabled
we could end up storing incorrect values to guest memory.
(In particular the i386 guest BIOS would crash on startup.)
Add code to the trampolines that call the store helpers to
do the zero extension as required.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 1490871151-29029-2-git-send-email-peter.maydell@linaro.org
Reviewed-by: Richard Henderson <rth@twiddle.net>
Merge the original development branch due to breakage caused by the
MTTCG merge.
Conflicts:
cpu-exec.c
translate-common.c
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
To fix the following warnings:
In file included from /users/pranith/qemu/tcg/tcg.c:255:
/users/pranith/qemu/tcg/aarch64/tcg-target.inc.c:879:24: warning: implicit conversion from enumeration type 'TCGMemOp' (aka 'enum TCGMemOp') to different enumeration type 'TCGType' (aka 'enum TCGType')
[-Wenum-conversion]
tcg_out_cmp(s, ext, a, b, b_const);
~~~~~~~~~~~ ^~~
/users/pranith/qemu/tcg/aarch64/tcg-target.inc.c:893:36: warning: implicit conversion from enumeration type 'TCGMemOp' (aka 'enum TCGMemOp') to different enumeration type 'TCGType' (aka 'enum TCGType')
[-Wenum-conversion]
tcg_out_insn(s, 3201, CBZ, ext, a, offset);
~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~
/users/pranith/qemu/tcg/aarch64/tcg-target.inc.c:389:65: note: expanded from macro 'tcg_out_insn'
glue(tcg_out_insn_,FMT)(S, glue(glue(glue(I,FMT),_),OP), ## __VA_ARGS__)
^
/users/pranith/qemu/tcg/aarch64/tcg-target.inc.c:895:37: warning: implicit conversion from enumeration type 'TCGMemOp' (aka 'enum TCGMemOp') to different enumeration type 'TCGType' (aka 'enum TCGType')
[-Wenum-conversion]
tcg_out_insn(s, 3201, CBNZ, ext, a, offset);
~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~
/users/pranith/qemu/tcg/aarch64/tcg-target.inc.c:389:65: note: expanded from macro 'tcg_out_insn'
glue(tcg_out_insn_,FMT)(S, glue(glue(glue(I,FMT),_),OP), ## __VA_ARGS__)
^
/users/pranith/qemu/tcg/aarch64/tcg-target.inc.c:1610:27: warning: implicit conversion from enumeration type 'TCGType' (aka 'enum TCGType') to different enumeration type 'TCGMemOp' (aka 'enum TCGMemOp')
[-Wenum-conversion]
tcg_out_brcond(s, ext, a2, a0, a1, const_args[1], arg_label(args[3]));
~~~~~~~~~~~~~~ ^~~
Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Message-Id: <20170217154311.13920-1-bobby.prani@gmail.com>
Signed-off-by: Richard Henderson <rth@twiddle.net>
This enables the multi-threaded system emulation by default for ARMv7
and ARMv8 guests using the x86_64 TCG backend. This is because on the
guest side:
- The ARM translate.c/translate-64.c have been converted to
- use MTTCG safe atomic primitives
- emit the appropriate barrier ops
- The ARM machine has been updated to
- hold the BQL when modifying shared cross-vCPU state
- defer powerctl changes to async safe work
All the host backends support the barrier and atomic primitives but
need to provide same-or-better support for normal load/store
operations.
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Acked-by: Peter Maydell <peter.maydell@linaro.org>
Tested-by: Pranith Kumar <bobby.prani@gmail.com>
Reviewed-by: Pranith Kumar <bobby.prani@gmail.com>
We know there will be cases where MTTCG won't work until additional work
is done in the front/back ends to support. It will however be useful to
be able to turn it on.
As a result MTTCG will default to off unless the combination is
supported. However the user can turn it on for the sake of testing.
Signed-off-by: KONRAD Frederic <fred.konrad@greensocs.com>
[AJB: move to -accel tcg,thread=multi|single, defaults]
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
We'll be using the memory ordering definitions to define values for
both the host and guest. To avoid fighting with circular header
dependencies just move these types into their own minimal header.
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
The icount interrupt flag and tcg_exit_req serve almost the same
purpose, let's make them completely the same.
The former TB_EXIT_REQUESTED and TB_EXIT_ICOUNT_EXPIRED cases are
unified, since we can distinguish them from the value of the
interrupt flag.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
tb_jmp_insn_offset and tb_jmp_reset_offset are pointers
and cannot be used with ARRAY_SIZE.
Signed-off-by: Stefan Weil <sw@weilnetz.de>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Message-id: 20170202195601.11286-1-sw@weilnetz.de
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This reverts commit 4ac7691073.
This fixes
http://lists.nongnu.org/archive/html/qemu-devel/2017-01/msg03062.html
While I think we could get away with relying on the undocumented
behaviour, the tcg constraint system isn't powerful enough to
properly describe the required (non-)overlap conditions.
Reported-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Richard Henderson <rth@twiddle.net>
There were some patterns, like 0x0000_ffff_ffff_00ff, for which we
would select to begin a multi-insn sequence with MOVN, but would
fail to set the 0x0000 lane back from 0xffff.
Signed-off-by: Richard Henderson <rth@twiddle.net>
Message-Id: <20161207180727.6286-3-rth@twiddle.net>
When al == xzr, we cannot use addi/subi because that encodes xsp.
Force a zero into the temp register for that (rare) case.
Signed-off-by: Richard Henderson <rth@twiddle.net>
Message-Id: <20161207180727.6286-2-rth@twiddle.net>
The number of actual invocations of ctpop itself does not warrent
an opcode, but it is very helpful for POWER7 to use in generating
an expansion for ctz.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>
The number of actual invocations does not warrent an opcode,
and the backends generating it. But at least we can eliminate
redundant helpers.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>
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>
