Commit Graph

349 Commits

Author SHA1 Message Date
Alex Bennée
e5ef4ec28b disas: include an optional note for the start of disassembly
This will become useful shortly for providing more information about
output assembly inline. While there fix up the indenting and code
formatting in disas().

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

Message-Id: <20200513175134.19619-9-alex.bennee@linaro.org>
2020-05-15 15:25:16 +01:00
Philippe Mathieu-Daudé
dcb32f1d8f tcg: Search includes from the project root source directory
We currently search both the root and the tcg/ directories for tcg
files:

  $ git grep '#include "tcg/' | wc -l
  28

  $ git grep '#include "tcg[^/]' | wc -l
  94

To simplify the preprocessor search path, unify by expliciting the
tcg/ directory.

Patch created mechanically by running:

  $ for x in \
      tcg.h tcg-mo.h tcg-op.h tcg-opc.h \
      tcg-op-gvec.h tcg-gvec-desc.h; do \
    sed -i "s,#include \"$x\",#include \"tcg/$x\"," \
      $(git grep -l "#include \"$x\""); \
    done

Acked-by: David Gibson <david@gibson.dropbear.id.au> (ppc parts)
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Stefan Weil <sw@weilnetz.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20200101112303.20724-2-philmd@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2020-01-15 15:13:10 -10:00
Robert Foley
7606488c0e Add use of RCU for qemu_logfile.
This now allows changing the logfile while logging is active,
and also solves the issue of a seg fault while changing the logfile.

Any read access to the qemu_logfile handle will use
the rcu_read_lock()/unlock() around the use of the handle.
To fetch the handle we will use atomic_rcu_read().
We also in many cases do a check for validity of the
logfile handle before using it to deal with the case where the
file is closed and set to NULL.

The cases where we write to the qemu_logfile will use atomic_rcu_set().
Writers will also use call_rcu() with a newly added qemu_logfile_free
function for freeing/closing when readers have finished.

Signed-off-by: Robert Foley <robert.foley@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20191118211528.3221-6-robert.foley@linaro.org>
2019-12-18 20:18:02 +00:00
Robert Foley
fc59d2d870 qemu_log_lock/unlock now preserves the qemu_logfile handle.
qemu_log_lock() now returns a handle and qemu_log_unlock() receives a
handle to unlock.  This allows for changing the handle during logging
and ensures the lock() and unlock() are for the same file.

Also in target/tilegx/translate.c removed the qemu_log_lock()/unlock()
calls (and the log("\n")), since the translator can longjmp out of the
loop if it attempts to translate an instruction in an inaccessible page.

Signed-off-by: Robert Foley <robert.foley@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20191118211528.3221-5-robert.foley@linaro.org>
2019-12-18 20:18:02 +00:00
Emilio G. Cota
38b47b19ec plugin-gen: add module for TCG-related code
We first inject empty instrumentation from translator_loop.
After translation, we go through the plugins to see what
they want to register for, filling in the empty instrumentation.
If if turns out that some instrumentation remains unused, we
remove it.

This approach supports the following features:

- Inlining TCG code for simple operations. Note that we do not
  export TCG ops to plugins. Instead, we give them a C API to
  insert inlined ops. So far we only support adding an immediate
  to a u64, e.g. to count events.

- "Direct" callbacks. These are callbacks that do not go via
  a helper. Instead, the helper is defined at run-time, so that
  the plugin code is directly called from TCG. This makes direct
  callbacks as efficient as possible; they are therefore used
  for very frequent events, e.g. memory callbacks.

- Passing the host address to memory callbacks. Most of this
  is implemented in a later patch though.

- Instrumentation of memory accesses performed from helpers.
  See the corresponding comment, as well as a later patch.

Signed-off-by: Emilio G. Cota <cota@braap.org>
[AJB: add alloc_tcg_plugin_context, use glib, rm hwaddr]
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
2019-10-28 15:12:38 +00:00
Tony Nguyen
14776ab5a1 tcg: TCGMemOp is now accelerator independent MemOp
Preparation for collapsing the two byte swaps, adjust_endianness and
handle_bswap, along the I/O path.

Target dependant attributes are conditionalized upon NEED_CPU_H.

Signed-off-by: Tony Nguyen <tony.nguyen@bt.com>
Acked-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Acked-by: Cornelia Huck <cohuck@redhat.com>
Message-Id: <81d9cd7d7f5aaadfa772d6c48ecee834e9cf7882.1566466906.git.tony.nguyen@bt.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2019-09-03 08:30:38 -07:00
tony.nguyen@bt.com
52bf9771fd configure: Define target access alignment in configure
This patch moves the define of target access alignment earlier from
target/foo/cpu.h to configure.

Suggested in Richard Henderson's reply to "[PATCH 1/4] tcg: TCGMemOp is now
accelerator independent MemOp"

Signed-off-by: Tony Nguyen <tony.nguyen@bt.com>
Message-Id: <11e818d38ebc40e986cfa62dd7d0afdc@tpw09926dag18e.domain1.systemhost.net>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: tony.nguyen@bt.com <tony.nguyen@bt.com>
2019-08-20 17:26:19 +02:00
Markus Armbruster
6a0acfff99 Clean up inclusion of exec/cpu-common.h
migration/qemu-file.h neglects to include it even though it needs
ram_addr_t.  Fix that.  Drop a few superfluous inclusions elsewhere.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20190812052359.30071-14-armbru@redhat.com>
2019-08-16 13:31:52 +02:00
Like Xu
5cc8767d05 general: Replace global smp variables with smp machine properties
Basically, the context could get the MachineState reference via call
chains or unrecommended qdev_get_machine() in !CONFIG_USER_ONLY mode.

A local variable of the same name would be introduced in the declaration
phase out of less effort OR replace it on the spot if it's only used
once in the context. No semantic changes.

Signed-off-by: Like Xu <like.xu@linux.intel.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20190518205428.90532-4-like.xu@linux.intel.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
2019-07-05 17:07:36 -03:00
Richard Henderson
f75da2988e tcg: Add support for vector compare select
Perform a per-element conditional move.  This combination operation is
easier to implement on some host vector units than plain cmp+bitsel.
Omit the usual gvec interface, as this is intended to be used by
target-specific gvec expansion call-backs.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2019-05-22 15:09:43 -04:00
Richard Henderson
38dc12947e tcg: Add support for vector bitwise select
This operation performs d = (b & a) | (c & ~a), and is present
on a majority of host vector units.  Include gvec expanders.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2019-05-22 15:09:43 -04:00
Richard Henderson
bcefc90208 tcg: Add support for vector absolute value
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2019-05-13 22:52:08 +00:00
Richard Henderson
37ee55a081 tcg: Add INDEX_op_dupm_vec
Allow the backend to expand dup from memory directly, instead of
forcing the value into a temp first.  This is especially important
if integer/vector register moves do not exist.

Note that officially tcg_out_dupm_vec is allowed to fail.
If it did, we could fix this up relatively easily:

  VECE == 32/64:
    Load the value into a vector register, then dup.
    Both of these must work.

  VECE == 8/16:
    If the value happens to be at an offset such that an aligned
    load would place the desired value in the least significant
    end of the register, go ahead and load w/garbage in high bits.

    Load the value w/INDEX_op_ld{8,16}_i32.
    Attempt a move directly to vector reg, which may fail.
    Store the value into the backing store for OTS.
    Load the value into the vector reg w/TCG_TYPE_I32, which must work.
    Duplicate from the vector reg into itself, which must work.

All of which is well and good, except that all supported
hosts can support dupm for all vece, so all of the failure
paths would be dead code and untestable.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2019-05-13 22:52:08 +00:00
Richard Henderson
d6ecb4a978 tcg: Add tcg_out_dupm_vec to the backend interface
Currently stubbed out in all backends that support vectors.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2019-05-13 14:44:03 -07:00
Richard Henderson
bab1671f0f tcg: Manually expand INDEX_op_dup_vec
This case is similar to INDEX_op_mov_* in that we need to do
different things depending on the current location of the source.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
v3: Added some commentary to the tcg_reg_alloc_* functions.
2019-05-13 14:44:03 -07:00
Richard Henderson
e7632cfa8b tcg: Promote tcg_out_{dup,dupi}_vec to backend interface
The i386 backend already has these functions, and the aarch64 backend
could easily split out one.  Nothing is done with these functions yet,
but this will aid register allocation of INDEX_op_dup_vec in a later patch.

Adjust the aarch64 tcg_out_dupi_vec signature to match the new interface.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2019-05-13 14:44:03 -07:00
Richard Henderson
240c08d099 tcg: Support cross-class moves without instruction support
PowerPC Altivec does not support direct moves between vector registers
and general registers.  So when tcg_out_mov fails, we can use the
backing memory for the temporary to perform the move.

Acked-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2019-05-13 14:44:03 -07:00
Richard Henderson
78113e83e0 tcg: Return bool success from tcg_out_mov
This patch merely changes the interface, aborting on all failures,
of which there are currently none.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2019-05-13 14:44:03 -07:00
Richard Henderson
d63e3b6e69 tcg: Assert fixed_reg is read-only
The only fixed_reg is cpu_env, and it should not be modified
during any TB.  Therefore code that tries to special-case moves
into a fixed_reg is dead.  Remove it.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2019-05-13 14:44:03 -07:00
Richard Henderson
aeee05f53a tcg: Restart TB generation after out-of-line ldst overflow
This is part c of relocation overflow handling.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2019-04-24 13:05:28 -07:00
Richard Henderson
1768987b73 tcg: Restart TB generation after constant pool overflow
This is part b of relocation overflow handling.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2019-04-24 13:05:28 -07:00
Richard Henderson
7ecd02a06f tcg: Restart TB generation after relocation overflow
If the TB generates too much code, such that backend relocations
overflow, try again with a smaller TB.  In support of this, move
relocation processing from a random place within tcg_out_op, in
the handling of branch opcodes, to a new function at the end of
tcg_gen_code.

This is not a complete solution, as there are additional relocs
generated for out-of-line ldst handling and constant pools.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2019-04-24 13:05:21 -07:00
Richard Henderson
6e6c4efed9 tcg: Restart after TB code generation overflow
If a TB generates too much code, try again with fewer insns.

Fixes: https://bugs.launchpad.net/bugs/1824853
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2019-04-24 13:04:33 -07:00
Richard Henderson
fce1296f13 tcg: Add INDEX_op_extract2_{i32,i64}
This will let backends implement the double-word shift operation.

Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2019-04-24 13:04:33 -07:00
Markus Armbruster
3de2faa9a8 tcg: Simplify how dump_exec_info() prints
dump_exec_info() takes an fprintf()-like callback and a FILE * to pass
to it.

Its only caller hmp_info_jit() passes monitor_fprintf() and the
current monitor cast to FILE *.  monitor_fprintf() casts it right
back, and is otherwise identical to monitor_printf().  The
type-punning is ugly.

Drop the callback, and call qemu_printf() instead.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20190417191805.28198-5-armbru@redhat.com>
2019-04-18 22:18:59 +02:00
Markus Armbruster
d4c51a0af3 tcg: Simplify how dump_opcount_info() prints
dump_opcount_info() takes an fprintf()-like callback and a FILE * to
pass to it.

Its only caller hmp_info_opcount() passes monitor_fprintf() and the
current monitor cast to FILE *.  monitor_fprintf() casts it right
back, and is otherwise identical to monitor_printf().  The
type-punning is ugly.

Drop the callback, and call qemu_printf() instead.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20190417191805.28198-4-armbru@redhat.com>
2019-04-18 22:18:59 +02:00
Richard Henderson
bef16ab4e6 tcg: Diagnose referenced labels that have not been emitted
Currently, a jump to a label that is not defined anywhere will
be emitted not be relocated.  This results in a jump to a random
jump target.  With tcg debugging, print a diagnostic to the -d op
file and abort.

This could help debug or detect errors like
c2d9644e6d ("target/arm: Fix crash on conditional instruction in an IT block")

Reported-by: Roman Kapl <code@rkapl.cz>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2019-02-11 08:52:44 -08:00
Richard Henderson
dd0a0fcdd8 tcg: Add opcodes for vector minmax arithmetic
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2019-01-28 07:03:34 -08:00
Richard Henderson
8afaf05066 tcg: Add opcodes for vector saturated arithmetic
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2019-01-28 07:03:34 -08:00
Paolo Bonzini
eae3eb3e18 qemu/queue.h: simplify reverse access to QTAILQ
The new definition of QTAILQ does not require passing the headname,
remove it.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2019-01-11 15:46:55 +01:00
Richard Henderson
4250da1092 tcg: Improve call argument loading
Free the argument register only after we have verified that the
temporary is not already in that register.  This case is likely
now that we are back propagating the preferred register.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-12-26 06:58:43 +11:00
Richard Henderson
25f49c5f15 tcg: Record register preferences during liveness
With these preferences, we can arrange for function call arguments to
be computed into the proper registers instead of requiring extra moves.

Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-12-26 06:58:35 +11:00
Richard Henderson
ae36a246ed tcg: Add TCG_OPF_BB_EXIT
Use this to notice the opcodes that exit the TB, which implies
that local temps are really dead and need not be synced.

Previously we so marked the true end of the TB, but that was
immediately overwritten by the la_bb_end invoked by any
TCG_OPF_BB_END opcode, like exit_tb.

Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-12-26 06:58:20 +11:00
Richard Henderson
f65a061c39 tcg: Split out more subroutines from liveness_pass_1
Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-12-26 06:58:17 +11:00
Richard Henderson
2616c80821 tcg: Rename and adjust liveness_pass_1 helpers
No need for a "tcg_" prefix for a static function; we already
have another "la_" prefix for indicating liveness analysis.
Pass in nb_globals and nb_temps, as we will already have them
in registers for other loops within the parent function.

Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-12-26 06:58:09 +11:00
Richard Henderson
152c35aab4 tcg: Reindent parts of liveness_pass_1
There are two blocks of the form

    if (foo) {
        stuff1;
        goto bar;
    } else {
    baz:
        stuff2;
    }

which have unnecessary and confusing indentation.
Remove the else and unindent stuff2.

Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-12-26 06:57:57 +11:00
Richard Henderson
1894f69a61 tcg: Dump register preference info with liveness
Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-12-26 06:57:48 +11:00
Richard Henderson
d62816f2db tcg: Improve register allocation for matching constraints
Try harder to honor the output_pref.  When we're forced to allocate
a second register for the input, it does not need to use the input
constraint; that will be honored by the register we allocate for the
output and a move is already required.

Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-12-26 06:57:40 +11:00
Richard Henderson
69e3706d2b tcg: Add output_pref to TCGOp
Allocate storage for, but do not yet fill in, per-opcode
preferences for the output operands.  Pass it in to the
register allocation routines for output operands.

Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-12-26 06:57:37 +11:00
Richard Henderson
ba87719cd2 tcg: Add preferred_reg argument to tcg_reg_alloc_do_movi
Pass this through to temp_sync.

Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-12-26 06:57:34 +11:00
Richard Henderson
98b4e186c1 tcg: Add preferred_reg argument to temp_sync
Pass this through to tcg_reg_alloc.

Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-12-26 06:57:32 +11:00
Richard Henderson
b722452aef tcg: Add preferred_reg argument to temp_load
Pass this through to tcg_reg_alloc.

Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-12-26 06:57:29 +11:00
Richard Henderson
b016486e7b tcg: Add preferred_reg argument to tcg_reg_alloc
This new argument will aid register allocation by indicating how
the temporary will be used in future.  If the preference cannot
be satisfied, fall back to the constraints of the current insn.

Short circuit the preference when it cannot be satisfied or if
it does not further constrain the operation.

With an eye toward optimizing function call sequences, optimize
for the preferred_reg set containing a single register.

For the moment, all users pass 0 for preference.

Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-12-26 06:57:06 +11:00
Richard Henderson
b4fc67c7af tcg: Add reachable_code_pass
Delete trivially dead code that follows unconditional branches and
noreturn helpers.  These can occur either via optimization or via
the structure of a target's translator following an exception.

Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-12-26 06:40:30 +11:00
Richard Henderson
d88a117eaa tcg: Reference count labels
Increment when adding branches, and decrement when removing them.

Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-12-26 06:40:27 +11:00
Emilio G. Cota
ac1043f6d6 tcg: Drop nargs from tcg_op_insert_{before,after}
It's unused since 75e8b9b7aa.

Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-Id: <20181209193749.12277-9-cota@braap.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-12-17 06:04:44 +03:00
Richard Henderson
6ac1778676 tcg: Return success from patch_reloc
This will move the assert for success from within (subroutines of)
patch_reloc into the callers.  It will also let new code do something
different when a relocation is out of range.

For the moment, all backends are trivially converted to return true.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-12-17 06:04:43 +03:00
Emilio G. Cota
72fd2efbbd tcg: distribute tcg_time into TCG contexts
When we implemented per-vCPU TCG contexts, we forgot to also
distribute the tcg_time counter, which has remained as a global
accessed without any serialization, leading to potentially missed
counts.

Fix it by distributing the field over the TCG contexts, embedding
it into TCGProfile with a field called "cpu_exec_time", which is more
descriptive than "tcg_time". Add a function to query this value
directly, and for completeness, fill in the field in
tcg_profile_snapshot, even though its callers do not use it.

Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-Id: <20181010144853.13005-5-cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-18 18:58:10 -07:00
Emilio G. Cota
c1f543b739 tcg: fix use of uninitialized variable under CONFIG_PROFILER
We forgot to initialize n in commit 15fa08f845 ("tcg: Dynamically
allocate TCGOps", 2017-12-29).

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-Id: <20181010144853.13005-3-cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-10-18 18:58:10 -07:00
Richard Henderson
9f75462065 tcg: Reduce max TB opcode count
Also, assert that we don't overflow any of two different offsets into
the TB. Both unwind and goto_tb both record a uint16_t for later use.

This fixes an arm-softmmu test case utilizing NEON in which there is
a TB generated that runs to 7800 opcodes, and compiles to 96k on an
x86_64 host.  This overflows the 16-bit offset in which we record the
goto_tb reset offset.  Because of that overflow, we install a jump
destination that goes to neverland.  Boom.

With this reduced op count, the same TB compiles to about 48k for
aarch64, ppc64le, and x86_64 hosts, and neither assertion fires.

Cc: qemu-stable@nongnu.org
Reported-by: "Jason A. Donenfeld" <Jason@zx2c4.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2018-06-15 09:39:53 -10:00