Let the backend do something special for truncation.
Signed-off-by: NRichard Henderson <rth@twiddle.net>

By inspection, for a deposit(x, y, 0, 64), we'd have a shift of (1<<64)
and everything else falls apart.  But we can reuse the existing deposit
logic to get this right.
Signed-off-by: NRichard Henderson <rth@twiddle.net>

The TCG result would be undefined, but we can at least produce one
plausible result and avoid triggering the wrath of analysis tools.
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRichard Henderson <rth@twiddle.net>

Recognize 0 operand to andc, and -1 operands to and, orc, eqv.
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NAurelien Jarno <aurelien@aurel32.net>
Signed-off-by: NRichard Henderson <rth@twiddle.net>

Like we already do for SUB and XOR.
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NAurelien Jarno <aurelien@aurel32.net>
Signed-off-by: NRichard Henderson <rth@twiddle.net>

Given, of course, an appropriate constant.  These could be generated
from the "canonical" operation for inversion on the guest, or via
other optimizations.
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NAurelien Jarno <aurelien@aurel32.net>
Signed-off-by: NRichard Henderson <rth@twiddle.net>

Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NAurelien Jarno <aurelien@aurel32.net>
Signed-off-by: NRichard Henderson <rth@twiddle.net>

Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>
Signed-off-by: NRichard Henderson <rth@twiddle.net>

The shl_i32 op might set some bits of the unused 32 high bits of the
mask. Fix that by clearing the unused 32 high bits for all 32-bit ops
except load/store which operate on tl values.
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>
Signed-off-by: NRichard Henderson <rth@twiddle.net>

Known-zero bits optimization is a great idea that helps to generate more
optimized code. However the current implementation only works in very few
cases as the computed mask is not saved.

Fix this to make it really working.
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>
Signed-off-by: NRichard Henderson <rth@twiddle.net>

32-bit versions of sar and shr ops should not propagate known-zero bits
from the unused 32 high bits. For sar it could even lead to wrong code
being generated.

Cc: qemu-stable@nongnu.org
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>
Signed-off-by: NRichard Henderson <rth@twiddle.net>

Signed-off-by: NStefan Weil <sw@weilnetz.de>

Reviewed-by: NAurelien Jarno <aurelien@aurel32.net>
Signed-off-by: NRichard Henderson <rth@twiddle.net>

Use them in places where mulu2 and muls2 are used.
Optimize mulx2 with dead low part to mulxh.
Reviewed-by: NAurelien Jarno <aurelien@aurel32.net>
Signed-off-by: NRichard Henderson <rth@twiddle.net>

When setcond2 is rewritten into setcond, the state of the destination
temp should be reset, so that a copy of the previous value is not
used instead of the result.
Reported-by: NMichael Tokarev <mjt@tls.msk.ru>
Reviewed-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

Cc: Blue Swirl <blauwirbel@gmail.com>
Signed-off-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

Signed-off-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

Matching the 32-bit multiword arithmetic that we already have.
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

This adds two optimizations using the non-zero bit mask.  In some cases
involving shifts or ANDs the value can become zero, and can thus be
optimized to a move of zero.  Second, useless zero-extension or an
AND with constant can be detected that would only zero bits that are
already zero.

The main advantage of this optimization is that it turns zero-extensions
into moves, thus enabling much better copy propagation (around 1% code
reduction).  Here is for example a "test $0xff0000,%ecx + je" before
optimization:

 mov_i64 tmp0,rcx
 movi_i64 tmp1,$0xff0000
 discard cc_src
 and_i64 cc_dst,tmp0,tmp1
 movi_i32 cc_op,$0x1c
 ext32u_i64 tmp0,cc_dst
 movi_i64 tmp12,$0x0
 brcond_i64 tmp0,tmp12,eq,$0x0

and after (without patch on the left, with on the right):

 movi_i64 tmp1,$0xff0000                 movi_i64 tmp1,$0xff0000
 discard cc_src                          discard cc_src
 and_i64 cc_dst,rcx,tmp1                 and_i64 cc_dst,rcx,tmp1
 movi_i32 cc_op,$0x1c                    movi_i32 cc_op,$0x1c
 ext32u_i64 tmp0,cc_dst
 movi_i64 tmp12,$0x0                     movi_i64 tmp12,$0x0
 brcond_i64 tmp0,tmp12,eq,$0x0           brcond_i64 cc_dst,tmp12,eq,$0x0

Other similar cases: "test %eax, %eax + jne" where eax is already 32-bit
(after optimization, without patch on the left, with on the right):

 discard cc_src                          discard cc_src
 mov_i64 cc_dst,rax                      mov_i64 cc_dst,rax
 movi_i32 cc_op,$0x1c                    movi_i32 cc_op,$0x1c
 ext32u_i64 tmp0,cc_dst
 movi_i64 tmp12,$0x0                     movi_i64 tmp12,$0x0
 brcond_i64 tmp0,tmp12,ne,$0x0           brcond_i64 rax,tmp12,ne,$0x0

"test $0x1, %dl + je":

 movi_i64 tmp1,$0x1                      movi_i64 tmp1,$0x1
 discard cc_src                          discard cc_src
 and_i64 cc_dst,rdx,tmp1                 and_i64 cc_dst,rdx,tmp1
 movi_i32 cc_op,$0x1a                    movi_i32 cc_op,$0x1a
 ext8u_i64 tmp0,cc_dst
 movi_i64 tmp12,$0x0                     movi_i64 tmp12,$0x0
 brcond_i64 tmp0,tmp12,eq,$0x0           brcond_i64 cc_dst,tmp12,eq,$0x0

In some cases TCG even outsmarts GCC. :)  Here the input code has
"and $0x2,%eax + movslq %eax,%rbx + test %rbx, %rbx" and the optimizer,
thanks to copy propagation, does the following:

 movi_i64 tmp12,$0x2                     movi_i64 tmp12,$0x2
 and_i64 rax,rax,tmp12                   and_i64 rax,rax,tmp12
 mov_i64 cc_dst,rax                      mov_i64 cc_dst,rax
 ext32s_i64 tmp0,rax                  -> nop
 mov_i64 rbx,tmp0                     -> mov_i64 rbx,cc_dst
 and_i64 cc_dst,rbx,rbx               -> nop
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

Add a "mask" field to the tcg_temp_info struct.  A bit that is zero
in "mask" will always be zero in the corresponding temporary.
Zero bits in the mask can be produced from moves of immediates,
zero-extensions, ANDs with constants, shifts; they can then be
be propagated by logical operations, shifts, sign-extensions,
negations, deposit operations, and conditional moves.  Other
operations will just reset the mask to all-ones, i.e. unknown.

[rth: s/target_ulong/tcg_target_ulong/]
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

The next patch will add to the TCG optimizer a field that should be
non-zero in the default case.  Thus, replace the memset of the
temps array with a loop.  Only the state field has to be up-to-date,
because others are not used except if the state is TCG_TEMP_COPY
or TCG_TEMP_CONST.

[rth: Extracted the loop to a function.]
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

Signed-off-by: NEvgeny Voevodin <e.voevodin@samsung.com>
Reviewed-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

The current helper flags, TCG_CALL_CONST and TCG_CALL_PURE might be
confusing and doesn't provide enough granularity for some helpers (FP
helpers for example).

This patch changes them into the following helpers flags:
- TCG_CALL_NO_READ_GLOBALS means that the helper does not read globals,
  either directly or via an exception. They will not be saved to their
  canonical location before calling the helper.
- TCG_CALL_NO_WRITE_GLOBALS means that the helper does not modify any
  globals. They will only be saved to their canonical locations before
  calling helpers, but they won't be reloaded afterwise.
- TCG_CALL_NO_SIDE_EFFECTS means that the call to the function is
  removed if the return value is not used.

It provides convenience flags, to avoid helper definitions longer than
80 characters. It also provides compatibility flags, and updates the
documentation.
Reviewed-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

Like add2, do operand ordering, constant folding, and dead operand
elimination.  The latter happens about 15% of all mulu2 during an
x86_64 bios boot.
Signed-off-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

Signed-off-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

Signed-off-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

We can re-use these for implementing double-word folding.
Signed-off-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

Signed-off-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

This saves a whole lot of repetitive code sequences.
Signed-off-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

Signed-off-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

Signed-off-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

Reduces code duplication and prefers

  movcond d, c1, c2, const, s
to
  movcond d, c1, c2, s, const

It also prefers

  add r, r, c
over
  add r, c, r

when both inputs are known constants.  This doesn't matter for true add, as
we will fully constant fold that.  But it matters for a follow-on patch using
this routine for add2 which may not be fully foldable.
Signed-off-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

There are several cases that can be handled easier inside both
translators and code generators if we have out-of-band values
for conditions.  It's easy enough to handle ALWAYS and NEVER in
the natural way inside the tcg middle-end.
Signed-off-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

Reviewed-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

The "op a, a, b" form is better handled on non-RISC host than the "op
a, b, a" form, so swap the arguments to this form when possible, and
when b is not a constant.

This reduces the number of generated instructions by a tiny bit.
Reviewed-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

When both argument of brcond/movcond/setcond are the same or when one
of the two values is a constant equal to zero, it's possible to do
further optimizations.
Reviewed-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

Now that it's possible to detect copies, we can optimize the case
the "op r, a, a => movi r, 0". This helps in the computation of
overflow flags when one of the two args is 0.
Reviewed-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

Now that we can easily detect all copies, we can optimize the
"op r, a, a => mov r, a" case a bit more.
Reviewed-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

It is possible to due copy propagation for all operations, even the one
that have side effects or clobber arguments (it only concerns input
arguments). That said, the call operation should be handled differently
due to the variable number of arguments.
Reviewed-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

The copy propagation pass tries to keep track what is a copy of what
and what has copy of what, and in addition it keep a circular list of
of all the copies. Unfortunately this doesn't fully work: a mov from
a temp which has a state "COPY" changed it into a state "HAS_COPY".
Later when this temp is used again, it is considered has not having
copy and thus no propagation is done.

This patch fixes that by removing the hiearchy between copies, and thus
only keeping a "COPY" state both meaning "is a copy" and "has a copy".
The decision of which copy to use is deferred to the actual temp
replacement. At this stage there is not one best choice to do, but only
better choices than others. For doing the best choice the operation
would have to be parsed in reversed to know if a temp is going to be
used later or not. That what is done by the liveness analysis. At this
stage it is known that globals will be always live, that local temps
will be dead at the end of the translation block, and that the temps
will be dead at the end of the basic block. This means that this stage
should try to replace temps by local temps or globals and local temps
by globals.
Reviewed-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>