Most hoisted values are used in the loop body (and that's really the
whole point of hoisting) but some are just temporaries to help produce
other hoisted values. This used_in_loop bit helps us distinguish the
two, and lets us recycle registers holding temporary hoisted values not
used in the loop.
The can-we-recycle logic now becomes:
- is this a real value?
- is it time for it to die?
- is it either not hoisted or a hoisted temporary?
The set-death-to-infinity approach for hoisted values is now gone. That
worked great for hoisted values used inside the loop, but was too
conservative for hoisted temporaries. This lifetime extension was
preventing us from recycling those registers, pinning enough registers
that we run out and fail to JIT.
Small amounts of refactoring to make this clearer:
- move the Instruction hash function definition near its operator==
- rename the two "hoist" variables to "can_hoist" for Instructions
and "try_hoisting" for the JIT approach
- add ↟ to mark hoisted temporaries, _really_ hoisted values.
There's some redundancy here between tracking the can_hoist bit, the
used_in_loop bit, and lifetime tracking. I think it should be true, for
instance, that !can_hoist && !used_in_loop implies an instruction is
dead code. I plan to continue refactoring lifetime analysis (in
particular reordering instructions to decrease register pressure) so
hopefully by the time I'm done that metadata will shake out a little
crisper.
Change-Id: I6460ca96d1cbec0315bed3c9a0774cd88ab5be26
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/248986
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Herb Derby <herb@google.com>
This makes the register recycling checks a bit more
precise. At head we never recycle a register that's
holding a hoisted value, which is overly conservative.
We really should never recycle a register that's still
needed. By extending the lifetime of any hoisted value
that's used in the loop, we prevent that, while still
allowing hoisted values that are only used in hoisted
computation to be reused.
This takes just a small tweak in the JIT code (removing
the !hoisted({x,y,z}) checks), and a somewhat larger
refactoring in the interpreter, making both hoisted and
non-hoisted code go through the same recycling register
assignment flow.
There's one diff in the existing cases where we now
reuse a hoisted register, and I've added a second test
just to make sure it's covered explicitly.
Change-Id: I25b37ab1f1fea3042d7fd167529abc8fed1dddff
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/233239
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
Add missing comparison and selection ops, bit casts, 16-bit memory
operations, gathers, uniform loads, and fill in math holes where
reasonable. Update some names to be a bit more regular.
I think all instructions are implemented in the interpreter,
and many tested. More testing and JITs to follow.
Change-Id: I8cf377e8b72a86ac950e020892ce82b39e9d7277
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/229893
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
Even if a JIT ultimately doesn't end up hoisting any values, it's going
to want this information while it decides. Writing it in one place also
ensures we only get it wrong in one place...
I'm no_ extending the lifetime of hoisted instructions here in Builder.
That's something to leave to the backend so they have the flexibility of
which of these values to hoist, if any. If they don't hoist, they'll
need to know when the value dies.
Moving this information back here lets the test expectation goldens
reflect the hoist bit again too. Kind of nice.
Change-Id: Ib165ca898a97c1d822cb28fe24f15bae4d570a17
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/229024
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
I'm slowly refactoring my way to where hoisting and register assignment
are done in backend-specific ways, but this liveness analysis is always
going to be useful for each backend.
Use deaths() to restore friendly ☠️ dead code markers in test dumps.
Change-Id: I3ab94665bbbbf0788b0b27e00d644eba927dff47
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/228113
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
Noticed we were only dumping the final register
programs for the integer code. Might as well also
track the value programs.
Change-Id: I417c5c655b632691557bbbb136dcbd3f3167af9a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/225324
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Herb Derby <herb@google.com>
I was just reading the ARM docs and realized that their BIC ("BIt
Clear") is the same as SSE's ANDN ("AND Not") instruction. It's kind of
a neat little tool to have laying around... comes up more than you'd
think, and it's sometimes the clearest way to express what you're doing,
as in the changed program here where the comment is "mask away the low
bits". That's a bit_clear with a mask for what you want to clear away!
And the real reason to write this up is that I want to have a CL to
point to that shows how to add an instruction top to bottom.
Change-Id: I99690ed9c1009427b3986955e7ae6264de4d215c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/223120
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Herb Derby <herb@google.com>
Reviewed-by: Mike Reed <reed@google.com>
Instruction is the fundamental data, and Analysis derived from it.
The fields in Analysis are only* needed in Builder::done(), and this
split seems to help clarify what done() can tweak (Analysis) and what
it cannot (fProgram, Instructions). done() is now const.
No speed change as far as I can tell.
* As you may notice looking at the test expectations, making analysis
ephemeral means that dump() can no longer print the skull for dead code
or the arrow for hoisted. The register program that's also in the
expectation file still reflects both of these optimizations, so we're
not really losing any information. Just maybe less demo-friendly.
Change-Id: I79feb57558525591baf3faadeb59c418c12793f3
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/223119
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Herb Derby <herb@google.com>
This cuts the overhead bench from about 19µs to about 15µs.
The key insight here is that the only registers that might become
available after any given instruction are the ones that hold that
instruction's inputs. We can check when they become available
directly from the original Builder::Program, without needing a
side death schedule data structure.
Marking hoisted instructions as having life == program size
helps make this logic a little simpler to reason through.
Change-Id: Ifb9957f2d0e323e0e5d07996a2cc988f7c8b4c3f
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/223117
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Herb Derby <herb@google.com>
- 32x8 i32 add,sub,mul
- add I32_Naive bench/test builder to get better i32 mul coverage
- minor refactoring all over
Change-Id: I13cc19ff37a2da0bcff289ba51baac08f456d6c5
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/222485
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
I'm staring at this assembly,
vmovups (%rsi), %ymm3
vpsrld $24, %ymm3, %ymm4
vpslld $16, %ymm4, %ymm15
vorps %ymm4, %ymm15, %ymm4
vpsubw %ymm4, %ymm0, %ymm4
Just knowing that could be
vmovups (%rsi), %ymm3
vpshufb 0x??(%rip), %ymm3, %ymm4
vpsubw %ymm4, %ymm0, %ymm4
That is, instead of shifting, shifting, and bit-oring
to create the 0a0a scale factor from ymm3, we could just
byte shuffle directly using some pre-baked control pattern
(stored at the end of the program like other constants)
pshufb lets you arbitrarily remix bytes from its argument and
zero bytes, and NEON has a similar family of vtbl instructions,
even including that same feature of injecting zeroes.
I think I've got this working, and the speedup is great,
from 0.19 to 0.16 ns/px for I32_SWAR, and
from 0.43 to 0.38 ns/px for I32.
Change-Id: Iab850275e826b4187f0efc9495a4b9eab4402c38
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/220871
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Herb Derby <herb@google.com>
Now that we've got shr_16x2, extract(..., 8, splat(0x00ff00ff)) is
better done as shr_16x2(..., 8). This swaps a 16-bit shift in for
the 32-bit shift, a wash, but lets us drop the bit_and at the end,
saving one whole instruction.
This places I32_SWAR a tiny little bit faster than the code in Opts,
like .19 ns/px vs .20 ns/px for Opts.
Change-Id: I4160dc03ecc8b855c0773a927f1510ad5cbb4b87
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/220856
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Herb Derby <herb@google.com>
This is the final bunny I've got in my hat, I think...
Remembering that none of the s += d*invA adds can overflow,
we can use a single 32-bit add to add them all at once.
This means we don't have to unpack the src pixel into rb/ga
halves. We need only extract the alpha for invA.
This brings I32_SWAR even with the Opts code!
curr/maxrss loops min median mean max stddev samples config bench
36/36 MB 133 0.206ns 0.211ns 0.208ns 0.211ns 1% ▁▇▁█▁▇▁▇▁▇ nonrendering SkVM_4096_I32_SWAR
37/37 MB 152 0.432ns 0.432ns 0.434ns 0.444ns 1% ▃▁▁▁▁▃▁▁█▁ nonrendering SkVM_4096_I32
37/37 MB 50 0.781ns 0.794ns 0.815ns 0.895ns 5% ▆▂█▃▅▂▂▁▂▁ nonrendering SkVM_4096_F32
37/37 MB 76 0.773ns 0.78ns 0.804ns 0.907ns 6% ▄█▅▁▁▁▁▂▁▁ nonrendering SkVM_4096_RP
37/37 MB 268 0.201ns 0.203ns 0.203ns 0.204ns 0% █▇▆▆▆▆▁▆▆▆ nonrendering SkVM_4096_Opts
Change-Id: Ibf0a9c5d90b35f1e9cf7265868bd18b7e0a76c43
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/220805
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
I figure the easiest way to expose 16-bit operations
is to expose 16x2 pair operations... this means we
can continue to always work with the same size vector.
Switching from 32-bit multiplies to 16-bit multiplies
is going to deliver the most oomph... they cost roughly
half what 32-bit multiplies do on x86.
Speed now:
I32_SWAR: 0.27 ns/px
I32: 0.43 ns/px
F32: 0.76 ns/px
RP: 0.8 ns/px
Opts: 0.2 ns/px
Change-Id: I8350c71722a9bde714ba18f97b8687fe35cc749f
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/220709
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Herb Derby <herb@google.com>
I just kind of remembered that if we're doing (xy+x)/256
and x is a destination channel and y is 255-sa, then you
can get the +x for free by multiplying by 256-sa instead.
(d * (255-sa) + d)
(d * (255-sa + 1))
(d * (256-sa) )
Duh. This is a trick we play in a lot of legacy code and
I've just now realized it's exactly equivalent to the trick
I want to play here... sigh.
Folding this math in kind of makes mul/mad_unorm8 moot.
Speed's getting good:
I32_SWAR: 0.3 ns/px
I32 : 0.55 ns/px
F32 : 0.8 ns/px
RP : 0.8 ns/px
Opts : 0.2 ns/px
Change-Id: I4d10db51ea80a3258c36e97b6b334ad253804613
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/220708
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
The mask-only special case for extract is wrong...
it never looked it its input!
This not only makes things correct-er, but oddly it also
makes them faster by breaking inter-loop data dependencies.
Disable tests for _I32... they're actually still broken
because of a much more systemic flaw in how I've evaluated
programs. The _F32 and _I32_SWAR JIT code and all interpreted
code is just getting lucky. o_O
While here, update the I32_SWAR code to use the same math as I32,
(x*y+x)/256 for unorm8 mul. This just helps keep me sane.
Change-Id: I1acc09adb84c426fca4b2be5ca8c2d46d9678dd8
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/220577
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Herb Derby <herb@google.com>
I used to have a dump of the value program before it was
translated to registers, but it went away a while ago.
This restores it.
Change-Id: I9b8bfcb124843cad4b0dc44bdf0a03e95a0c83d8
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/219757
Commit-Queue: Mike Klein <mtklein@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: Mike Klein <mtklein@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Convert extract(x,bits,z) to be (x >> bits) & z,
now a more explicit parallel to pack().
This lets us eliminate the funky bit counting required from the old
instruction, but more saliently it makes it more likely that the masks
we AND with will be the same value.
Ultimately down at the x86 or ARM ISA level, the AND instructions don't
really benefit from having an immediate argument (while the shifts do).
We might as well treat the mask as a normal value, letting it get
commoned with identical values, loop hoisted, etc.
Change-Id: I48a38468b46f2c730574c025f412262296472447
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/219597
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
At some point adding more and more complex instructions reduces
to the absurdity of SolveTheWholeProblem-The-Instruction, but
I think this one will come up often enough to still make sense.
mad() makes sense for unorm8 just about everywhere mad() makes
sense for f32.
This instruction won't matter to a JIT, but helps the interpreter.
Change-Id: Iace92296cffbb6fbc3acd1f853cb01c51792f796
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/218716
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
I'm of two minds about this... it adds register pressure and really only
tends to hoist few instructions that are fairly cheap anway. On the
other hand, it's neat, it's easy to turn off (just set the initial
hoist value to false in Builder::push()) and it does deliver a
noticeable though slight performance improvement in the interpreter.
I think the final decision will probably come down to what we think
about maintainability?
Change-Id: Idd6346f70f03188917918406731154246a7c6fcb
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/218584
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
This reverts commit 346f82c1c3.
Reason for revert: *SAN bots
Original change's description:
> print 1/K floats as fractions
>
> Change-Id: Id00cbd0950e77debb5ab5d45541dc0f8d13a3c42
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/218338
> Reviewed-by: Brian Osman <brianosman@google.com>
> Commit-Queue: Mike Klein <mtklein@google.com>
TBR=mtklein@google.com,brianosman@google.com
Change-Id: Ic35cec97d2dc2c1e19dbdf8ea7b505ad75072da1
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/218529
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
Change-Id: Id00cbd0950e77debb5ab5d45541dc0f8d13a3c42
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/218338
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
Change-Id: Ib0d4f354787e413749fdda8b59ccc2f94472b0ce
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/218243
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
Kind of the flip side of pack.
Made slightly awkward by instructions having only one immediate...
calling _BitScanForward / __builtin_ctz() at runtime seems to work
fine, but it really could have been done at compile time.
Change-Id: Ic83fe8e0a1603fb9189598dcc26c842cc797bf45
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/218241
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
This instruction can lower to some useful SSE/NEON
instructions, and even if not, is a handy way to
express the frequent paring of << and |.
I32_SWAR: 2.3 -> 1.9
I32: 2.6 -> 2.4
F32: 5.1 -> 4.7
Change-Id: Ia169ad40f0aaef32417e05d9bf91c2d2542e7b5f
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/218238
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Another way for an interpreter to go faster
is to provide better instructions.
mul_unorm8 is one we use all the time.
Drops _I32 bench from ~3.6ns/px to ~2.6ns/px.
Change-Id: I9d08914c114048b79075796af9ec802236b35706
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/218236
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Eliminate the duplicate functionality,
and better testing for the bench builders.
Change-Id: If20e52107738903f854aec431416e573d7a7d640
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/218041
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
This is mostly to test how easy rebaselining SkVMTest is.
Change-Id: I27ab6f6bb8b7e126327374009783afd86d416f55
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/218039
Reviewed-by: Brian Osman <brianosman@google.com>
- keep expectations in resources/
- overwrite automatically if needed
so we can see the diff in Git
Change-Id: I2486b127ebcc7f40332fd0462e38b1af04d3e32b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/218038
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
