as far as flags go, they're identical: set ZF for zero output, set CF for output
= DestSize, undef the rest. merge the impls, so we get the optimized lzcnt impl
for tzcnt.
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
This has the Frontend and OpcodeDispatcher select their operating mode
depending on the incoming code segment long-mode flag.
Adds some asserts since currently it is unexpected if the configuration
changes at runtime.
This is fairly straightforward for an initial setup but isn't fully
fleshed out.
Right now FEX's x86 tables aren't setup in a way to support choosing a
different instruction decoding depending on runtime operating mode
change, so that would break in interesting ways.
Primarily this just gets FEX setup to start piping the operating mode
through from the frontend to the backend. This is a long term task, so
it is going to take a long time to iron out all the issues.
Many flag-generating instructions like cmp need to save calculations for
deferred PF and AF flag calculation. Currently, they require a store per flag,
which is prohibitively expensive for hot instructions like cmp. By instead
pinning PF/AF temporary results to registers (x26/x27 by convention here), we
eliminate many stores altogether and turn the rest into zero-cycle moves (on
64-bit at least, this isn't optimal for 32-bit emulation due to CTX->GetGPRSize
shenanigans, need to check if this requirement can be lifted..).
To implement, we model as SRA and then the existing SRA code is able to generate
good code with little manual tuning. (Future work will get us to excellent code
with more tuning ;) ).
The tradeoff is reducing the working dynamic GPR set by 2 registers, which might
increase spilling in some cases. I think it's worth it in practice, though.
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
- sha1nexte
- Takes advantage of sha1h if supported
- Does the operation in a vector otherwise
- sha1msg2
- Instead of dumping everything to GPRs, we can do this with vectors
- Mostly matches ARM's sha1su1 instruction, but it is /just/
different enough to be annoying.
- sha256msg1
- Directly matches sha256u0
- Leaves the previous implementation alone
Not supposed to touch flags at all, so don't! instead of making a terrible mess
of csels. a lot less instructions, and probably faster because the branch should
be predicted correctly in practice in hot loops.
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Semantics differ markedly from the non-NZCV flags, splitting this out makes it a
lot easier to do things correctly imho. Gets the dest/src size correct
(important for spilling), as well as makes our existing opt passes skip this
which is needed for correctness at the moment anyway.
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Replace every instance of the Op overwrite pattern, and ban that anti-pattern
from the codebase in the future. This will prevent piles of NZCV related
regressions.
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Requires #3238 to be merged first since this uses the tbx IR operation.
Worst case is now a three instruction sequence of ldr+ldr+tbx.
Some operations are special-cased, which definitely doesn't cover all
possible cases we could use without tbx, but as a worst case improvement
this is a significant improvement.
A bunch of blendps swizzles weren't optimal. This optimizes all swizzles
to be optimal.
Two instructions can be more optimal without a tbx but the rest required
tbx to be optimal since they don't match ARM's swizzle mechanics.
Ryan Houdek