In order to implement the SSE4.2 string instructions in a reasonable
manner, we can make use of a fallback implementation for the time
being.
This implementation just returns the intermediate result and leaves it
up to the function making use of it to derive the final result from said
intermediate result. This is fine, considering we have the immediate
control byte that tells us exactly what is desired as far as output
formats go.
Given that the result of this IR op will never take up more than
16-bits, we store the flags we need to set in the upper 16 bits of the
result to avoid needing to implement multiple return values in the JIT.
Also, since the IR op just returns the intermediate result, this can be
used to implement all of the explicit string instructions with a single IR op.
The implementation is pretty heavily documented to help make heads or
tails of these monster instructions.
The dispatcher was saving AVX state even though FEX doesn't support it
currently. This is due to it checking for the config option rather than
the HostFeatures option.
The `EnableAVX` config option is supposed to be used to inform FEXCore
if we want AVX disabled or not when the host supports the feature. In
this case it is universally enabled because we haven't encountered any
games that have issues with AVX state being saved with signals. (We know
they exist, we just don't have configurations for them).
The HostFeatures option `SupportsAVX` is the option that is supposed to
be getting used for determining if the runtime AVX feature is enabled.
This also had an issue though that this was **also** always enabled if
running on an x86 host with AVX, or an ARM host with SVE2-256bit.
It was then disabled if the config option was disabled; But, since
FEX-Emu doesn't support AVX fully yet, we need to ensure this isn't yet
enabled.
But this only solves half the problem. In order for our CI to test AVX
features before fully supporting AVX, it needs to be able to enable AVX
so that the CPU state is correctly saved.
So we need to change the default configuration option to be false, and
have CI enable it for the tests that matter before AVX is fully
implemented.
The previous log in the frontend is super useful when an instruction
decoding wasn't supported.
Now that most of AVX is covered, a game will crash on SIGILL (and
usually catch it) and close without any indication.
Now if the instruction is decoded but it is invalid for the
configuration, still output a message as a good indicator that the game
is using instructions that the host doesn't support.
Will let us still pick up on games crashing due to lack of SVE very
easily.
This is an undocumented but supported instruction. It behaves just like
an `sbb al, al` but doesn't set flags and is one byte shorter.
The end result is that al is set to 0xFF or 0 depending on if CF is set
or not.
And with that, we support all of the AVX1-only instructions.
The remaining instructions for full AVX1 support is now just the SSE4.2
string instructions.
Will be used to implement the load variants of VMASKMOVP{D, S} and
VPMASKMOV{D, Q}
Particularly useful, since with SVE this behavior can be collapsed into
two instructions (CMPGT followed by the relevant LD1 load instruction)
These conditionals were accidentally inverted and were treating 32-bit
elements as 64-bit ones, when this is unintended.
Also add missing tests to ensure this doesn't slip through in the
future.
Lioncache