this skips the constant folding, which saves the branching in the rotate
immediate implementations.
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Noticed this while writing #3342.
Fixes#3343
The syscall instruction is defined in the documentation that it will set
RCX to the next instruction's RIP and R11 to be RFLAGS. We entirely
skipped this which I noticed while writing unit tests.
Adds unittests to test both 32-bit and 64-bit behaviour because our
helper shares code with both.
I don't know if anything actually relied on this behaviour but we should
definitely support it.
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.
When the address calculation for SIB has both index and base then we can
optimize this to an add with a shifted register. This will convert a
three instruction sequence in to one instruction in most cases.
they're all copypastes of each other, unify into one general "bit test & perform
action" template. this means most of the wins from the previous commits now
apply for bt* without more copypaste.
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
if the shift is < N, and we grab bit 0 after, we only need to consider <=N
bits of the source. this lets us use 32-bit lsr for 32-bit bt, which will
reduce masking in the next commit.
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
When a 32-bit imul was being executed it had a chance of returning
garbage data in the upper 32-bits of the 64-bit result.
While this didn't typically cause problems, this gets exacerbated from
32-bit applications executing multiplies for address calculations.
A combination of commits 7146691360 and
d01b457727 exposed this problem where
previously there would be multiple moves between the calculation and
data use which would have zero'd the upper bits for us previously.
Now that we are no longer doing that, we need to make sure the opcode
dispatcher doesn't generate broken code instead.
Fixes Dungeon Defenders, which hasn't worked since FEX-2308.
Adds an ASM test that ensures we don't break it again.
Alyssa Rosenzweig