The only functional difference is that the new handler always uses
half-barriers for vector atomics. There's no technical reason for
paranoid TSO not to use these and it was just missed initially.
ARM64 branches have fairly small relative distances they can encode.
These can be +-1MB, or even +-32KB. The largest relative branch is
+-128MB, which we already set as an upper limit of our block JIT cache
size.
We have for a long time just compiled these without checking with the
expectation that things just happen to work. We didn't hit the asserts
so it was relatively low priority. Apparently now with Steam and a
MaxInst limit of 5000, we are now hitting an assert where we are
encoding too large of a range.
Implement support for long jumping from anywhere in the JIT for when a
long jump tries to be encoded and fails, allowing us to restart the JIT
at any moment. This is implemented as a long jump when this singular
feature could have gotten away with some sort of invasive check and
early exit path for two reasons. For one, that would be even more
invasive, effectively doing try-catch logic manually. And two, the next
step is supporting JIT buffer overflow for when our block size heuristic
fails.
This next step will mandate longjump on SIGSEGV (with cooperative
interaction with the frontend) from effectively /anywhere/ in the JIT.
One of the design goals of the CodeEmitter is that every code emission
function doesn't do a size remaining check to allow the compiler to do
some very effective optimization of emitting code blocks to memory (and
it works!).
But we lose the ability to sanely size check. When writing the emitter I
knew we were going to need to write this cooperative guard page handler,
and we're finally at a point where it needs to be done. This will be in
the next PR although.
These get stored based on the current rotation of TOP. So we need to be
a bit careful with how we do this storing. A smidge of overhead, but
nothing unexpected.
Two bug fixes here.
- We weren't reporting a correctl ErrorRegister. Needs to contain
PF_INSTR at least.
- We weren't setting siginfo->si_addr in the case of `FaultToTopAndGeneratedException`
Fixes Mafia 2 (Classic)
We were paying a large cost per Literal type that we can special case
for the two class of instructions that use a 64-bit literal.
If we packed this would get to a further 62 bytes but probably not worth
it.
x87 80-bit loads, both BCD and regular tword were loading 128-bits of
data when reduced precision was enabled. This was an oversight from the
previous fix a while ago.
Adds a specific reduced precision test for this, and updates the current
test to ensure stores are still tested as well.
This is now cached internally in the X87 pass, and all operations
outside of that that use it are rare so can afford loading/storing
directly from context after flushing x87 regs.
Flushing other regs is not necessary, and breaks any ConvertNZCVToX87 use
which relies previously saved NZCV values as the flag-setting NZCV op after
the save could trigger a flush of NZCV.
Billy Laws