It is common practice for games to use CPUID as an instruction barrier
for various reasons. Ensure that we respect this by adding support for
an instruction barrier.
FEAT_ECV added a new synchronizing cycle counter instruction that
restrict speculation across the cycle counter access. Because it
restricts speculation, it effectively acts like an isb and load dsb.
Luckily for us, this actually matches behaviour for what rdtscp does, so
we can take advantage of it if the host supports FEAT_ECV.
In the Push/Pop CalleeSavedRegisters these vectors were getting created
on the heap, allocating memory and then just iterating them.
Just use a std::array which makes it stop allocating memory and saves
the number of instructions.
And also use it at the same time, since the function signatures changed.
Instead of relying on the host libc math libraries for `long double` ALU
operations, rewrite the entire thing to use softfloat-3e fixed width
float128_t types.
This is a very invasive change in cephes but is a necessary requirement
for getting the precision we require in environments that map `long
double` to be the same as `double`, like Win32 and MacOS.
This fixes the precision issue in transcendental operations when running
under WINE.
This is solving a different problem than what #4411 is specifically
trying to solve.
For our transcendental operations, we can't currently guarantee that
these functions will actually operate at the 128-bit softfloat
precision. While this is true with glibc, this is /not/ true for musl
and likely more libraries.
Instead of relying on our libc implementation to implement these,
instead include the cephes math library directly which is what most
people use for this. Including musl even, but not for all operations.
With this we are no longer beholden to the standard libraries for
providing a correct implementation.
Telemetry value address generation was forcing an indirection at all
times which was unnecessary. These values live in the BSS, zero
initialized at process start and is unnecessary.
Instead change the wrapper defines to directly operate on the enum
passed in which saves an indirection on all of these telemetry
operations (except for the ones in the JIT which are required to be PIC
compliant).
This also fixes an annoying warning about
`FEXCORE_TELEMETRY_STATIC_INIT` causing initialization and destruction
order being unspecified, so two wins.
These three options are mutually exclusive with each other and could
potentially result in invalid encodings of the table on accident.
Change over to a 2-bit bitfield to encode if the operand that consumes
the VEX option is none, destination, 1st src, or 2nd src.
This ensures the table can't ever be incorrectly encoded.
Billy Laws