Replace CallNativeSafe round-trips with fcvtl/fcvtl2 for half-to-float
conversion. A rev64 fixup corrects the PPC word-pair ordering. FLOAT16_2
uses ext to rotate the two source halfs into position and sets the
constant {0.0, 1.0} tail lanes. PACK_FLOAT16 kept as C helpers since
fcvtn doesn't match Xenos overflow saturation semantics.
Replace CallNativeSafe round-trips with inline TBL shuffles. LVL uses
a single-register TBL where out-of-range indices naturally produce
zero. LVR uses a 2-register TBL over {zeros, mem} so indices 0-15 map
to zeros and 16-31 map to memory bytes.
Add sentinel bits after the left-shift so clz stops at the correct
count (8 or 16) instead of counting through all 32 bits of the
widened register. Unlikely to hit in practice since PPC only has
cntlzw/cntlzd, but corrects existing sub-word variants.
Expands the vector register allocator from 20 to 28 registers by
including v8-v15. The HostToGuestThunk now saves/restores full Q8-Q15
(128-bit) instead of just D8-D15, and the GuestToHostThunk adds Q8-Q15
to its save/restore set since AAPCS64 only preserves their lower 64
bits across C calls.
Reduces register pressure for VMX-heavy guest code at the cost of
slightly larger thunk stack frames.
Reserves x19 to permanently hold the A64BackendContext pointer
(x20 - sizeof(A64BackendContext)), set once in the HostToGuestThunk.
Since x19 is AAPCS64 callee-saved, it survives all host calls for free.
Eliminates repeated 2-instruction mov+sub sequences in stackpoint
push/pop, stack synchronization, FPCR management, and reserved
load/store paths.
Reduces allocatable GPRs from 8 to 7 (like on x64).
Use the provided scratch register-index, defaults to W0/X0, and insert 64-bit elements directly into the vector-register rather than writing/reading to scratch memory.
Should allow certain splats to opportunistically emit the best assembly when possible.
Also use `std::bit_cast` rather than an inline `union` type to directly
cast a `float` into a `uint32_t`.
The `BRK` instruction code needs to be specified correctly so that a debugger can handle it properly(and continue from it). `brk 0xF000` implements a debug-breakpoint that can be continued from, and `brk 0xF001` is implemented an assertion failing. Any other codes like `0` and `F1` will not be able to be continued from or handled correctly by debuggers.
These seem to be standard brk codes:
```
Breakpoint 0xF000
Assert 0xF001
Debug Service 0xF002
Fastfail 0xF003
Divide by 0 0xF004
```
Rather than using a `mov` and vector-`dup` for vector-splats, just use the `movi` instruction where applicable(8-bit element-splats).
Eventually we might want to detect opportunities to use `FMOV` and the 64-bit form of `MOVI` over in `LoadV128Const`.
Track PPC scalar FP state in the backend context and restore it at
host/guest boundaries so translated FP code has a stable rounding mode.
Convert remaining VMX sequences to scoped EmitWithVmxFpcr. Remove
unnecessary ChangeFpcrMode from sequences that only call native helpers.
Co-Authored-By: Reality <reality@xenios.jp>
Save and restore FPCR around each VMX FP operation so vector code
doesn't leak FPCR state into scalar paths. Drop the DN bit so NaN
propagation fixup can inspect original payloads.
The A64 sequence table is populated by registration statics spread across
multiple translation units. Keeping the backing map as a global object makes
registration depend on cross-TU initialization order and can hit the table
before it has been constructed.
Move the sequence table behind a function-local static so sequence
registration is safe regardless of which unit initializes first.
Based entirely off existing xbyak x86 implementation and available
tests. Still needs a lot of optimization and testing on non-Windows
platforms.
So far passes all tests and boots at least some games on Windows.
