After clang's ARMv7 output for vfpu_dot_neon(), in Q8-Q15, which the register
cache leaves alone. The end is done in 32-bit integers instead of 64-bit ones,
checked bit-exact against vfpu_dot_finish(). The call site gathers the lanes into
Q8 and Q9 and flushes whatever guest state is in R2, R3, R12 and LR, usually
nothing. Inf and NaN go through a routine that calls vfpu_dot_reference().
Without NEON, Vec4VfpuDot still goes through the IR interpreter.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
