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J. Nick Koston
c2e6787e23
Two small wins on the per-loop Scheduler::call path:
1. Mark the scheduler's `millis_64()` wrapper `ESPHOME_ALWAYS_INLINE`.
The inner `esphome::millis_64()` is already always_inline, but the
wrapper was not, so GCC emitted an out-of-line `$isra$0` clone with
its own `entry`/`retw` register-window prologue/epilogue at every
call site. Inlining removes the wrapper's call overhead and the
register-window thunk on ESP32.
2. Collapse the two atomic reads of `to_remove_` in `Scheduler::call`
into one. The previous sequence
cleanup_(); // loads to_remove_
if (to_remove_count_() >= MAX_...) ... // reloads to_remove_
produced `memw; l32i; beqz; memw; l32i; bltui` on the fast path
because the compiler cannot CSE across the `memw` barriers that
std::atomic<uint32_t>::load emits on Xtensa. Reading the counter
once and branching on the result leaves a single
`memw; l32i; beqz` on the common zero-case; the slow path
(cleanup_slow_path_ + re-read + optional full_cleanup) pays an
extra read but already holds the scheduler mutex.
