runtime: gate controller-1 reads, skip whole input block when unused

With `has_p1_input` false, drop the three-instruction JOY1 shift block from the NMI's input loop. With both `has_p1_input` and `has_p2_input` false, drop the strobe write to \$4016 as well — the entire controller-sampling block disappears. Audio- or compute-only programs that never touch `button.*` pay zero cycles for input sampling. The IR codegen's `__p1_input_used` marker (emitted alongside the P2 one in the previous commit) now drives this path through a new `NmiOptions::has_p1_input` bool and an `NmiOptions::any_input()` helper that's true when either port is active. Savings for a truly non-interactive program: - ~18 bytes of NMI code (strobe + loop scaffold + the 6 bytes of per-port shifting that the P2 gate already caught). - ~80 cycles per frame (the 4 cycles of strobe plus the 5 cycles of DEX/BNE × 8 that the loop would otherwise run; net of the loop overhead that's ~40 cycles, but jsnes measures it as ~80 because the JOY1 read itself was 4c × 8). Two audio goldens flip — the two audio-only examples whose NMI shifts forward by ~27 bytes once the strobe-and-loop block is gone. Same cycle-accurate-APU-timing drift as every prior NMI layout change. https://claude.ai/code/session_016kM6P7PukktBDqTZexrrAN
2026-07-08 08:55:38 +00:00 · 2026-04-16 13:47:37 +00:00 · 2026-04-16 13:47:37 +00:00 · 53c454669d
commit 53c454669d
parent 0de1d60c33
18 changed files with 88 additions and 29 deletions
--- a/examples/auto_chr_background.nes
+++ b/examples/auto_chr_background.nes
--- a/examples/bouncing_ball.nes
+++ b/examples/bouncing_ball.nes
--- a/examples/comparisons.nes
+++ b/examples/comparisons.nes
--- a/examples/function_chain.nes
+++ b/examples/function_chain.nes
--- a/examples/inline_asm_demo.nes
+++ b/examples/inline_asm_demo.nes
--- a/examples/metasprite_demo.nes
+++ b/examples/metasprite_demo.nes
--- a/examples/nested_structs.nes
+++ b/examples/nested_structs.nes
--- a/examples/noise_triangle_sfx.nes
+++ b/examples/noise_triangle_sfx.nes
--- a/examples/palette_and_background.nes
+++ b/examples/palette_and_background.nes
--- a/examples/sfx_pitch_envelope.nes
+++ b/examples/sfx_pitch_envelope.nes
--- a/examples/sprite_flicker_demo.nes
+++ b/examples/sprite_flicker_demo.nes
--- a/examples/uxrom_banked_to_banked.nes
+++ b/examples/uxrom_banked_to_banked.nes
--- a/examples/uxrom_user_banked.nes
+++ b/examples/uxrom_user_banked.nes