nx_x86_regalloc_use_gate.nx

nx_x86_regalloc_use_gate.nx -- GATE for LN7 "backend consumes its register allocation" (lang.plan rung LN7, watch symbol x86_use_regalloc in nx_x86_64_ctx.nx). THE RUNG'S DONE-RULE: the x86 emitter reads a homed/forwarded value IN PLACE as a source operand of a compare/binop/SIB instead of copying it into a scratch register first, and the allocator no longer spends a home register on a load it can forward. Measured on the estate's own instrument runtime/nx_probe_bchk_asm.nx (a bounds-checked hot loop over [1024]i64): pre-LN7 loop head: movq %r12, %r15 ; cmpq $1024, %r15 (copy the homed counter, THEN compare) LN7 loop head: cmpq $1024, %r12 (compare the homed counter in place) main() real instructions (crash-guard ON, the default build this gate uses): 62 -> 58 (--no-crash-guard shape is 64 -> 60; the guard adds a fixed prologue to both) the loop-bound check reads the homed counter DIRECTLY: pre-LN7 copies it to a scratch reg first (movq %r12,%r15 ; cmpq $1024,%r15), LN7 emits `cmpq $1024, %r12` -- present iff LN7. checked-loop bench nx_bounds_perf: 8229/8278/8385 us -> 6939/6904/6912 us (median -16.5%) All measured 2026-08-23 on the SOUND rule (X86_LN7_BLOCK_FWD_ENABLE with the cut-the-load-block availability check; an earlier merge-unsound draft forwarded more but miscompiled self-host and was rewritten). Instruction method = the awk equivalent ln7_main_instrs below. Subject = the compiler under test (argv[1], default the live builder). This gate does NOT mutate its own source to bite: the discriminator is the COMPILER, so the bite is running it against the banked pre-LN7 compiler (T2 and T3 go RED) vs the LN7 compiler (all GREEN). Drive it as: nx_x86_regalloc_use_gate _offc/nx_cc_sovereign.elf (LN7 live -> GREEN) nx_x86_regalloc_use_gate /path/to/pre-ln7-compiler.elf (bite -> RED on T2,T3) Driver = nx_ccgate_lib (the one compiler-gate driver): .s capture in /tmp/nxln7/, per-pid paths, runnables under _build/ (NAS /tmp is noexec). ASCII-only source. license_tier: ORIGINAL. No hw writes (Rule 26).