nx_fma_unroll_matmul_gate.nx
buildroot/runtime/nx_fma_unroll_matmul_gate.nx
about
nx_fma_unroll_matmul_gate.nx -- unlock the FMA throughput win: MULTIPLE independent accumulators.
The single-accumulator FMA (nx_fma_matmul_gate) was only ~1.03x over AVX2-dot because each vfmadd231ps
depends on the previous (store->load->fma serial chain) = LATENCY-bound. FMA has ~4-5 cycle latency but
~0.5 cycle throughput, so to fill the pipeline you need >=4 INDEPENDENT accumulators in flight. This
unrolls the k-loop by 4 (a0..a3, each its own 8-wide accumulator, disjoint k-chunks) so the 4 FMAs have
NO inter-dependency -> the CPU pipelines them -> hides the latency. NishiLang-only (reuses __f32x8_fma/
__f32x8_hsum) -- NO compiler change. Same data, BIT-EXACT vs scalar. No hw writes (Rule 26).
expect_exit: 0 license_tier: ORIGINAL
dependencies 1 imports · 0 importers
imports: nx_syscalls.nx
imported by: nobody (leaf or entry point)
call flow from main pre-order; caps 40 nodes / depth 6 declared; ↻ = already shown
structs
| none |
consts
| none |
functions
| 11 | func gx_puts(s: *u8) -> i64 { var n: i64=0; while s[n]!=(0 as u8){n=n+1} sys_write(1,s,n); return 0 } |
| 12 | func gx_num(v: i64) -> i64 { let b: *u8=sys_mmap(28); var m: i64=v; if m<0{m=0-m;sys_write(1,"-" as *u8,1)} let t: *u8=sys_mmap(28); var k: i64=0; if m==0{t[0]=48 as u8;k=1} while m>0{t[k]=(48+(m%10)) as u8;m=m/10;k=k+1} var i: i64=0; while i<k{b[i]=t[k-1-i];i=i+1} sys_write(1,b,k); return 0 } |
| 13 | func pack4(buf: *u8, idx: i64, bits: i64) -> i64 { buf[idx*4+0]=(bits) as u8; buf[idx*4+1]=(bits>>8) as u8; buf[idx*4+2]=(bits>>16) as u8; buf[idx*4+3]=(bits>>24) as u8; return 0 } called by 1: main |
| 15 | func mm_scalar(sa: *i64, sb: *i64, c: *i64, M: i64, N: i64, K: i64) -> i64 called by 1: main |
| 25 | func mm_fma1(pa: *u8, pb: *u8, c: *i64, acc: *u8, M: i64, N: i64, K: i64) -> i64 called by 1: main |
| 38 | func mm_fma4(pa: *u8, pb: *u8, c: *i64, a0: *u8, a1: *u8, a2: *u8, a3: *u8, M: i64, N: i64, K: i64) -> i64 called by 1: main |
| 69 | func main() -> i64 |