ludic/tools/ludic-cli/split.ludic
Orkuncakilkaya 9cc3f24c56 ludic build on every core: the IR split with llvm-split and compiled by a clang per part at once
Most of a build was one clang -O2 on one .ll (the game: 32 s of a 41 s headless build, one core).
Both paths that assemble - the CLI's (build.ludic: ludicc --emit-llvm, then clang) and ludicc's own
(-o, which ludic bundle and the examples use) - now cut the program's IR into N parts with llvm-split
(externalizing what the parts share), compile them with one clang each in parallel (-x ir -O<opt>
-mmacosx-version-min=11.0, the link's own clang taking the objects where it took the .ll), and remove
the parts and objects after. N is $LUDIC_JOBS, else min(cores, free GB / 1.5).

It needs an llvm-split and a clang of the same LLVM (Homebrew's LLVM 22 writes attributes Apple's
clang 17 cannot read): $LUDIC_LLVM, else /opt/homebrew/opt/llvm/bin. With either missing, on Windows
(its shell cannot run the parts at once yet), with LUDIC_SPLIT=0, or when a part fails, it compiles the
.ll whole as before.

$LUDIC_OPT=1 is a developer's faster build; ludic bundle sets LUDIC_OPT=2 for its compile whatever the
shell says.

Measured before the compile-only rule (this Mac, 12 cores, one build at a time):
- the game headless: 37-41 s -> 13-15.5 s (8 parts / by free memory), peak 2.1 GB -> 1.0-1.1 GB;
- the lab headless: 43.1 s -> 12.7 s, peak 2.4 GB -> 1.0 GB;
- the game at LUDIC_OPT=1, split: 11.8 s (fps cost not measured).
Both built and linked clean; the goldens and a headless shot of the result are not run here.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-09-29 17:12:27 +03:00

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# split.ludic - `ludic build` on every core: the program's IR cut into N parts (llvm-split), a clang
# each at once, their objects linked where the one .ll was (the game: clang was 32 s of a 41 s
# build, on one core). ludicc's own link does the same (selfhost/split_build.ludic). It needs an
# llvm-split and a clang of one LLVM - $LUDIC_LLVM, else Homebrew's - or it compiles the .ll whole.
function split_opt() -> pointer { return getenv_or("LUDIC_OPT", "2") } # 1: a developer's faster build
# " a.o b.o ..." for the link, or "" when not split (the caller compiles the .ll as before)
function split_objs(ll: pointer, out: pointer) -> pointer {
if host_windows() or getenv_or("LUDIC_SPLIT", "1") == "0" { return "" }
let d = getenv_or("LUDIC_LLVM", "/opt/homebrew/opt/llvm/bin")
if not is_exec(`"{d}/llvm-split"`) or not is_exec(`"{d}/clang"`) { return "" }
let n = split_n()
if n < 2 { return "" }
let pre = tmp_path(`{file_of_path(out)}.part`)
if not shq(`"{d}/llvm-split" -j {n} -o "{pre}" "{ll}"`) { return "" }
var sh = ""
for i in 0 .. n {
sh = sh + `"{d}/clang" -x ir -O{split_opt()} -mmacosx-version-min=11.0 -Wno-override-module -Wno-missing-sysroot -c "{pre}{i}" -o "{pre}{i}.o" & `
}
shell(`{sh}wait`)
var objs = ""
var ok = true
for i in 0 .. n {
shell(`rm -f "{pre}{i}"`)
if not file_exists(`"{pre}{i}.o"`) { ok = false }
objs = objs + ` "{pre}{i}.o"`
}
if ok { return objs }
shell(`rm -f {objs}`)
return ""
}
# $LUDIC_JOBS, else the cores - no more than the free memory allows at 1.5 GB a clang
function split_n() -> int {
let j = getenv("LUDIC_JOBS")
if j != null { return s_to_int(j) }
let aw = "awk '/Pages free/{f=$3} /Pages inactive/{i=$3} END{print int((f+i)*p/1073741824)}'"
let line = capture_line(`echo $(sysctl -n hw.ncpu) $(vm_stat | {aw} p=$(sysctl -n hw.pagesize))`)
var cores = 0
var i = 0
while i < len(line) and line[i] >= '0' and line[i] <= '9' { cores = cores * 10 + (line[i] - '0'); i += 1 }
while i < len(line) and line[i] == ' ' { i += 1 }
var gb = 0
while i < len(line) and line[i] >= '0' and line[i] <= '9' { gb = gb * 10 + (line[i] - '0'); i += 1 }
let by_mem = (gb * 2) / 3
if by_mem < cores { return by_mem }
return cores
}