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pikuma_ps1/scripts/passes/auto_reg.lua
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2026-08-10 19:53:34 -04:00

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Lua

--- passes/auto_reg.lua — Per-phase automatic GPR allocator + gen/auto_reg.h emitter.
---
--- Reads the per-source + corpus-level `atom_auto_regs` + `phase_auto_regs` registries populated by `passes/scan_source.lua`.
--- Runs a deterministic first-fit allocator in the `R_T0..R_T7 + R_V0..R_V1` pool (10 physical GPRs).
--- Emits one `#define R_<Sym>_Code R_Tn_Code` per marker into per-directory `gen/auto_reg.h`.
---
--- User-pinned GPRs : The corpus's `register_alias_registry` is consulted to exclude GPRs the user has pinned via
--- `atom_reg` + `_Code` defs (e.g. carriers like `R_ResolveScratch = R_T4 atom_reg`).
--- These GPRs are unavailable to EVERY atom's source pool.
--- Carriers are preserved across atoms by context discipline and must never be reallocated.
--- Per-atom body parsing also catches alias references (R_<Alias>) and hardcoded R_Tn references,
--- so the user can write either `R_T4` or `R_ResolveScratch` in an atom body and the pass will
--- exclude R_T4 from that atom's pool.
---
--- Conflict detection: If the user hardcodes `R_Tn` in an atom body that shares a phase with an auto-reg that picked `R_Tn`,
--- emit `phase_register_clash` as an info finding (no build stop).
--- Should be unreachable after the user-pinning + body-parsing fix above; kept as a defensive safety net.
---
--- Pool exhaustion: If a phase declares more `R_<Sym>` mappings than the 10-register pool can hold,
--- emit `phase_register_pool_exhausted` as a build-stopping error.
--- @class AutoRegResult
--- @field outputs table[] -- {kind=, path=} entries
--- @field errors table[] -- {line=, msg=} entries (build-stops)
--- @field warnings table[] -- {line=, msg=} entries (build-continues)
local _bootstrap_dir = debug.getinfo(1, "S").source:match("^@?(.*[/\\])") or "./"
local duffle = dofile(_bootstrap_dir .. "../duffle_paths.lua")
--- ════════════════════════════════════════════════════════════════════════════
--- THE GPR ALLOCATION POOL — what is allocatable, and (more importantly) WHY
--- ════════════════════════════════════════════════════════════════════════════
---
--- The auto-reg pass picks physical GPRs for `atom_auto_reg(...)` / `phase_auto_reg(...)` markers.
--- It allocates from a FIXED 10-register pool.
--- This comment block makes the inclusion AND exclusion criteria obvious so a reader doesn't have
--- to grep lottes_tape.h + mips.h to understand the design.
---
--- ── WHAT'S IN THE POOL (10 GPRs, all caller-trash per the O32 ABI) ────────
--- R_T0..R_T7 (GPR codes 8..15), R_V0..R_V1 (GPR codes 2..3)
--- The workhorse of every atom body. The uesr should be aware of atom allocation across atoms they chain.
--- If they have a collision it means either they didn't saturate the register file optimally for a phase,
--- or the may have made the workload to large for the run.
---
--- ── WHAT'S NOT IN THE POOL — and WHY (the "obvious exclusions") ────────────
--- R_T9 (GPR code 25) — R_TapePtr, the tape instruction stream pointer.
--- Owned by the tape runtime (in tape_run / tape_run_a02_s07).
--- `rgcc(R_TapePtr)` register-variable ties the C compiler's view to $t9 across the whole tape_run.
--- The auto-reg pass MUST NOT clobber this; doing so would desync the C-side tape pointer from the
--- hardware pointer and crash on the next tape_run.
---
--- R_T8 (GPR code 24) — R_AtomJmp, the atom-jump register used by the 4-word yield handshake.
--- Every `mac_yield()` / `mac_yield_tail` does `load_word R_AtomJmp, R_TapePtr, 0` then
--- `jump_reg R_AtomJmp`. The auto-reg pass MUST NOT clobber this either, or the atom dispatcher breaks.
--- Owned by the tape runtime, same family as R_TapePtr.
---
--- R_AT (GPR code 1) — Assembler temporary. Reserved by the MIPS O32 ABI for pseudoinstruction expansion
--- (lottes_tape.h:86, mips.h:93). The ISA's psuedo instructions use it as a scratch temporary.
---
--- R_A0..A3 (codes 4..7) — Function arguments. Used in tape_run_a02_s07, see below.
--- R_S0..S7 (codes 16..23) — Callee-saved. Preserved across C-ABI calls by convention.
--- The `tape_run_a02_s07` variant clobbers them deliberately, but the default `tape_run` does NOT.
--- Kept out of POOL to preserve the conservative default.
--- Add them in a separate "big clobber" pool if/when needed.
---
--- R_K0/K1 (codes 26..27) — Kernel / interrupt handler reserves. Never touched by user code; OS-internal.
--- R_GP/SP/FP/RA (codes 28..31) — Stack frame + return-address. Owned by the C compiler; never allocatable.
--- R_0 (code 0) — Hardwired zero. Cannot be written.
---
local POOL = {
"R_T0", "R_T1", "R_T2", "R_T3",
"R_T4", "R_T5", "R_T6", "R_T7",
"R_V0", "R_V1",
}
-- Map from integer MIPS GPR code (the `code` field on AliasEntry) to the physical GPR ident in POOL.
-- The standard MIPS O32 ABI register numbering matches mips.h's R_*_Code #defines (mips.h).
-- Only the POOL entries matter for auto_reg — non-pool aliases
-- (R_AT=1, R_A0..A3=4..7, R_T8=24, R_T9=25, R_K0/K1=26..27, R_GP/SP/FP/RA=28..31)
-- are deliberately omitted — see the comment block above for the WHY of each exclusion.
local INT_CODE_TO_POOL_GPR = {
[2] = "R_V0", [3] = "R_V1",
[8] = "R_T0", [9] = "R_T1", [10] = "R_T2", [11] = "R_T3",
[12] = "R_T4", [13] = "R_T5", [14] = "R_T6", [15] = "R_T7",
}
-- Stable sort for deterministic allocation order.
local function stable_sort_keys(tbl)
local keys = {}
for k in pairs(tbl) do keys[#keys + 1] = k end
table.sort(keys)
return keys
end
-- Allocate one phase's auto-reg mappings.
-- Returns (allocated_map, errors). On pool exhaustion, errors is populated and the function halts.
local function allocate_phase(phase_label, decls)
-- Deep-copy POOL into a fresh sequence table. The original `table.unpack and table.unpack(POOL) or { unpack(POOL) }`
-- idiom wraps the unpacked values in a single inner table under LuaJIT 5.1 (`table.unpack` is nil; the `or` returns one value),
-- which corrupts the pool into `{ {R_T0, R_T1, ...} }` — making `table.remove(pool, 1)` return the inner table on iteration.
local pool = {}
for i = 1, #POOL do pool[i] = POOL[i] end
local result = {}
local errors = {}
for _, sym in ipairs(stable_sort_keys(decls)) do
local next_gpr = table.remove(pool, 1)
if not next_gpr then
errors[#errors + 1] = {
line = 0,
msg = string.format("phase_register_pool_exhausted: "
.. "phase '%s' requested symbol '%s' but the pool has no remaining registers "
.. "(max 10 per phase: R_T0..R_T7 + R_V0..R_V1). Split the phase or use hardcoded GPRs."
, phase_label, sym),
}
return result, errors
end
result[sym] = next_gpr
end
return result, errors
end
-- Build two projections from corpus.register_alias_registry:
-- user_pinned -- { [physical_gpr_ident] = true } -- GPRs unavailable to auto_reg globally (wave-context carriers, file-scope pinned aliases)
-- alias_to_gpr -- { [alias_ident] = physical_gpr_ident } -- for body parsing
-- Both projections are derived from the same set of entries: every AliasEntry in register_alias_registry has `has_atom_reg = true`
-- (only those entries are added to the registry; see passes/scan_source.lua parse_enum_entry).
-- Each entry's `code` is the integer MIPS GPR number (0..31); INT_CODE_TO_POOL_GPR translates it back to the physical GPR ident.
-- Aliases whose `code` points to a non-POOL GPR (e.g. R_S0, R_T8, R_K1) are ignored —
-- they don't affect the auto_reg pool, and they're already excluded from POOL above.
local function build_user_pins(corpus)
local user_pinned = {}
local alias_to_gpr = {}
if not corpus.register_alias_registry then return user_pinned, alias_to_gpr end
for alias_name, alias_entry in pairs(corpus.register_alias_registry) do
if alias_entry.has_atom_reg and alias_entry.code then
local gpr = INT_CODE_TO_POOL_GPR[alias_entry.code]
if gpr then
user_pinned[gpr] = true
alias_to_gpr[alias_name] = gpr
end
end
end
return user_pinned, alias_to_gpr
end
-- Find every physical GPR referenced in the atom body, via EITHER:
-- (a) a hardcoded physical GPR ident (R_T\d+|R_V\d+|R_A\d+|R_S\d+) — the existing regex;
-- (b) an alias ident (R_<Alias>) resolved via alias_to_gpr back to its physical GPR ident.
-- Returns { [physical_gpr_ident] = count }. The clash-detection and source-pool-exclusion logic
-- only needs the presence of each GPR (boolean test), but keeping the count preserves the
-- original find_hardcoded_rn shape so callers can switch without churn.
-- The alias pattern is sorted lexicographically to keep the regex deterministic.
local function find_used_gprs(body_text, alias_to_gpr)
local found = {}
-- (a) Hardcoded physical GPRs (R_T0..R_T7, R_V0..R_V1, R_A0..R_A3, R_S0..R_S7).
for gpr in body_text:gmatch("(R_T%d+|R_V%d+|R_A%d+|R_S%d+)") do
found[gpr] = (found[gpr] or 0) + 1
end
-- (b) Alias references (R_<Alias>) resolved to physical GPRs via the registry.
-- Sorted by name so the regex is byte-stable across runs.
if alias_to_gpr and next(alias_to_gpr) then
local aliases = {}
for alias_name in pairs(alias_to_gpr) do
aliases[#aliases + 1] = alias_name
end
table.sort(aliases)
local pattern = "(" .. table.concat(aliases, "|") .. ")"
for alias_name in body_text:gmatch(pattern) do
local gpr = alias_to_gpr[alias_name]
if gpr and not found[gpr] then
found[gpr] = 1
end
end
end
return found
end
-- Emit one gen/auto_reg.h header per directory.
local function emit_auto_reg_h(out_dir, dir, sources, mappings)
if not mappings or next(mappings) == nil then return end
local out_path = out_dir .. "/" .. "auto_reg.h"
duffle.ensure_dir(out_dir)
local lines = {
"#ifdef INTELLISENSE_DIRECTIVES",
"#pragma once",
"#endif",
"// Auto-generated by ps1_meta.lua (passes/auto_reg.lua) — DO NOT EDIT",
"// Directory: " .. dir:gsub("/", "\\"),
}
for _, src in ipairs(sources) do
lines[#lines + 1] = "// source: " .. src.path
end
lines[#lines + 1] = "// Per-phase register allocations resolved by the lua pass."
lines[#lines + 1] = "// R_<Sym>_Code = <chosen GPR's _Code constant> for every marker in this directory."
lines[#lines + 1] = ""
for _, sym in ipairs(stable_sort_keys(mappings)) do
local gpr = mappings[sym]
local gpr_code = gpr .. "_Code"
lines[#lines + 1] = "#define " .. sym .. "_Code " .. gpr_code
end
lines[#lines + 1] = ""
duffle.write_file_lf(out_path, table.concat(lines, "\n") .. "\n")
print(" -> " .. out_path)
return out_path
end
-- ════════════════════════════════════════════════════════════════════════════
-- Pass entry
-- ════════════════════════════════════════════════════════════════════════════
local M = {}
--- @param ctx PassCtx
--- @return AutoRegResult
function M.run(ctx)
local outputs = {}
local errors = {}
local warnings = {}
local corpus = ctx.shared and ctx.shared.corpus
if type(corpus) ~= "table" then
error("auto_reg.run requires ctx.shared.corpus", 0)
end
-- 0. Build the user-pinned GPR exclusion set + alias-to-GPR resolution map.
-- Wave-context carriers (e.g. `R_ResolveScratch = R_T4 atom_reg` in hello_camera.atom.c)
-- MUST NOT be allocated to any auto-reg marker — they're preserved across atoms by the wave-context discipline.
-- The corpus's register_alias_registry is the source of truth for these opt-in pins.
-- Body references to those aliases (via alias_to_gpr) are also excluded on a per-atom basis in step 2 below.
local user_pinned, alias_to_gpr = build_user_pins(corpus)
-- 1. Allocate phase pools first (phase declarations take precedence over per-atom declarations).
local phase_allocations = {}
for phase_label, decls in pairs(corpus.phase_auto_regs or {}) do
local mapping, errs = allocate_phase(phase_label, decls)
for sym, gpr in pairs(mapping) do
phase_allocations[phase_label] = phase_allocations[phase_label] or {}
phase_allocations[phase_label][sym] = gpr
end
for _, e in ipairs(errs) do
errors[#errors + 1] = e
end
end
-- 2. Allocate per-atom auto-regs. If the atom scope matches a phase, reuse the phase pool.
-- Otherwise, allocate a private pool for the atom.
-- The phase membership is in `corpus.atom_phases[phase_label].atoms` (an array of atom names declared via `atom_phase(<phase>)`
-- in the atom's `atom_info` line). Build a reverse map `atom_name -> phase_label` so the lookup is O(1) per atom scope.
local atom_name_to_phase = {}
for phase_label, entry in pairs(corpus.atom_phases or {}) do
for _, atom_name in ipairs(entry.atoms or {}) do
atom_name_to_phase[atom_name] = phase_label
end
end
local atom_allocations = {}
for atom_scope, decls in pairs(corpus.atom_auto_regs or {}) do
local phase_label = atom_name_to_phase[atom_scope]
-- Build the atom's source pool: start with the full POOL, subtract:
-- (a) every GPR already committed (phase allocations + prior atom allocations)
-- (b) every USER-PINNED GPR (wave-context carriers + file-scope pinned aliases)
-- (c) every GPR referenced in the atom's body — either hardcoded R_X or alias R_Xxx
-- (the latter resolved via alias_to_gpr; this catches cases where the user wrote R_ResolveScratch instead of R_T4 directly)
-- Atoms whose scope matches a phase share the global pool with the phase allocations;
-- the original `source_pool = phase_allocations[phase_label]` form used the phase
-- allocation MAP as a pool, but that map has no array part, so `table.remove(source_pool, 1)`
-- returned nil and every atom-with-phase marker errored with `phase_register_pool_exhausted`.
local used = {}
for _, m in pairs(phase_allocations) do for _, gpr in pairs(m) do used[gpr] = true end end
for _, m in pairs(atom_allocations) do for _, gpr in pairs(m) do used[gpr] = true end end
-- (c) Body references — scan the atom body for hardcoded + alias-resolved GPRs.
-- Folded into `used` so the source_pool exclusion is a single check.
local atom = corpus.atoms_by_name and corpus.atoms_by_name[atom_scope]
if atom and atom.body then
local body_used = find_used_gprs(atom.body, alias_to_gpr)
for gpr in pairs(body_used) do used[gpr] = true end
end
local source_pool = {}
for _, gpr in ipairs(POOL) do
-- Exclude (a) prior commitments, (b) USER-PINNED GPRs (wave-context carriers
-- declared via atom_reg + _Code defs, preserved across atoms globally).
if not used[gpr] and not user_pinned[gpr] then
source_pool[#source_pool + 1] = gpr
end
end
local result = {}
for _, sym in ipairs(stable_sort_keys(decls)) do
local next_gpr = table.remove(source_pool, 1)
if not next_gpr then
errors[#errors + 1] = {
line = 0,
msg = string.format("phase_register_pool_exhausted: atom '%s' requested symbol '%s' "
.. "but no free registers remain in its scope pool."
, atom_scope, sym),
}
else
result[sym] = next_gpr
end
end
atom_allocations[atom_scope] = result
end
-- 3. Conflict-with-hardcoded detection (defensive — should be unreachable now).
-- The source_pool exclusion in step 2 (b) + (c) already accounts for both user-pinned GPRs
-- and body-referenced GPRs (hardcoded R_Tn OR alias R_<Alias>).
-- An auto-reg allocation that matched an existing body reference would be impossible by construction.
-- This warning is kept as a defensive safety net for cases the body scanner might miss
-- (e.g. macros that expand to register references the scanner cannot resolve).
-- For each resolved (scope, sym) -> R_Tn mapping, scan the atom body source for used GPRs.
for atom_scope, decls in pairs(atom_allocations) do
local atom = corpus.atoms_by_name and corpus.atoms_by_name[atom_scope]
if atom and atom.body then
local used_in_body = find_used_gprs(atom.body, alias_to_gpr)
for sym, allocated_gpr in pairs(decls) do
if used_in_body[allocated_gpr] and used_in_body[allocated_gpr] > 0 then
warnings[#warnings + 1] = {
line = atom.line or 0,
msg = string.format("phase_register_clash: atom '%s' has hardcoded '%s' in its body AND an auto-reg marker '%s' "
.. "that was allocated to '%s' (same phase). Resolve by removing the hardcoded reference or renaming the auto-reg."
, atom_scope, allocated_gpr, sym, allocated_gpr),
}
end
end
end
end
-- 4. Emit per-directory gen/auto_reg.h.
-- For each source directory that has atom_auto_regs or phase_auto_regs entries, emit one header.
local sources_by_dir = corpus.sources_by_dir or {}
for dir, sources in pairs(sources_by_dir) do
local per_dir_mappings = {}
for _, src in ipairs(sources) do
-- Collect every (sym -> gpr) entry that originated from a source in this directory.
-- `src.scan.atom_auto_regs` is keyed by ATOM SCOPE NAME; `pairs(t)` iterates KEYS so `scope_name` here is the scope ident (e.g. "cube_g4_face").
-- The previous `for _, scan_atom_auto` form silently assigned the VALUE (a `{sym = sym}` table) to the variable,
-- which made `atom_allocations[scan_atom_auto]` a table-indexed lookup that never resolved.
for scope_name in pairs(src.scan and src.scan.atom_auto_regs or {}) do
for sym, gpr in pairs(atom_allocations[scope_name] or {}) do
per_dir_mappings[sym] = gpr
end
end
for scope_name in pairs(src.scan and src.scan.phase_auto_regs or {}) do
for sym, gpr in pairs(phase_allocations[scope_name] or {}) do
per_dir_mappings[sym] = gpr
end
end
end
local out_dir = dir .. "/gen"
local out_path = emit_auto_reg_h(out_dir, dir, sources, per_dir_mappings)
if out_path then outputs[#outputs + 1] = { auto_reg_h = out_path } end
end
return { outputs = outputs, errors = errors, warnings = warnings }
end
return M