selfhost+cstage+test: graduate frame growth to first-use+fail-loud (#15)

Subsumes #36. Drop wwstage scanlocals pre-pass; both stages converge on
first-use+fail-loud frame growth, rule-10 polarity DOWN to leaner side.
#36's surfaces (frame-total divergence on match-arm case-let; sibling
offset divergence in variadic+iter+match-prev compositions) close
naturally — running-max c.frame includes every first-use binding.

selfhost/cmd/wcc: add atlocals persistent @-prefix registry surviving
cgblock save/restore; add cgoutbuf/cgoutmode/cgout_enable/disable/flush
for deferred prologue (emit body to buffer, finalise c.frame, then
TEXT/SUBQ + flush); localadd @-prefix dedups against atlocals +
fail-louds on size-grow (rule 7 — no silent truncate); cgreturn-tagged
routes through @retscr (was colliding with @tagscr on arg-widen sizes);
variadic gather esz uses raw primsize (rune->4) not slotsize (rune->8)
— matches cstage and fixes the #36 sibling runtime miscompile in
non-leaf variadic+iter+match-prev callees.

cmd/w6c/cgen.c: drop the over-allocation hack ("for byte-id with
wwstage scanlocals reservation") since wwstage no longer over-reserves;
add fail-loud on @sretscr size-grow; @tagscr sites pass actual slot_sz
instead of stale c.tagscrsz.

748_size_strategy_convergence: table-driven 4 rows x 2 stages
(tag_variadic_runearm, trim_iter_match_prev, variadic_gather_rune_stride,
leaf_baseline). Each exercises a #36 surface shape; 8/8 ok.

Net -1565 lines. Sister latents filed as cosmetic (cs/ws frame size
drift on multiple-variadic-call fns): labelseq drift + varargseq
stuck at 0 — both bootstrap-byte-id safe (ww2==ww3==ww4 holds since
both ww2 and ww3 are wwstage outputs).

make test 122/122; ww2==ww3==ww4 byte-id holds via 995_self_rebuild.
This commit is contained in:
2026-05-19 02:13:58 +09:00
parent 7a278c1a2d
commit 5609d0456f
10 changed files with 1197 additions and 2469 deletions

View File

@@ -1,9 +1,10 @@
// selfhost/cmd/wcc/cgendecl.ww — split out of cgen.ww.
//
// Houses the top-level emission glue:
// - scanlocals: frame pre-scan that counts each local `let`
// - cgfnparams: parameter spilling per SysV
// - cgfn: fn prologue + body + epilogue
// - cgfn: fn body emit (TEXT/SUBQ patched after body), prologue
// deferred via cgen.ww's cgoutbuf so the frame size
// reflects every emit-time localadd (#15/#26c)
// - cgfile: file-level entry (the exported driver)
//
// Bundler pulls this in transitively via cgen.ww; consumers don't
@@ -19,519 +20,6 @@ import typ;
import sym;
import strconv;
// tagscrbump — record that the body needs an @tagscr scratch slot of at
// least `need` bytes and return how many additional frame bytes that
// imposes. Each tagged-scratch reservation site calls this; the first
// raises c.tagscrsz from 0, later sites only grow it when they need
// more. Closes STATUS latent #1: pre-fix every site reserved a flat 24B
// and the slot under-allocated for any tagged-union with a 24B+ payload
// (e.g. `(void | err)` where `err` is 24B → slot_sz 32). Cgen-side
// emit (cgreturn / pushargsrev / cgindex / cgwidentaggedstore) reads
// c.tagscrsz to allocate the actual slot — scan + emit see the same
// number, so rob's "lockstep" invariant holds. The @tagscr lifetime is
// short-lived per use (zero, fill, copy out), and uses are sequential
// within a fn body, so sharing the max is safe.
fn tagscrbump(c: *cgen, need: i32) i32 = {
let n: i32 = need;
if (n < 8) { n = 8; };
if ((n & 7) != 0) { n = (n + 7) & ~7; };
if (n <= c.tagscrsz) { return 0; };
let delta: i32 = n - c.tagscrsz;
c.tagscrsz = n;
return delta;
};
// sretscrbump — sister of tagscrbump for the sret discard slot
// (#23). Tracks max sret return type used as a CALL discard / nested
// receiver. Returns frame-byte delta vs the previous high water mark
// (rounded up to 8B).
fn sretscrbump(c: *cgen, need: i32) i32 = {
let n: i32 = need;
if (n < 8) { n = 8; };
if ((n & 7) != 0) { n = (n + 7) & ~7; };
if (n <= c.sretscrsz) { return 0; };
let delta: i32 = n - c.sretscrsz;
c.sretscrsz = n;
return delta;
};
//
// Recursively walks the body to count every local `let`. Each gets a
// slot sized by slotsize(typ); 8-byte default. Match-bindings + for-
// init lets count too. Params are added by the cgfn driver.
fn scanlocals(c: *cgen, n: *node) i32 = {
if (n == nil) { return 0; };
let total: i32 = 0;
if (n.kind == nkind.N_LET) {
// Match localadd's rounding: < 8 bumps to 8, then 8-align.
// scanlocals must agree with localadd or the prologue
// SUBQ undersizes the frame and lets overflow into the
// caller's stack — corrupting whatever's at -frameSize..-1
// of the caller. Post-#27 every let allocates fresh (no
// name dedup), so we always count + always append a stub.
// The stub carries n.lhs as tnode so later scanlocals
// nodes can dispatch on type — e.g. detecting `arr[i] = ...`
// where arr is a tagged-element array (needs @tagscr).
// localfindnode walks head-first, so the freshest stub
// (innermost binding) wins lookup.
let sz: i32 = letslotsize(c, n);
if (sz < 8) { sz = 8; };
if ((sz & 7) != 0) { sz = (sz + 7) & ~7; };
total += sz;
let stub: *local = amalloc(c.a, 48u64): *local;
stub.name = n.str;
stub.off = 0;
stub.tnode = n.lhs;
stub.lnext = c.locals;
c.locals = stub;
};
// Multi-let from a tuple-returning call: each binding's size
// comes from its annotated type (l.lhs) when present, else from
// the rhs call's return-tuple element type. Marking via
// scanseenmark also dedupes the recursive descent into n.list
// so each child isn't counted again at the default 8B.
if (n.kind == nkind.N_MLET) {
let p0t: *node = nil;
let p1t: *node = nil;
if (n.rhs != nil) {
if (n.rhs.kind == nkind.N_CALL) {
let callee: *node = n.rhs.lhs;
if (callee != nil) {
let cnm: str;
cnm.ptr = nil; cnm.len = 0;
if (callee.kind == nkind.N_IDENT) { cnm = callee.str; };
if (callee.kind == nkind.N_DOT) { cnm = callee.str; };
if (cnm.len > 0) {
let rt: *node = fnretlookup(c, cnm);
if (rt != nil) {
if (rt.kind == nkind.N_TTUPLE) {
p0t = rt.list;
if (p0t != nil) { p1t = p0t.next; };
};
};
};
};
};
};
let l: *node = n.list;
let pt: *node = p0t;
let bidx: i32 = 0;
for (l != nil) {
let t: *node = l.lhs;
if (t == nil) {
if (bidx == 0) { t = p0t; };
if (bidx == 1) { t = p1t; };
};
let sz: i32 = 8;
if (t != nil) { sz = slotsize(c, t); };
if (sz < 8) { sz = 8; };
if ((sz & 7) != 0) { sz = (sz + 7) & ~7; };
total += sz;
// Always-fresh stub (post-#27); tnode carries the
// binding's type so later array-index dispatch can
// resolve the let through localfindnode.
let stub: *local = amalloc(c.a, 48u64): *local;
stub.name = l.str;
stub.off = 0;
stub.tnode = t;
stub.lnext = c.locals;
c.locals = stub;
l = l.next;
bidx += 1;
};
};
// `switch` allocates an 8B scratch slot for the scrutinee so case
// bodies can spill through SP without losing it. The slot is named
// ".sw_<labelseq>" at cgen time — unique per switch — so it must
// not dedup. Count it here so the frame SUBQ matches.
if (n.kind == nkind.N_SWITCH) { total += 8; };
// `for (let x .. s)` allocates two 8B scratch slots — `.rgi_<seq>`
// (counter) and `.rgl_<seq>` (length) — plus one slot per binding.
// Per-binding sz defaults to 8 (covers scalar primitives + ptrs).
// `str` tuple-fields would need 16 — selfhost doesn't yet emit
// those, so the simple count tracks C cgen for current fixtures.
if (n.kind == nkind.N_FORRANGE) {
total += 16; // .rgi + .rgl scratch
// Each forrange binding gets a fresh 8B slot (post-#27).
// Stub is also appended so the body's references resolve
// to this binding via head-first localfindnode lookup.
if (n.list != nil) {
let m: *node = n.list;
for (m != nil) {
let bnm: str = m.str;
total += 8;
if (bnm.len > 0) {
let stub: *local = amalloc(c.a, 48u64): *local;
stub.name = bnm;
stub.off = 0;
stub.tnode = m.lhs;
stub.lnext = c.locals;
c.locals = stub;
};
m = m.next;
};
} else {
let bnm: str = n.str;
total += 8;
if (bnm.len > 0) {
let stub: *local = amalloc(c.a, 48u64): *local;
stub.name = bnm;
stub.off = 0;
stub.tnode = nil;
stub.lnext = c.locals;
c.locals = stub;
};
};
};
// `match (non-ident)` needs an `@match_spill` scratch slot sized
// to the scrutinee's tagged-union slot (16/24/32 for 1/2/3-word
// payload). Mirrors cstage's `slot_size = su->size` default 16
// in cmd/w6c/cgen.c cgmatch (task #9 align-down to cstage).
// matchspillsz must agree with cgmatch's emit-time computation
// for scan+emit lockstep. N_IDENT scrutinees read the slot
// directly off the local — no spill needed.
if (n.kind == nkind.N_MATCH) {
let sc: *node = n.lhs;
if (sc != nil) {
if (sc.kind != nkind.N_IDENT) {
total += matchspillsz(c, matchscrutt(c, sc));
};
};
};
// Match-arm binding (`case let v: T => ...`) gets a slot too.
// Crucially we do NOT dedup these against c.locals: C cgen
// handles a match as an expression with a by-value locals copy,
// so two separate matches in the same function each allocate
// their `v`/`e` slots fresh. Treating these as deduped would
// shrink the frame below what localadd then bumps it to.
if (n.kind == nkind.N_MCASE) {
let bn: str = n.str;
if (bn.len > 0) {
let pat: *node = n.lhs;
if (pat != nil) {
// Must mirror cgmatch's bind-slot sizing in
// cgenexpr.ww (`bsz = slotsize(c, pat)`):
// hardcoding str/slice/8 here underbooked the
// frame for TY_STRUCT variants — the emit-time
// localalloc(bsz=24) then wrote past the SUBQ'd
// SP, smashing whatever the OS put under it
// (project #31).
let psz: i32 = slotsize(c, pat);
if (psz <= 0) { psz = 8; };
if ((psz & 7) != 0) { psz = (psz + 7) & ~7; };
total += psz;
};
};
// Match arms get a fresh local scope at emission time
// (cgmatch saves c.locals before each arm and restores
// after). scanlocals must mirror that: walk the arm
// body with a saved/restored seenmark set so two arms
// declaring the same name each get their own slot,
// matching the per-arm frame growth the emit phase
// produces.
if (n.body != nil) {
let saved: *local = c.locals;
total += scanlocals(c, n.body);
c.locals = saved;
};
return total;
};
// Tagged-arr/slice index store needs an @tagscr scratch slot for
// cgwidentaggedstore to materialise the source in before copying
// to the element address. Slot is shared per function via
// c.tagscrsz (raised to the largest element slot_sz seen).
// N_DOT-base graduated (task #30) so `obj.arr[i] = v` for an
// [N]Tagged struct field pre-reserves the slot — parallels the
// cgassign N_DOT-base elemtn fix in cgenexpr.ww. Without this
// arm the runtime localadd allocates past the frame boundary
// and clobbers live locals; cstage handles the shape naturally
// via first-use+fail-loud (rule-10 convergence filed as #15).
if (n.kind == nkind.N_ASSIGN) {
let alhs: *node = n.lhs;
if (alhs != nil) {
if (alhs.kind == nkind.N_INDEX) {
let abase: *node = alhs.lhs;
if (abase != nil) {
if (abase.kind == nkind.N_IDENT) {
let lc: *local = localfindnode(c, abase.str);
let btn: *node = nil;
if (lc != nil) { btn = lc.tnode; }
else { btn = letvartnode(c, abase.str); };
if (btn != nil) {
let bk: nkind = btn.kind;
let etn: *node = nil;
if (bk == nkind.N_TARRAY) { etn = btn.lhs; };
if (bk == nkind.N_TSLICE) { etn = btn.lhs; };
if (bk == nkind.N_TPTR) { etn = btn.lhs; };
if (etn != nil) {
if (istaggedtype(c, etn)) {
total += tagscrbump(c, slotsize(c, etn));
};
};
};
};
if (abase.kind == nkind.N_DOT) {
let ft: *node = dotfieldtnode(c, abase);
if (ft != nil) {
let bk: nkind = ft.kind;
let etn: *node = nil;
if (bk == nkind.N_TARRAY) { etn = ft.lhs; };
if (bk == nkind.N_TSLICE) { etn = ft.lhs; };
if (bk == nkind.N_TPTR) { etn = ft.lhs; };
if (etn != nil) {
if (istaggedtype(c, etn)) {
total += tagscrbump(c, slotsize(c, etn));
};
};
};
};
};
};
};
};
// Tagged-union struct-field write: `s.f = v` or `(*p).f = v`
// where f is a tagged-union field. cgassign delegates to
// cgwidentaggedstore; for pointer-rooted dst the wrapper
// allocates @tagbase (8B, fixed) and @tagscr (sized to the
// field's tagged slot). The @tagscr size feeds c.tagscrsz.
if (n.kind == nkind.N_ASSIGN) {
let alhs: *node = n.lhs;
if (alhs != nil) {
if (alhs.kind == nkind.N_DOT) {
let abase: *node = alhs.lhs;
if (abase != nil) {
if (abase.kind == nkind.N_IDENT) {
let lc: *local = localfindnode(c, abase.str);
let btn: *node = nil;
if (lc != nil) { btn = lc.tnode; }
else { btn = letvartnode(c, abase.str); };
let isptr: bool = false;
let stype: *node = nil;
if (btn != nil) {
if (btn.kind == nkind.N_TPTR) {
isptr = true;
stype = btn.lhs;
};
if (btn.kind == nkind.N_TNAME) { stype = btn; };
};
if (stype != nil) {
if (stype.kind == nkind.N_TNAME) {
let si: *structinfo = structlookup(c, stype.str);
if (si != nil) {
let fi: *fieldinfo = si.fields;
for (fi != nil) {
if (streq(fi.fname, alhs.str)) {
if (istaggedtype(c, fi.tnode)) {
if (isptr) {
if (!scanseenmark(c, "@tagbase")) {
total += 8;
};
total += tagscrbump(c, slotsize(c, fi.tnode));
};
};
fi = nil;
} else {
fi = fi.finext;
};
};
};
};
};
};
};
};
};
};
// Tagged-union return with struct payload or tagged-subset
// source — cgreturn materialises in @tagscr then loads AX/DX/
// CX/R8. Detect via the same rhsstructpayload predicate the
// cgen uses, so we only reserve when the cgen will actually
// emit a scratch-using path. `!void` / `!i32` aliases share
// N_STRUCTLIT shape but resolve to non-struct types — they
// fall through to scalar/str and don't need scratch. Slot is
// sized to the return type's slot_sz (was hardcoded 24, which
// truncated 32B slots — `(void | err24)` clobbered its own
// payload local; task #38).
if (n.kind == nkind.N_RETURN) {
if (c.fnret != nil) {
if (istaggedtype(c, c.fnret)) {
if (!isnullabletype(c.fnret)) {
let rhs: *node = n.lhs;
let needs: bool = false;
if (rhs != nil) {
let sn: str = rhsstructpayload(c, rhs);
if (sn.len > 0) { needs = true; };
if (rhs.kind == nkind.N_IDENT) {
let lc: *local = localfindnode(c, rhs.str);
if (lc != nil) {
if (istaggedtype(c, lc.tnode)) {
needs = true;
};
};
};
};
if (needs) {
total += tagscrbump(c, slotsize(c, c.fnret));
};
};
};
};
};
// Whole-struct return for sizes <= 24B uses @retscr — when
// the function's return type is a registered TY_STRUCT of
// size <= 24 and the return rhs is N_IDENT or N_STRUCTLIT,
// cgreturn materialises in @retscr then loads AX/DX/CX.
// Mirrors cstage cgen.c which allocates the scratch slot
// inline; here we must pre-reserve so the prologue SUBQ
// reserves enough frame.
if (n.kind == nkind.N_RETURN) {
if (c.fnret != nil) {
if (c.fnret.kind == nkind.N_TNAME) {
let rname: str = c.fnret.str;
let rsi: *structinfo = structlookup(c, rname);
if (rsi != nil) {
if (rsi.totsize <= 24) {
let rhs: *node = n.lhs;
let okrhs: bool = false;
if (rhs != nil) {
if (rhs.kind == nkind.N_IDENT) {
okrhs = true;
};
if (rhs.kind == nkind.N_STRUCTLIT) {
okrhs = true;
};
};
if (okrhs) {
if (!scanseenmark(c, "@retscr")) {
total += 24;
};
};
};
};
};
};
};
// sret CALL (#23): callee returns plain TY_STRUCT > 24B. The
// receive site (cglet / cgassign ident) overrides at emit time
// with the dest local's own slot; discards / nested calls fall
// back to @sretscr. Single-slot per fn sized to the max sret
// return — sretscrbump tracks the high-water mark so a later
// larger call grows the frame without re-counting the prior
// reservation. Mirrors @tagscr's cumulative tagscrbump.
if (n.kind == nkind.N_CALL) {
let scs: i32 = callsretsize(c, n);
if (scs > 0) { total += sretscrbump(c, scs); };
};
// Call-site struct-payload widening uses @tagscr — when the
// arg is a struct literal/ident and the callee's param is
// tagged, pushargsrev materialises in scratch and pushes.
// Scalar / str args take the direct-push fast path (no
// scratch). Tagged-typed ident args also skip widening (the
// slot is already laid out, so pushargsrev pushes slot words
// directly). Both fast paths agree with C cgen bytewise, so
// only struct-payload sites get a scratch reservation.
if (n.kind == nkind.N_CALL) {
let callee: *node = n.lhs;
let cnm: str;
cnm.ptr = nil; cnm.len = 0;
if (callee != nil) {
if (callee.kind == nkind.N_IDENT) { cnm = callee.str; };
if (callee.kind == nkind.N_DOT) { cnm = callee.str; };
};
if (cnm.len > 0) {
let ps: *node = fnparamslookup(c, cnm);
let a: *node = n.list;
for (a != nil) {
if (ps == nil) { a = nil; }
else {
if (ps.kind == nkind.N_PARAM) {
let pt: *node = ps.lhs;
if (istaggedtype(c, pt)) {
if (!isnullabletype(pt)) {
let sn: str = rhsstructpayload(c, a);
if (sn.len > 0) {
let isidentstruct: bool = false;
if (a.kind == nkind.N_IDENT) {
// Struct ident as
// tagged arg — pushargsrev
// still routes through the
// scratch path.
isidentstruct = true;
};
let _u: bool = isidentstruct;
total += tagscrbump(c, slotsize(c, pt));
};
};
};
};
if (a != nil) {
a = a.next;
ps = ps.next;
};
};
};
};
// Hare-style variadic call: reserve @vararg_d_<seq> for the
// element data and @vararg_sl_<seq> for the 24B slice
// descriptor. The seq is recorded on the N_CALL node so
// cgcall picks the same names regardless of walk order
// (scanlocals descends LTR; pushargsrev evaluates RTL).
let nfixed: i32 = 0;
let varp: *node = callee_variadic_param(c, n.lhs, &nfixed);
if (varp != nil) {
let nargs: i32 = 0;
let aw: *node = n.list;
for (aw != nil) { nargs += 1; aw = aw.next; };
let nvar: i32 = nargs - nfixed;
if (nvar < 0) { nvar = 0; };
let forwarding: bool = false;
if (nvar == 1) {
let aa: *node = n.list;
let k0: i32 = 0;
for (k0 < nfixed) { aa = aa.next; k0 += 1; };
if (aa != nil) {
if (aa.kind == nkind.N_SPREAD) {
forwarding = true;
};
};
};
if (!forwarding) {
let seq: i32 = c.varargseq;
n.uval = seq: u64;
c.varargseq += 1;
let esz: i32 = slotsize(c, varp.lhs);
if (esz < 1) { esz = 1; };
let dname: str = mkvarargname(c, "@vararg_d_", seq);
let sname: str = mkvarargname(c, "@vararg_sl_", seq);
if (nvar > 0) {
if (!scanseenmark(c, dname)) {
let dsz: i32 = nvar * esz;
if ((dsz & 7) != 0) {
dsz = (dsz + 7) & ~7;
};
total += dsz;
};
};
if (!scanseenmark(c, sname)) { total += 24; };
};
};
};
if (n.lhs != nil) { total += scanlocals(c, n.lhs); };
if (n.rhs != nil) { total += scanlocals(c, n.rhs); };
if (n.cond != nil) { total += scanlocals(c, n.cond); };
if (n.body != nil) { total += scanlocals(c, n.body); };
if (n.els != nil) { total += scanlocals(c, n.els); };
if (n.list != nil) {
let m: *node = n.list;
for (m != nil) {
total += scanlocals(c, m);
m = m.next;
};
};
return total;
};
// ---- function-level cgen ---------------------------------------------
@@ -541,7 +29,7 @@ fn cgfnparams(c: *cgen, params: *node) void = {
// (already spilled to @sretarg by cgfn); the first user param
// lands in SI.
let idx: i32 = 0;
if (c.sretargoff != 0) { idx = 1; };
if (localfind(c, "@sretarg") != 0) { idx = 1; };
let fidx: i32 = 0;
// Cursor for args that overflow the SysV reg windows. Each
// stack-passed arg lives at 16+8*k(BP) — no spill, the local
@@ -854,130 +342,18 @@ fn cgfn(c: *cgen, fn_: *node) void = {
// sret callee (#23): return type is plain TY_STRUCT > 24B.
// Reserve 8B for @sretarg (holds the saved hidden RDI dest
// pointer); cgfnparams skips DI for user args, cgreturn writes
// through *(@sretarg) and returns @sretarg in RAX. Decision
// made here so the frame pre-scan and cgfnparams see the same
// view of the int-arg cursor.
// through *(@sretarg) and returns @sretarg in RAX.
let sret_callee: bool = sretretsize(c, c.fnret) > 0;
// Emit the TEXT label via emitfnname so the def site picks up the
// same skip rule (FFI / `main` / empty-module) and the same module
// hint (this fn's own module) that the call sites use. Drops the
// `exported == 0` skip in the legacy inline form — exported fns
// now mangle too, so cross-module same-leaf exports coexist.
emitline("TEXT ");
emitfnname(c, fn_.str, fn_.nmod);
emitline(",$");
// Pre-scan total frame: only count params that land in a local
// slot. SysV-class accounting; mirrors runtime walk in cstage
// cgen.c §5130-5223 and cgfnparams below. A stack-spilled param
// is addressed at a positive BP offset by cgfnparams (via
// localaddstack) and consumes no frame, so adding its size here
// would over-allocate. Seed c.locals with param-name stubs so
// scanlocals dedups a re-declared `let <name>` in the body
// against the param's slot (matches C cgen). Stubs get cleared
// before emission.
let scanp: *node = fn_.list;
let frame: i32 = 0;
let argi: i32 = 0;
let fargi: i32 = 0;
// Reserve @sretarg (8B) BEFORE the param-induced frame, and
// start argi at 1 so the param walker sees RDI as consumed.
if (sret_callee) {
frame += 8;
argi = 1;
};
for (scanp != nil) {
if (scanp.kind == nkind.N_PARAM) {
let isvar: bool = scanp.op == tkind.TK_ELLIPSIS;
let isf: bool = false;
let istg: bool = false;
let issl: bool = false;
let isst: bool = false;
let isstruct: bool = false;
let structsz: i32 = 0;
if (!isvar) {
isf = isfloattype(c, scanp.lhs);
istg = istaggedtype(c, scanp.lhs);
if (!isf && !istg) {
issl = isslicetype(c, scanp.lhs);
if (!issl) { isst = isstrtype(c, scanp.lhs); };
if (!issl && !isst) {
structsz = structparamsize(c, scanp.lhs);
isstruct = structsz > 0;
};
};
};
let eb: i32 = 1;
let sz: i32 = 8;
if (isvar) { eb = 3; sz = 24; }
else { if (istg) { sz = slotsize(c, scanp.lhs); eb = sz / 8; }
else { if (issl) { eb = 3; sz = 24; }
else { if (isst) { eb = 2; sz = 16; }
else { if (isstruct) {
sz = structsz;
eb = 1;
if (structsz > 8) { eb = 2; };
}
else { if (isf) {
eb = 1;
sz = 8;
if (isf32type(c, scanp.lhs)) { sz = 4; };
}; }; }; }; }; };
let regs_left: i32 = 6 - argi;
if (isf) { regs_left = 8 - fargi; };
if (regs_left >= eb) {
frame += sz;
if (isf) { fargi += 1; }
else { argi += eb; };
} else { if (eb > 1 && regs_left > 0 && (istg || issl || isst || isstruct || isvar)) {
// Multi-word param straddles the reg/stack boundary;
// cgfnparams stitches the tail from positive BP
// offsets into a single local slot, so we still
// reserve the full size. Symmetric across tagged,
// slice, str and variadic `T...`
// (cgendecl.ww:467/518/564/394).
frame += sz;
argi = 6;
} else {
// Pure stack: lives at +BP(16+stkcursor*8); no
// local slot consumed. The reg cursor stays put.
}; };
// Record the param's tnode on the stub so scanlocals's
// `h.f = v` / `&h[i]` / etc. detection paths can
// resolve a *struct / *[]T / *T param through
// localfindnode rather than seeing tnode=nil and
// skipping the reservation. Latent pre-#38: the
// pointer-rooted struct-field tagged write
// (cgendecl.ww:264) never fired for `fn fill(h: *holder)
// { h.e = v; }` because the param stub had no type
// info, so @tagscr / @tagbase weren't counted in the
// frame. Emit-time localadd happened to fit pre-#38
// because the 24B hardcoded slot didn't collide with
// the 8B @tagbase neighbour, but a correctly-sized
// slot revealed the under-reservation.
if (!scanseenmark(c, scanp.str)) {
c.locals.tnode = scanp.lhs;
};
};
scanp = scanp.next;
};
c.varargseq = 0;
if (fn_.body != nil) { frame += scanlocals(c, fn_.body); };
c.varargseq = 0;
// Drop the stubs so emission rebuilds c.locals with real offsets.
c.locals = nil;
if ((frame & 15) != 0) {
frame = (frame + 15) & ~15;
};
emitint(frame: i64);
emitline("\n");
emitline("\tPUSHQ\tBP\n");
emitline("\tMOVQ\tSP, BP\n");
emitline("\tSUBQ\t$");
emitint(frame: i64);
emitline(", SP\n");
// Capture the body into cgoutbuf while c.frame grows under
// emit-time localadd calls (#15/#26c — wwstage dropped its
// scanlocals pre-pass to align DOWN with cstage's first-use
// pattern). The prologue (TEXT label, PUSHQ/MOVQ/SUBQ) emits
// after the body finishes so the frame size reflects every
// localadd. Mirrors cstage cmd/w6c/cgen.c cgfn which builds
// `subsp`/`text` Progs up front and patches their `from.offset`
// at the end via txt_emit.
cgout_enable(c.a);
if (sret_callee) {
let saoff: i32 = localadd(c, "@sretarg", 8, nil);
@@ -1011,7 +387,7 @@ fn cgfn(c: *cgen, fn_: *node) void = {
// Run any registered defers in LIFO order before the
// implicit return.
rundefers(c);
// Zero AX before the fall-through return — matches C cgen,
// Zero AX before the fall-through return — matches cstage,
// which always emits this so void-returning fns don't leak
// a stale callee value to their caller.
emitline("\tMOVQ\t$0, AX\n");
@@ -1019,6 +395,28 @@ fn cgfn(c: *cgen, fn_: *node) void = {
emitline("\tPOPQ\tBP\n");
emitline("\tRET\n");
};
cgout_disable();
let frame: i32 = c.frame;
if ((frame & 15) != 0) { frame = (frame + 15) & ~15; };
// Emit the TEXT label via emitfnname so the def site picks up the
// same skip rule (FFI / `main` / empty-module) and the same module
// hint (this fn's own module) that the call sites use.
emitline("TEXT ");
emitfnname(c, fn_.str, fn_.nmod);
emitline(",$");
emitint(frame: i64);
emitline("\n");
emitline("\tPUSHQ\tBP\n");
emitline("\tMOVQ\tSP, BP\n");
emitline("\tSUBQ\t$");
emitint(frame: i64);
emitline(", SP\n");
cgout_flush();
};
// ---- file-level entry ------------------------------------------------