Files
ww/selfhost/cmd/wcc/cgenstmt.ww
Hojun-Cho d68d3c7eb4 lib: extract rt module from os, sweep imports
Hare puts runtime allocation in rt::, not os:: (ref/hare/rt/malloc.ha:27,
README). ww's `@symbol("rt_alloc") fn alloc(n: u64) *void;` lived at
lib/os/os.ww as a historical bootstrap shortcut; this commit relocates
it to a new lib/rt/malloc.ww and sweeps every site that depended on
`import os` for the alloc decl over to `import rt`.

This is commit 1 of 3 in the lib/rt extraction (#35):
  1. (this) move decl, sweep imports — preserves shape
  2. rename rt_alloc → rt_malloc (#38)
  3. nullable return type + OOM-propagating builtin lowering (#39)

No rename here. Symbol stays rt_alloc, function stays `alloc`, return
stays *void. Behavior identical — same ffi resolution outcome, just
sourced from a different module file. The rt::ensure runtime helper at
selfhost/rt/ensure.ww is its own compilation unit with a local decl and
is untouched.

Side effect: every wcc cgen file used `rt` as a local *node variable
name for "return type." `import rt;` shadows the module, so each
selfhost/cmd/wcc/{check,cgenstmt,cgenexpr,cgenutil}.ww site renamed
to `rtyp`. Mechanical follow-through; only the wcc module-import was
forced to do this rename.

Verified 132/132 + 995_self_rebuild byte-identity (5 wwstage tools
round-trip byte-identical).
2026-05-20 20:39:52 +09:00

1641 lines
48 KiB
Plaintext

// selfhost/cmd/wcc/cgenstmt.ww — split out of cgen.ww.
//
// cgstmt is a thin dispatcher over n.kind; each branch defers to a
// per-kind helper: cgblock, cgreturn, cgexprstmt, cglet, cgif, cgfor,
// cgmassign, cgbreak, cgcontinue.
//
// The expression generator (cgexpr) lives in cgenexpr.ww; the
// foundation (types, emit primitives, collect* tables, FFI/module
// maps) lives in cgen.ww.
package wcc;
import os;
import mem;
import ast;
import tok;
import typ;
import sym;
import strconv;
// ---- statement cgen --------------------------------------------------
fn cgstmt(c: *cgen, n: *node) void = {
if (n == nil) { return; };
let k: nkind = n.kind;
if (k == nkind.N_BLOCK) { cgblock(c, n); return; };
if (k == nkind.N_RETURN) { cgreturn(c, n); return; };
if (k == nkind.N_EXPRSTMT) { cgexprstmt(c, n); return; };
if (k == nkind.N_LET) { cglet(c, n); return; };
if (k == nkind.N_IF) { cgif(c, n); return; };
if (k == nkind.N_FOR) { cgfor(c, n); return; };
if (k == nkind.N_FORRANGE) { cgforrange(c, n); return; };
if (k == nkind.N_SWITCH) { cgswitch(c, n); return; };
if (k == nkind.N_MASSIGN) { cgmassign(c, n); return; };
if (k == nkind.N_MLET) { cgmlet(c, n); return; };
if (k == nkind.N_BREAK) { cgbreak(c, n); return; };
if (k == nkind.N_CONTINUE) { cgcontinue(c, n); return; };
if (k == nkind.N_YIELD) { cgyield(c, n); return; };
if (k == nkind.N_DEFER) {
if (c.defertop < DEFER_MAX) {
c.deferbuf[c.defertop] = n.lhs;
c.defertop += 1;
};
return;
};
c.lastwasreturn = 0;
};
fn cgyield(c: *cgen, n: *node) void = {
// Evaluate the value into AX (and BX for str), then JMP to the
// enclosing match's end label. Falls through silently if there
// is no active match — should be a checker error eventually.
if (n.lhs != nil) { cgexpr(c, n.lhs); };
if (c.yieldtop > 0) {
let tgt: str = c.yieldbuf[c.yieldtop - 1];
emitline("\tJMP\t");
emitline(tgt);
emitline("\n");
};
c.lastwasreturn = 0;
return;
};
fn cgblock(c: *cgen, n: *node) void = {
// Save/restore the locals head across the block (post-#27).
// Inner-scope `let` bindings prepend to c.locals via localadd;
// without this restore, the prepended stubs leak into sibling
// and ancestor scopes, and localfind (head-first) returns the
// inner binding's offset for an identifier that semantically
// belongs to the outer scope. The frame is left grown — we
// don't reclaim popped slots, matching cstage's lowering.
//
// cgfn iterates fn_.body.list directly to bypass this save/
// restore at the function's outermost block — defers (and the
// implicit-return epilogue) need locals intact.
let saved: *local = c.locals;
let s: *node = n.list;
for (s != nil) {
cgstmt(c, s);
s = s.next;
};
c.locals = saved;
return;
};
// rundefers — emit cgexpr for every queued defer in LIFO order.
// Called from cgreturn and the cgfn implicit-return path.
fn rundefers(c: *cgen) void = {
let i: i32 = c.defertop - 1;
for (i >= 0) {
cgexpr(c, c.deferbuf[i]);
i -= 1;
};
return;
};
fn cgreturn(c: *cgen, n: *node) void = {
rundefers(c);
let rhs: *node = n.lhs;
if (rhs != nil) {
// Tuple return `return a, b;`:
// (scalar, scalar) — AX = v0, DX = v1.
// (scalar, str) / (str, scalar) — AX = scalar elem,
// DX = str.ptr, CX = str.len.
// 24B convention mirrors the tagged-union return below; receive
// sites destructure off the same regs regardless of position.
if (rhs.kind == nkind.N_TUPLE) {
let v: *node = rhs.list;
if (v != nil) {
let v2: *node = v.next;
if (v2 != nil) {
let v0_is_str: bool = nodeisstr(c, v);
let v1_is_str: bool = nodeisstr(c, v2);
if ((v0_is_str || v1_is_str) && !(v0_is_str && v1_is_str)) {
let strn: *node = v;
let scaln: *node = v2;
if (v1_is_str) { strn = v2; scaln = v; };
cgexpr(c, scaln);
emitline("\tPUSHQ\tAX\n");
cgexpr(c, strn);
emitline("\tMOVQ\tBX, CX\n");
emitline("\tMOVQ\tAX, DX\n");
emitline("\tPOPQ\tAX\n");
} else {
cgexpr(c, v2);
emitline("\tPUSHQ\tAX\n");
cgexpr(c, v);
emitline("\tPOPQ\tDX\n");
};
} else {
cgexpr(c, v);
};
};
emitline("\tMOVQ\tBP, SP\n");
emitline("\tPOPQ\tBP\n");
emitline("\tRET\n");
c.lastwasreturn = 1;
return;
};
// Tagged-union return: pack as (AX=tag, DX=value0, CX=value1).
// For str variant, cgexpr leaves (AX=ptr, BX=len), so we
// shuffle DX←AX (ptr) and CX←BX (len), then load tag.
// For other variants, cgexpr leaves AX, shuffle DX←AX.
// Nullable folded `(*T | void)`: just one word; AX is
// already the pointer (or 0). No shuffle, no tag.
if (istaggedtype(c, c.fnret)) {
// Forwarding a fallible call: `return f();` where f
// also returns a tagged union. The result is already
// in (AX=tag, DX=v0, CX=v1) — no shuffle, no tag.
// Mirrors the rhsreturnstagged path in cglet and the
// !type_istagged guard in C cgen's N_RETURN.
let forwardtagged: bool = false;
if (rhs.kind == nkind.N_CALL) {
let callee: *node = rhs.lhs;
if (callee != nil) {
let calleename: str;
calleename.ptr = nil; calleename.len = 0;
let cmod: str;
cmod.ptr = nil; cmod.len = 0;
if (callee.kind == nkind.N_IDENT) {
calleename = callee.str;
cmod = c.curmod;
};
if (callee.kind == nkind.N_DOT) {
calleename = callee.str;
if (callee.lhs != nil) {
if (callee.lhs.kind == nkind.N_IDENT) {
cmod = callee.lhs.str;
};
};
};
if (calleename.len > 0) {
let rtyp: *node = fnretlookupmod(c, calleename, cmod);
if (istaggedtype(c, rtyp)) { forwardtagged = true; };
};
};
};
// Struct payload or tagged-subset return — materialise
// the widened value in scratch via cgwidentaggedstore
// (handles tag remap and zero pad), then load AX/DX/CX
// from the slot.
let needswiden: bool = false;
if (!isnullabletype(c.fnret)) {
if (!forwardtagged) {
let sname: str = rhsstructpayload(c, rhs);
if (sname.len > 0) { needswiden = true; };
if (rhstaggedident(c, rhs) != nil) {
needswiden = true;
};
};
};
if (needswiden) {
let rsz: i32 = slotsize(c, c.fnret);
// @retscr (not @tagscr) for the return materialise
// path. Cstage cmd/w6c/cgen.c cgreturn uses
// `@retscr` here and reserves the @tagscr SSoT
// for arg-widen / non-BP-base store / N_INDEX
// tagged-element write. Sharing the name in a fn
// that BOTH returns a 32B tagged AND pushes a
// smaller tagged arg fatals localadd's @-prefix
// size-grow guard (rule 7); routing returns
// through their own slot keeps each cache
// monotonic. Hardcoding 24 truncated 32B-slot
// returns and overwrote adjacent locals during
// the pre-zero loop (#38).
let scroff: i32 = localadd(c, "@retscr", rsz, nil);
emitline("\tXORQ\tAX, AX\n");
let zz: i32 = 0;
for (zz < rsz) {
emitline("\tMOVQ\tAX, ");
emitoff((scroff + zz): i64);
emitline("(BP)\n");
zz += 8;
};
cgwidentaggedstore(c, c.fnret, rhs, "BP",
scroff, rsz);
emitline("\tMOVQ\t");
emitoff(scroff: i64);
emitline("(BP), AX\n");
if (rsz > 8) {
emitline("\tMOVQ\t");
emitoff((scroff + 8): i64);
emitline("(BP), DX\n");
};
if (rsz > 16) {
emitline("\tMOVQ\t");
emitoff((scroff + 16): i64);
emitline("(BP), CX\n");
};
if (rsz > 24) {
emitline("\tMOVQ\t");
emitoff((scroff + 24): i64);
emitline("(BP), R8\n");
};
emitline("\tMOVQ\tBP, SP\n");
emitline("\tPOPQ\tBP\n");
emitline("\tRET\n");
c.lastwasreturn = 1;
return;
};
cgexpr(c, rhs);
if (isnullabletype(c.fnret)) {
emitline("\tMOVQ\tBP, SP\n");
emitline("\tPOPQ\tBP\n");
emitline("\tRET\n");
c.lastwasreturn = 1;
return;
};
if (forwardtagged) {
emitline("\tMOVQ\tBP, SP\n");
emitline("\tPOPQ\tBP\n");
emitline("\tRET\n");
c.lastwasreturn = 1;
return;
};
let idx: i32 = taggedvariantindex(c, c.fnret, rhs);
// Tagged-return ABI: AX=tag, DX=word0, CX=word1,
// R8=word2. Receiver (cgwidentaggedstore call-source
// arm) writes AX/DX/CX/R8 unconditionally sized by the
// dst slot; unused ABI words must be zeroed here so a
// stale CX/R8 from the caller (e.g. a slice-stride
// IMULQ before the call) does not land in slot+16 /
// slot+24. (Task #18.)
let rsz: i32 = slotsize(c, c.fnret);
if (nodeisslice(c, rhs)) {
// cgexpr leaves (AX=ptr, BX=len, CX=cap).
// Shuffle into return ABI: DX=ptr, CX=len,
// R8=cap.
emitline("\tMOVQ\tCX, R8\n");
emitline("\tMOVQ\tBX, CX\n");
emitline("\tMOVQ\tAX, DX\n");
} else { if (nodeisstr(c, rhs)) {
emitline("\tMOVQ\tBX, CX\n");
emitline("\tMOVQ\tAX, DX\n");
// str fills DX,CX. Zero R8 if dst covers slot+24.
if (rsz > 24) {
emitline("\tMOVQ\t$0, R8\n");
};
} else {
emitline("\tMOVQ\tAX, DX\n");
// scalar fills DX only. Zero CX / R8 if dst
// covers slot+16 / slot+24.
if (rsz > 16) {
emitline("\tMOVQ\t$0, CX\n");
};
if (rsz > 24) {
emitline("\tMOVQ\t$0, R8\n");
};
};};
emitline("\tMOVQ\t$");
if (idx < 0) { idx = 0; };
emitint(idx: i64);
emitline(", AX\n");
emitline("\tMOVQ\tBP, SP\n");
emitline("\tPOPQ\tBP\n");
emitline("\tRET\n");
c.lastwasreturn = 1;
return;
};
// sret return (#23): plain TY_STRUCT > 24B. Callee writes
// through *(@sretarg) (the caller-prealloc dest saved at
// the prologue), then loads @sretarg into RAX and rets —
// the SysV "return the pointer" discipline. Two rhs shapes
// are wired: N_IDENT (word-copy from rhs slot to *(dest))
// and N_STRUCTLIT (cgstructlitfill with mode=1 PTR_LOCAL).
let sretargoff: i32 = localfind(c, "@sretarg");
if (sretargoff != 0) {
let scs: i32 = sretretsize(c, c.fnret);
if (scs > 0) {
// sret return-forwarding (task #9 follow-up to
// #23): `return f();` where outer + inner both
// return the same >24B struct shape. Outer's
// @sretarg already holds its caller's prealloc
// dest; pass it to inner in RDI (set by cgcall
// via c.sretforward), inner writes directly
// there, inner's RAX (dest pointer) is already
// outer's return value. The trailing MOVQ
// @sretarg(BP), AX is redundant after inner's
// RET but kept for byte-id symmetry with the
// N_IDENT / N_STRUCTLIT arms below.
if (rhs.kind == nkind.N_CALL) {
c.sretforward = 1;
cgexpr(c, rhs);
emitline("\tMOVQ\t");
emitoff(sretargoff: i64);
emitline("(BP), AX\n");
emitline("\tMOVQ\tBP, SP\n");
emitline("\tPOPQ\tBP\n");
emitline("\tRET\n");
c.lastwasreturn = 1;
return;
};
let okrhs: bool = false;
if (rhs.kind == nkind.N_IDENT) { okrhs = true; };
if (rhs.kind == nkind.N_STRUCTLIT) { okrhs = true; };
if (okrhs) {
if (rhs.kind == nkind.N_STRUCTLIT) {
let trefn: *node = rhs.lhs;
let sname: str;
sname.ptr = nil; sname.len = 0;
if (trefn != nil) {
if (trefn.kind == nkind.N_IDENT) { sname = trefn.str; }
else { if (trefn.kind == nkind.N_TNAME) { sname = trefn.str; }; };
};
let sret_si: *structinfo = structlookup(c, sname);
if (sret_si != nil) {
let emptys: str;
emptys.ptr = nil; emptys.len = 0;
// mode=1 (PTR_LOCAL): base reg = BX,
// reloaded from @sretarg(BP) before
// each field store. disp = 0 because
// the dest pointer IS the struct base.
cgstructlitfill(c, sret_si, rhs,
1, sretargoff, emptys,
0, scs);
};
} else {
let rl: *local = localfindnode(c, rhs.str);
if (rl != nil) {
emitline("\tMOVQ\t");
emitoff(sretargoff: i64);
emitline("(BP), BX\n");
let k: i32 = 0;
for (k + 8 <= scs) {
emitline("\tMOVQ\t");
emitoff((rl.off + k): i64);
emitline("(BP), AX\n");
emitline("\tMOVQ\tAX, ");
emitoff(k: i64);
emitline("(BX)\n");
k += 8;
};
for (k + 4 <= scs) {
emitline("\tMOVL\t");
emitoff((rl.off + k): i64);
emitline("(BP), AX\n");
emitline("\tMOVL\tAX, ");
emitoff(k: i64);
emitline("(BX)\n");
k += 4;
};
for (k < scs) {
emitline("\tMOVB\t");
emitoff((rl.off + k): i64);
emitline("(BP), AX\n");
emitline("\tMOVB\tAX, ");
emitoff(k: i64);
emitline("(BX)\n");
k += 1;
};
};
};
// sret return: RAX = dest pointer.
emitline("\tMOVQ\t");
emitoff(sretargoff: i64);
emitline("(BP), AX\n");
emitline("\tMOVQ\tBP, SP\n");
emitline("\tPOPQ\tBP\n");
emitline("\tRET\n");
c.lastwasreturn = 1;
return;
};
};
};
// Whole-struct return for sizes <= 24B. ABI: AX=bytes[0..7],
// DX=bytes[8..15], CX=bytes[16..23]. Mirrors cstage cgen.c
// N_RETURN TY_STRUCT branch. Two rhs shapes are wired:
// N_IDENT (word-copy from rhs local slot) and N_STRUCTLIT
// (field-by-field store at scratch+foff, with tagged fields
// delegated to cgwidentaggedstore). Call-result chain return
// is deferred to #5's receive side. Sizes > 24B route through
// the sret arm above.
let rname: str;
rname.ptr = nil; rname.len = 0;
if (c.fnret != nil) {
if (c.fnret.kind == nkind.N_TNAME) {
rname = c.fnret.str;
};
};
if (rname.len > 0) {
let rsi: *structinfo = structlookup(c, rname);
if (rsi != nil) {
let rsz: i32 = rsi.totsize;
if (rsz <= 24) {
let okrhs: bool = false;
if (rhs.kind == nkind.N_IDENT) {
okrhs = true;
};
if (rhs.kind == nkind.N_STRUCTLIT) {
okrhs = true;
};
if (okrhs) {
let scroff: i32 = localadd(c,
"@retscr", 24, nil);
emitline("\tXORQ\tAX, AX\n");
emitline("\tMOVQ\tAX, ");
emitoff(scroff: i64);
emitline("(BP)\n");
emitline("\tMOVQ\tAX, ");
emitoff((scroff + 8): i64);
emitline("(BP)\n");
emitline("\tMOVQ\tAX, ");
emitoff((scroff + 16): i64);
emitline("(BP)\n");
if (rhs.kind == nkind.N_STRUCTLIT) {
// Delegate to the shared BP-relative
// structlit fill helper. Same store
// sequence the inline pre-#17 walk
// emitted (tagged + float + scalar),
// plus nested struct-typed structlit
// values recurse instead of dropping
// trailing bytes.
cgstructlitfillbp(c, rsi, rhs, scroff);
} else {
// N_IDENT: word-copy from rhs slot
// to scratch. Whole 8B words via
// MOVQ; tail via MOVL/MOVB so we
// read no further than the source
// slot's declared size.
let rl: *local = localfindnode(c, rhs.str);
if (rl != nil) {
let k: i32 = 0;
for (k + 8 <= rsz) {
emitline("\tMOVQ\t");
emitoff((rl.off + k): i64);
emitline("(BP), AX\n");
emitline("\tMOVQ\tAX, ");
emitoff((scroff + k): i64);
emitline("(BP)\n");
k += 8;
};
for (k + 4 <= rsz) {
emitline("\tMOVL\t");
emitoff((rl.off + k): i64);
emitline("(BP), AX\n");
emitline("\tMOVL\tAX, ");
emitoff((scroff + k): i64);
emitline("(BP)\n");
k += 4;
};
for (k < rsz) {
emitline("\tMOVB\t");
emitoff((rl.off + k): i64);
emitline("(BP), AX\n");
emitline("\tMOVB\tAX, ");
emitoff((scroff + k): i64);
emitline("(BP)\n");
k += 1;
};
};
};
emitline("\tMOVQ\t");
emitoff(scroff: i64);
emitline("(BP), AX\n");
emitline("\tMOVQ\t");
emitoff((scroff + 8): i64);
emitline("(BP), DX\n");
emitline("\tMOVQ\t");
emitoff((scroff + 16): i64);
emitline("(BP), CX\n");
emitline("\tMOVQ\tBP, SP\n");
emitline("\tPOPQ\tBP\n");
emitline("\tRET\n");
c.lastwasreturn = 1;
return;
};
};
};
};
cgexpr(c, rhs);
} else {
// Bare `return;` from a tagged-union-returning fn is
// the void variant: emit its tag. Payload is undefined
// (void has size 0). Otherwise zero AX for determinism.
if (istaggedtype(c, c.fnret)) {
if (isnullabletype(c.fnret)) {
// null = void variant; AX = 0.
emitline("\tMOVQ\t$0, AX\n");
} else {
let idx: i32 = voidvariantindex(c.fnret);
if (idx < 0) { idx = 0; };
emitline("\tMOVQ\t$");
emitint(idx: i64);
emitline(", AX\n");
};
emitline("\tMOVQ\tBP, SP\n");
emitline("\tPOPQ\tBP\n");
emitline("\tRET\n");
c.lastwasreturn = 1;
return;
};
emitline("\tMOVQ\t$0, AX\n");
};
// SysV: 16-byte aggregates (str, 2-tuple) return in (AX, DX).
// cgexpr leaves str in (AX, BX); shuffle BX→DX.
if (isstrtype(c, c.fnret)) {
emitline("\tMOVQ\tBX, DX\n");
};
emitline("\tMOVQ\tBP, SP\n");
emitline("\tPOPQ\tBP\n");
emitline("\tRET\n");
c.lastwasreturn = 1;
return;
};
fn cgexprstmt(c: *cgen, n: *node) void = {
if (n.lhs != nil) { cgexpr(c, n.lhs); };
c.lastwasreturn = 0;
return;
};
fn cglet(c: *cgen, n: *node) void = {
let nm: str = n.str;
let sz: i32 = letslotsize(c, n);
// `let x = f()?` has no annotation but the cgen's struct-field
// paths need a tnode to dispatch off. Infer from f's tagged
// success variant — see inferletcalltype.
let tn: *node = n.lhs;
if (tn == nil) { tn = inferletcalltype(c, n.rhs); };
let off: i32 = localadd(c, nm, sz, tn);
if (n.rhs != nil) {
let rhs: *node = n.rhs;
// `let s: []T = alloc([], n)!;` / `?` shortcut (#32, #45).
// Mirror of cstage cgen.c N_LET arrlit-empty branch: allocate
// n*esz bytes via rt_alloc, then build the {ptr, 0, n} slice
// header in the let slot. The `!`/`?` wraps the builtin's
// `([]T | nomem)` return; walk into the N_TRYUNW / N_TRYPROP
// to keep the direct-store fast path rather than falling
// through to cgalloc (which models scalar alloc and would
// land an 8B region and a junk slice header). `?` propagates
// nomem via AX = tag of nomem in c.fnret, then epilogue RET.
{
let scall: *node = nil;
let viatryunw: bool = false;
let viatryprop: bool = false;
if (rhs.kind == nkind.N_TRYUNW) {
if (rhs.lhs != nil) {
if (rhs.lhs.kind == nkind.N_CALL) {
scall = rhs.lhs;
viatryunw = true;
};
};
} else { if (rhs.kind == nkind.N_TRYPROP) {
if (rhs.lhs != nil) {
if (rhs.lhs.kind == nkind.N_CALL) {
scall = rhs.lhs;
viatryprop = true;
};
};
}; };
let shapeok: bool = false;
// #43: route the slice-shape size guard through SSoT.
// The N_TSLICE kind gate already discriminates here, so
// this is belt-and-suspenders, but the literal would
// silently miss after #1 if check.ww's astsize ever
// drifted from this dispatch.
if (scall != nil && tn != nil
&& tn.kind == nkind.N_TSLICE && sz == tyslicesize(): i32) {
let callee: *node = scall.lhs;
let a0: *node = scall.list;
let a1: *node = nil;
let a2: *node = nil;
if (a0 != nil) { a1 = a0.next; };
if (a1 != nil) { a2 = a1.next; };
if (callee != nil && a0 != nil && a1 != nil
&& a2 == nil) {
if (callee.kind == nkind.N_IDENT
&& streq(callee.str, "alloc")
&& a0.kind == nkind.N_ARRLIT
&& a0.list == nil) {
shapeok = true;
};
};
};
if (shapeok) {
// #32: cstage uses `lu->sub->size` (cgen.c:6387), so
// the element width must resolve struct/tagged/alias
// names too — not just primitives. elemsizeofc follows
// TNAME through structlookup/aliaslookup, matching the
// cstage path byte-identically. A bare primsize/slotsize
// fork would silently land esz=1 on `[]point`.
let esz: i32 = elemsizeofc(c, tn);
let count: *node = scall.list.next;
cgexpr(c, count);
emitline("\tPUSHQ\tAX\n");
if (esz > 1) {
emitline("\tMOVQ\t$");
emitint(esz: i64);
emitline(", BX\n");
emitline("\tIMULQ\tBX, AX\n");
};
emitline("\tMOVQ\tAX, DI\n");
emitline("\tCALL\t");
emitline(ffiresolve(c, "alloc"));
emitline("(SB)\n");
if (viatryunw) {
let okl: str = mklabel(c, "tryunw_ok");
emitline("\tCMPQ\t$0, AX\n");
emitline("\tJNE\t");
emitline(okl);
emitline("\n");
emitline("\tMOVQ\t$1, DI\n");
emitline("\tMOVQ\t$60, AX\n");
emitline("\tSYSCALL\n");
emitlabel(okl);
};
if (viatryprop) {
// #45: null = nomem; propagate to the
// enclosing fn's tagged return. AX = tag
// of nomem variant in c.fnret, epilogue
// RETs to caller.
let okl: str = mklabel(c, "tryprop_ok");
emitline("\tCMPQ\t$0, AX\n");
emitline("\tJNE\t");
emitline(okl);
emitline("\n");
let nidx: i32 = flatvariantidx(c, c.fnret, "nomem");
if (nidx < 0) { nidx = 1; };
emitline("\tMOVQ\t$");
emitint(nidx: i64);
emitline(", AX\n");
emitline("\tMOVQ\tBP, SP\n\tPOPQ\tBP\n\tRET\n");
emitlabel(okl);
};
emitline("\tPOPQ\tBX\n");
emitline("\tMOVQ\tAX, ");
emitoff(off: i64);
emitline("(BP)\n");
emitline("\tMOVQ\t$0, ");
emitoff((off + 8): i64);
emitline("(BP)\n");
emitline("\tMOVQ\tBX, ");
emitoff((off + 16): i64);
emitline("(BP)\n");
c.lastwasreturn = 0;
return;
};
};
// Tagged-union init: delegate to cgwidentaggedstore, which
// handles nullable fold, tagged source (ident or AX/DX/CX
// ABI call), struct payload (literal/ident), str payload,
// scalar payload — with tag remap for tagged-subset widening.
if (istaggedtype(c, tn)) {
cgwidentaggedstore(c, tn, rhs, "BP", off, sz);
c.lastwasreturn = 0;
return;
};
// 24B tuple init for `let t: (scalar, str) = call()` /
// `let t: (str, scalar) = call()`. Per the AX:DX:CX return
// convention: AX = scalar elem, DX = str.ptr, CX = str.len.
// Layout is positional, so we route each register to the
// slot dictated by element type, not by AX/DX position.
if (n.lhs != nil) {
if (n.lhs.kind == nkind.N_TTUPLE) {
let p0: *node = n.lhs.list;
let p1: *node = nil;
if (p0 != nil) { p1 = p0.next; };
let s0_is_str: bool = isstrtyperaw(p0);
let s1_is_str: bool = isstrtyperaw(p1);
if (p0 != nil) {
if (p1 != nil) {
if (s0_is_str != s1_is_str) {
cgexpr(c, rhs);
if (s0_is_str) {
emitline("\tMOVQ\tDX, ");
emitoff(off: i64);
emitline("(BP)\n");
emitline("\tMOVQ\tCX, ");
emitoff((off + 8): i64);
emitline("(BP)\n");
emitline("\tMOVQ\tAX, ");
emitoff((off + 16): i64);
emitline("(BP)\n");
} else {
emitline("\tMOVQ\tAX, ");
emitoff(off: i64);
emitline("(BP)\n");
emitline("\tMOVQ\tDX, ");
emitoff((off + 8): i64);
emitline("(BP)\n");
emitline("\tMOVQ\tCX, ");
emitoff((off + 16): i64);
emitline("(BP)\n");
};
c.lastwasreturn = 0;
return;
};
};
};
};
};
// Array literal init: `let xs: [N]T = [a, b, c];` (or [_]T).
// Walk elements in declaration order, store each at off + i*esz
// using the right width for the element type. Trailing `...`
// after the last value (an nkind.N_FIELD with str=="...") fills the
// remaining slots up to the declared length with that value.
//
// str element (16B = ptr+len) needs both halves stored. cgstrlit
// / cgident leave a str as (AX=ptr, BX=len) and a single MOVQ
// from AX would leave .len as whatever the stack held — silent
// miscompile. Worse, primsize("str") returns 0 so esz would fall
// back to 8, also collapsing the per-element stride (element i+1
// would overwrite element i's would-be .len half). Detect the
// str-element case up front so both esz and the store path are
// right. (primsize's default-to-8-on-zero pattern is brittle for
// composites generally; same gap blocks slice / struct / tuple /
// tagged element arrays — tracked as a follow-up.)
if (rhs.kind == nkind.N_ARRLIT) {
let elemn: *node = n.lhs.lhs;
let esz: i32 = 8;
let isstrel: bool = false;
if (elemn != nil) {
if (elemn.kind == nkind.N_TNAME) {
if (streq(elemn.str, "str")) {
esz = primtypesize("str"): i32;
isstrel = true;
} else {
let ps: i32 = primsize(elemn.str);
if (ps > 0) { esz = ps; };
};
};
};
let mop: str = tnodestoreop(c, elemn, esz);
let idx: i32 = 0;
let repeat: bool = false;
let e: *node = rhs.list;
for (e != nil) {
let isellip: bool = false;
if (e.kind == nkind.N_FIELD) {
if (streq(e.str, "...")) {
repeat = true;
isellip = true;
};
};
if (isellip) {
e = nil;
} else {
cgexpr(c, e);
if (isstrel) {
emitline("\tMOVQ\tAX, ");
emitoff((off + idx * esz): i64);
emitline("(BP)\n");
emitline("\tMOVQ\tBX, ");
emitoff((off + idx * esz + 8): i64);
emitline("(BP)\n");
} else {
emitline("\t");
emitline(mop);
emitline("\tAX, ");
emitoff((off + idx * esz): i64);
emitline("(BP)\n");
};
idx += 1;
e = e.next;
};
};
// AX (and BX for str) still holds the last stored value;
// fill remaining slots up to the declared length with it.
if (repeat) {
let total: i32 = idx;
if (n.lhs != nil) {
if (n.lhs.kind == nkind.N_TARRAY) {
if (n.lhs.rhs != nil) {
if (n.lhs.rhs.kind == nkind.N_INTLIT) {
total = n.lhs.rhs.uval: i32;
};
};
};
};
for (idx < total) {
if (isstrel) {
emitline("\tMOVQ\tAX, ");
emitoff((off + idx * esz): i64);
emitline("(BP)\n");
emitline("\tMOVQ\tBX, ");
emitoff((off + idx * esz + 8): i64);
emitline("(BP)\n");
} else {
emitline("\t");
emitline(mop);
emitline("\tAX, ");
emitoff((off + idx * esz): i64);
emitline("(BP)\n");
};
idx += 1;
};
};
c.lastwasreturn = 0;
return;
};
// Struct literal init: `let p: point = point{x=..., y=...};`.
// Delegates to the shared cgstructlitfillbp helper: TK_ELLIPSIS
// autofill + per-field walk, with nested struct-typed structlit
// values recursing into the helper instead of landing only AX
// (the #17 silent-zero fix). Mirror of cstage cgen.c N_LET
// structlit branch.
if (rhs.kind == nkind.N_STRUCTLIT) {
let trefn: *node = rhs.lhs;
let sname: str;
sname.ptr = nil; sname.len = 0;
if (trefn != nil) {
if (trefn.kind == nkind.N_IDENT) { sname = trefn.str; }
else { if (trefn.kind == nkind.N_TNAME) { sname = trefn.str; }; };
};
let si: *structinfo = structlookup(c, sname);
if (si != nil) {
cgstructlitfillbp(c, si, rhs, off);
c.lastwasreturn = 0;
return;
};
};
// sret receive (#23): plain TY_STRUCT > 24B from a call.
// The let's own slot IS the caller-prealloc dest; the
// nested cgexpr → cgcall path emits `LEAQ off(BP), DI`
// before the CALL and the callee writes through it. No
// AX/DX/CX shuffle; AX returns the dest pointer per SysV
// sret discipline (irrelevant here).
if (rhs.kind == nkind.N_CALL) {
let scs: i32 = callsretsize(c, rhs);
if (scs > 0) {
c.sretdestoff = off;
cgexpr(c, rhs);
c.sretdestoff = 0;
c.lastwasreturn = 0;
return;
};
};
// Whole-struct receive for sizes <=24B (call-result rhs).
// Counterpart of #4's cgreturn ABI: cgexpr leaves
// AX=bytes[0..7], DX=bytes[8..15], CX=bytes[16..23],
// zero-padded to 24B by the producer.
//
// ASYMMETRY (do NOT mirror the sender): producer emits three
// uniform MOVQs into a zero-padded 24B scratch slot; the
// receiver writes only `sz` bytes — MOVQ for full 8B chunks
// plus a sized tail (MOVL/MOVW/MOVB) by the *declared*
// struct size. Otherwise a trailing 1..7-byte chunk would
// overrun into the next local slot.
//
// Tail chunks in {3,5,6,7} (unreachable under WW struct
// alignment rules — field aligns force size%align==0) fall
// through to the generic scalar store rather than emit a
// stomping MOVQ tail. Sizes >24B also fall through (sret
// deferred, same constraint as #4). Mirrors the cstage
// cgen.c N_LET receive branch.
if (rhs.kind == nkind.N_CALL) {
let sname: str;
sname.ptr = nil; sname.len = 0;
if (tn != nil) {
if (tn.kind == nkind.N_TNAME) {
sname = tn.str;
};
};
if (sname.len > 0) {
let lsi: *structinfo = structlookup(c, sname);
if (lsi != nil) {
// si.totsize is slot-padded (rounded to 8) for
// stack-slot use; the receive ABI needs the
// TYPE's natural size — see structnaturalsize.
let lsz: i32 = structnaturalsize(lsi);
let tlm: i32 = lsz - (lsz / 8) * 8;
if (lsz <= 24) {
if (tlm == 0 || tlm == 1
|| tlm == 2 || tlm == 4) {
cgexpr(c, rhs);
let full: i32 = lsz / 8;
let i: i32 = 0;
for (i < full) {
let reg: str = "AX";
if (i == 1) { reg = "DX"; };
if (i == 2) { reg = "CX"; };
emitline("\tMOVQ\t");
emitline(reg);
emitline(", ");
emitoff((off + i * 8): i64);
emitline("(BP)\n");
i += 1;
};
if (tlm > 0) {
let top: str = "MOVB";
if (tlm == 4) { top = "MOVL"; };
if (tlm == 2) { top = "MOVW"; };
let treg: str = "AX";
if (full == 1) { treg = "DX"; };
if (full == 2) { treg = "CX"; };
emitline("\t");
emitline(top);
emitline("\t");
emitline(treg);
emitline(", ");
emitoff((off + full * 8): i64);
emitline("(BP)\n");
};
c.lastwasreturn = 0;
return;
};
};
};
};
};
// Struct ident copy: `let p2: T = p1;` where T is a struct
// >8B and rhs is a local ident. Per-qword MOVQ from src
// slot to dst slot, with a sized tail (MOVL/MOVB) for
// natural sizes that aren't 8-aligned (e.g. `struct
// { i32, i32, i32 }` is 12B). Pre-fix this path fell
// through to `cgexpr + MOVQ AX, off(BP)` which stored
// only the first qword (and a stale BX for sz==16 lets
// via the str-init tail) — silent partial copy. Mirrors
// cstage cgen.c N_LET struct-ident branch (Task #32).
if (rhs.kind == nkind.N_IDENT) {
let sname: str;
sname.ptr = nil; sname.len = 0;
if (tn != nil) {
if (tn.kind == nkind.N_TNAME) { sname = tn.str; };
};
if (sname.len > 0) {
let lsi: *structinfo = structlookup(c, sname);
if (lsi != nil) {
let lsz: i32 = structnaturalsize(lsi);
if (lsz > 8) {
let lc: *local = localfindnode(c, rhs.str);
if (lc != nil) {
let soff: i32 = lc.off;
let ki: i32 = 0;
for (ki + 8 <= lsz) {
emitline("\tMOVQ\t");
emitoff((soff + ki): i64);
emitline("(BP), AX\n");
emitline("\tMOVQ\tAX, ");
emitoff((off + ki): i64);
emitline("(BP)\n");
ki += 8;
};
if (ki < lsz) {
let tail: i32 = lsz - ki;
let lop: str = "MOVQ";
if (tail == 4) { lop = "MOVL"; }
else { if (tail == 1) { lop = "MOVB"; }; };
emitline("\t");
emitline(lop);
emitline("\t");
emitoff((soff + ki): i64);
emitline("(BP), AX\n");
emitline("\t");
emitline(lop);
emitline("\tAX, ");
emitoff((off + ki): i64);
emitline("(BP)\n");
};
c.lastwasreturn = 0;
return;
};
};
};
};
};
cgexpr(c, rhs);
// Float local: cgexpr leaves the value in X0. Spill via
// MOVSS (f32, 4B) or MOVSD (f64, 8B).
if (isfloattype(c, n.lhs)) {
let mov: str = "MOVSD";
if (isf32type(c, n.lhs)) { mov = "MOVSS"; };
emitline("\t");
emitline(mov);
emitline("\tX0, ");
emitoff(off: i64);
emitline("(BP)\n");
c.lastwasreturn = 0;
return;
};
emitline("\tMOVQ\tAX, ");
emitoff(off: i64);
emitline("(BP)\n");
// str init: cgexpr also leaves len in BX; store both.
// #60: gate by kind too — under #1's str=24 bump, sizeof(str)
// and sizeof(slice) collide, so a bare `sz ==` check fires
// both branches for one let. Mirrors cstage cgen.c:6439's
// `type_isstr(lt) && sz == ty_str->size` shape.
if (isstrtype(c, tn) && sz == primtypesize("str"): i32) {
emitline("\tMOVQ\tBX, ");
emitoff((off + 8): i64);
emitline("(BP)\n");
};
// slice init: ptr/len/cap in AX/BX/CX. Same kind+size gate as
// the str arm — without the kind check this fires on a str let
// once sz==24 (#60).
if (isslicetype(c, tn) && sz == tyslicesize(): i32) {
emitline("\tMOVQ\tBX, ");
emitoff((off + 8): i64);
emitline("(BP)\n");
emitline("\tMOVQ\tCX, ");
emitoff((off + 16): i64);
emitline("(BP)\n");
};
} else {
// Bare `let x: T;` with no initializer. C cgen
// (cmd/w6c/cgen.c N_LET no-rhs branch) zero-inits in two
// shapes:
// - 8B primitives (scalar/ptr/fn/chan/`[8]bool` etc.):
// single `MOVQ $0, off(BP)`.
// - multi-word composites (str/slice/tuple/struct/tagged):
// `XORQ AX,AX` + a run of `MOVQ AX, ...` over the slot
// so reads after the bare let see {0...} rather than
// stack garbage.
// `[N]T` arrays of size != 8 keep the per-index-write
// contract — they're left uninit.
let isarr: bool = false;
if (n.lhs != nil) {
if (n.lhs.kind == nkind.N_TARRAY) { isarr = true; };
};
if (typeis8byteprimitive(c, n.lhs)) {
emitline("\tMOVQ\t$0, ");
emitoff(off: i64);
emitline("(BP)\n");
} else { if (!isarr) { if (sz > 8) {
emitline("\tXORQ\tAX, AX\n");
let zi: i32 = 0;
for (zi + 8 <= sz) {
emitline("\tMOVQ\tAX, ");
emitoff((off + zi): i64);
emitline("(BP)\n");
zi += 8;
};
for (zi + 4 <= sz) {
emitline("\tMOVL\tAX, ");
emitoff((off + zi): i64);
emitline("(BP)\n");
zi += 4;
};
for (zi < sz) {
emitline("\tMOVB\tAX, ");
emitoff((off + zi): i64);
emitline("(BP)\n");
zi += 1;
};
}; }; };
};
c.lastwasreturn = 0;
return;
};
fn cgif(c: *cgen, n: *node) void = {
let els: str = mklabel(c, "else");
let endl: str = mklabel(c, "end");
cgexpr(c, n.cond);
emitline("\tCMPQ\t$0, AX\n");
emitline("\tJE\t");
if (n.els != nil) { emitline(els); }
else { emitline(endl); };
emitline("\n");
if (n.body != nil) { cgstmt(c, n.body); };
if (n.els != nil) {
emitline("\tJMP\t"); emitline(endl); emitline("\n");
emitlabel(els);
cgstmt(c, n.els);
};
emitlabel(endl);
c.lastwasreturn = 0;
return;
};
fn cgfor(c: *cgen, n: *node) void = {
// Match C cgen's label scheme: <fn>_loop_N for the top,
// <fn>_endloop_N for the post-body merge. No separate cont
// label when there's no post-expression.
let topl: str = mklabel(c, "loop");
let endl: str = mklabel(c, "endloop");
// `else` runs at natural cond-false exit; break skips it. When
// present, branch the cond-fail edge to a separate natural_exit
// label so the else body sits between it and the break target.
let naturall: str = endl;
if (n.els != nil) { naturall = mklabel(c, "elseloop"); };
if (n.lhs != nil) { cgstmt(c, n.lhs); };
emitlabel(topl);
if (n.cond != nil) {
cgexpr(c, n.cond);
emitline("\tCMPQ\t$0, AX\n");
emitline("\tJE\t"); emitline(naturall); emitline("\n");
};
c.loopendbuf[c.looptop] = endl;
c.loopcontbuf[c.looptop] = topl;
c.looptop += 1;
if (n.body != nil) { cgstmt(c, n.body); };
c.looptop -= 1;
if (n.rhs != nil) { cgexpr(c, n.rhs); };
emitline("\tJMP\t"); emitline(topl); emitline("\n");
if (n.els != nil) {
emitlabel(naturall);
cgstmt(c, n.els);
};
emitlabel(endl);
c.lastwasreturn = 0;
return;
};
// Tuple-destructure assign: `a, b = call();`. The call's tuple
// return lands in (AX, DX); push DX to free it, store AX into
// the first lvalue, then pop DX into the second. Mirrors
// cmd/w6c/cgen.c:2424-2440. Lvalues beyond two are dropped (same
// as C — no fixture uses >2 today).
fn cgmassign(c: *cgen, n: *node) void = {
if (n.rhs != nil) { cgexpr(c, n.rhs); };
emitline("\tPUSHQ\tDX\n");
let l0: *node = n.list;
let l1: *node = nil;
if (l0 != nil) { l1 = l0.next; };
if (l0 != nil) {
if (l0.kind == nkind.N_IDENT) {
let off: i32 = localfind(c, l0.str);
if (off != 0) {
emitline("\tMOVQ\tAX, ");
emitoff(off: i64);
emitline("(BP)\n");
};
};
};
emitline("\tPOPQ\tDX\n");
if (l1 != nil) {
if (l1.kind == nkind.N_IDENT) {
let off: i32 = localfind(c, l1.str);
if (off != 0) {
emitline("\tMOVQ\tDX, ");
emitoff(off: i64);
emitline("(BP)\n");
};
};
};
c.lastwasreturn = 0;
return;
};
// Multi-let from a tuple-returning call: `let n, s = call();` or
// `let (n, s) = call();`. wwstage has no checker, so each binding's
// type is taken from its explicit annotation (l.lhs) when present
// or inferred from the called fn's return-type tuple element.
//
// Per the AX:DX:CX return convention (mirrors C cgen nkind.N_MLET):
// (scalar, scalar) — AX → l0, DX → l1.
// (scalar, str) — AX → scalar slot, (DX, CX) → str slot
// as (.ptr, .len). Position-agnostic — the
// regs are routed by element type, not by AX/DX.
fn cgmlet(c: *cgen, n: *node) void = {
let rhs: *node = n.rhs;
if (rhs == nil) { return; };
let p0t: *node = nil;
let p1t: *node = nil;
if (rhs.kind == nkind.N_CALL) {
let callee: *node = rhs.lhs;
if (callee != nil) {
let cnm: str;
cnm.ptr = nil; cnm.len = 0;
let cmod: str;
cmod.ptr = nil; cmod.len = 0;
if (callee.kind == nkind.N_IDENT) {
cnm = callee.str;
cmod = c.curmod;
};
if (callee.kind == nkind.N_DOT) {
cnm = callee.str;
if (callee.lhs != nil) {
if (callee.lhs.kind == nkind.N_IDENT) {
cmod = callee.lhs.str;
};
};
};
if (cnm.len > 0) {
let rtyp: *node = fnretlookupmod(c, cnm, cmod);
if (rtyp != nil) {
if (rtyp.kind == nkind.N_TTUPLE) {
p0t = rtyp.list;
if (p0t != nil) { p1t = p0t.next; };
};
};
};
};
};
let l0: *node = n.list;
let l1: *node = nil;
if (l0 != nil) { l1 = l0.next; };
let t0: *node = nil;
let t1: *node = nil;
if (l0 != nil) { t0 = l0.lhs; };
if (l1 != nil) { t1 = l1.lhs; };
if (t0 == nil) { t0 = p0t; };
if (t1 == nil) { t1 = p1t; };
let s0_is_str: bool = isstrtyperaw(t0);
let s1_is_str: bool = isstrtyperaw(t1);
cgexpr(c, rhs);
if (l0 != nil) {
if (l1 != nil) {
if (s0_is_str != s1_is_str) {
let sz0: i32 = 8;
let sz1: i32 = 8;
if (s0_is_str) { sz0 = primtypesize("str"): i32; };
if (s1_is_str) { sz1 = primtypesize("str"): i32; };
let off0: i32 = localadd(c, l0.str, sz0, t0);
let off1: i32 = localadd(c, l1.str, sz1, t1);
if (s0_is_str) {
emitline("\tMOVQ\tDX, ");
emitoff(off0: i64);
emitline("(BP)\n");
emitline("\tMOVQ\tCX, ");
emitoff((off0 + 8): i64);
emitline("(BP)\n");
emitline("\tMOVQ\tAX, ");
emitoff(off1: i64);
emitline("(BP)\n");
} else {
emitline("\tMOVQ\tAX, ");
emitoff(off0: i64);
emitline("(BP)\n");
emitline("\tMOVQ\tDX, ");
emitoff(off1: i64);
emitline("(BP)\n");
emitline("\tMOVQ\tCX, ");
emitoff((off1 + 8): i64);
emitline("(BP)\n");
};
c.lastwasreturn = 0;
return;
};
};
};
if (l0 != nil) {
let off: i32 = localadd(c, l0.str, 8, t0);
emitline("\tMOVQ\tAX, ");
emitoff(off: i64);
emitline("(BP)\n");
};
if (l1 != nil) {
let off: i32 = localadd(c, l1.str, 8, t1);
emitline("\tMOVQ\tDX, ");
emitoff(off: i64);
emitline("(BP)\n");
};
c.lastwasreturn = 0;
return;
};
// paramfieldsize — raw byte size of a tuple-field type. Mirrors the
// `tp->type->size` read in C cgen N_FORRANGE: 1 for i8/u8/bool, 4 for
// i32/u32, 8 for i64/u64/*T/fn/slice-elt, 16 for str, default 8.
fn paramfieldsize(t: *node) i32 = {
if (t == nil) { return 8; };
let k: nkind = t.kind;
if (k == nkind.N_TPTR) { return 8; };
if (k == nkind.N_TFN) { return 8; };
if (k == nkind.N_TCHAN) { return 8; };
if (k == nkind.N_TNAME) {
let nm: str = t.str;
if (streq(nm, "str")) { return primtypesize("str"): i32; };
let ps: i32 = primsize(nm);
if (ps > 0) { return ps; };
};
return 8;
};
// paramissigned — does this type need sign-extending on a sub-word
// (1/2/4B) load? Mirrors cstage's signed_field check via
// fieldissignedc (resolves TBANG / TENUM / alias chains).
fn paramissigned(c: *cgen, t: *node) bool = {
return fieldissignedc(c, t);
};
// cgforrange — lower `for (let x .. slice) body` (and the tuple-
// destructure cousin `for (let (a, b) .. slice) body`). The body is
// wrapped in a counted loop driven by stack-spilled `.rgi`/`.rgl`.
// Each iteration computes the element address `s.ptr + i*esz` and
// either loads the whole element into the named local or pulls each
// tuple field into its own local. Mirrors cmd/w6c/cgen.c N_FORRANGE
// byte-for-byte (label names + labelseq consumption order).
fn cgforrange(c: *cgen, n: *node) void = {
let slc: *node = n.lhs;
let slclocal: *local = nil;
let slctn: *node = nil;
if (slc != nil) {
if (slc.kind == nkind.N_IDENT) {
slclocal = localfindnode(c, slc.str);
if (slclocal != nil) { slctn = slclocal.tnode; };
};
};
// Element type — peek through TSLICE/TARRAY for the tuple param walk.
let elemt: *node = nil;
if (slctn != nil) {
let sk: nkind = slctn.kind;
if (sk == nkind.N_TSLICE) { elemt = slctn.lhs; };
if (sk == nkind.N_TARRAY) { elemt = slctn.lhs; };
};
// esz: raw elem byte size. For tuple-element slices `[](T0, T1)`,
// C cgen reads the resolved tuple's size (sum of raw param sizes,
// no slot-padding) so e.g. `(i64, i64)` is 16, `(i32, i32)` is 8.
// elemsizeof returns 8 for non-primitive elem, which would be
// wrong here — compute from the tuple param walk instead.
let esz: i32 = elemsizeof(slctn);
if (elemt != nil) {
if (elemt.kind == nkind.N_TTUPLE) {
let total: i32 = 0;
let p: *node = elemt.list;
for (p != nil) {
total += paramfieldsize(p);
p = p.next;
};
esz = total;
};
};
let destruct: bool = (n.list != nil);
// .rgi (counter) + .rgl (length) scratch slots.
let iname: str = mkscratchname(c, "rgi");
let lname: str = mkscratchname(c, "rgl");
let ioff: i32 = localalloc(c, iname, 8, nil);
let loff: i32 = localalloc(c, lname, 8, nil);
// Per-binding (up to 8 — matches the C array). Parallel arrays so
// we don't depend on local-struct cgen.
let bind_off: [8]i32;
let bind_sz: [8]i32;
let bind_foff: [8]i32;
let bind_signed: [8]bool;
let nbinds: i32 = 0;
if (destruct) {
let tp: *node = nil;
if (elemt != nil) {
if (elemt.kind == nkind.N_TTUPLE) { tp = elemt.list; };
};
let field_off: i32 = 0;
let m: *node = n.list;
for (m != nil) {
if (nbinds >= 8) { m = nil; }
else {
let fsz: i32 = 8;
let signf: bool = false;
if (tp != nil) {
fsz = paramfieldsize(tp);
signf = paramissigned(c, tp);
};
let slot_sz: i32 = fsz;
if (slot_sz < 8) { slot_sz = 8; };
bind_sz[nbinds] = fsz;
bind_foff[nbinds] = field_off;
bind_signed[nbinds] = signf;
let bnm: str = m.str;
if (bnm.len > 0) {
bind_off[nbinds] = localadd(c, bnm, slot_sz, tp);
} else {
bind_off[nbinds] = localalloc(c, mkscratchname(c, "fr"), slot_sz, tp);
};
field_off += fsz;
nbinds += 1;
if (tp != nil) { tp = tp.next; };
m = m.next;
};
};
} else {
let slot_sz: i32 = esz;
if (slot_sz < 8) { slot_sz = 8; };
bind_sz[0] = esz;
bind_foff[0] = 0;
// Single-binding signed-narrow detection: mirror C which
// reads `u->sub->kind` for the elem type.
bind_signed[0] = false;
if (elemt != nil) {
bind_signed[0] = paramissigned(c, elemt);
};
if (n.str.len > 0) {
// Register with elem tnode so x.field on a loop
// var resolves through the standard local-typed
// path instead of falling into the SB fallback.
bind_off[0] = localadd(c, n.str, slot_sz, elemt);
} else {
bind_off[0] = localalloc(c, mkscratchname(c, "fr"), slot_sz, elemt);
};
nbinds = 1;
};
// init: ioff(BP) = 0
emitline("\tMOVQ\t$0, ");
emitoff(ioff: i64);
emitline("(BP)\n");
// loff(BP) = len
let isarr: bool = false;
let isslicestr: bool = false;
if (slctn != nil) {
let tk: nkind = slctn.kind;
if (tk == nkind.N_TSLICE) { isslicestr = true; };
if (tk == nkind.N_TARRAY) { isarr = true; };
if (tk == nkind.N_TNAME) {
if (streq(slctn.str, "str")) { isslicestr = true; };
};
};
if (isslicestr) {
if (slc.kind == nkind.N_IDENT) {
if (slclocal != nil) {
emitline("\tMOVQ\t");
emitoff((slclocal.off + 8): i64);
emitline("(BP), AX\n");
emitline("\tMOVQ\tAX, ");
emitoff(loff: i64);
emitline("(BP)\n");
};
};
} else { if (isarr) {
let alen: i64 = 0i64;
if (slctn.rhs != nil) {
if (slctn.rhs.kind == nkind.N_INTLIT) { alen = slctn.rhs.uval: i64; };
};
emitline("\tMOVQ\t$");
emitint(alen);
emitline(", ");
emitoff(loff: i64);
emitline("(BP)\n");
} else {
cgexpr(c, slc);
emitline("\tMOVQ\tAX, ");
emitoff(loff: i64);
emitline("(BP)\n");
};};
let loopl: str = mklabel(c, "rloop");
let endl: str = mklabel(c, "rend");
let naturall: str = endl;
if (n.els != nil) { naturall = mklabel(c, "relseloop"); };
c.loopcontbuf[c.looptop] = loopl;
c.loopendbuf[c.looptop] = endl;
c.looptop += 1;
emitlabel(loopl);
emitline("\tMOVQ\t");
emitoff(ioff: i64);
emitline("(BP), AX\n");
emitline("\tMOVQ\t");
emitoff(loff: i64);
emitline("(BP), BX\n");
emitline("\tCMPQ\tBX, AX\n");
emitline("\tJGE\t"); emitline(naturall); emitline("\n");
// BX = base + i*esz
if (esz > 1) {
emitline("\tMOVQ\t$");
emitint(esz: i64);
emitline(", CX\n");
emitline("\tIMULQ\tCX, AX\n");
};
if (slc.kind == nkind.N_IDENT) {
if (slclocal != nil) {
if (isarr) {
emitline("\tLEAQ\t");
emitoff(slclocal.off: i64);
emitline("(BP), BX\n");
} else {
emitline("\tMOVQ\t");
emitoff(slclocal.off: i64);
emitline("(BP), BX\n");
};
};
};
emitline("\tADDQ\tAX, BX\n");
// Per-binding load from BX+foff. Signedness comes from bind_signed
// (set via paramissigned → fieldissignedc), so enum-aliased narrows
// pick the right MOVS*Q without a literal-name gate.
let b: i32 = 0;
for (b < nbinds) {
let op: str = loadopsz(bind_signed[b], bind_sz[b]);
emitline("\t");
emitline(op);
emitline("\t");
emitoff(bind_foff[b]: i64);
emitline("(BX), AX\n");
emitline("\tMOVQ\tAX, ");
emitoff(bind_off[b]: i64);
emitline("(BP)\n");
b += 1;
};
if (n.body != nil) { cgstmt(c, n.body); };
c.looptop -= 1;
emitline("\tADDQ\t$1, ");
emitoff(ioff: i64);
emitline("(BP)\n");
emitline("\tJMP\t"); emitline(loopl); emitline("\n");
if (n.els != nil) {
emitlabel(naturall);
cgstmt(c, n.els);
};
emitlabel(endl);
c.lastwasreturn = 0;
return;
};
// cgswitch — lower `switch (e) { case 1, 2: ...; case: default; }` to
// a chain of compares against the scrutinee. Scrutinee lands in a
// fresh 8B local slot so case bodies can spill SP without losing it.
// Cases are tried top-to-bottom; the `case:` arm with no exprs is the
// default and runs after all named arms fail. Mirrors cmd/w6c/cgen.c
// N_SWITCH: same labelseq consumption order so labels match byte-for-
// byte.
fn cgswitch(c: *cgen, n: *node) void = {
let swname: str = mkscratchname(c, "sw");
let sloff: i32 = localalloc(c, swname, 8, nil);
if (n.lhs != nil) { cgexpr(c, n.lhs); };
emitline("\tMOVQ\tAX, ");
emitoff(sloff: i64);
emitline("(BP)\n");
let endl: str = mklabel(c, "swend");
let defcase: *node = nil;
let cs: *node = n.list;
for (cs != nil) {
if (cs.list == nil) {
defcase = cs;
cs = cs.next;
continue;
};
let body: str = mklabel(c, "swcase");
let nxt: str = mklabel(c, "swnext");
let e: *node = cs.list;
for (e != nil) {
cgexpr(c, e);
emitline("\tMOVQ\t");
emitoff(sloff: i64);
emitline("(BP), BX\n");
emitline("\tCMPQ\tBX, AX\n");
emitline("\tJE\t");
emitline(body);
emitline("\n");
e = e.next;
};
emitline("\tJMP\t");
emitline(nxt);
emitline("\n");
emitlabel(body);
if (cs.body != nil) { cgstmt(c, cs.body); };
emitline("\tJMP\t");
emitline(endl);
emitline("\n");
emitlabel(nxt);
cs = cs.next;
};
if (defcase != nil) {
if (defcase.body != nil) { cgstmt(c, defcase.body); };
};
emitlabel(endl);
c.lastwasreturn = 0;
return;
};
fn cgbreak(c: *cgen, n: *node) void = {
if (c.looptop > 0) {
let lbl: str = c.loopendbuf[c.looptop - 1];
emitline("\tJMP\t"); emitline(lbl); emitline("\n");
};
c.lastwasreturn = 0;
return;
};
fn cgcontinue(c: *cgen, n: *node) void = {
if (c.looptop > 0) {
let lbl: str = c.loopcontbuf[c.looptop - 1];
emitline("\tJMP\t"); emitline(lbl); emitline("\n");
};
c.lastwasreturn = 0;
return;
};