w6c+selfhost: cg_widen_tagged_store basereg + N_ASSIGN tagged field (closes #26)

Extended cg_widen_tagged_store (cstage) / cgwidentaggedstore (wwstage)
to take a base_reg/basereg parameter so the primitive supports non-BP
destinations. Cstage extends body in-place via via_outer gate +
spill+scratch+copy-out; wwstage splits into wrapper (non-BP) +
cgwidentaggedstorebp (BP-only) to dodge the no-goto constraint. New
N_ASSIGN field TY_TAGGED branch routes through the primitive for all
rhs shapes.

Scope-adjacent: fieldsize recurses through N_TTAGGED via slotsize and
TNAME-aliased-to-tagged via aliaslookup. Needed for the test fixtures.

Wwstage read-side N_DOT-of-tagged-field source is filed as task #28;
test rows use mark-canary verification until that lands.
This commit is contained in:
2026-05-14 19:12:20 +09:00
parent 1726bcef18
commit a5919ed8da
8 changed files with 644 additions and 116 deletions

View File

@@ -5744,7 +5744,7 @@ fn pushargsrev(c: *cgen, arg: *node, param: *node) i32 = {
emitline("(BP)\n");
zz += 8;
};
cgwidentaggedstore(c, ptype, arg, scroff, widensz);
cgwidentaggedstore(c, ptype, arg, "BP", scroff, widensz);
let pp: i32 = widensz - 8;
for (pp >= 0) {
emitline("\tMOVQ\t");
@@ -6938,6 +6938,7 @@ fn slotsize(c: *cgen, typn: *node) i32 = {
fn fieldsize(c: *cgen, tnode: *node) i32 = {
if (tnode == nil) { return 8; };
let k: nkind = tnode.kind;
if (k == nkind.N_TTAGGED){ return slotsize(c, tnode); };
if (k == nkind.N_TNAME) {
let nm: str = tnode.str;
if (streq(nm, "str")) { return 16; };
@@ -6957,6 +6958,13 @@ fn fieldsize(c: *cgen, tnode: *node) i32 = {
};
return 4; // default storage is i32
};
// Type alias to a tagged-union — recurse through aliaslookup
// so `e: ev` (where `ev = (i64 | i32)`) takes 16B in the
// containing struct rather than the 8B default.
if (c != nil) {
let aliased: *node = aliaslookup(c, nm);
if (aliased != nil) { return fieldsize(c, aliased); };
};
return 8;
};
if (k == nkind.N_TPTR) { return 8; };
@@ -7633,9 +7641,20 @@ fn rhstaggedabicall(c: *cgen, src: *node) bool = {
return false;
};
// cgwidentaggedstore — write tagged-union slot bytes for `src` into the
// slot at BP+slot_off, sized to slot_sz. Mirrors cg_widen_tagged_store
// in cmd/w6c/cgen.c. Branches by source shape:
// cgwidentaggedstore — write tagged-union slot bytes for `src` into
// the slot at `basereg`+slot_off, sized to slot_sz. Mirrors
// cg_widen_tagged_store in cmd/w6c/cgen.c.
//
// `basereg` selects the addressing root:
// - "BP": function-frame slot (let / assign / return / structlit /
// array-elem scratch). Body writes straight to slot_off(BP).
// - else (e.g. "BX" for *struct field, top-level struct LEAQ
// base): pointer-rooted dst. cgexpr inside trashes every GPR,
// so we route through a fresh BP-rooted scratch slot, spill
// basereg before the body, reload after, then word-copy
// scratch → (basereg, slot_off).
//
// Branches by source shape:
// - nullable dst (8B slot): cgexpr → AX → slot+0.
// - tagged src ident: copy slot words, zero-pad, tag-remap.
// - tagged src via AX/DX/CX ABI (call / tagged-arr index): cgexpr,
@@ -7646,7 +7665,53 @@ fn rhstaggedabicall(c: *cgen, src: *node) bool = {
// tag last.
// - str src: tag@+0, ptr@+8, len@+16.
// - scalar src: tag@+0, value@+8.
fn cgwidentaggedstore(c: *cgen, dst: *node, src: *node, slot_off: i32, slot_sz: i32) void = {
fn cgwidentaggedstore(c: *cgen, dst: *node, src: *node,
basereg: str, slot_off: i32, slot_sz: i32) void = {
if (streq(basereg, "BP")) {
cgwidentaggedstorebp(c, dst, src, slot_off, slot_sz);
return;
};
// Pointer-rooted dst: spill basereg (cgexpr will trash it),
// materialise into a BP-rooted scratch via the BP path, then
// reload basereg and word-copy scratch → caller's slot.
let bspill: i32 = localadd(c, "@tagbase", 8, nil);
emitline("\tMOVQ\t");
emitline(basereg);
emitline(", ");
emitoff(bspill: i64);
emitline("(BP)\n");
let scr: i32 = localadd(c, "@tagscr", slot_sz, nil);
emitline("\tXORQ\tAX, AX\n");
let z: i32 = 0;
for (z < slot_sz) {
emitline("\tMOVQ\tAX, ");
emitoff((scr + z): i64);
emitline("(BP)\n");
z += 8;
};
cgwidentaggedstorebp(c, dst, src, scr, slot_sz);
emitline("\tMOVQ\t");
emitoff(bspill: i64);
emitline("(BP), ");
emitline(basereg);
emitline("\n");
let k: i32 = 0;
for (k < slot_sz) {
emitline("\tMOVQ\t");
emitoff((scr + k): i64);
emitline("(BP), AX\n");
emitline("\tMOVQ\tAX, ");
emitdispreg((slot_off + k): i64, basereg);
emitline("\n");
k += 8;
};
};
// cgwidentaggedstorebp — BP-rooted body. Called via cgwidentaggedstore
// for the natural "BP" case and via the wrapper's scratch path for
// pointer-rooted dst. Direct callers exist only in case of future
// inlined uses inside this file; new code should call the wrapper.
fn cgwidentaggedstorebp(c: *cgen, dst: *node, src: *node, slot_off: i32, slot_sz: i32) void = {
let dt: *node = resolvetagged(c, dst);
if (dt == nil) { return; };
// Nullable fold: one 8B word holding the pointer (or 0 for void).
@@ -10793,7 +10858,7 @@ fn cgcall(c: *cgen, n: *node) void = {
let slot: i32 = doff + j * esz;
if (velemtagged) {
cgwidentaggedstore(c, varp.lhs,
aa2, slot, esz);
aa2, "BP", slot, esz);
} else { if (velemstr) {
cgexpr(c, aa2);
emitline("\tMOVQ\tAX, ");
@@ -11049,7 +11114,7 @@ fn cgassign(c: *cgen, n: *node) void = {
if (istaggedtype(c, lc.tnode)) {
let lsz: i32 = slotsize(c, lc.tnode);
cgwidentaggedstore(c, lc.tnode,
n.rhs, lc.off, lsz);
n.rhs, "BP", lc.off, lsz);
return;
};
};
@@ -11273,7 +11338,7 @@ fn cgassign(c: *cgen, n: *node) void = {
zz += 8;
};
cgwidentaggedstore(c, elemtn, n.rhs,
scroff, slot_sz);
"BP", scroff, slot_sz);
cgexpr(c, idx);
if (slot_sz > 1) {
emitline("\tMOVQ\t$");
@@ -11619,6 +11684,20 @@ fn cgassign(c: *cgen, n: *node) void = {
for (fi != nil) {
let fn_: str = fi.fname;
if (streq(fn_, fld)) {
// Tagged-union field via *struct base — full slot
// rewrite via cgwidentaggedstore basereg="BX". Pre-#26
// fell through to the scalar store and dropped tag
// + payload.
if (n.op == tkind.TK_ASSIGN
&& istaggedtype(c, fi.tnode)) {
let fsz: i32 = slotsize(c, fi.tnode);
emitline("\tMOVQ\t");
emitoff(lc.off: i64);
emitline("(BP), BX\n");
cgwidentaggedstore(c, fi.tnode,
n.rhs, "BX", fi.foff, fsz);
return;
};
// struct-typed field, struct-ident rhs through
// *struct base: cgexpr can't materialise a whole
// struct value, so word-copy from the rhs slot
@@ -11769,6 +11848,17 @@ fn cgassign(c: *cgen, n: *node) void = {
for (fi != nil) {
let fn_: str = fi.fname;
if (streq(fn_, fld)) {
// Tagged-union field in a direct struct local —
// full slot rewrite at (lc.off + fi.foff)(BP)
// via cgwidentaggedstore basereg="BP". Pre-#26
// fell through and dropped tag + payload.
if (n.op == tkind.TK_ASSIGN
&& istaggedtype(c, fi.tnode)) {
let fsz: i32 = slotsize(c, fi.tnode);
cgwidentaggedstore(c, fi.tnode,
n.rhs, "BP", lc.off + fi.foff, fsz);
return;
};
// struct-typed field, struct-ident rhs:
// word-copy direct, skipping cgexpr (no
// register convention for a whole struct
@@ -12978,8 +13068,8 @@ fn cgreturn(c: *cgen, n: *node) void = {
emitline("(BP)\n");
zz += 8;
};
cgwidentaggedstore(c, c.fnret, rhs, scroff,
rsz);
cgwidentaggedstore(c, c.fnret, rhs, "BP",
scroff, rsz);
emitline("\tMOVQ\t");
emitoff(scroff: i64);
emitline("(BP), AX\n");
@@ -13101,7 +13191,7 @@ fn cglet(c: *cgen, n: *node) void = {
// 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, off, sz);
cgwidentaggedstore(c, tn, rhs, "BP", off, sz);
c.lastwasreturn = 0;
return;
};
@@ -14118,6 +14208,61 @@ fn scanlocals(c: *cgen, n: *node) i32 = {
};
};
};
// 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) and @tagscr (slot_sz). Both names
// dedup with other tagged scratch users in the same function.
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;
};
if (!scanseenmark(c, "@tagscr")) {
total += 24;
};
};
};
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. Detect via the same rhsstructpayload predicate

View File

@@ -204,6 +204,61 @@ fn scanlocals(c: *cgen, n: *node) i32 = {
};
};
};
// 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) and @tagscr (slot_sz). Both names
// dedup with other tagged scratch users in the same function.
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;
};
if (!scanseenmark(c, "@tagscr")) {
total += 24;
};
};
};
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. Detect via the same rhsstructpayload predicate

View File

@@ -2745,7 +2745,7 @@ fn cgcall(c: *cgen, n: *node) void = {
let slot: i32 = doff + j * esz;
if (velemtagged) {
cgwidentaggedstore(c, varp.lhs,
aa2, slot, esz);
aa2, "BP", slot, esz);
} else { if (velemstr) {
cgexpr(c, aa2);
emitline("\tMOVQ\tAX, ");
@@ -3001,7 +3001,7 @@ fn cgassign(c: *cgen, n: *node) void = {
if (istaggedtype(c, lc.tnode)) {
let lsz: i32 = slotsize(c, lc.tnode);
cgwidentaggedstore(c, lc.tnode,
n.rhs, lc.off, lsz);
n.rhs, "BP", lc.off, lsz);
return;
};
};
@@ -3225,7 +3225,7 @@ fn cgassign(c: *cgen, n: *node) void = {
zz += 8;
};
cgwidentaggedstore(c, elemtn, n.rhs,
scroff, slot_sz);
"BP", scroff, slot_sz);
cgexpr(c, idx);
if (slot_sz > 1) {
emitline("\tMOVQ\t$");
@@ -3571,6 +3571,20 @@ fn cgassign(c: *cgen, n: *node) void = {
for (fi != nil) {
let fn_: str = fi.fname;
if (streq(fn_, fld)) {
// Tagged-union field via *struct base — full slot
// rewrite via cgwidentaggedstore basereg="BX". Pre-#26
// fell through to the scalar store and dropped tag
// + payload.
if (n.op == tkind.TK_ASSIGN
&& istaggedtype(c, fi.tnode)) {
let fsz: i32 = slotsize(c, fi.tnode);
emitline("\tMOVQ\t");
emitoff(lc.off: i64);
emitline("(BP), BX\n");
cgwidentaggedstore(c, fi.tnode,
n.rhs, "BX", fi.foff, fsz);
return;
};
// struct-typed field, struct-ident rhs through
// *struct base: cgexpr can't materialise a whole
// struct value, so word-copy from the rhs slot
@@ -3721,6 +3735,17 @@ fn cgassign(c: *cgen, n: *node) void = {
for (fi != nil) {
let fn_: str = fi.fname;
if (streq(fn_, fld)) {
// Tagged-union field in a direct struct local —
// full slot rewrite at (lc.off + fi.foff)(BP)
// via cgwidentaggedstore basereg="BP". Pre-#26
// fell through and dropped tag + payload.
if (n.op == tkind.TK_ASSIGN
&& istaggedtype(c, fi.tnode)) {
let fsz: i32 = slotsize(c, fi.tnode);
cgwidentaggedstore(c, fi.tnode,
n.rhs, "BP", lc.off + fi.foff, fsz);
return;
};
// struct-typed field, struct-ident rhs:
// word-copy direct, skipping cgexpr (no
// register convention for a whole struct

View File

@@ -188,8 +188,8 @@ fn cgreturn(c: *cgen, n: *node) void = {
emitline("(BP)\n");
zz += 8;
};
cgwidentaggedstore(c, c.fnret, rhs, scroff,
rsz);
cgwidentaggedstore(c, c.fnret, rhs, "BP",
scroff, rsz);
emitline("\tMOVQ\t");
emitoff(scroff: i64);
emitline("(BP), AX\n");
@@ -311,7 +311,7 @@ fn cglet(c: *cgen, n: *node) void = {
// 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, off, sz);
cgwidentaggedstore(c, tn, rhs, "BP", off, sz);
c.lastwasreturn = 0;
return;
};

View File

@@ -174,7 +174,7 @@ fn pushargsrev(c: *cgen, arg: *node, param: *node) i32 = {
emitline("(BP)\n");
zz += 8;
};
cgwidentaggedstore(c, ptype, arg, scroff, widensz);
cgwidentaggedstore(c, ptype, arg, "BP", scroff, widensz);
let pp: i32 = widensz - 8;
for (pp >= 0) {
emitline("\tMOVQ\t");
@@ -1368,6 +1368,7 @@ fn slotsize(c: *cgen, typn: *node) i32 = {
fn fieldsize(c: *cgen, tnode: *node) i32 = {
if (tnode == nil) { return 8; };
let k: nkind = tnode.kind;
if (k == nkind.N_TTAGGED){ return slotsize(c, tnode); };
if (k == nkind.N_TNAME) {
let nm: str = tnode.str;
if (streq(nm, "str")) { return 16; };
@@ -1387,6 +1388,13 @@ fn fieldsize(c: *cgen, tnode: *node) i32 = {
};
return 4; // default storage is i32
};
// Type alias to a tagged-union — recurse through aliaslookup
// so `e: ev` (where `ev = (i64 | i32)`) takes 16B in the
// containing struct rather than the 8B default.
if (c != nil) {
let aliased: *node = aliaslookup(c, nm);
if (aliased != nil) { return fieldsize(c, aliased); };
};
return 8;
};
if (k == nkind.N_TPTR) { return 8; };
@@ -2063,9 +2071,20 @@ fn rhstaggedabicall(c: *cgen, src: *node) bool = {
return false;
};
// cgwidentaggedstore — write tagged-union slot bytes for `src` into the
// slot at BP+slot_off, sized to slot_sz. Mirrors cg_widen_tagged_store
// in cmd/w6c/cgen.c. Branches by source shape:
// cgwidentaggedstore — write tagged-union slot bytes for `src` into
// the slot at `basereg`+slot_off, sized to slot_sz. Mirrors
// cg_widen_tagged_store in cmd/w6c/cgen.c.
//
// `basereg` selects the addressing root:
// - "BP": function-frame slot (let / assign / return / structlit /
// array-elem scratch). Body writes straight to slot_off(BP).
// - else (e.g. "BX" for *struct field, top-level struct LEAQ
// base): pointer-rooted dst. cgexpr inside trashes every GPR,
// so we route through a fresh BP-rooted scratch slot, spill
// basereg before the body, reload after, then word-copy
// scratch → (basereg, slot_off).
//
// Branches by source shape:
// - nullable dst (8B slot): cgexpr → AX → slot+0.
// - tagged src ident: copy slot words, zero-pad, tag-remap.
// - tagged src via AX/DX/CX ABI (call / tagged-arr index): cgexpr,
@@ -2076,7 +2095,53 @@ fn rhstaggedabicall(c: *cgen, src: *node) bool = {
// tag last.
// - str src: tag@+0, ptr@+8, len@+16.
// - scalar src: tag@+0, value@+8.
fn cgwidentaggedstore(c: *cgen, dst: *node, src: *node, slot_off: i32, slot_sz: i32) void = {
fn cgwidentaggedstore(c: *cgen, dst: *node, src: *node,
basereg: str, slot_off: i32, slot_sz: i32) void = {
if (streq(basereg, "BP")) {
cgwidentaggedstorebp(c, dst, src, slot_off, slot_sz);
return;
};
// Pointer-rooted dst: spill basereg (cgexpr will trash it),
// materialise into a BP-rooted scratch via the BP path, then
// reload basereg and word-copy scratch → caller's slot.
let bspill: i32 = localadd(c, "@tagbase", 8, nil);
emitline("\tMOVQ\t");
emitline(basereg);
emitline(", ");
emitoff(bspill: i64);
emitline("(BP)\n");
let scr: i32 = localadd(c, "@tagscr", slot_sz, nil);
emitline("\tXORQ\tAX, AX\n");
let z: i32 = 0;
for (z < slot_sz) {
emitline("\tMOVQ\tAX, ");
emitoff((scr + z): i64);
emitline("(BP)\n");
z += 8;
};
cgwidentaggedstorebp(c, dst, src, scr, slot_sz);
emitline("\tMOVQ\t");
emitoff(bspill: i64);
emitline("(BP), ");
emitline(basereg);
emitline("\n");
let k: i32 = 0;
for (k < slot_sz) {
emitline("\tMOVQ\t");
emitoff((scr + k): i64);
emitline("(BP), AX\n");
emitline("\tMOVQ\tAX, ");
emitdispreg((slot_off + k): i64, basereg);
emitline("\n");
k += 8;
};
};
// cgwidentaggedstorebp — BP-rooted body. Called via cgwidentaggedstore
// for the natural "BP" case and via the wrapper's scratch path for
// pointer-rooted dst. Direct callers exist only in case of future
// inlined uses inside this file; new code should call the wrapper.
fn cgwidentaggedstorebp(c: *cgen, dst: *node, src: *node, slot_off: i32, slot_sz: i32) void = {
let dt: *node = resolvetagged(c, dst);
if (dt == nil) { return; };
// Nullable fold: one 8B word holding the pointer (or 0 for void).

View File

@@ -5744,7 +5744,7 @@ fn pushargsrev(c: *cgen, arg: *node, param: *node) i32 = {
emitline("(BP)\n");
zz += 8;
};
cgwidentaggedstore(c, ptype, arg, scroff, widensz);
cgwidentaggedstore(c, ptype, arg, "BP", scroff, widensz);
let pp: i32 = widensz - 8;
for (pp >= 0) {
emitline("\tMOVQ\t");
@@ -6938,6 +6938,7 @@ fn slotsize(c: *cgen, typn: *node) i32 = {
fn fieldsize(c: *cgen, tnode: *node) i32 = {
if (tnode == nil) { return 8; };
let k: nkind = tnode.kind;
if (k == nkind.N_TTAGGED){ return slotsize(c, tnode); };
if (k == nkind.N_TNAME) {
let nm: str = tnode.str;
if (streq(nm, "str")) { return 16; };
@@ -6957,6 +6958,13 @@ fn fieldsize(c: *cgen, tnode: *node) i32 = {
};
return 4; // default storage is i32
};
// Type alias to a tagged-union — recurse through aliaslookup
// so `e: ev` (where `ev = (i64 | i32)`) takes 16B in the
// containing struct rather than the 8B default.
if (c != nil) {
let aliased: *node = aliaslookup(c, nm);
if (aliased != nil) { return fieldsize(c, aliased); };
};
return 8;
};
if (k == nkind.N_TPTR) { return 8; };
@@ -7633,9 +7641,20 @@ fn rhstaggedabicall(c: *cgen, src: *node) bool = {
return false;
};
// cgwidentaggedstore — write tagged-union slot bytes for `src` into the
// slot at BP+slot_off, sized to slot_sz. Mirrors cg_widen_tagged_store
// in cmd/w6c/cgen.c. Branches by source shape:
// cgwidentaggedstore — write tagged-union slot bytes for `src` into
// the slot at `basereg`+slot_off, sized to slot_sz. Mirrors
// cg_widen_tagged_store in cmd/w6c/cgen.c.
//
// `basereg` selects the addressing root:
// - "BP": function-frame slot (let / assign / return / structlit /
// array-elem scratch). Body writes straight to slot_off(BP).
// - else (e.g. "BX" for *struct field, top-level struct LEAQ
// base): pointer-rooted dst. cgexpr inside trashes every GPR,
// so we route through a fresh BP-rooted scratch slot, spill
// basereg before the body, reload after, then word-copy
// scratch → (basereg, slot_off).
//
// Branches by source shape:
// - nullable dst (8B slot): cgexpr → AX → slot+0.
// - tagged src ident: copy slot words, zero-pad, tag-remap.
// - tagged src via AX/DX/CX ABI (call / tagged-arr index): cgexpr,
@@ -7646,7 +7665,53 @@ fn rhstaggedabicall(c: *cgen, src: *node) bool = {
// tag last.
// - str src: tag@+0, ptr@+8, len@+16.
// - scalar src: tag@+0, value@+8.
fn cgwidentaggedstore(c: *cgen, dst: *node, src: *node, slot_off: i32, slot_sz: i32) void = {
fn cgwidentaggedstore(c: *cgen, dst: *node, src: *node,
basereg: str, slot_off: i32, slot_sz: i32) void = {
if (streq(basereg, "BP")) {
cgwidentaggedstorebp(c, dst, src, slot_off, slot_sz);
return;
};
// Pointer-rooted dst: spill basereg (cgexpr will trash it),
// materialise into a BP-rooted scratch via the BP path, then
// reload basereg and word-copy scratch → caller's slot.
let bspill: i32 = localadd(c, "@tagbase", 8, nil);
emitline("\tMOVQ\t");
emitline(basereg);
emitline(", ");
emitoff(bspill: i64);
emitline("(BP)\n");
let scr: i32 = localadd(c, "@tagscr", slot_sz, nil);
emitline("\tXORQ\tAX, AX\n");
let z: i32 = 0;
for (z < slot_sz) {
emitline("\tMOVQ\tAX, ");
emitoff((scr + z): i64);
emitline("(BP)\n");
z += 8;
};
cgwidentaggedstorebp(c, dst, src, scr, slot_sz);
emitline("\tMOVQ\t");
emitoff(bspill: i64);
emitline("(BP), ");
emitline(basereg);
emitline("\n");
let k: i32 = 0;
for (k < slot_sz) {
emitline("\tMOVQ\t");
emitoff((scr + k): i64);
emitline("(BP), AX\n");
emitline("\tMOVQ\tAX, ");
emitdispreg((slot_off + k): i64, basereg);
emitline("\n");
k += 8;
};
};
// cgwidentaggedstorebp — BP-rooted body. Called via cgwidentaggedstore
// for the natural "BP" case and via the wrapper's scratch path for
// pointer-rooted dst. Direct callers exist only in case of future
// inlined uses inside this file; new code should call the wrapper.
fn cgwidentaggedstorebp(c: *cgen, dst: *node, src: *node, slot_off: i32, slot_sz: i32) void = {
let dt: *node = resolvetagged(c, dst);
if (dt == nil) { return; };
// Nullable fold: one 8B word holding the pointer (or 0 for void).
@@ -10793,7 +10858,7 @@ fn cgcall(c: *cgen, n: *node) void = {
let slot: i32 = doff + j * esz;
if (velemtagged) {
cgwidentaggedstore(c, varp.lhs,
aa2, slot, esz);
aa2, "BP", slot, esz);
} else { if (velemstr) {
cgexpr(c, aa2);
emitline("\tMOVQ\tAX, ");
@@ -11049,7 +11114,7 @@ fn cgassign(c: *cgen, n: *node) void = {
if (istaggedtype(c, lc.tnode)) {
let lsz: i32 = slotsize(c, lc.tnode);
cgwidentaggedstore(c, lc.tnode,
n.rhs, lc.off, lsz);
n.rhs, "BP", lc.off, lsz);
return;
};
};
@@ -11273,7 +11338,7 @@ fn cgassign(c: *cgen, n: *node) void = {
zz += 8;
};
cgwidentaggedstore(c, elemtn, n.rhs,
scroff, slot_sz);
"BP", scroff, slot_sz);
cgexpr(c, idx);
if (slot_sz > 1) {
emitline("\tMOVQ\t$");
@@ -11619,6 +11684,20 @@ fn cgassign(c: *cgen, n: *node) void = {
for (fi != nil) {
let fn_: str = fi.fname;
if (streq(fn_, fld)) {
// Tagged-union field via *struct base — full slot
// rewrite via cgwidentaggedstore basereg="BX". Pre-#26
// fell through to the scalar store and dropped tag
// + payload.
if (n.op == tkind.TK_ASSIGN
&& istaggedtype(c, fi.tnode)) {
let fsz: i32 = slotsize(c, fi.tnode);
emitline("\tMOVQ\t");
emitoff(lc.off: i64);
emitline("(BP), BX\n");
cgwidentaggedstore(c, fi.tnode,
n.rhs, "BX", fi.foff, fsz);
return;
};
// struct-typed field, struct-ident rhs through
// *struct base: cgexpr can't materialise a whole
// struct value, so word-copy from the rhs slot
@@ -11769,6 +11848,17 @@ fn cgassign(c: *cgen, n: *node) void = {
for (fi != nil) {
let fn_: str = fi.fname;
if (streq(fn_, fld)) {
// Tagged-union field in a direct struct local —
// full slot rewrite at (lc.off + fi.foff)(BP)
// via cgwidentaggedstore basereg="BP". Pre-#26
// fell through and dropped tag + payload.
if (n.op == tkind.TK_ASSIGN
&& istaggedtype(c, fi.tnode)) {
let fsz: i32 = slotsize(c, fi.tnode);
cgwidentaggedstore(c, fi.tnode,
n.rhs, "BP", lc.off + fi.foff, fsz);
return;
};
// struct-typed field, struct-ident rhs:
// word-copy direct, skipping cgexpr (no
// register convention for a whole struct
@@ -12978,8 +13068,8 @@ fn cgreturn(c: *cgen, n: *node) void = {
emitline("(BP)\n");
zz += 8;
};
cgwidentaggedstore(c, c.fnret, rhs, scroff,
rsz);
cgwidentaggedstore(c, c.fnret, rhs, "BP",
scroff, rsz);
emitline("\tMOVQ\t");
emitoff(scroff: i64);
emitline("(BP), AX\n");
@@ -13101,7 +13191,7 @@ fn cglet(c: *cgen, n: *node) void = {
// 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, off, sz);
cgwidentaggedstore(c, tn, rhs, "BP", off, sz);
c.lastwasreturn = 0;
return;
};
@@ -14118,6 +14208,61 @@ fn scanlocals(c: *cgen, n: *node) i32 = {
};
};
};
// 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) and @tagscr (slot_sz). Both names
// dedup with other tagged scratch users in the same function.
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;
};
if (!scanseenmark(c, "@tagscr")) {
total += 24;
};
};
};
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. Detect via the same rhsstructpayload predicate