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selfhost: fix 4B array load/store width + 8B uninit zero-init

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Hojun-Cho
2026-05-12 16:30:24 +09:00
parent e087c843e9
commit 67eaa9796a
6 changed files with 279 additions and 141 deletions
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66
selfhost/cmd/wcc/cgenstmt.ww
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@@ -504,13 +504,11 @@ fn cglet(c: *cgen, n: *node) void = {
};
} else {
// Bare `let x: T;` with no initializer. C cgen
// (cmd/w6c/cgen.c:2181-2183) zero-inits only when
// the underlying type's natural size is 8 — pointers,
// i64/u64, function pointers, ints. Structs/arrays/
// slices/strings/tagged/tuples are left for per-field
// writes. ww's slotsize pads struct slots up to 8,
// so we can't just check sz == 8: walk the type AST
// directly to make the same call.
// (cmd/w6c/cgen.c:3317) zero-inits whenever the raw type size
// is 8: scalar primitives, pointers, fn/chan handles, plus 8B
// composites like `[8]bool`, `[2]i32`, `[4]i16`, `[1]i64`.
// Larger composites and `[N]T` with size != 8 are left for
// per-field writes.
if (typeis8byteprimitive(c, n.lhs)) {
emitline("\tMOVQ\t$0, ");
emitoff(off: i64);
@@ -799,15 +797,12 @@ fn cgforrange(c: *cgen, n: *node) void = {
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 i64 arrays
// keep every elem at 8B so the indexed-store hits the working MOVQ
// path (selfhost cgen doesn't yet emit MOVL for i32-array writes,
// and doesn't zero-init `[8]bool` uninit slots — both byte-diverge
// from C w6c on the wwstage rebuild).
let bind_off: [8]i64;
let bind_sz: [8]i64;
let bind_foff: [8]i64;
let bind_signed: [8]i64; // 0 / 1
// 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) {
@@ -828,15 +823,14 @@ fn cgforrange(c: *cgen, n: *node) void = {
};
let slot_sz: i32 = fsz;
if (slot_sz < 8) { slot_sz = 8; };
bind_sz[nbinds] = fsz: i64;
bind_foff[nbinds] = field_off: i64;
if (signf) { bind_signed[nbinds] = 1i64; }
else { bind_signed[nbinds] = 0i64; };
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, nil): i64;
bind_off[nbinds] = localadd(c, bnm, slot_sz, nil);
} else {
bind_off[nbinds] = localalloc(c, mkscratchname(c, "fr"), slot_sz, nil): i64;
bind_off[nbinds] = localalloc(c, mkscratchname(c, "fr"), slot_sz, nil);
};
field_off += fsz;
nbinds += 1;
@@ -847,18 +841,18 @@ fn cgforrange(c: *cgen, n: *node) void = {
} else {
let slot_sz: i32 = esz;
if (slot_sz < 8) { slot_sz = 8; };
bind_sz[0] = esz: i64;
bind_foff[0] = 0i64;
bind_sz[0] = esz;
bind_foff[0] = 0;
// Single-binding signed-narrow detection: mirror C which
// reads `u->sub->kind` for the elem type.
let signf0: bool = false;
if (elemt != nil) { signf0 = paramissigned(elemt); };
if (signf0) { bind_signed[0] = 1i64; }
else { bind_signed[0] = 0i64; };
bind_signed[0] = false;
if (elemt != nil) {
bind_signed[0] = paramissigned(elemt);
};
if (n.str.len > 0) {
bind_off[0] = localadd(c, n.str, slot_sz, nil): i64;
bind_off[0] = localadd(c, n.str, slot_sz, nil);
} else {
bind_off[0] = localalloc(c, mkscratchname(c, "fr"), slot_sz, nil): i64;
bind_off[0] = localalloc(c, mkscratchname(c, "fr"), slot_sz, nil);
};
nbinds = 1;
};
@@ -952,18 +946,18 @@ fn cgforrange(c: *cgen, n: *node) void = {
let b: i32 = 0;
for (b < nbinds) {
let op: str = "MOVQ";
if (bind_sz[b] == 1i64) { op = "MOVZBQ"; }
else { if (bind_sz[b] == 4i64) {
if (bind_signed[b] != 0i64) { op = "MOVSXD"; }
else { op = "MOVL"; };
if (bind_sz[b] == 1) { op = "MOVZBQ"; }
else { if (bind_sz[b] == 4) {
if (bind_signed[b]) { op = "MOVSXD"; }
else { op = "MOVL"; };
};};
emitline("\t");
emitline(op);
emitline("\t");
emitoff(bind_foff[b]);
emitoff(bind_foff[b]: i64);
emitline("(BX), AX\n");
emitline("\tMOVQ\tAX, ");
emitoff(bind_off[b]);
emitoff(bind_off[b]: i64);
emitline("(BP)\n");
b += 1;
};