Hojun-Cho
23670d7c4e
Indexing a GLOBAL `str` or GLOBAL slice (`s[i]` / `g[i]` where s/g are
module-level lets) read a wide {ptr,len,cap} header with an 8-byte stride
and a full-word MOVQ load instead of the .ptr + element-width load. So
`s[1]` over a global str read 8 bytes at ptr+8 rather than the single byte
at ptr+1 (cstage emits MOVZBQ). LOCAL str/slice index was already clean.
Root: wwstage cgindex (selfhost/cmd/wcc/cgenexpr.ww) dispatched the element
size + base-materialisation off the base tnode KIND, enumerating only
N_TARRAY (global `[N]T`) and N_TPTR (global `*T`). A global str (tnode
N_TNAME "str") and a global slice (N_TSLICE) matched NEITHER arm, so esz
stayed at the default 8 and the base fell through to the wide-header
fallback. cstage `case N_INDEX:` (cmd/w6c/cgen.c) dispatches esz off the
RESOLVED base type (`idx_eff(lhs->type)->sub->size`), uniform across
local/global/str/slice/ptr.
Fix aligns cgindex's global-resolution arm UP to cstage's uniform type-
driven dispatch — the same template the sister fn cgslice already uses:
resolve esz via elemsizeofc(c, tn) with no kind gate, then drive the base
load by tn.kind == N_TARRAY ? LEAQ : MOVQ name(SB). A global str/slice now
resolves esz=1 off the type table (elemsizeofc, just fixed in #8 to read
stamped tinfo) and routes through the EXISTING isglobalptr emission
(MOVQ name(SB),BX; ADDQ; MOVZBQ (BX),AX) — byte-identical to cstage. The
element-kind flags (elemisstr/elemisslice) for a global `[]str`/`[][]u8`
element are still set by the downstream block, so those route to cgslicehdr
unchanged.
Close-by-construction: cgindex's one global-ident resolution arm is the
single site computing a global element base for the read-index path (the
&arr[i] address-of in cgun and the arr[i]=v store in cgassign are separate
node paths, out of scope). Any indexable global base now resolves esz off
the type table, exactly like cstage and like cgslice.
combined.ww embeds regenerate (w6c + wwdump). New 803_globalidx_run pins
runtime (cstage build+run) + cs==ww byte-id across global str index
(positions 0/1/2 + sum), global slice index (TEXT-only byte-id — a bare
`let g: []u8;` decl emits a divergent zero-header DATAW orthogonal to the
index read, the #7/#18 static-init family), and local str/slice/array
index regression pins. A stride-8 regression re-fails the 5 global rows.