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wcc: cstage array-init dispatches MOVW for esz==2 (#128a)

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cstage cgen.c array-literal init dispatch now uses MOVW for esz==2
(u16/i16 element width). Was deferred (cgen.c:7194-7198 explicit
TODO: "Add MOVW to w6a if real i16 arrays land") until A_MOVW
landed in both stages' w6a; that prereq is now met. Fixes silent
partial-init clobber where MOVQ writes 8B over a 2B slot,
overwriting neighbouring elements/locals.

Wwstage was already correct (selfhost/cmd/wcc/cgenutil.ww:872-877
emits MOVW for sz==2 in tnodestoreop) — cstage aligns UP to
wwstage's correctness here, a rule-10 inversion from the usual
align-richer-DOWN.

Test 914 (4 rows: u16 full-init, u16 small-values, u8 control,
i16 signed) catches the bug via the rule-10 cs==ww byte-id gate.
Runtime is not a reliable lever — ww rejects truly-partial inits,
and fully-init [N]u16 accident-corrects via MOVQ-overlap (each
write rewrote the prior write's trailing 6B). Reviewer non-vacuity:
stash the fix → 3/4 rows fail on byte-id, restore → 4/4 green.

Bootstrap NEUTRAL: 990-997 byte-id + combined_ww_fresh green; zero
pre-existing partial-init narrow-element callers in lib/+selfhost/.
strconv stof_data tables emit DATAW (raw bytes) and bypass this
path, which is why fold-2 landed clean despite the bug.

Sibling bugs filed for backlog (reviewer-128a flag-don't-bundle per
rule-11): #141 (cgen.c:4894-4898 variadic-gather array-store has
the same dispatch gap) and #142 (wwstage cgenstmt.ww:976-990
primsize(elemn.str) returns 0 for TY_NAMED alias names → wrong-
stride store on [N]alias-of-u16; cstage already TY_NAMED-peeled).
This commit is contained in:
Hojun-Cho
2026-05-27 02:32:31 +09:00
parent 684f59c48c
commit 7230f3aa61
3 changed files with 234 additions and 5 deletions
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6
Makefile
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@@ -336,6 +336,7 @@ TESTS = $(BIN)/test_smoke $(BIN)/test_lex $(BIN)/test_parse $(BIN)/test_check \
$(BIN)/test_continue_run \
$(BIN)/test_sar_shr_run \
$(BIN)/test_def_mangle_run \
$(BIN)/test_arr_u16_store_run \
$(BIN)/test_f64cgen_run \
$(BIN)/test_f64crossmod_run \
$(BIN)/test_tuprecv_run \
@@ -1129,6 +1130,11 @@ $(BIN)/test_def_mangle_run: test/wcc/913_def_mangle_run.c $(BIN)/ww \
$(LIB)/libwwrt.a | $(BIN)
$(CC) $(CFLAGS) -o $@ $<
$(BIN)/test_arr_u16_store_run: test/wcc/914_arr_u16_store_run.c $(BIN)/ww \
$(BIN)/w6c $(BIN)/w6c_ww $(BIN)/w6a $(BIN)/w6l \
$(LIB)/libwwrt.a | $(BIN)
$(CC) $(CFLAGS) -o $@ $<
$(BIN)/test_f64cgen_run: test/wcc/951_f64cgen_run.c $(BIN)/ww $(BIN)/w6c \
$(BIN)/w6a $(BIN)/w6l $(LIB)/libwwrt.a | $(BIN)
$(CC) $(CFLAGS) -o $@ $<