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wcc: continue runs post-step in 3-clause for and range form (#138)

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`for (init; cond; post) { ... continue; ... }` and `for (let i .. xs)
{ ... continue; ... }` now emit a `post` (3-clause) or `rpost` (range)
label between the body and the JMP back to the cond-test. `continue`
jumps to that label, runs the post-step, then re-tests the loop
condition — mirrors C/Go/Hare semantics. Pre-fix both stages emitted
`JMP loop_top` for continue, SKIPPING the post-step → the value that
triggered continue never advanced → silent infinite loop on the first
matching iteration. Found by impl-strconv-fold2 during the fold-3
decimal.ha port: `leftshift_newdigits`'s `for (... i+=1) { ... else
if (d.digits[i]==p5[i]) continue; ... }` would infinite-loop at the
first equal digit.

BOTH stages were identically buggy → 990-997 cs==ww byte-id held →
gate-blind. Bootstrap audit (`grep -rE 'for \(let .*\.\.' lib/
selfhost/`) confirmed zero existing callers with continue in either
the 3-clause or range form; bootstrap-NEUTRAL.

Sites: cmd/w6c/cgen.c N_FOR + N_FORRANGE; selfhost/cmd/wcc/
cgenstmt.ww cgfor + cgforrange. 1-clause `for (cond)` byte-id
preserved (cont_target stays = loop_top when n.rhs == nil). Rule-11
carve-out: 3-clause and range share the lowered structure; fixing
one without the other would leave the same silent miscompile in
N_FORRANGE — one-class closure on the continue-skips-post bug, same
precedent as #133-expanded.

911_continue_run: 4 rows. for3_skip_one (lead's repro, was infinite
loop, now 4), for3_skip_two (nested continues, 30), range_skip
(Hare-range continue, was infinite loop, now 120), for1_continue_
byteid (1-clause regression assertion — bootstrap shape unchanged).
Pre-existing parser-side divergences (cstage silently drops post in
the never-used 2-clause `for (cond; post)`; wwstage doesn't support
infinite `for {}`) deferred to #139 — not in decimal.ha, no shared
class with the cgen continue-skips-post.
This commit is contained in:
Hojun-Cho
2026-05-27 00:12:39 +09:00
parent ade6840610
commit d960971c6e
6 changed files with 316 additions and 12 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
Makefile
View File

@@ -332,6 +332,7 @@ TESTS = $(BIN)/test_smoke $(BIN)/test_lex $(BIN)/test_parse $(BIN)/test_check \
$(BIN)/test_deref_narrow_run \
$(BIN)/test_idx_compound_run \
$(BIN)/test_dotbase_arr_run \
$(BIN)/test_continue_run \
$(BIN)/test_f64cgen_run \
$(BIN)/test_f64crossmod_run \
$(BIN)/test_tuprecv_run \
@@ -1106,6 +1107,11 @@ $(BIN)/test_dotbase_arr_run: test/wcc/949_dotbase_arr_run.c $(BIN)/ww \
$(LIB)/libwwrt.a | $(BIN)
$(CC) $(CFLAGS) -o $@ $<
$(BIN)/test_continue_run: test/wcc/911_continue_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 $@ $<

25
cmd/w6c/cgen.c
View File

@@ -7812,8 +7812,15 @@ cgstmt(Cg *c, Node *n, Local **locals, int *frame)
char *end = mklabel(c, "rend");
char *natural_exit = end;
if (n->els) natural_exit = mklabel(c, "relseloop");
/* #138 (range form): `continue` must run the implicit `i+=1`
* post-step before re-testing the loop bound. Pre-fix the
* cont-target was `loop` (top), skipping the ADDQ $1, ioff
* below the body — infinite loop on the value that triggered
* continue. Dedicated `rpost` label; bootstrap-NEUTRAL (no
* range-form continue callers in lib/ or selfhost/). */
char *rpost = mklabel(c, "rpost");
if (nloops < LOOP_MAX) {
loop_cont[nloops] = loop;
loop_cont[nloops] = rpost;
loop_brk[nloops] = end;
nloops++;
}
@@ -7842,6 +7849,7 @@ cgstmt(Cg *c, Node *n, Local **locals, int *frame)
ins2(c, A_MOVQ, areg(D_AX), amem(D_BP, binds[b].off));
}
cgstmt(c, n->body, locals, frame);
label(c, rpost);
ins2(c, A_ADDQ, aimm(1), amem(D_BP, ioff));
ins1(c, A_JMP, abranch(loop));
if (n->els) {
@@ -7860,6 +7868,14 @@ cgstmt(Cg *c, Node *n, Local **locals, int *frame)
* the else block sits between them. */
char *natural_exit = end;
if (n->els) natural_exit = mklabel(c, "elseloop");
/* #138: `continue` in a 3-clause `for (init; cond; post)` must
* run the post-step before re-testing cond. Pre-fix the
* continue-target was `loop` (top), which SKIPPED post → state
* never advanced → infinite loop. Allocate a dedicated `post`
* label only when there IS a post-step (`n->rhs`); else keep
* continue → loop-top, byte-id with 1-clause for. */
char *cont_target = loop;
if (n->rhs) cont_target = mklabel(c, "post");
if (n->lhs) cgstmt(c, n->lhs, locals, frame);
label(c, loop);
if (n->cond) {
@@ -7868,13 +7884,16 @@ cgstmt(Cg *c, Node *n, Local **locals, int *frame)
ins1(c, A_JE, abranch(natural_exit));
}
if (nloops < LOOP_MAX) {
loop_cont[nloops] = loop;
loop_cont[nloops] = cont_target;
loop_brk[nloops] = end;
nloops++;
}
cgstmt(c, n->body, locals, frame);
if (nloops > 0) nloops--;
if (n->rhs) cgexpr(c, n->rhs, *locals);
if (n->rhs) {
label(c, cont_target);
cgexpr(c, n->rhs, *locals);
}
ins1(c, A_JMP, abranch(loop));
if (n->els) {
label(c, natural_exit);

23
selfhost/cmd/w6c/main.combined.ww
View File

@@ -22365,6 +22365,14 @@ fn cgfor(c: *cgen, n: *node) void = {
// label so the else body sits between it and the break target.
let naturall: str = endl;
if (n.els != nil) { naturall = mklabel(c, "elseloop"); };
// #138: `continue` in a 3-clause `for (init; cond; post)` must
// run the post-step before re-testing cond. Pre-fix the continue-
// target was `topl`, which SKIPPED the post-step → state never
// advanced → infinite loop. Allocate a dedicated `post` label
// only when there IS a post-step (`n.rhs != nil`); else keep
// continue → loop-top, byte-id with 1-clause for.
let conttgt: str = topl;
if (n.rhs != nil) { conttgt = mklabel(c, "post"); };
if (n.lhs != nil) { cgstmt(c, n.lhs); };
@@ -22376,14 +22384,17 @@ fn cgfor(c: *cgen, n: *node) void = {
};
c.loopendbuf[c.looptop] = endl;
c.loopcontbuf[c.looptop] = topl;
c.loopcontbuf[c.looptop] = conttgt;
c.looptop += 1;
if (n.body != nil) { cgstmt(c, n.body); };
c.looptop -= 1;
if (n.rhs != nil) { cgexpr(c, n.rhs); };
if (n.rhs != nil) {
emitlabel(conttgt);
cgexpr(c, n.rhs);
};
emitline("\tJMP\t"); emitline(topl); emitline("\n");
if (n.els != nil) {
emitlabel(naturall);
@@ -22738,8 +22749,13 @@ fn cgforrange(c: *cgen, n: *node) void = {
let endl: str = mklabel(c, "rend");
let naturall: str = endl;
if (n.els != nil) { naturall = mklabel(c, "relseloop"); };
// #138 (range form): `continue` must run the implicit `i+=1`
// post-step before re-testing the bound. Pre-fix cont = loopl
// (top), skipping the ADDQ $1, ioff below — infinite loop on
// the value that triggered continue. Dedicated `rpost` label.
let rpost: str = mklabel(c, "rpost");
c.loopcontbuf[c.looptop] = loopl;
c.loopcontbuf[c.looptop] = rpost;
c.loopendbuf[c.looptop] = endl;
c.looptop += 1;
@@ -22796,6 +22812,7 @@ fn cgforrange(c: *cgen, n: *node) void = {
c.looptop -= 1;
emitlabel(rpost);
emitline("\tADDQ\t$1, ");
emitoff(ioff: i64);
emitline("(BP)\n");

23
selfhost/cmd/wcc/cgenstmt.ww
View File

@@ -1362,6 +1362,14 @@ fn cgfor(c: *cgen, n: *node) void = {
// label so the else body sits between it and the break target.
let naturall: str = endl;
if (n.els != nil) { naturall = mklabel(c, "elseloop"); };
// #138: `continue` in a 3-clause `for (init; cond; post)` must
// run the post-step before re-testing cond. Pre-fix the continue-
// target was `topl`, which SKIPPED the post-step → state never
// advanced → infinite loop. Allocate a dedicated `post` label
// only when there IS a post-step (`n.rhs != nil`); else keep
// continue → loop-top, byte-id with 1-clause for.
let conttgt: str = topl;
if (n.rhs != nil) { conttgt = mklabel(c, "post"); };
if (n.lhs != nil) { cgstmt(c, n.lhs); };
@@ -1373,14 +1381,17 @@ fn cgfor(c: *cgen, n: *node) void = {
};
c.loopendbuf[c.looptop] = endl;
c.loopcontbuf[c.looptop] = topl;
c.loopcontbuf[c.looptop] = conttgt;
c.looptop += 1;
if (n.body != nil) { cgstmt(c, n.body); };
c.looptop -= 1;
if (n.rhs != nil) { cgexpr(c, n.rhs); };
if (n.rhs != nil) {
emitlabel(conttgt);
cgexpr(c, n.rhs);
};
emitline("\tJMP\t"); emitline(topl); emitline("\n");
if (n.els != nil) {
emitlabel(naturall);
@@ -1735,8 +1746,13 @@ fn cgforrange(c: *cgen, n: *node) void = {
let endl: str = mklabel(c, "rend");
let naturall: str = endl;
if (n.els != nil) { naturall = mklabel(c, "relseloop"); };
// #138 (range form): `continue` must run the implicit `i+=1`
// post-step before re-testing the bound. Pre-fix cont = loopl
// (top), skipping the ADDQ $1, ioff below — infinite loop on
// the value that triggered continue. Dedicated `rpost` label.
let rpost: str = mklabel(c, "rpost");
c.loopcontbuf[c.looptop] = loopl;
c.loopcontbuf[c.looptop] = rpost;
c.loopendbuf[c.looptop] = endl;
c.looptop += 1;
@@ -1793,6 +1809,7 @@ fn cgforrange(c: *cgen, n: *node) void = {
c.looptop -= 1;
emitlabel(rpost);
emitline("\tADDQ\t$1, ");
emitoff(ioff: i64);
emitline("(BP)\n");

23
selfhost/cmd/wwdump/main.combined.ww
View File

@@ -22365,6 +22365,14 @@ fn cgfor(c: *cgen, n: *node) void = {
// label so the else body sits between it and the break target.
let naturall: str = endl;
if (n.els != nil) { naturall = mklabel(c, "elseloop"); };
// #138: `continue` in a 3-clause `for (init; cond; post)` must
// run the post-step before re-testing cond. Pre-fix the continue-
// target was `topl`, which SKIPPED the post-step → state never
// advanced → infinite loop. Allocate a dedicated `post` label
// only when there IS a post-step (`n.rhs != nil`); else keep
// continue → loop-top, byte-id with 1-clause for.
let conttgt: str = topl;
if (n.rhs != nil) { conttgt = mklabel(c, "post"); };
if (n.lhs != nil) { cgstmt(c, n.lhs); };
@@ -22376,14 +22384,17 @@ fn cgfor(c: *cgen, n: *node) void = {
};
c.loopendbuf[c.looptop] = endl;
c.loopcontbuf[c.looptop] = topl;
c.loopcontbuf[c.looptop] = conttgt;
c.looptop += 1;
if (n.body != nil) { cgstmt(c, n.body); };
c.looptop -= 1;
if (n.rhs != nil) { cgexpr(c, n.rhs); };
if (n.rhs != nil) {
emitlabel(conttgt);
cgexpr(c, n.rhs);
};
emitline("\tJMP\t"); emitline(topl); emitline("\n");
if (n.els != nil) {
emitlabel(naturall);
@@ -22738,8 +22749,13 @@ fn cgforrange(c: *cgen, n: *node) void = {
let endl: str = mklabel(c, "rend");
let naturall: str = endl;
if (n.els != nil) { naturall = mklabel(c, "relseloop"); };
// #138 (range form): `continue` must run the implicit `i+=1`
// post-step before re-testing the bound. Pre-fix cont = loopl
// (top), skipping the ADDQ $1, ioff below — infinite loop on
// the value that triggered continue. Dedicated `rpost` label.
let rpost: str = mklabel(c, "rpost");
c.loopcontbuf[c.looptop] = loopl;
c.loopcontbuf[c.looptop] = rpost;
c.loopendbuf[c.looptop] = endl;
c.looptop += 1;
@@ -22796,6 +22812,7 @@ fn cgforrange(c: *cgen, n: *node) void = {
c.looptop -= 1;
emitlabel(rpost);
emitline("\tADDQ\t$1, ");
emitoff(ioff: i64);
emitline("(BP)\n");

228
test/wcc/911_continue_run.c Normal file
View File

@@ -0,0 +1,228 @@
/*
* 911_continue_run — runtime + byte-id net for #138: `continue` in a
* loop with a post-step (3-clause C-style `for (init; cond; post)` OR
* Hare-range `for (let x .. xs)` with its implicit `i+=1`) must run
* the post-step BEFORE re-testing the cond / bound. Pre-fix the
* continue-target was the loop top, which SKIPPED the post-step → the
* value that triggered continue never advanced → infinite loop.
*
* Pre-fix BOTH STAGES emitted identical buggy asm (`JMP loop_top` for
* continue, post-step JMP'd over) — cs==ww byte-id held → 990-997 gate
* was BLIND to the miscompile. Found by impl-strconv-fold2 during the
* fold-3 decimal.ha port: leftshift_newdigits uses `for (let i: u32 =
* 0u32; i < n; i += 1u32) { ... else if (d.digits[i]==p5[i]) continue;
* ... }`; pre-fix that path infinite-looped at the first equal digit.
*
* Fix (both stages): allocate a dedicated `post` (3-clause) / `rpost`
* (range) label; continue jumps to that label; the label emits before
* the post-step; fall-through naturally hits it too. For 1-clause `for
* (cond)` with no post-step, the cont-target stays = loop-top
* (unchanged from pre-#138, byte-id preserved on the corpus's
* 1-clause shape).
*
* Rows cover the 3 shapes the fix targets PLUS a 1-clause regression
* row asserting the byte-id surface for the 1-clause path is
* unchanged. cstage `ww build` + run for runtime; w6c vs w6c_ww `.s`
* cmp for rule-10 byte-id.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/wait.h>
static int
runwait(const char *cmd)
{
int rc = system(cmd);
if (rc == -1) return -1;
if (WIFEXITED(rc)) return WEXITSTATUS(rc);
return -1;
}
struct row { const char *label; const char *src; int want_exit; };
static const struct row rows[] = {
/* The lead's repro: 3-clause for with continue. Pre-fix infinite
* loop on i=2; post-fix count=4 (i=0,1,3,4 all increment count). */
{ "for3_skip_one",
"package main;\n"
"export fn main() i32 = {\n"
" let count: i32 = 0;\n"
" for (let i: i32 = 0; i < 5; i += 1) {\n"
" if (i == 2) { continue; };\n"
" count += 1;\n"
" };\n"
" return count;\n"
"};\n", 4 },
/* Two skips: continue must advance i correctly each time. count
* over i=0,2,4 only (skip 1 and 3); 3 hits × 10 = 30. */
{ "for3_skip_two",
"package main;\n"
"export fn main() i32 = {\n"
" let c: i32 = 0;\n"
" for (let i: i32 = 0; i < 5; i += 1) {\n"
" if (i == 1) { continue; };\n"
" if (i == 3) { continue; };\n"
" c += 10;\n"
" };\n"
" return c;\n"
"};\n", 30 },
/* Hare-range form `for (let x .. xs)`. Continue must run the
* implicit `i+=1` increment. Pre-fix infinite-loop on first
* matching element; post-fix sum over non-skipped values. xs =
* [10, 20, 30, 40, 50]; skip 30; sum = 10+20+40+50 = 120. */
{ "range_skip",
"package main;\n"
"export fn main() i32 = {\n"
" let xs: [5]i32 = [10, 20, 30, 40, 50];\n"
" let sum: i32 = 0;\n"
" for (let v .. xs) {\n"
" if (v == 30) { continue; };\n"
" sum += v;\n"
" };\n"
" return sum;\n"
"};\n", 120 },
/* 1-clause `for (cond)` with continue. No post-step, so cont-
* target stays = loop-top. Pre-#138 emission must be byte-id
* preserved — this is the bootstrap shape. Manual post-step
* inside the body. count over i=0,1,3,4 (skip i=2) → 4. */
{ "for1_continue_byteid",
"package main;\n"
"export fn main() i32 = {\n"
" let count: i32 = 0;\n"
" let i: i32 = 0;\n"
" for (i < 5) {\n"
" let cur: i32 = i;\n"
" i += 1;\n"
" if (cur == 2) { continue; };\n"
" count += 1;\n"
" };\n"
" return count;\n"
"};\n", 4 },
{ NULL, NULL, 0 }
};
static int
slurp_eq(const char *a, const char *b)
{
FILE *fa = fopen(a, "rb");
FILE *fb = fopen(b, "rb");
if (!fa || !fb) { if (fa) fclose(fa); if (fb) fclose(fb); return -1; }
int rc = 0;
for (;;) {
int ca = fgetc(fa);
int cb = fgetc(fb);
if (ca != cb) { rc = -1; break; }
if (ca == EOF) break;
}
fclose(fa); fclose(fb);
return rc;
}
int
main(void)
{
const char *bin = getenv("BIN");
if (!bin) bin = "out/bin";
char absbin[1024];
if (bin[0] != '/') {
char cwd[1024];
if (getcwd(cwd, sizeof cwd) == NULL) return 1;
snprintf(absbin, sizeof absbin, "%s/%s", cwd, bin);
bin = absbin;
}
char w6c[1100], w6c_ww[1100];
snprintf(w6c, sizeof w6c, "%s/w6c", bin);
snprintf(w6c_ww, sizeof w6c_ww, "%s/w6c_ww", bin);
if (access(w6c_ww, X_OK) != 0) {
fprintf(stderr, "continue: w6c_ww missing — cannot run the "
"cs==ww byte-id gate (the whole point of this test)\n");
return 1;
}
int n = 0, fail = 0;
for (int i = 0; rows[i].src; i++, n++) {
char src[64];
snprintf(src, sizeof src, "/tmp/wwcont_%d_%d.ww", getpid(), i);
FILE *f = fopen(src, "wb");
if (f == NULL) { fail++; continue; }
fputs(rows[i].src, f);
fclose(f);
char tmpdir[64];
snprintf(tmpdir, sizeof tmpdir, "/tmp/wwcont_%d_d_%d",
getpid(), i);
mkdir(tmpdir, 0755);
/* Build with 5s timeout — pre-fix the buggy rows infinite-
* looped; post-fix all rows must exit cleanly under it. */
char cmd[2048];
snprintf(cmd, sizeof cmd, "cd %s && %s/ww build %s",
tmpdir, bin, src);
if (runwait(cmd) != 0) {
fprintf(stderr, "row[%s]: cstage build failed\n",
rows[i].label);
fail++;
unlink(src); rmdir(tmpdir);
continue;
}
char outbin[128];
const char *base = strrchr(src, '/');
base = base ? base + 1 : src;
snprintf(outbin, sizeof outbin, "%s/%s", tmpdir, base);
char *dot = strrchr(outbin, '.');
if (dot && strcmp(dot, ".ww") == 0) *dot = '\0';
/* timeout wrapper: pre-fix bug = infinite loop; want clean
* exit. exit 124 = timeout/hang. */
char rcmd[256];
snprintf(rcmd, sizeof rcmd, "timeout 5 %s", outbin);
int got = runwait(rcmd);
if (got != rows[i].want_exit) {
fprintf(stderr, "row[%s]: cstage exit %d, want %d "
"(124 = timeout / pre-fix infinite loop)\n",
rows[i].label, got, rows[i].want_exit);
fail++;
}
unlink(outbin); rmdir(tmpdir);
char cs_s[64], ws_s[64];
snprintf(cs_s, sizeof cs_s, "/tmp/wwcont_%d_%d_cs.s",
getpid(), i);
snprintf(ws_s, sizeof ws_s, "/tmp/wwcont_%d_%d_ww.s",
getpid(), i);
snprintf(cmd, sizeof cmd, "%s -o %s %s 2>/dev/null",
w6c, cs_s, src);
if (runwait(cmd) != 0) {
fprintf(stderr, "row[%s]: w6c failed\n", rows[i].label);
fail++; unlink(src); continue;
}
snprintf(cmd, sizeof cmd, "%s -o %s %s 2>/dev/null",
w6c_ww, ws_s, src);
if (runwait(cmd) != 0) {
fprintf(stderr, "row[%s]: w6c_ww failed\n",
rows[i].label);
fail++; unlink(src); unlink(cs_s); continue;
}
if (slurp_eq(cs_s, ws_s) != 0) {
fprintf(stderr,
"row[%s]: cstage/wwstage .s DIFFER (rule-10 "
"byte-id violation)\n", rows[i].label);
fail++;
}
unlink(src); unlink(cs_s); unlink(ws_s);
}
if (fail) {
fprintf(stderr, "%d/%d continue tests failed\n", fail, n);
return 1;
}
printf("continue: %d/%d ok (cstage run + cs==ww byte-id)\n",
n, n);
return 0;
}