w6c: global *struct base field store loads the pointer from g(SB)

cstage dereferenced 0(BP) for the base — a SEGV on every store
through a module-global struct pointer; wwstage was already correct
(the inverse-set member). Mirror ww's global-pointer load. New
989_globptrfield_run pins cs==ww both stages. Task #47.
This commit is contained in:
2026-06-12 22:48:37 +09:00
parent e09a8c1775
commit 77747061c6
3 changed files with 179 additions and 1 deletions

View File

@@ -0,0 +1,146 @@
/*
* 989_globptrfield_run — inverse-set cstage fix (report-item [58], ww correct):
* a field store through a module-GLOBAL `*struct` pointer must load the pointer
* value from g(SB), not deref the saved-BP word.
*
* THE BUG (cat-A divergence — cstage SEGV, wwstage correct): in cgen.c the
* N_DOT-lhs scalar field-store via_ptr arm loaded the base pointer with
* `MOVQ boff(BP),BX`. For a module-global `*struct` ident boff==0, so cstage
* emitted `MOVQ (BP),BX` — derefing the saved BP word as if it were the
* pointer → store through garbage → SEGV (rc=139). wwstage already loaded the
* pointer from the symbol (`LEAQ gp(SB),BX; MOVQ (BX),BX`) and ran correctly
* (rc=7). This is the INVERSE of the F8 #263 set: ww is the runtime-correct
* reference; the cstage half is filed as ww-core TASK #47.
*
* THE CSTAGE FIX (align cstage UP to ww): the via_ptr scalar store detects a
* global base (boff==0 && let_islet) and emits the ww-correct global-pointer
* load — PUSHQ AX; LEAQ gp(SB),BX; MOVQ (BX),BX; POPQ AX — before the store.
* Local bases keep the BP load (byte-id). Both stages now emit the identical
* .s and exit 7.
*
* The static-init form `let gp: *S = &backing;` is blocked on wwstage by a
* separate static-init-of-&global gap (ww-core TASK #48), so the repro uses
* the nil-init + runtime `gp = &backing` form, which builds on both stages.
*/
#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; /* cs==ww==want */
};
static const struct row rows[] = {
{ "global_ptr_field_store",
"package main;\n"
"type S = struct { f: i64, g: i64 };\n"
"let backing: S = S { f = 0, g = 0 };\n"
"let gp: *S = nil;\n"
"export fn main() int = {\n"
" gp = &backing;\n"
" gp.f = 7;\n"
" return backing.f: int;\n"
"};\n",
7 },
};
/* run_build — build+run `src` via `driver`; returns the binary's exit
* code, or -1 on a build failure. */
static int
run_build(const char *driver, const struct row *r, int i)
{
char src[64], tmpdir[64], cmd[1024];
snprintf(src, sizeof src, "/tmp/gpf_%d_%d.ww", getpid(), i);
snprintf(tmpdir, sizeof tmpdir, "/tmp/gpf_%d_d_%d", getpid(), i);
FILE *f = fopen(src, "wb");
if (!f) return -2;
fputs(r->src, f);
fclose(f);
mkdir(tmpdir, 0755);
snprintf(cmd, sizeof cmd, "cd %s && %s build %s 2>/dev/null",
tmpdir, driver, src);
int brc = runwait(cmd);
const char *base = strrchr(src, '/');
base = base ? base + 1 : src;
char outbin[128];
snprintf(outbin, sizeof outbin, "%s/%s", tmpdir, base);
char *dot = strrchr(outbin, '.');
if (dot && strcmp(dot, ".ww") == 0) *dot = '\0';
int got = -1;
if (brc == 0) got = runwait(outbin);
unlink(src); unlink(outbin); rmdir(tmpdir);
return brc == 0 ? got : -1;
}
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 cdrv[1024], wdrv[1024];
snprintf(cdrv, sizeof cdrv, "%s/ww", bin);
snprintf(wdrv, sizeof wdrv, "%s/ww_ww", bin);
struct { const char *name; const char *drv; int gated; }
drivers[] = {
{ "cstage", cdrv, 0 },
{ "wwstage", wdrv, 1 },
{ NULL, NULL, 0 },
};
int n = (int)(sizeof rows / sizeof rows[0]);
int total = 0, fail = 0;
for (int d = 0; drivers[d].name; d++) {
if (drivers[d].gated && access(drivers[d].drv, X_OK) != 0) {
fprintf(stderr, "globptrfield_run: skip %s (no %s)\n",
drivers[d].name, drivers[d].drv);
continue;
}
for (int i = 0; i < n; i++) {
total++;
int got = run_build(drivers[d].drv, &rows[i], i);
if (got != rows[i].want) {
fprintf(stderr, "globptrfield_run[%s][%s]: exit=%d "
"want=%d\n", drivers[d].name, rows[i].label,
got, rows[i].want);
fail++;
}
}
}
if (fail) {
fprintf(stderr, "globptrfield_run: %d/%d fixtures failed\n",
fail, total);
return 1;
}
printf("globptrfield_run: %d/%d ok\n", total, total);
return 0;
}