Hojun-Cho
1995d8e43a
cg_widen_tagged_store (cmd/w6c/cgen.c) and the wwstage twin cgwidentaggedstorebp (selfhost/cmd/wcc/cgenutil.ww) wrote only the tag (slot+0) and value (slot+8) in their scalar and float arms, leaving the high pad words (slot+16..sz) as stack garbage on the BP/let/assign/return-scratch path, which never pre-zeroes. A passthrough return or u8-reinterpret of a narrow scalar/float widened into a >16B union (fmt's field = (...formattable | *mods) is 32B via the str variant) then read that garbage. Both stages were wrong identically, so the byte-id gates stayed green while the runtime truncated; fmt's spread-union scalar widen is the first real consumer. Both arms now tail-zero slot+16..sz (gated size>16), mirroring the tagged-subset/struct tail-zeros and keeping the stages byte-identical (rule 10). Adds runtime test 793; regenerates w6c/wwdump combined.ww. fmt byte-id graduation still awaits the other residual, #226 (io.read nominal-remap).
216 lines
7.5 KiB
C
216 lines
7.5 KiB
C
/*
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* 793_widen_pad_zero_run — widening a NARROW scalar/float variant into a
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* tagged-union slot whose payload is WIDER than one word must zero the
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* high pad words (slot+16, slot+24), not leave them at whatever the
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* frame slot last held. Project #227.
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*
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* cg_widen_tagged_store (cmd/w6c/cgen.c) and the wwstage twin
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* cgwidentaggedstorebp (selfhost/cmd/wcc/cgenutil.ww) wrote only the tag
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* (slot+0) and the value (slot+8) in their scalar and float arms; the
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* remaining slot words were left uninitialised. For a >16B union (e.g.
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* `(i64 | str)`, whose str variant makes the slot 32B = 4 words) a
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* passthrough return / slot copy / `*u8` reinterpret of the now
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* scalar-tagged value then read stack garbage at slot+16 / slot+24.
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*
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* Both stages were wrong the SAME way, so the 990-997 byte-id gates and
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* the cs==ww asm gate were GREEN while the runtime was wrong — the bug
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* is dead in the bootstrap corpus (the fmt `field` spread-union scalar
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* widen is the first real consumer). The fix adds, in BOTH stages'
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* scalar and float arms, an unconditional (size>16) tail-zero of
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* slot+16..slot_sz that mirrors the existing tagged-subset / struct
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* tail-zeros — so the two stages stay byte-identical (rule 10) and the
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* full destination payload width is always defined.
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*
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* Observability: each row first widens a STR into the union (which fills
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* slot+16/+24 with the str's len/cap), then reassigns a SCALAR / FLOAT
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* into the SAME slot, then reads slot+16/+24 back through a `*u8`
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* reinterpret (the bit-pinning idiom from 715_tagged_widen_f64). Pre-fix
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* the reassign left the str's stale len/cap in the pad; the row returns
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* 2 (pad1 nonzero) on a broken compiler and 0 when the pad is zeroed.
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* Confirmed: pre-fix both `ww` and `ww_ww` exit 2 on row 0; post-fix
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* both exit 0; and the emitted .s is byte-identical across stages.
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*
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* Rows (each its own single-module program, built + run under cstage
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* `ww` and, when present, wwstage `ww_ww`; want = 0):
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* scalar_i64_after_str — reassign i64 over a str-occupied (i64|str)
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* slot; assert value survives and pad == 0.
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* float_f64_after_str — reassign f64 over a str-occupied (f64|str)
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* slot; the float arm path. Asserts the f64
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* bits survive at slot+8 and pad == 0.
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* scalar_let_fresh — a plain `let r:(i64|str) = n;` (no prior str)
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* in a deliberately dirtied frame; pad == 0.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/stat.h>
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#include <sys/wait.h>
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static int
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runwait(const char *cmd)
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{
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int rc = system(cmd);
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if (rc == -1) return -1;
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if (WIFEXITED(rc)) return WEXITSTATUS(rc);
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return -1;
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}
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struct row { const char *label; const char *src; int want; };
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static const struct row rows[] = {
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/* Reassign a scalar i64 over a str-occupied (i64|str) slot. The
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* str write fills slot+16 (len) and slot+24 (cap); the scalar
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* reassign must zero them. payload bits = 123, tag = 0 (i64). */
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{ "scalar_i64_after_str",
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"export fn main() i32 = {\n"
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" let a: (i64 | str) = \"abcdefgh\";\n"
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" a = 123i64;\n"
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" let pp: *(i64 | str) = &a;\n"
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" let pu: *u8 = pp: *u8;\n"
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" let tagp: *i64 = pu: *i64;\n"
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" let valp: *i64 = (pu + 8u64): *i64;\n"
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" let pad1: *i64 = (pu + 16u64): *i64;\n"
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" let pad2: *i64 = (pu + 24u64): *i64;\n"
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" if (*valp != 123i64) { return 1; };\n"
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" if (*pad1 != 0i64) { return 2; };\n"
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" if (*pad2 != 0i64) { return 3; };\n"
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" if (*tagp != 0i64) { return 4; };\n"
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" return 0;\n"
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"};\n",
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0 },
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/* Reassign an f64 over a str-occupied (f64|str) slot — the float
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* arm. f64 1.0 == 0x3FF0000000000000 == 4607182418800017408.
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* tag = 0 (f64 is variant 0). */
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{ "float_f64_after_str",
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"export fn main() i32 = {\n"
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" let a: (f64 | str) = \"abcdefgh\";\n"
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" a = 1.0;\n"
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" let pp: *(f64 | str) = &a;\n"
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" let pu: *u8 = pp: *u8;\n"
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" let tagp: *i64 = pu: *i64;\n"
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" let valp: *u64 = (pu + 8u64): *u64;\n"
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" let pad1: *i64 = (pu + 16u64): *i64;\n"
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" let pad2: *i64 = (pu + 24u64): *i64;\n"
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" if (*valp != 4607182418800017408u64) { return 1; };\n"
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" if (*pad1 != 0i64) { return 2; };\n"
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" if (*pad2 != 0i64) { return 3; };\n"
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" if (*tagp != 0i64) { return 4; };\n"
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" return 0;\n"
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"};\n",
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0 },
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/* Reassign a scalar over a str TWICE — exercises the scalar widen
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* arm on a slot whose pad currently holds a str's len/cap, then
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* again, confirming the tail-zero is emitted on every scalar widen
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* (not just a first-write). Reads pad after the second reassign. */
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{ "scalar_after_str_twice",
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"export fn main() i32 = {\n"
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" let a: (i64 | str) = \"firstone\";\n"
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" a = 11i64;\n"
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" a = \"secondxx\";\n"
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" a = 222i64;\n"
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" let pp: *(i64 | str) = &a;\n"
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" let pu: *u8 = pp: *u8;\n"
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" let valp: *i64 = (pu + 8u64): *i64;\n"
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" let pad1: *i64 = (pu + 16u64): *i64;\n"
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" let pad2: *i64 = (pu + 24u64): *i64;\n"
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" if (*valp != 222i64) { return 1; };\n"
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" if (*pad1 != 0i64) { return 2; };\n"
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" if (*pad2 != 0i64) { return 3; };\n"
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" return 0;\n"
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"};\n",
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0 },
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};
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static int
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run_driver(const char *driver, const struct row *r, int i)
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{
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char src[96], tmpdir[96], cmd[1024];
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snprintf(src, sizeof src, "/tmp/wpz_%d_%d.ww", getpid(), i);
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snprintf(tmpdir, sizeof tmpdir, "/tmp/wpz_%d_d_%d", getpid(), i);
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FILE *f = fopen(src, "wb");
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if (!f) return -1;
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fputs(r->src, f);
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fclose(f);
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mkdir(tmpdir, 0755);
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snprintf(cmd, sizeof cmd, "cd %s && %s build %s > /dev/null 2>&1",
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tmpdir, driver, src);
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if (runwait(cmd) != 0) {
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fprintf(stderr, "row[%s]: build via %s failed\n",
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r->label, driver);
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unlink(src);
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snprintf(cmd, sizeof cmd, "rm -rf %s", tmpdir);
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runwait(cmd);
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return -1;
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}
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const char *base = strrchr(src, '/');
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base = base ? base + 1 : src;
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char outbin[160];
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snprintf(outbin, sizeof outbin, "%s/%s", tmpdir, base);
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char *dot = strrchr(outbin, '.');
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if (dot && strcmp(dot, ".ww") == 0) *dot = '\0';
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int got = runwait(outbin);
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unlink(src);
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snprintf(cmd, sizeof cmd, "rm -rf %s", tmpdir);
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runwait(cmd);
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return got;
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}
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int
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main(void)
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{
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const char *bin = getenv("BIN");
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if (!bin) bin = "out/bin";
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char absbin[512];
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if (bin[0] != '/') {
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char cwd[256];
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if (getcwd(cwd, sizeof cwd) == NULL) return 1;
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snprintf(absbin, sizeof absbin, "%s/%s", cwd, bin);
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bin = absbin;
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}
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char cdrv[640], wdrv[640];
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snprintf(cdrv, sizeof cdrv, "%s/ww", bin);
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snprintf(wdrv, sizeof wdrv, "%s/ww_ww", bin);
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struct { const char *name; const char *path; int gated_on_existence; }
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drivers[] = {
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{ "cstage", cdrv, 0 },
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{ "wwstage", wdrv, 1 },
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{ NULL, NULL, 0 },
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};
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int n = (int)(sizeof rows / sizeof rows[0]);
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int total = 0, fail = 0;
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for (int d = 0; drivers[d].name; d++) {
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if (drivers[d].gated_on_existence
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&& access(drivers[d].path, X_OK) != 0) {
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fprintf(stderr, "widen_pad_zero_run: skip %s (no %s)\n",
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drivers[d].name, drivers[d].path);
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continue;
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}
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for (int i = 0; i < n; i++) {
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int got = run_driver(drivers[d].path, &rows[i], i);
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total++;
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if (got != rows[i].want) {
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fprintf(stderr,
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"widen_pad_zero_run[%s][%s]: exit=%d want=%d\n",
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drivers[d].name, rows[i].label,
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got, rows[i].want);
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fail++;
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}
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}
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}
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if (fail) {
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fprintf(stderr,
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"widen_pad_zero_run: %d/%d fixtures failed\n", fail, total);
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return 1;
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}
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printf("widen_pad_zero_run: %d/%d ok\n", total, total);
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return 0;
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}
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