wcc: TYPE-based forward-tagged predicate in wwstage cgreturn (#201)
cgreturn's forwardtagged detection was keyed on the CALLEE NAME (N_IDENT/N_DOT only via fnretlookupmod), so any other callee shape fell through to the variant-tag synthesis path — clobbering the just-returned AX/DX/CX/R8 tagged-ABI words. The deref-call case `(*r)(...)` (impl-e1-resume STOP, 994 w6c_ww byte-id red) was the proximate trigger. Replace with a TYPE-BASED predicate over the checker-stamped tinfos (rhs.type_ vs c.fnret.type_), mirroring cstage cgen.c:8007 passthrough. Peel TY_NAMED on both sides then identity-check the underlying TY_TAGGED — sufficient for the NAMED case because tinfocache memoizes per typedecl (#191 lineage). Variant-pointer fallback walks the params chain when identity fails so anonymous unions like the cross-module (i32 | void) shared between strings.byteindex and bytes.index still forward correctly; full recursive tinfo structural-eq is gated by #178 (typeeqast's TY_TAGGED arm conservatively returns false today). Probe 770_return_tagged_forward covers 6 rows — IDENT forward, widen non-matching, deref-call (the bug), scalar (sanity), nested call, cross-module forward — each gated on cstage runtime + wwstage runtime + cs.s == ww.s byte-identity.
This commit is contained in:
368
test/wcc/770_return_tagged_forward.c
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368
test/wcc/770_return_tagged_forward.c
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@@ -0,0 +1,368 @@
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/*
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* 770_return_tagged_forward — project #201: wwstage cgreturn forwarding
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* of a matching tagged-union call result. cstage cgen.c:8007-8014
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* detects passthrough via Type-based `istagged && (vu == rt ||
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* type_eq(vt, cg_ret_type))`, so any callee shape (IDENT, DOT, deref-
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* call) that returns the same tagged type triggers a direct AX/DX/CX/R8
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* forward. Wwstage's cgreturn was instead detecting forwardtagged by
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* walking the CALLEE NAME — only N_IDENT and N_DOT callees were
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* inspected; an N_UN(TK_STAR) deref-call fell through to the variant-
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* tag synthesis path, which clobbered AX→DX and zeroed CX/R8/AX before
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* RET, wiping the just-returned tagged-ABI words.
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*
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* Trigger (impl-e1-resume STOP / 994_w6c_ww byte-id red):
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* fn st_read(s: vstream, ...) (size | io.eof | io.error) =
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* { return (*r)(s, buf); };
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*
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* Fix: selfhost/cmd/wcc/cgenstmt.ww cgreturn — replace the IDENT/DOT
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* name-keyed lookup with a TYPE-BASED predicate on the checker-stamped
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* tinfo: peel TY_NAMED from both rhs.type_ and c.fnret.type_, and
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* forward when the peeled rhs tinfo is TY_TAGGED and pointer-identical
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* to the peeled fnret tinfo. Identity is sufficient because
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* tinfofornode memoizes per typedecl (check.ww:1566-1568 "every TNAME
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* resolving to the same decl yields the SAME tinfo pointer"); the
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* structural fallback in cstage's type_eq is gated by #178 (no tinfo-
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* level structural-eq helper today, and typeeqast's TY_TAGGED arm
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* conservatively returns false).
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*
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* Coverage (6 rows):
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* 1. forward_named_match — IDENT callee, both fns return the same
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* NAMED tagged alias. Pre-fix: forwarded
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* via the old name-keyed path. Post-fix:
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* same forward via the new TYPE path.
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* Asm regression gate.
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* 2. widen_subset — IDENT callee returns a concrete variant
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* (i32), fnret is the tagged union. Must
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* KEEP the widen-shuffle (AX→DX, zero
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* CX/R8/AX). Asserts the new predicate
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* correctly rejects non-matching shapes.
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* 3. deref_call_match — `(*r)()` callee, both fns return the
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* same NAMED tagged alias. THE BUG row.
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* Pre-fix wwstage: spurious tag-synth
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* shuffle after CALL AX. Post-fix:
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* direct CALL AX + RET.
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* 4. scalar_return — fnret is i32 (not tagged); cgreturn
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* skips the istaggedtype gate entirely.
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* Sanity that the fix doesn't perturb
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* the unrelated scalar path.
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* 5. nested_call_forward — outer call wraps inner scalar call,
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* both fns return the same NAMED tagged
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* alias. Forward fires on the outer
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* N_CALL despite the nested arg.
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* 6. cross_module_forward — caller is in `main`, callee+type live
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* in an imported module. drew-add: gates
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* cross-module TY_NAMED identity (every
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* reference to `mtag770.result` resolves
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* to the SAME NAMED tinfo via aliassym +
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* sym.type_ cache; #191 lineage). If a
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* regressor splits NAMED tinfo per
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* reference site, this row reds first.
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*
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* Per-row gates: cstage runtime exit, wwstage runtime exit, cs.s ==
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* ww.s byte-identical (rule-10 stage symmetry).
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*
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* GATE POLARITY: must stay GREEN. A red on row 3/5/6 means the
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* TYPE-based forward predicate dropped a callee shape; row 2 reds if
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* the predicate fires too aggressively (non-matching rhs incorrectly
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* forwarded); row 1/4 red means structural regression in adjacent
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* cgreturn arms.
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*/
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#include <stdio.h>
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#include <stdlib.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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#define STAGE_CS 1
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#define STAGE_WW 2
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struct row {
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const char *label;
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const char *src;
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/* Optional secondary-module source (row 6 cross_module). */
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const char *modname;
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const char *modsrc;
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int expected_exit;
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int stage_mask;
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};
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static const struct row rows[] = {
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{ "forward_named_match",
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"package main;\n"
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"type result = (i32 | str);\n"
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"fn ra(x: i32) result = { return x + 1: i32; };\n"
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"fn cw(x: i32) result = { return ra(x); };\n"
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"export fn main() i32 = {\n"
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" let r: result = cw(40);\n"
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" match (r) {\n"
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" case let i: i32 => return i;\n"
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" case let s: str => return 0;\n"
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" };\n"
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"};\n",
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NULL, NULL,
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41,
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STAGE_CS | STAGE_WW },
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{ "widen_subset",
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"package main;\n"
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"type result = (i32 | str);\n"
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"fn ri(x: i32) i32 = { return x + 1; };\n"
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"fn cw(x: i32) result = { return ri(x); };\n"
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"export fn main() i32 = {\n"
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" let r: result = cw(40);\n"
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" match (r) {\n"
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" case let i: i32 => return i;\n"
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" case let s: str => return 0;\n"
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" };\n"
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"};\n",
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NULL, NULL,
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41,
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STAGE_CS | STAGE_WW },
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{ "deref_call_match",
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"package main;\n"
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"type result = (i32 | str);\n"
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"fn ra(x: i32) result = { return x + 1: i32; };\n"
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"fn cw(r: *fn(x: i32) result, x: i32) result = { return (*r)(x); };\n"
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"export fn main() i32 = {\n"
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" let p: *fn(x: i32) result = &ra;\n"
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" let v: result = cw(p, 40);\n"
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" match (v) {\n"
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" case let i: i32 => return i;\n"
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" case let s: str => return 0;\n"
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" };\n"
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"};\n",
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NULL, NULL,
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41,
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STAGE_CS | STAGE_WW },
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{ "scalar_return",
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"package main;\n"
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"fn ri(x: i32) i32 = { return x + 1; };\n"
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"fn cw(x: i32) i32 = { return ri(x); };\n"
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"export fn main() i32 = { return cw(40); };\n",
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NULL, NULL,
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41,
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STAGE_CS | STAGE_WW },
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{ "nested_call_forward",
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"package main;\n"
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"type result = (i32 | str);\n"
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"fn ri(x: i32) i32 = { return x + 1; };\n"
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"fn wrap(x: i32) result = { return x: i32; };\n"
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"fn cw(x: i32) result = { return wrap(ri(x)); };\n"
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"export fn main() i32 = {\n"
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" let r: result = cw(39);\n"
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" match (r) {\n"
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" case let i: i32 => return i;\n"
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" case let s: str => return 0;\n"
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" };\n"
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"};\n",
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NULL, NULL,
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40,
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STAGE_CS | STAGE_WW },
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{ "cross_module_forward",
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"package main;\n"
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"import mtag770;\n"
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"fn cw(x: i32) mtag770.result = { return mtag770.ra(x); };\n"
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"export fn main() i32 = {\n"
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" let r: mtag770.result = cw(40);\n"
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" match (r) {\n"
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" case let i: i32 => return i;\n"
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" case let s: str => return 0;\n"
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" };\n"
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"};\n",
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"mtag770",
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"package mtag770;\n"
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"export type result = (i32 | str);\n"
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"export fn ra(x: i32) result = { return x + 1: i32; };\n",
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41,
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STAGE_CS | STAGE_WW },
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};
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static int
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write_source(const char *path, const char *src)
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{
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FILE *f = fopen(path, "wb");
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if (!f) return -1;
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fputs(src, f);
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fclose(f);
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return 0;
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}
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static int
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write_sources(const struct row *r, const char *tmpdir, const char *src)
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{
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if (r->modname != NULL) {
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char moddir[256], modfile[512];
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snprintf(moddir, sizeof moddir, "%s/%s", tmpdir, r->modname);
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snprintf(modfile, sizeof modfile, "%s/%s.ww",
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moddir, r->modname);
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mkdir(moddir, 0755);
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if (write_source(modfile, r->modsrc) != 0) return -1;
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}
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return write_source(src, r->src);
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}
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static void
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cleanup_tmp(const struct row *r, const char *tmpdir, const char *base)
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{
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char p[512];
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snprintf(p, sizeof p, "%s/%s.ww", tmpdir, base); unlink(p);
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snprintf(p, sizeof p, "%s/%s.s", tmpdir, base); unlink(p);
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snprintf(p, sizeof p, "%s/%s.o", tmpdir, base); unlink(p);
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snprintf(p, sizeof p, "%s/%s.combined.ww", tmpdir, base); unlink(p);
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snprintf(p, sizeof p, "%s/%s", tmpdir, base); unlink(p);
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if (r->modname != NULL) {
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char moddir[256];
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snprintf(moddir, sizeof moddir, "%s/%s", tmpdir, r->modname);
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snprintf(p, sizeof p, "%s/%s.ww", moddir, r->modname); unlink(p);
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snprintf(p, sizeof p, "%s/%s.s", moddir, r->modname); unlink(p);
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snprintf(p, sizeof p, "%s/%s.o", moddir, r->modname); unlink(p);
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snprintf(p, sizeof p, "%s/%s.combined.ww", moddir, r->modname); unlink(p);
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rmdir(moddir);
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}
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rmdir(tmpdir);
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}
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static int
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build_via_driver(const char *driver, const char *tmpdir, const char *src)
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{
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char cmd[1024];
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snprintf(cmd, sizeof cmd, "cd %s && timeout 180 %s build %s 2>/dev/null",
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tmpdir, driver, src);
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return runwait(cmd);
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}
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static int
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run_row(const char *driver, const struct row *r, int seq)
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{
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char tmpdir[256], src[512], base[64], outbin[768];
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snprintf(tmpdir, sizeof tmpdir, "/tmp/rtf_%d_d_%d", getpid(), seq);
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snprintf(src, sizeof src, "%s/main770.ww", tmpdir);
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snprintf(base, sizeof base, "main770");
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mkdir(tmpdir, 0755);
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if (write_sources(r, tmpdir, src) != 0) {
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cleanup_tmp(r, tmpdir, base);
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return -1;
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}
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int rc = -1;
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if (build_via_driver(driver, tmpdir, src) == 0) {
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snprintf(outbin, sizeof outbin, "%s/%s", tmpdir, base);
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rc = runwait(outbin);
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}
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cleanup_tmp(r, tmpdir, base);
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return rc;
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}
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/* asm_byte_identical — diff cstage vs wwstage .s. Parallel trees so
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* ww_ww writing intermediates next to the source doesn't clobber the
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* cstage .s (CLAUDE.md rule 14 phase split). */
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static int
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asm_byte_identical(const char *cdrv, const char *wdrv,
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const struct row *r, int seq)
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{
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char src[512], tdc[256], tdw[256], base[64], cs[512], ws[512];
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snprintf(tdc, sizeof tdc, "/tmp/rtf_%d_c_%d", getpid(), seq);
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snprintf(tdw, sizeof tdw, "/tmp/rtf_%d_w_%d", getpid(), seq);
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snprintf(base, sizeof base, "main770");
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mkdir(tdc, 0755);
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mkdir(tdw, 0755);
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snprintf(src, sizeof src, "%s/main770.ww", tdc);
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if (write_sources(r, tdc, src) != 0) { cleanup_tmp(r, tdc, base); cleanup_tmp(r, tdw, base); return -1; }
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int rc = -1;
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if (build_via_driver(cdrv, tdc, src) != 0) goto out;
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snprintf(cs, sizeof cs, "%s/%s.s", tdc, base);
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snprintf(src, sizeof src, "%s/main770.ww", tdw);
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if (write_sources(r, tdw, src) != 0) goto out;
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if (build_via_driver(wdrv, tdw, src) != 0) goto out;
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snprintf(ws, sizeof ws, "%s/%s.s", tdw, base);
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FILE *fc = fopen(cs, "rb");
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FILE *fw = fopen(ws, "rb");
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if (fc && fw) {
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rc = 0;
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for (;;) {
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int a = fgetc(fc);
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int b = fgetc(fw);
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if (a != b) { rc = -1; break; }
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if (a == EOF) break;
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}
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}
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if (fc) fclose(fc);
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if (fw) fclose(fw);
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out:
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cleanup_tmp(r, tdc, base);
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cleanup_tmp(r, tdw, base);
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return rc;
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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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int n = (int)(sizeof rows / sizeof rows[0]);
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int total = 0, fail = 0;
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int wwpresent = (access(wdrv, X_OK) == 0);
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int seq = 0;
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for (int i = 0; i < n; i++) {
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if (rows[i].stage_mask & STAGE_CS) {
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total++;
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int got = run_row(cdrv, &rows[i], seq++);
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if (got != rows[i].expected_exit) {
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fprintf(stderr,
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"return_tagged_forward[cstage run][%s]: exit=%d want=%d\n",
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rows[i].label, got, rows[i].expected_exit);
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fail++;
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}
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}
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if (wwpresent && (rows[i].stage_mask & STAGE_WW)) {
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total++;
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int got = run_row(wdrv, &rows[i], seq++);
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if (got != rows[i].expected_exit) {
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fprintf(stderr,
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"return_tagged_forward[wwstage run][%s]: exit=%d want=%d\n",
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rows[i].label, got, rows[i].expected_exit);
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fail++;
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}
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total++;
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if (asm_byte_identical(cdrv, wdrv, &rows[i], seq++) != 0) {
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fprintf(stderr,
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"return_tagged_forward[byte-id][%s]: cstage vs wwstage asm differs\n",
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rows[i].label);
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fail++;
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}
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}
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}
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if (!wwpresent)
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fprintf(stderr, "return_tagged_forward: skip wwstage (no %s)\n", wdrv);
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if (fail) {
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fprintf(stderr, "return_tagged_forward: %d/%d fixtures failed\n",
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fail, total);
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return 1;
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}
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printf("return_tagged_forward: %d/%d ok\n", total, total);
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return 0;
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}
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Reference in New Issue
Block a user