Hojun-Cho
b3f4990979
The in-cap aggregate-receive materialise emitted a single narrow tail MOV that fell to MOVB for a 3/5/6/7-byte sub-8 tail, storing one byte while the scratch->dest copy read the full tail from uninitialised scratch — silently dropping members at the C2c whole-element arm (arr[i]=mk()) and loud-stopping at the #11 field arm. The scratch slot is ceil-8 padded (local_alloc/localadd round to 8) and the copy reads only tsz bytes, so flipping the tail default MOVB->MOVQ stores the full register harmlessly into the slot's own pad (in-bounds for in-cap <=24B); 1/2/4-byte tails stay byte-identical. Both stages symmetric. Removes the now-redundant #11 sub-8-tail loud-stop (keeps the float #165 and over-cap #234 loud-stops). The same narrow-tail materialise recurs at 6 other cstage sites (task #14). Retires the obsolete idx_dot_aggret_subtail_loud //ww:error fixture (both stages now compile the case) and converts it to a positive cstage run-test; the struct-field shape is byte-id-divergent only via the pre-existing #9 frame-size bug, so the value pin uses array-field shapes. Value-asserting, reddens under each stage's independent revert.
83 lines
3.5 KiB
Plaintext
83 lines
3.5 KiB
Plaintext
// aggregate_tail_test — in-cap aggregate-receive sub-8 tail materialise (#10).
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// An in-cap (<=24B) aggregate-returning CALL received into an INDEXED dest is a
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// two-step: (1) materialise the AX/DX/CX return regs into a frame scratch, (2)
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// word-copy scratch -> dest. Step 1's sub-8 TAIL stored a single narrow MOV
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// picked by (tail==4)?MOVL:(tail==2)?MOVW:MOVB, so for tail in {3,5,6,7} it fell
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// to MOVB: one byte written while the copy reads the FULL tail, so the high tail
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// bytes stayed uninitialised => dropped members. Two arms shared the gap — the
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// C2c whole-element arr[i]=mk() (SILENT both stages, byte-id-BLIND: both emitted
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// IDENTICAL wrong asm) and the #11 field-of-indexed arr[i].f=mk() (LOUD-STOPped).
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// The fix stores the FULL register (MOVQ) into the ceil-8-padded scratch; the
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// over-stored bytes die in the pad and the copy reads only the real size.
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// A repro element must be align-<=2 UNPADDED: [7]i16 = 14B keeps a real tail-6;
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// an i64-bearing struct pads to 16B (tail 0) and never trips it. PRIMITIVE-only
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// asserts (deref_callarg lineage): a dropped word fails. The C2c value assert is
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// the SOLE tooth there (byte-id blind); the #11 case re-arms a compile-error
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// loud-stop on revert. Distinct nonzero per-element values so a stale read (the
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// fully-dropped members read uninitialised, 0 on a fresh frame) mismatches.
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package aggregate_tail_test;
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type s = struct { f: [7]i16, g: i16 }; // f at off 0 (14B tail-6), g at off 14
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fn mk7() [7]i16 = { return [10i16, 20i16, 30i16, 40i16, 50i16, 60i16, 70i16]; };
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fn mk11() [11]u8 = { return [1u8,2u8,3u8,4u8,5u8,6u8,7u8,8u8,9u8,10u8,11u8]; };
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fn mk13() [13]u8 = { return [1u8,2u8,3u8,4u8,5u8,6u8,7u8,8u8,9u8,10u8,11u8,12u8,13u8]; };
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fn mk15() [15]u8 = { return [1u8,2u8,3u8,4u8,5u8,6u8,7u8,8u8,9u8,10u8,11u8,12u8,13u8,14u8,15u8]; };
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@test fn c2c_whole_element() void = {
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let arr: [3][7]i16;
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arr[1] = mk7();
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assert(arr[1][0] == 10i16);
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assert(arr[1][1] == 20i16);
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assert(arr[1][2] == 30i16);
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assert(arr[1][3] == 40i16);
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assert(arr[1][4] == 50i16); // eb1 byte 0-1
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assert(arr[1][5] == 60i16); // eb1 byte 2-3 — dropped by the buggy MOVB tail
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assert(arr[1][6] == 70i16); // eb1 byte 4-5 — dropped (fully-uninit tooth)
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};
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@test fn field_of_indexed() void = {
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let arr: [3]s;
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arr[1].g = 999i16; // neighbour set first
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arr[1].f = mk7();
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assert(arr[1].f[0] == 10i16);
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assert(arr[1].f[4] == 50i16);
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assert(arr[1].f[5] == 60i16);
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assert(arr[1].f[6] == 70i16);
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assert(arr[1].g == 999i16); // tail MOVQ writes the padded SCRATCH, not g
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};
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// The STRUCT-field-of-indexed variant ({t14,pad} struct field) is NOT pinned here:
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// #10's materialise is byte-id clean for it, but the [N]box local frame size
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// diverges cs!=ww (task #9, slotsize-vs-natural) — benign (both stages correct)
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// yet byte-id-RED, so it stays out of the T2 corpus. Positive cstage coverage of
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// that shape lives in test/wcc/data/idx_dot_aggret_subtail_run (converted from the
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// retired loud-stop tripwire).
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@test fn tail3() void = {
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let a: [2][11]u8;
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a[1] = mk11();
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assert(a[1][0] == 1u8);
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assert(a[1][7] == 8u8);
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assert(a[1][8] == 9u8); // tail byte 0 (MOVB wrote only this)
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assert(a[1][9] == 10u8); // tail byte 1 — dropped
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assert(a[1][10] == 11u8); // tail byte 2 — dropped
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};
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@test fn tail5() void = {
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let a: [2][13]u8;
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a[1] = mk13();
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assert(a[1][0] == 1u8);
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assert(a[1][8] == 9u8);
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assert(a[1][12] == 13u8); // tail byte 4 — dropped
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};
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@test fn tail7() void = {
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let a: [2][15]u8;
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a[1] = mk15();
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assert(a[1][0] == 1u8);
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assert(a[1][8] == 9u8);
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assert(a[1][14] == 15u8); // tail byte 6 — dropped
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};
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