Cesarus85--mjolnir-vr/docs/object_matching_logs/path_structure_bsp_obj.md

path_structure_bsp.obj atomic closeout log

Target: January 14, 2002 Xbox build. Compiler: XDK 3911 CL 13.00.9254.1 with /O2 /Oy- /DDEBUG /Dxbox.

This log records an atomic six-function closeout attempt. January COFF bytes, relocations, section ownership, and the hardened comparator are authoritative. HCEX/HCEA names and source topology were used only as hypotheses. No matching credit, compiler flag, comparator rule, configuration, or object label changed.

Inventory and provenance

Symbol	Target bytes	Relocations	Best result
_structure_test_ray2d	480	14	strict exact
_structure_surfaces_are_equivalent	128	4	strict exact
_clip_empty_interval_by_solid_interval	112	0	strict exact
_structure_test_line2d	1,104	29	same size/frame/count; nonexact
_structure_surface_index_from_point	96	1	strict exact
_structure_test_pill2d	624	11	same size/count; nonexact

The object owns no .data or .bss. Its named table _rdata_0024ec0c is 64 bytes, has zero relocations, and compares strict exact with normalized SHA-256 74970b924ac1a42d16bd2b93cf0db13c54a0df7e5c6da7f1980eb8c22dc7fbe1. The remaining .rdata contributions are compiler constants and assertion strings whose identities are checked through the code relocations.

All six function names have exact-unique HCEX mappings. HCEA source for structure_test_line2d and structure_test_pill2d confirmed the broad control flow, local roles, and two-probe pill algorithm. It did not determine January declaration lifetimes or VC7 scheduling; every accepted statement order below was adjudicated against January bytes.

Strict exact results recovered in this lane

Symbol	Bytes	Relocations	Normalized SHA-256
_structure_test_ray2d	480/480	14/14	6d8124c8c4241b78053d9354c96d8d7527b7c055c2c68ebc2d6e7578916e93eb
_structure_surfaces_are_equivalent	128/128	4/4	821f618f6425baa324bfbe68c75e8c144d5d0d4bd190dff1606fcd276f781b83
_clip_empty_interval_by_solid_interval	112/112	0/0	dcef7f55dd07ed3e27a77950d3436383dc2151902aaf5a752fb8b704e4aa1330
_structure_surface_index_from_point	96/96	1/1	29cfb8955fc45cfc7972505dddb757d4374ca33735024c18aa7f5baac71b8f49

The ray result layout is 12 bytes: real distance, long surface_index, and long edge_index. The pill/line result layout is 28 bytes with t at +0x18. Typed tag-block accessors, named engine math types, and house formatting were kept throughout.

clip_empty_interval_by_solid_interval

Seven measured source families are retained in this file's Git history. The winning legal-C control assigns each selection arm to a distinct local and copies that local back to the parameter. It preserves January's redundant false-arm load/store and reaches strict exactness. Earlier MAX/MIN, direct selection, pointer selection, alias, and expression-order variants were 96 bytes or reordered the x87 comparison. See the detailed history in this log's predecessor commit.

_structure_test_line2d

The full 26-experiment matrix lives in docs/object_matching_logs/path_structure_bsp_line2d.md. It established the complete algorithm, exact 0x70 frame, exact 1,104-byte envelope, exact 29 relocation identities, native aggregate lifetimes, statement order, assertion spelling, and recursive state order.

Current best:

• Target/base size: 1104/1104.
• Target/base frame: 0x70/0x70.
• Relocations: 29/29; all identities match, with addresses exact through +0x376.
• Target SHA-256: 664912aede956fbb3bc49b4517a90d315d445777054a1823c0eafadd2a1f2bc0.
• Best base SHA-256: 55ccd1c4c2cab82eb867a354392b848b9a1851bc29a4c0dab3f4e64aadaece83.
• Final projection call addresses target/base: +0x3a7/+0x3a4, +0x3de/+0x3ee, +0x426/+0x423.

The remaining mechanism is bounded: January spills t with fstps [ebp+8] and reloads it for both hit coordinates; this compiler/source combination emits fsts [ebp+8], retains t in x87 for one coordinate, and then chooses a different final basic-block order. Twenty-six readable source families, including all meaningful declaration, scope, alias, expression, helper, and CFG spellings, did not produce the January pairing. A barrier proved the spill mechanism but rescheduled earlier bytes and was rejected.

_structure_test_pill2d experiment matrix

The baseline January-adapted HCEA topology was 624 bytes and 11 relocations, but normalized SHA-256 bbbc822... and relocation addresses drifted after the initial normalization. The following bounded families were built and strictly measured:

1. Perpendicular declaration/assignment order. Naming perpendicular_j before assigning i computed the y component first and did not match.
2. Explicit HCEA scalars. dx, dy, length, and inverse_length kept the 0x84 frame but regressed relocation addresses and scheduling.
3. set_real_vector2d. Inlining the helper returned to the baseline y-first ordering; neutral and rejected.
4. vector_from_points2d plus component swap. Added an fxch and a stack temporary; rejected.
5. vector_from_points2d followed by component overwrite. Added redundant stores and loads; rejected.
6. Aggregate initializer. { -dy, dx } emitted y-first stores and did not alter the normalization lifetime.
7. Separate direction vector, scoped and unscoped. Both grew the frame to 0x88; rejected.
8. Small semantic static helper. VC7 emitted an unwanted out-of-line helper section while inlining the same baseline body; rejected and removed.
9. HCEA point declaration order. p0, p1, q0, q1 permutations were byte-neutral.
10. Readable expanded normalization. magnitude2d, inverse, and two *= stores reproduced the baseline bytes exactly; useful proof, not a fix.
11. point_from_line2d for four offset points. The native inline helper was byte-neutral.
12. Reverse multiplication operand spelling for q1. Byte-neutral; VC7 canonicalized the commutative products.
13. Reverse magnitude component sum. Byte-neutral; restored the helper.
14. HCEA local declaration sequence. All meaningful point/result/vector orderings were byte-neutral under the exact 0x84 frame.
15. Success-fallthrough tail CFG. Replacing the false-first tail with if (!(distance_squared < radius_squared)) { success } else { false } was the only material improvement. It kept 624/624 and 11/11, changed the hash to e4f034ffebad19d3bd8fd3e57828bc62b622810acd55bcf77b71375ef2ad6ba1, and reproduced January's forward false branch and success block order.
16. Direct early returns. Eliminated the shared result local and shifted every later relocation; rejected.
17. Set the boolean before the success copy. Byte-neutral relative to the improved CFG.
18. Distinct memcpy false arm. Added an out-of-line _csmemcpy relocation and grew the candidate to 640 bytes with 12 relocations; rejected immediately.

Current best pill evidence:

• Size: target/base 624/624.
• Frame: target/base 0x84/0x84.
• Relocation count and semantic targets: 11/11, identical sequence.
• Target SHA-256: c3dac4abc09c7afb09ef84a44f434814cb3e22ea87d563991b222183e9fdb2f4.
• Best base SHA-256: e4f034ffebad19d3bd8fd3e57828bc62b622810acd55bcf77b71375ef2ad6ba1.
• Target relocation addresses: 56, 73, 99, 162, 201, 254, 299, 337, 382, 432, 477.
• Best base relocation addresses: 56, 73, 95, 158, 197, 249, 285, 323, 368, 418, 463.

January keeps perpendicular.j live through the fourth offset-point construction, spills/scales both perpendicular components, and recomputes the negative-radius products for q1. The candidate coalesces those products and reuses the second component's stack slot for a surface index. At the tail, January loads the output pointer and rep movsl count after its x87 predicate; the candidate hoists those branch-common values before the predicate. The experiment matrix shows these are coupled local-colouring/scheduling effects, not missing calls, fields, data, or control-flow behavior.

Preserved shipped behavior

Two January defects were identified and must remain documented if this object is reopened:

• _structure_test_line2d reads pathfinding_surfaces[neighbor_surface_index] before checking the NONE sentinel. On a boundary edge that reads one byte before the array. A safe derivative should check the sentinel first.
• _structure_test_pill2d copies result0 to the output on the false within-radius path. A safe derivative could leave the output untouched or explicitly clear it, but the exact decomp must preserve January behavior.

Atomic verdict and reopen criteria

PARKED, not Matching. Four of six functions and the named data table are strict exact, but an atomic object cannot retain partial production changes. The production/header/config changes from this lane are restored before the evidence commit; only these logs remain.

Reopen only with one of the following:

1. January local-variable or statement records showing the original lifetime topology for either residual.
2. A readable exact donor compiled by the same VC7 flags whose source explains the fstps/reload or pill component-colouring pattern.
3. A new measured compiler-control rule that changes one of those exact mechanisms without changing section size, relocation identity, or sibling functions.

Do not repeat the declaration, scope, alias, helper, operand-order, early return, barrier, or branch-copy families enumerated above and in the line2d log.