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sots-re/verify/results/fpu-cw/run-137f/shim.log
alex 849c5069fc lane F: x87 precision sensitivity measured; STATE_CHECKSUM 3.5 closed 
Seven End Turns from ref-turn2.sav on VM140, six control words, whole-state
checksum on every post-turn autosave.

53-bit and 64-bit x87 give byte-identical state across all 35,394 leaves, so
an x64/SSE port computing in IEEE double has NO double-rounding budget to
preserve and floats=bits is free. Two settings do move state, each reproduced
on a repeat run:

  0x007f (24-bit)   Sys[112 "Gamma Cephei"]/Pop2/PopG/PopC 540000000 -> 540000002
  0x1a7f (round-up) Flt[34 "Beta Fleet"]/Pos/.[0] and /Pos/.[2], 1 ULP each

So the port must hold intermediates at 53 bits and use round-to-nearest --
both SSE defaults, now measured rather than assumed, each with a named
regression witness.

The briefed triple was under-powered: 0x027f is 53-bit (it differs from 0x127f
only in bit 12, infinity control, ignored since the 387) and 0x137f is 64-bit,
not a rounding change. Run as written all three come back identical, and that
would have "proved" something false on both axes that matter.

Evidence the forced word actually held: read-back at each force site plus 38
independent in-pipeline hook samples per run spanning turn phases 4, 6 and 8,
all reading the forced value. Mars::Application::Run calls
_controlfp(0x50000,0x3070300) at 0x0089f606 every frame, which is 0x127f, so
forcing at StrategyClient::EndTurn is wiped before the turn runs;
StrategyServer::BeginProcessTurn is the point that works.

Also re-confirms the End-Turn determinism oracle on engine cef889e:
bb4fd9ac... / 978041ac... unchanged.

New tools: verify/fpu-cw/cw_census.py, verify/fpu-cw/trace_bitdiff.py (the
latter exists because under a forced 24-bit word the CRT's own %g rendering
degrades, so trace text is not a valid comparison surface).
2026-09-08 05:07:53 -04:00

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04:34:28.562 [tid 7608] ==== sots-engine shim (binkw32 proxy) build fpucw-cef889e-20260908T0803Z ====
04:34:28.562 [tid 7608] exe: C:\SOTS\Sword of the Stars.exe
04:34:28.562 [tid 7608] exe base=0x00e80000 (link-time image base 0x00400000, ASLR delta +11010048) pid=3296 shim=696a0000
04:34:28.562 [tid 7608] addresses: Source: sots-re ghidra/addresses.json @ f5b37c2, generated 2026-09-08 by tools/gen_addresses.py
04:34:28.562 [tid 7608] config: hooks=trace
04:34:28.562 [tid 7608] config: hook.Shim::SelfTest::Fill=off
04:34:28.562 [tid 7608] config: hook.Mars::GlobalConsts::LoadFile=off
04:34:28.562 [tid 7608] config: hook.Game::WeaponDictionary::Init=off
04:34:28.562 [tid 7608] config: hook.Game::SectionDictionary::SectionDictionary=off
04:34:28.562 [tid 7608] config: hook.Game::StrategyServer::ProcessFleetMovement=off
04:34:28.562 [tid 7608] config: hook.Game::TechTree::ProcessResearch=trace
04:34:28.562 [tid 7608] config: hook.Game::ServerPlayer::ComputeBudget=trace
04:34:28.562 [tid 7608] config: hook.Game::ServerPlayer::OnTechResearched=trace
04:34:28.562 [tid 7608] config: hook.Game::ServerSystem::ProcessTurn=trace
04:34:28.562 [tid 7608] config: hook.Game::StrategyServer::MoveFleet=trace
04:34:28.562 [tid 7608] config: trace.path=C:\SOTS\shim.trace.jsonl
04:34:28.562 [tid 7608] config: trace.inline_max=256
04:34:28.562 [tid 7608] config: trace.flush=always
04:34:28.562 [tid 7608] config: fpu.force=0x137f
04:34:28.562 [tid 7608] config: fpu.sample_ticks=on
04:34:28.640 [tid 7608] trace: C:\SOTS\shim.trace.jsonl (default mode trace, inline_max 256, flush always)
04:34:28.640 [tid 7608] hook: Mars_Application_Initialize rva=0x004a0e50 -> va=01320e50
04:34:28.640 [tid 7608] hook: MH_Initialize -> MH_OK
04:34:28.640 [tid 7608] hook: MH_CreateHook -> MH_OK (trampoline=003f0fe0)
04:34:28.672 [tid 7608] hook: MH_EnableHook -> MH_OK
04:34:28.672 [tid 7608] cfg: GlobalConsts hook ready (scale constant 0.017453292519943295)
04:34:28.672 [tid 7608] hook: Mars::GlobalConsts::LoadFile rva=0x004b73c0 mode=off (not installed)
04:34:28.672 [tid 7608] dict: dictionaries hook ready (crt new=6adc232b delete=6adc0174)
04:34:28.672 [tid 7608] hook: Game::WeaponDictionary::Init rva=0x0019a4c0 mode=off (not installed)
04:34:28.672 [tid 7608] hook: Game::SectionDictionary::SectionDictionary rva=0x00176f40 mode=off (not installed)
04:34:28.672 [tid 7608] research: ProcessResearch hook ready (Cost=00ffda00, node=0x34, rng=0x9cc, fpu_cw=0x027f)
04:34:28.672 [tid 7608] hook: Game::TechTree::ProcessResearch rva=0x001876c0 -> va=010076c0 MH_CreateHook -> MH_OK (trampoline=003f0fc0)
04:34:28.687 [tid 7608] hook: Game::TechTree::ProcessResearch MH_EnableHook -> MH_OK mode=trace
04:34:28.687 [tid 7608] techfx: OnTechResearched hook ready (regions=15, gate=0/0, fpu_cw=0x027f)
04:34:28.687 [tid 7608] hook: Game::ServerPlayer::OnTechResearched rva=0x00491790 -> va=01311790 MH_CreateHook -> MH_OK (trampoline=003f0fa0)
04:34:28.703 [tid 7608] hook: Game::ServerPlayer::OnTechResearched MH_EnableHook -> MH_OK mode=trace
04:34:28.703 [tid 7608] hook: Game::ServerPlayer::ComputeBudget rva=0x00463030 -> va=012e3030 MH_CreateHook -> MH_OK (trampoline=003f0f80)
04:34:28.718 [tid 7608] hook: Game::ServerPlayer::ComputeBudget MH_EnableHook -> MH_OK mode=trace
04:34:28.718 [tid 7608] hook: Game::ServerSystem::ProcessTurn rva=0x003598e0 -> va=011d98e0 MH_CreateHook -> MH_OK (trampoline=003f0f60)
04:34:28.718 [tid 7608] hook: Game::ServerSystem::ProcessTurn MH_EnableHook -> MH_OK mode=trace
04:34:28.734 [tid 7608] hook: Game::StrategyServer::MoveFleet rva=0x003d9ee0 -> va=01259ee0 MH_CreateHook -> MH_OK (trampoline=003f0f40)
04:34:28.734 [tid 7608] hook: Game::StrategyServer::MoveFleet MH_EnableHook -> MH_OK mode=trace
04:34:28.734 [tid 7608] hook: Game::StrategyServer::ProcessFleetMovement rva=0x003da9a0 mode=off (not installed)
04:34:28.734 [tid 7608] fpu: module init, entry cw=0x027f 53bit-double/nearest; force=on value=0x137f sample_ticks=on
04:34:28.734 [tid 7608] fpu: StrategyClient::EndTurn rva=0x00383be0 -> va=01203be0 MH_CreateHook -> MH_OK (trampoline=003f0f20)
04:34:28.750 [tid 7608] fpu: StrategyClient::EndTurn MH_EnableHook -> MH_OK
04:34:28.750 [tid 7608] fpu: StrategyServer::BeginProcessTurn rva=0x003d98e0 -> va=012598e0 MH_CreateHook -> MH_OK (trampoline=003f0f00)
04:34:28.765 [tid 7608] fpu: StrategyServer::BeginProcessTurn MH_EnableHook -> MH_OK
04:34:28.765 [tid 7608] fpu: StrategyServer::ProcessTurn rva=0x003dc6c0 -> va=0125c6c0 MH_CreateHook -> MH_OK (trampoline=003f0ee0)
04:34:28.781 [tid 7608] fpu: StrategyServer::ProcessTurn MH_EnableHook -> MH_OK
04:34:28.781 [tid 7608] fpu: DemoApp::OnTick rva=0x0049a640 -> va=0131a640 MH_CreateHook -> MH_OK (trampoline=003f0ec0)
04:34:28.797 [tid 7608] fpu: DemoApp::OnTick MH_EnableHook -> MH_OK
04:34:28.797 [tid 7608] selftest: Shim::SelfTest::Fill mode=off checksum=075ef0c3 records=0
04:34:28.812 [tid 7608] Application::Initialize called (this=02da8128)
04:34:29.562 [tid 7608] fpu: TICK BASELINE at OnTick (this=02da8128): cw=0x127f 53bit-double/nearest
04:38:23.424 [tid 7608] fpu: FORCE at StrategyClient::EndTurn (this=0e02e4b0): observed=0x127f 53bit-double/nearest -> requested=0x137f -> readback=0x137f 64bit-extended/nearest OK
04:38:26.502 [tid 7608] fpu: FORCE at StrategyClient::EndTurn (this=338724a0): observed=0x127f 53bit-double/nearest -> requested=0x137f -> readback=0x137f 64bit-extended/nearest OK
04:38:26.534 [tid 7608] fpu: FORCE at StrategyClient::EndTurn (this=33876d70): observed=0x137f 64bit-extended/nearest -> requested=0x137f -> readback=0x137f 64bit-extended/nearest OK
04:38:26.565 [tid 7608] fpu: FORCE at StrategyClient::EndTurn (this=33871d58): observed=0x137f 64bit-extended/nearest -> requested=0x137f -> readback=0x137f 64bit-extended/nearest OK
04:38:27.534 [tid 7608] fpu: FORCE at StrategyServer::BeginProcessTurn (this=0df4cbf8): observed=0x127f 53bit-double/nearest -> requested=0x137f -> readback=0x137f 64bit-extended/nearest OK
04:38:27.534 [tid 7608] fpu: sample at StrategyServer::ProcessTurn (this=0df4cbf8): cw=0x137f 64bit-extended/nearest
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