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fix(cpu): store PC plus six for Thumb empty register lists

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Correct the shared Thumb block-store PC offset from four to six bytes. Retain ARM PC+12, 64-byte empty-list writeback, normal load behavior, alignment, flags, and nominal timing. Correct prior internal expectations and add original regressions for bases, banks, alignment, ROM windows, writeback, clocks, and atomic errors.

The pinned public Thumb ROM now passes its unchanged ARM-state r7 checkpoint after 807 steps and 4170 nominal cycles. The pinned ARM ROM still passes. Neither external ROM nor result assertion is modified.

Validated on Darwin arm64: 848 workspace tests in debug and release; 779 core/demo tests separately; 21 Python adapter tests; both public suites in both profiles; native ROM-window tests; all ten demo window smoke tests; fmt, clippy, rustdoc, and local documentation links.
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0xrsydn 2026-10-05 20:47:20 +07:00
commit 3d67b136ba
12 changed files with 222 additions and 17 deletions
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docs/testing.md
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@ -65,7 +65,11 @@ They verify loaded-value precedence, preserved flags, unchanged stores, nominal
ARM open-bus regressions cover unused-range boundaries, PC+8 source regions, byte lanes, signed/unaligned loads, writeback, and block loads.
They check branch-target resampling, missing lookahead, skipped conditions, nominal timing, device progress, and retained host/fetch/Thumb/DMA diagnostics.
The pinned public ARM ROM now reaches its completion checkpoint with r12 = 0 in debug and release builds.
This does not establish public Thumb, timing, graphics, BIOS, or commercial-game compatibility.
The pinned public Thumb ROM also reaches its ARM-state checkpoint with r7 = 0 in both builds.
Empty-list Thumb regressions cover PC+6, all low bases and processor modes, banked stacks, both code alignments, and unaligned data.
They check one-word writes, 64-byte writeback, ROM windows, the following PC operand, nominal timing, and atomic errors.
Existing ARM empty-list and Thumb empty-load tests continue to pass. `PUSH {lr}` retains its normal link value.
These results do not establish public timing, memory, graphics, BIOS, or commercial-game compatibility.
ROM-runner tests use temporary files containing original instructions, without Nintendo assets or a desktop session.
They check file-size boundaries, bounded reads, short reads, I/O errors, paths, symlinks, and read-only loading.