[Know-It-All-Brother]

Part of the Ampere accuracy series (#2040). It depends on #2041 for the test: the commits before this PR's own are #2041's and drop out once it lands, so this PR's own change is the last commit.

What and why

cvt.sat.s8.s32 and its kin compile to I2I.<type>.S32.SAT (opcode 0x238), which clamps a 32-bit integer to a narrower type's range. The translator had no emitter for it, so a shader with one failed to translate. The existing entry named I2I at 0x013 is really IABS.

AI2i clamps to the destination's limits, with the type in bits 76–77 (U8, S8, U16, S16), as every I2I in CuAssembler's sm_75 to sm_86 instruction lists has, and the fixture's two encodings agree. A signed result comes out sign-extended in the 32-bit register, as F2I's narrow results do. No other form appears in those lists, so other bits fail the shader rather than guessing. It costs one clamp.

Reference entry: "I2I clamps an integer to a narrower type" in docs/reference/shaders.md.

How to verify

DMSH_TEST_XLATE=dm/gfx/tools/dmsh_xlate_bin/dmsh_xlate AMPERE_ORIN_ONLY=i2i_s8_sat,i2i_u16_sat python3 dm/gfx/tests/test_dmsh_ampere_orin.py

i2i_s8_sat and i2i_u16_sat failed to translate on main and now match the Orin in all 1,024 lanes, so they come out of KNOWN. One thing the data can't show: both programs sign-extend or mask the result right after the I2I, so what the GPU leaves in the upper bits of a narrow result rests on the F2I convention. U8 and S16 destinations aren't in the fixture.

Checked

• Tests: test_dmsh_ampere_orin.py; every other test_dmsh_* gives the same result as on main (test_dmsh_ampere_mem.py, test_dmsh_meshstage.py and test_dmsh_pairs.py fail on main the same way); test_nsp_chain.py, test_xlate_anycpu.py, test_docs.py.
• Translator: the dlls are rebuilt from this tree with .NET 10; tool_lock.py --update-lock and dmsh_chain.py --header were run (chain e2f3ca1adb6d).
• Devices and OS: MacBook Pro M5 Max, macOS 27.
• regress.py: not run. My only local Switch 2 build's shader package comes from an older shader split than main's map, so main's chain can't build it. Ocarina of Time's build already translates every shader, so it can't contain this instruction.
• Games run: none.

Docs

• docs/reference/shaders.md has the entry, and python3 dm/tools/docs_symptoms.py was run
• A chain tool changed: dmsh_chain.py --header was run, and dmsh_chain.h, the translator dlls and the lock are part of the change
• No game files, keys or data extracted from a game