cmd/llvmplugin: test X86 ABI0 entry argument maps

[zhouguangyuan0718]

Summary

• add a GoABI0 three-pointer statepoint fixture using the GoALLC GC strategy
• exercise final GoObj emission through the statepoint plugin
• use goallc-objview to verify ArgsPointerMaps, LocalsPointerMaps, and stack-map query selection

Dependency

Draft: this test requires goallc/llvm-project#68 and a release payload containing that change. The current pinned payload is expected to fail at final GoObj emission with an invalid stack-growth argument pointer slot.

Expected maps

• FuncInfo Args is 24 bytes
• entry ArgsPointerMaps bits are 0, 1, and 2
• the ordinary-call argument map and both locals maps are empty
• morestack selects map 0 and the ordinary call selects map 1

Validation with patched payload

• fresh Go make.bash passed
• full plugin CTest: 67/67 passed, including the new GoObj and ObjView tests
• internal/runtime/maps O2 package tests passed initially and in 3/3 repeat runs
• math/big production O2 build passed; the separate test-only rounding libcall limitation remains

[zhouguangyuan0718]

Dependency CI behaved as expected with pinned LLVM revision 90e5e5c7c626: both linux-amd64 and linux-arm64 reached Test pass plugin, then X86ABI0EntryArgsGoObj failed with GoObj stack-growth statepoint contains an invalid argument pointer slot. The ObjView failure is a cascade because the object was not produced. Validation with the patched payload passes both tests and the full 67/67 suite.