xtensa: class instantiation (VMT + ctor) not supported

• Type: feature (backend parity)
• Track: A — compiler/ir_codegen_xtensa.inc
• Status: done
• Opened: 2026-07-03
• Found while: verifying docs/targets/esp32.md claims against the pinned compiler (Track D discovery loop).

Problem

TA.Create fails with target xtensa: class instantiation not yet supported. riscv32 got the full path on 2026-07-03 (alloc + VMT store + ctor call + IR_VIRTUAL_CALL, mirroring arm32); xtensa still has the stage-1 error in its tkGetMem branch and no IR_VIRTUAL_CALL case.

Scope

Port the riscv32/arm32 shape: GetMem class branch (VMT via EmitLoadDataRefXtensa + ctor call, windowed + Call0 arg conventions) and IR_VIRTUAL_CALL ([Self] -> VMT -> slot*8, callx8/callx0).

Acceptance

• The doc snippet (class + virtual Get) compiles for --target=xtensa --esp-profile=bare and boots correctly under tools/esp_run_bare.sh --chip esp32s3 (UART-verified vs x86-64 oracle).
• docs/targets/esp32.md caveat sentence removed.

Log

• 2026-07-03 — Filed by Track A while writing user docs.
• 2026-07-03 — Implemented (Track A). GetMem class branch: alloc, VMT via EmitLoadDataRefXtensa + s32i to [Self], ctor call with Self kept in its arg slot across the call (windowed: sp-constant XtSpillDepth slot; Call0: block kept across the call, dropped after). IR_VIRTUAL_CALL: [Self] -> VMT -> slot*8, callx8 (windowed, a10.. args, result a10->a2) / callx0 (Call0, a2.. args). 6-word arg cap matching the direct-call path. VMT slot patching was already generic (PatchDataU64). Acceptance verified: test/test_esp_class.pas (ctor + virtual override + multi-arg virtual) UART-matches the x86-64 oracle on esp32s3 AND esp32c3 under tools/esp_run_bare.sh; wired into make test-esp-bare. Windowed-ABI compile smoke ok. docs/targets/esp32.md caveat sentence updated.