ESP32 managed-feature port (xtensa + riscv32, qemu-validated)

• Type: feature
• Status: done
• Owner: —
• Opened: 2026-06-17
• Commits: ae9727f, 84ceb95, 54bc954, e28857c, 8152eac, a346c2b, bb23475, 239ccc2, 8256282

Motivation

Stage-1 ESP codegen (done/feature-target-esp32) only ran procs/params/calls/ loops/ifs/globals/int arith. This arc brings the managed-runtime spine to both ESP ISAs and, critically, establishes a runnable output-equality harness so ESP features are validated against the x86-64 oracle on real Espressif QEMU, not just llvm-mc encodings.

What landed

Harness. tools/esp_run.sh [--chip esp32s3|esp32c3] <prog.pas> compiles for the chip's ISA, links it as app_main via examples/esp32/hello-{s3,c3}, merges a flash image, boots it under the Espressif qemu-system-{xtensa,riscv32} fork, and prints exactly what app_main wrote (IDF banner + trailing qemu signal stripped, serial CRLF→LF). Output is diffed against the program's x86-64 run. Heavy / env-dependent (needs . ~/esp/esp-idf/export.sh), so NOT in make test.

Codegen / runtime, both ESP backends (unless noted):

• Native div/mod — xtensa quos/rems (LX7, esp-as encodings; llvm-mc lacks them) + SAR shifts ssl/sll,ssr/srl; riscv already had M-extension. Baseline = S2+/Cx+; LX6 soft-fallback deferred (feature-esp-isa-baseline- softfallback).
• Xtensa windowed-ABI constant-sp fix — the codegen moved sp for a manual expression stack, desyncing the window spill area at [sp-16] past 4-deep calls (Guru Meditation). Now keeps sp constant: expression stack in a reserved frame region (sp-relative, XtSpillDepth), entry+addmi one-shot frame, bare retw. Unblocked all nested/recursive Pascal on real S3.
• Heap: static-arena HeapMmap (64 KiB BSS, no mmap); New/GetMem/Dispose; IR_TERMINATE (early Exit / AN_HALT self-loop).
• Dynamic arrays: lean unmanaged-element PXXDynSetLen; SetLength/Length/ index; IR_LEA derefs local dynarrays + open-array value params to the handle.
• array of const writeln: IR_DEFAULT_MEM→PXXMemZero, IR_SLOTADDR, TVarRec vector build, Length/field over the open-array param.
• Ord/Chr/Integer()/LongWord() type-pun passthroughs.

Validated (qemu, both esp32s3 + esp32c3, == x86-64 oracle)

test_esp_{print,hello,heap,dynarray,aoc,cast}.pas — ints/recursion (1..5/15), fixed bytes (PXX/OK), heap (100/20/3/123), dynarrays (5/150/2/30), array-of-const writeln (1 2 3 / 42 -7 100 999), casts (ABZ!). make test + self-host byte-identical after every step.

Acceptance

• Both ESP ISAs run the managed-feature spine (heap → dynarrays → array-of-const → portable writeln) under Espressif QEMU with output identical to x86-64. ✓
• Repeatable harness (tools/esp_run.sh). ✓

Notes / follow-ups

• Managed strings (tyAnsiString, the PXX default — PXX_MANAGED_STRING is seeded by PasInitDefines) are NOT yet ported: the PXXStr* runtime is guarded out on ESP, so s := 'lit' stores the frozen-literal pointer and Length reads junk. Tracked in feature-esp32-managed-strings.
• Records-by-value, classes/VMT, sets, exceptions, RTTI on ESP — later.
• Real-hardware flash (vs qemu) — feature-esp32-idf-xtensa.