Cross compiler.pas probe walls

• Type: feature
• Status: done
• Owner: codex
• Unblocks: feature-cross-bootstrap-selfhost
• Opened: 2026-06-13 (after arm32 SysOpen family milestone)

Motivation

The full cross self-host fixedpoint gate is still too large to attack as one step. Before a target can self-host under QEMU, the native compiler must at least be able to compile compiler/compiler.pas for that target.

This ticket tracks the current stage-1 probe walls precisely and keeps them from getting buried across several broader backend tickets.

Current Probe

Run from repo root:

for arch in i386 aarch64 arm32; do
  ./compiler/pascal26 -dPXX_MANAGED_STRING --target=$arch \
    compiler/compiler.pas /tmp/compiler_$arch
done

Baseline results after commit 3047bdd:

i386    line 86    target i386: only ordinal/pointer/string variables supported yet
aarch64 line 86    target aarch64: non-integer binop not yet supported
arm32   line 35914 target arm32: builtin/special call not yet supported

Current results:

i386    ok         emits /tmp/compiler_i386
aarch64 ok         emits /tmp/compiler_aarch64
arm32   ok         emits /tmp/compiler_arm32

Line numbers are from the expanded compiler source stream reported by pascal26, not necessarily direct line numbers in compiler/compiler.pas.

Scope

• Add or keep a repeatable probe recipe that reports the current wall for each Linux cross target.
• Burn down the three current stage-1 walls enough that compiler.pas emits a target binary for i386, AArch64, and ARM32.
• Keep focused oracle tests for each backend behavior fixed on the way.
• Avoid folding in the full QEMU self-host fixedpoint. That remains feature-cross-bootstrap-selfhost once stage-1 emits exist.

Likely Ownership Split

• i386 line 123: Int64/large-constant support in the FloatToStr builtin body. The previous fixed-string admission, fixed-string result, and internal Double parameter walls have been cleared.
• AArch64 line 86: non-integer binop support on an early compiler expression; likely a legacy-string / pointer-sized expression lowering gap.
• ARM32: stage-1 emit is clear. The former line 35914 wall was ArgCount / ParamStr argv handling.

Acceptance

• compiler/compiler.pas compiles successfully with -dPXX_MANAGED_STRING --target=i386.
• compiler/compiler.pas compiles successfully with -dPXX_MANAGED_STRING --target=aarch64.
• compiler/compiler.pas compiles successfully with -dPXX_MANAGED_STRING --target=arm32.
• Existing make test, cross target suites, and progress check remain green.

Log

• 2026-06-13 — ticket opened and claimed by Codex after the SysOpen-family milestone. Baseline probe results recorded above.
• 2026-06-13 — advanced the i386 probe from line 86 to line 123 by admitting legacy fixed strings in the i386 scalar/result gates and adding internal Single/Double parameter stack handling. Added test_i386_float_params and kept make test-i386 green.
• 2026-06-13 — cleared the ARM32 line 35914 wall. ARM32 now saves the initial stack pointer, lowers ArgCount, managed ParamStr, and fixed-string ArgStr, and emits compiler/compiler.pas with --target=arm32. Added test_arm32_arg_runtime and kept make test-arm32 green.
• 2026-06-13 — cleared the i386 and AArch64 stage-1 emit walls. The burn-down covered fixed-string concat/results on AArch64, managed-string SetLength, constant in lowering, managed aggregate local zero-init, LoadFile, the SysOpen/SysWrite/SysClose/SysFchmod family, and argv runtime (ArgCount, managed ParamStr, fixed ArgStr) on the remaining Linux cross targets. compiler/compiler.pas now emits for i386, AArch64, and ARM32 with -dPXX_MANAGED_STRING. Added i386/AArch64 oracle coverage for setlen-str, in-operator, loadfile, sysopen-family, and args; make test-i386 test-aarch64 test-arm32 is green.

Closure (2026-06-16)

feature-cross-bootstrap-selfhost is DONE — byte-identical self-fixedpoint on i386/aarch64/arm32 (and x86-64). This ticket existed to unblock that gate, so its blocking purpose is met: every code path compiler.pas itself exercises now works byte-identically on all cross targets. Residual gaps are only in language features the compiler does NOT self-use (e.g. classes, interfaces, some param/ ABI shapes user code hits) — those move to the language-surface hardening effort driven by the synthetic conformance harness ([[feature-synthetic-feature-matrix-test]]). Closed.