Exception runtime on cross targets (i386 / ARM32 / AArch64)

• Type: feature
• Status: done
• Owner: Antigravity [email protected]
• Unblocks: feature-cross-bootstrap-selfhost
• Opened: 2026-06-11 (user request)

Motivation

try/except, try/finally, and raise are unsupported on every cross target — EnableExceptionRuntime and the exception IR ops (IR_EXC_ENTER/LEAVE/MATCH/ STORE/CLEAR, IR_RAISE) are x86-64 machine code only. compiler.pas itself is built around try/except (the Error path), so this is the dominant wall for the cross self-host (see feature-cross-bootstrap-selfhost). Cross compiling the compiler currently fails fast: target arm32: builtin/exception runtime not yet supported.

Scope

• Port the exception runtime to i386, ARM32, AArch64. The frame model (BSS_EXC_TOP, EXC_FRAME_SIZE, setjmp/longjmp-style unwinding) is in exception_emit.inc / ir_codegen.inc as x86-64 byte emission.
• Two routes, mirroring the managed-runtime approach:
  1. Move the unwinder body into a portable Pascal helper in builtinheap (or a new builtinexc unit) so the cross backends only emit thin register-setup shims — preferred, matches the layout-RTTI precedent.
  2. Or hand-emit the per-arch unwinder. Heavier, avoid unless the Pascal route can't express the stack juggling.
• Wire the exception IR ops in ir_codegen386.inc, ir_codegen_arm32.inc, ir_codegen_aarch64.inc.
• Relax the per-target hasExceptions guard in ParseProgram.

Acceptance

A program using try/except/raise compiles and runs on i386, ARM32, AArch64 with output identical to x86-64 (oracle). New test/test_cross_exception.pas joins the cross suites.

Notes

• The unhandled-exception terminator and the unwind ABI must agree with the managed-local release that runs during unwinding (currently leaked on cross targets — see feature-cross-codegen-gaps).

Log

• 2026-06-11 — Completed implementation of exception runtime and branch patchers on all cross-compilation targets, verified via emulator testing suite (commit 53c87bb).