M3 emit TU: runtime spine skip-list + emit phase diagnostics (#2442)

[PurHur]

Problem

M3 emit-TU helper translation units can link but do not reliably execute natively yet: running the resulting binary still hits parse returned null and the probe falls back to emit_path=zend partial (tracked as the primary gate in #2442).

This issue documents the concrete emitter skip-list + diagnostics work needed on the emit-TU path, with clear file paths and repro commands.

Gates / repro

Minimal repro (harness-safe Docker):

./script/docker-exec.sh -- bash -lc '
  source script/php-env.sh
  script/apply-patches.sh
  BOOTSTRAP_M3_LINK_COMPILE_DRIVER=1   BOOTSTRAP_M3_COMPILE_DRIVER_REAL_LOWERING=1   BOOTSTRAP_M3_RUNTIME_COMPILE=1   ./script/bootstrap-selfhost-helloworld-probe.sh
'

Expected: emit_path=native.

Actual (today): emit_path=zend partial and/or parse returned null unless the runtime spine is bound to real-lowered symbols.

Scope (files / symbols)

• lib/JIT.php
  • emit-TU compile path: compileM3EmitTuMainNative() (bridge ordering dependency tracked by Self-host M3: defer emit-bridge IR until after spine pre-lower in compileM3EmitTuMainNative #2512)
  • runtime-spine filter hooks used by emit-TU: isM3EmitTuRuntimeSpineLoweringName()
  • log prefixes / phase markers used by probes (PHP_COMPILER_M3_EMIT_LOG_PREFIX, etc.)
• Emit TU entrypoints (smallest → largest):
  • test/bootstrap-aot/runtime_m3_emit_native_entry.php
  • test/bootstrap-aot/compile_smoke_m3_emit_native_entry.php
  • test/bootstrap-aot/helloworld_m3_emit_native_entry.php
• Probes / drivers:
  • ./script/bootstrap-selfhost-helloworld-probe.sh
  • make bootstrap-selfhost-runtime-compile-smoke
  • bin/compile.php (M3 env dispatch)

Done when

• Emit-TU helpers execute far enough to print their *: compile OK smoke line and exit 0
• ./script/bootstrap-selfhost-helloworld-probe.sh reports emit_path=native (strict off)
• BOOTSTRAP_M3_HELLOWORLD_STRICT=1 passes once Self-host M3: native emit-TU binaries run without startup crash #2442 is green

Dependencies

• Parent gate: Self-host M3: native emit-TU binaries run without startup crash #2442 (emit-TU native execute)
• Root-cause ordering: Self-host M3: defer emit-bridge IR until after spine pre-lower in compileM3EmitTuMainNative #2512 (bridge IR ordering) / VM init: Self-host M3: VM\Context native object allocation — complete C-floor for Runtime::initVmContext #2513 (VM\Context allocation)
• Allowlist batches: Self-host M3: compile-driver real lowering symbol batch tracker #1768 (do not duplicate symbol lists here)
• Epic: Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492

Made with Cursor

[PurHur]

Harness repro confirms remaining blocker after link:

BOOTSTRAP_M3_LINK_COMPILE_DRIVER=1 BOOTSTRAP_M3_COMPILE_DRIVER_REAL_LOWERING=1 \
  PHP_COMPILER_EMIT_HELPER_LINK=1 ./script/bootstrap-m3-emit-tu-execute.sh
# runtime_compile_smoke_m3_emit: parseAndCompile returned null

Parent: #2442. Closed duplicate #2508 (same repro).

[PurHur]

Partial overlap with merged #2526 (bridge ordering) and #2523 (emit-helper Runtime spine + operand-chain helpers). Remaining unique value here looks like isM3EmitTuRuntimeSpineLoweringName + BootstrapCompileSmokeM3Emit phase diagnostics — please rebase onto current master and re-run make bootstrap-selfhost-compile-smoke / helloworld probe before merge.

[PurHur]

Harness verification (May 26)

Progress: Identified LLVM 9 link crash root cause — eager compileM3EmitTuRuntimeSpineDecls PHP CFG pre-lower of initParsePipeline / Compiler::compile / markObjectConstructed during emit-helper link. Latest commit replaces that with native LLVM spine stubs and drops compiler-spine PHP lowering from emit TU compile path.

Still red:

./script/docker-exec.sh -- bash -lc '
  source script/php-env.sh && script/apply-patches.sh
  BOOTSTRAP_M3_LINK_COMPILE_DRIVER=1 \
  BOOTSTRAP_M3_COMPILE_DRIVER_REAL_LOWERING=1 \
  BOOTSTRAP_M3_RUNTIME_COMPILE=1 \
  ./script/bootstrap-selfhost-helloworld-probe.sh
'
# emit helper link failed (segfault) — emit_path=zend partial

Narrow repro:

PHP_COMPILER_SELFHOST_AOT=1 PHP_COMPILER_M3_COMPILE_DRIVER=1 PHP_COMPILER_EMIT_HELPER_LINK=1 \
  php bin/compile.php -o build/emit test/bootstrap-aot/runtime_m3_emit_native_entry.php
# exit 139 during JIT compile (after spine stubs register; crash in emitMainEntry IR)

Next: #2516 Batch A — real Runtime::parse / init* / standalone lowering; then re-enable bridge execute path for emit_path=native.