Self-host M3: emit-TU parseAndCompile returns null (runtime_m3_emit_native_entry)

[PurHur]

Problem

M3 emit-helper translation units link, but native execute fails before AOT emit completes. Harness repro (May 2026):

script/apply-patches.sh
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

Observed:

runtime_compile_smoke_m3_emit: parseAndCompile returned null (CFG/compile spine)
runtime_compile_smoke_m3_emit: native emit failed at phase=parseAndCompile

HelloWorld probe still reports emit_path=zend partial with NEXT_LOWER: M3 emit TU runtime init.

Parent tracker #2442 covers emit-TU startup crash / execute; this issue owns the parseAndCompile null failure mode on the smallest emit entry first.

Goal

runtime_m3_emit_native_entry.php (then compile_smoke_m3_emit_native_entry.php, helloworld_m3_emit_native_entry.php) completes native emit:

runtime_compile_smoke_m3_emit: compile OK
emit_path=native

Strict gates (#1937, #1968) can follow once all three entries pass.

Implementation hints

Piece	Path	Notes
Smallest TU	test/bootstrap-aot/runtime_m3_emit_native_entry.php	Bisect here first
Driver	test/bootstrap-aot/runtime_compile_smoke_m3_emit.php	Calls Runtime::parseAndCompile
JIT allowlist	lib/JIT.php	m3CompileDriverSpineDenyNames(), isM3CompileDriverRealLoweringName()
Runtime	lib/Runtime.php	Parser → CFG → Compiler path
Batch tracker	#1768	Symbol allowlist growth (parallel)
Execute umbrella	#2442	Link both ways; close together when probes green

Suggested bisect order

1. runtime_m3_emit_native_entry.php — parseAndCompile null
2. compile_smoke_m3_emit_native_entry.php
3. helloworld_m3_emit_native_entry.php
4. make bootstrap-selfhost-helloworld → emit_path=native

Gates

Gate	Command
Emit-TU execute	BOOTSTRAP_M3_LINK_COMPILE_DRIVER=1 BOOTSTRAP_M3_COMPILE_DRIVER_REAL_LOWERING=1 ./script/bootstrap-m3-emit-tu-execute.sh
HelloWorld partial	make bootstrap-selfhost-helloworld
M3 strict	BOOTSTRAP_M3_HELLOWORLD_STRICT=1 make bootstrap-selfhost-helloworld
M4 full loop	make bootstrap-loop-probe (blocked until M3 strict)

Done when

• bootstrap-m3-emit-tu-execute.sh exits 0 (runtime entry first)
• make bootstrap-selfhost-helloworld reports emit_path=native without strict env
• Self-host M3: native emit-TU binaries run without startup crash #2442 can close when all emit TUs execute; Self-host M3: native bin/compile.php execute smoke (post-#2442 emit-TU) #2466 unblocked

Repro (Docker)

./script/docker-exec.sh -- bash -lc '
  script/apply-patches.sh
  source script/php-env.sh
  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
'

Links

• Self-host M3: native emit-TU binaries run without startup crash #2442 · Self-host M3: compile-driver real lowering symbol batch tracker #1768 · Self-host M3: lib/Runtime.php native compile batch (parser front-door after #2216) #2294 ✅ (runtime smoke probe landed)
• Epic Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492 · docs/bootstrap-m5-fast-path.md

[PurHur]

Duplicate of #2442 (emit-TU execute umbrella) and active implementation tracker #2506 (runtime spine skip-list + phase diagnostics). Harness repro (parseAndCompile returned null) is tracked there — closing to keep one emit-TU workstream.