AOT-safe UndefinedVariableJitHelper guards without broken LLVM bridge (#10360)

[PurHur]

Strategic pillar

Pillar 4 Correctness — UndefinedVariable guards (#10360), AOT-safe

Aligns with #10533 compiler excellence map.

Priority

P2 — after #10523 merged; do not block initial AOT/web gate restore

Problem

Forward-porting #10360 / UndefinedVariableJitHelper compiled LLVM bridge breaks examples-aot-smoke (module verify on 000-HelloWorld).

Symptoms during phpc build:

• Global is referenced by parentless instruction (@__value__readString, @phpc_scope_var_init_*)
• Function return type does not match operand type of return inst
• Incorrect arg count on undefinedvariablejithelper__emitWarning

Root causes (triaged)

1. Compiled helper bridge passes (i8*, i32) but PHP emitWarning(string) expects __string__*.
2. UndefinedVariableRuntime::ensureStandaloneBodies duplicated StringTriggerErrorJit::implement during standalone init (corrupts module).
3. Nested helper compile without isolation pollutes outer CFG maps (fixed by NestedJitCompileScope in Fix AOT smoke: nested JIT helper compile isolation (#10343) #10498).

Safe interim approach (works for guards)

• JIT guards call UndefinedVariableRuntime::emitWarningForName() → UndefinedVariableJitHelper::warningMessage() SSOT + __compiler_trigger_error.
• Do not compile UndefinedVariableJitHelper.php into the standalone module until bridge signatures are correct.
• Do not register UndefinedVariableRuntime::ensureStandaloneBodies in Context (StringTriggerError already linked).

Done when

• Guards enabled on master with AOT + VM parity tests green
• Optional: php-in-PHP emitWarning LLVM bridge with correct __string__* arg (or drop bridge if unused)
• examples-aot-smoke + UndefinedVariableRuntimeShrinkTest + compliance cases pass

Related

• Fix AOT smoke: nested JIT helper compile isolation (#10343) #10498, Land PR #10498: NestedJitCompileScope + AOT/web smoke gates #10523, php-in-php: JIT UndefinedVariableWarning — route E_WARNING undefined-variable fetch through VmErrorReporter PHP not silent null (#1492) #10360, 🗺️ ROADMAP: Self-host + web-capable PHP subset (living) #78

[PurHur]

claim: cursor-agent-lane-a — starting this run

[PurHur]

Merged via #10543.

Fix: AOT-safe undefined-variable warnings — no compiled UndefinedVariableJitHelper in standalone modules; warningMessage() SSOT + __compiler_trigger_error inline bridge; skip guards during NestedJitCompileScope; includes #10498 nested JIT isolation base.

Verification:

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && ./script/examples-aot-smoke.sh'
# examples-aot-smoke: ok
vendor/bin/phpunit test/unit/UndefinedVariableRuntimeShrinkTest.php
# OK (3 tests)

Follow-up: Re-enable JIT guardBeforeRuntimeRead CFG once ScopeVariableAssignedFlags is AOT-safe (MiniWebApp LLVM verify on assigned-flag globals).

[PurHur]

claim: cursor-agent-lane-a — continuing this run (rebase incremental #10524 fixes onto master)

[PurHur]

Merged via #10543 — rebased incremental #10524 fixes onto master.

Verification:

• UndefinedVariableRuntimeShrinkTest — OK (4 tests)
• ScalarDimFetchRuntimeStandaloneTest — OK
• ./script/examples-aot-smoke.sh — ok (default slice)

Changes: skip duplicate StringTriggerError when __compiler_trigger_error already linked; skip undefined-var JIT guards during nested helper compile (PHP_COMPILER_SELFHOST_AOT=0); document Context standalone init omission.