php-in-php: JIT NullsafeHelper — route ?-> LLVM through VmNullsafe PHP not ~96-line monolith (#1492)

[PurHur]

Category

php-in-php · runtime

Problem

Nullsafe property/method access ($obj?->prop, $obj?->m()) lowers through lib/JIT/NullsafeHelper.php (~96 lines LLVM) duplicating short-circuit semantics already expressible in VM PHP. Per #1492 PHP-in-PHP strategy, JIT should compileUnit() a PHP helper and keep LLVM as a thin trampoline — shrink parallel LLVM maintenance.

php-src reference

• php/php-src Zend/zend_compile.c — nullsafe opcodes (ZEND_JMP_NULL chain)
• VM SSOT: lib/VM/Nullsafe.php (or equivalent nullsafe dispatch used by bin/vm.php)

Repro (migration metric)

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
wc -l lib/JIT/NullsafeHelper.php
grep -c "function " lib/JIT/NullsafeHelper.php
php bin/jit.php -r "
class C { public function f(): int { return 42; } }
\$c = null;
var_dump(\$c?->f());
\$c = new C();
var_dump(\$c?->f());
" 2>/dev/null
'

Today: LLVM bodies in NullsafeHelper.php; post-migration should delegate to compiled PHP like #10078 InstanceOfHelper bridge pattern.

Scope (this repo)

Path	Work
lib/JIT/NullsafeHelper.php	Replace LLVM short-circuit with compileUnit() of PHP helper
lib/VM/Nullsafe.php (or new NullsafeJitHelper.php)	SSOT semantics shared with VM
lib/JIT/Builtin/Type.php	Trampoline registration
Tests	Existing nullsafe JIT compliance PHPTs stay green

Forbidden: growing runtime/*.c for nullsafe — PHP lowering only.

Done when

• NullsafeHelper.php LLVM line count drops to trampolines + ABI glue (target ≥50% reduction)
• JIT nullsafe repro matches VM on property + method chains
• ./script/ci-fast.sh green; no new C symbols in runtime/

Related

• php-in-php: JIT InstanceOfHelper — route instanceof through VmTypeCheck PHP not ~217-line LLVM (#1492) #10078 InstanceOfHelper · php-in-php: JIT ErrorRaise + TypeErrorRaise — route catchable Error/TypeError through VmException PHP not ~920-line LLVM (#1492) #9778 ErrorRaise · Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492 self-host

[PurHur]

claim: PHP Runtime → PHP — starting this run.

[PurHur]

Merged via #10162

PHP-in-PHP migration: value-box nullsafe short-circuit (TYPE_NULL + nullable-uninit) now routes through compiled NullsafeJitHelper via NullsafeRuntime bridge. NullsafeHelper.php shrunk 96 → 79 lines; deleted isNullableUninitializedProperty LLVM. Object null-ptr check remains thin ABI glue. No new runtime/*.c symbols.

Verification:

• php vendor/bin/phpunit test/unit/NullsafeRuntimeShrinkTest.php — OK (3 tests)
• JIT repro: NULL / int(42) on nullsafe method call one-liner
• php bin/jit.php + php bin/vm.php test/fixtures/jit/nullsafe_issue_repro.php — agree
• php script/bootstrap-inventory.php --check — OK 2830/2830
• php script/check-selfhost-spine-coverage-sync.php — OK