php-in-php: JIT SpaceshipCompareJit — route <=> through VM compare PHP not ~1.2k-line LLVM (#1492)

[PurHur]

Category

php-in-php | language | runtime

Problem

The spaceship operator (<=>) JIT lowering is lib/JIT/Builtin/SpaceshipCompareJit.php (~1.2k lines LLVM), ported from former lib/AOT/runtime/phpc_spaceship.c. VM semantics SSOT is PHPCompiler\VM\Variable compare/spaceship helpers in PHP.

Enum ordering regressions (#9288) and mixed-type compares must be fixed twice while LLVM tables diverge from VM. PHP-in-PHP first: compile the VM compare path for JIT/AOT instead of maintaining parallel type-switch LLVM.

php-src reference

• Zend/zend_operators.c — compare_function, object/enumeration spaceship
• Zend/zend_enum.c — backed enum comparison ordering

Repro

<?php
declare(strict_types=1);
enum E: int { case A = 1; case B = 2; }
var_dump(E::A <=> E::B);   // Zend: -1 (see #9288 if inverted)
var_dump(null <=> 1);      // -1
var_dump('a' <=> 'b');     // -1

Commands

./script/docker-exec.sh php bin/vm.php repro.php
./script/docker-exec.sh php bin/jit.php repro.php

Scope (this repo)

• Delete/shrink: lib/JIT/Builtin/SpaceshipCompareJit.php and lib/JIT/Builtin/SpaceshipRuntime.php linker stubs
• Route through: shared PHP compare helper (new CompareJitHelper or VmVariableCompare extraction under lib/VM/)
• Touch: lib/Compiler.php spaceship opcode lowering, JIT compare call sites
• Coordinate with enum ordering fix Regression: enum relational operators — < and <=> order inverted vs Zend (re-#9016, zend_enum.c) #9288 — single SSOT

Done when (php-src-strict)

• JIT/AOT <=> uses compiled PHP compare helper; enum/object/array cases match VM and Zend on repro + Regression: enum relational operators — < and <=> order inverted vs Zend (re-#9016, zend_enum.c) #9288 guard.
• PR body: lines removed from SpaceshipCompareJit.php / any C spaceship symbols.
• VM-only fallback acceptable only behind explicit gap doc until JIT bridge lands.

Refs: #1492, #5185, #9288

[PurHur]

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

[PurHur]

Merged via #9422

What landed (phase 1 — scalar SSOT):

• New lib/VM/CompareJitHelper.php — PHP SSOT for long/double/string/mixed-kind spaceship
• SpaceshipRuntime compiles CompareJitHelper before spaceship LLVM dispatch
• SpaceshipCompareJit scalar paths call compiled PHP helpers (removed inline strcmp/strtod/JitFloatCompare scalar tables)

Still LLVM (phase 2): object property walks + hashtable iteration — ObjectEntry/HashTable instance-method JIT calls do not compile yet.

Verification:

vendor/bin/phpunit test/unit/SpaceshipCompareJitHelperTest.php — OK (4 tests)
php bin/vm.php test/repro/issue_9381_spaceship_compare_jit.php — OK
php bin/jit.php test/repro/issue_9381_spaceship_compare_jit.php — OK (matches VM)
make bootstrap-selfhost-vm-driver-execute-probe — OK