php-in-php: JIT MemoryRuntime — route memory_get_usage()/gc_mem_caches() through VmMemory PHP not LLVM RSS/emalloc globals (#1492) #9377

Category

php-in-php | stdlib

Problem

memory_get_usage(), memory_get_peak_usage(), and gc_mem_caches() JIT/AOT lowering lives in lib/JIT/Builtin/MemoryRuntime.php (~300 lines LLVM): module globals for emalloc peaks, RSS reads via __phpc_memory_read_rss_bytes, and __phpc_gc_mem_caches. VM semantics already live in ext/standard/VmMemory.php (PHP).

This duplicates php-src memory accounting in LLVM instead of calling the existing PHP implementation through the JIT helper bridge pattern (Utf8JitHelper, HrtimeJitHelper, …). Blocks shrinking JIT surface and keeps VM/JIT divergence risk (#9333, #9336).

php-src reference

• ext/standard/basic_functions.c — PHP_FUNCTION(memory_get_usage), memory_get_peak_usage
• ext/standard/php_gc.c — PHP_FUNCTION(gc_mem_caches)
• Stubs: ext/standard/basic_functions.stub.php — enum MemoryUsage: int

Repro (today: VM works; issue is LLVM duplication + parity guards)

<?php
declare(strict_types=1);
$a = array_fill(0, 5000, str_repeat('x', 100));
unset($a);
var_dump(memory_get_usage(true));
var_dump(gc_mem_caches()); // VM returns 0 today — #9333

Commands

./script/docker-exec.sh php bin/vm.php repro.php
./script/docker-exec.sh php bin/jit.php repro.php   # uses MemoryRuntime LLVM

Scope (this repo)

• Delete/shrink: lib/JIT/Builtin/MemoryRuntime.php LLVM bodies (__phpc_memory_*, __phpc_gc_mem_caches)
• Route through: ext/standard/VmMemory.php via compiled helper (MemoryJitHelper or reuse VmMemory static entrypoints)
• Touch: ext/standard/memory_get_usage.php, memory_get_peak_usage.php, gc_mem_caches.php, lib/JIT/Builtin/MemoryUsageJit.php
• Do not add new logic in runtime/*.c — thin ABI trampoline only if unavoidable

Done when (php-src-strict)

• JIT/AOT memory_get_* and gc_mem_caches() call the same PHP SSOT as VM (helper bridge), not bespoke LLVM globals.
• docs/capabilities.md unchanged or notes JIT via PHP helper.
• Targeted compliance guard: real-usage bool + MemoryUsage enum rejection (Stdlib: memory_get_usage() accepts arbitrary int-backed enum — must reject non-MemoryUsage (ext/standard/basic_functions.c) #9336) green on VM and JIT.
• PR body lists lines removed from MemoryRuntime.php (target: delete file or <50-line linker stub).

Refs: #1492, #3134, #5377, #9333, #9336