JIT: Dynamic hashtable read/write for $_GET[$key] and $_POST[$key]

[PurHur]

Problem

JIT/AOT already fold literal superglobal access:

• $_GET['name'] → compile-time string (SuperglobalInit::compileTimeReadString)
• isset($_GET['name']) → constant fold when key is literal

Real apps use dynamic keys:

$key = 'page';
$page = $_GET[$key];
if (isset($_POST[$field])) { ... }

IssetHelper and array-dim lowering must call __hashtable__ runtime lookups when the offset is not a compile-time literal.

Goal

Runtime hashtable get/set/isset for superglobals (and general __hashtable__) with non-constant keys in JIT/AOT.

Tasks

• Extend HashTableHelper with dynamic string key load/store
• Wire ArrayDimFetch in lib/JIT.php for TYPE_HASHTABLE containers
• IssetHelper::compileHashTableOffsetIsSet — dynamic key path (not only compileTimeOffsetIsSet)
• Depends on Web: Runtime-populated superglobals for JIT and AOT (per-request $_GET/$_POST) #49: tables must be populated per request before reads
• PHPT: $_GET[$k] with $k from variable; two requests, different output
• Type errors for non-string keys (match PHP subset documented)

Acceptance criteria

foreach (['a', 'b'] as $k) {
    if (isset($_GET[$k])) echo $_GET[$k];
}

Compiles in JIT; correct output when superglobals refreshed per request.

Key files

• lib/JIT/IssetHelper.php, lib/JIT/HashTableHelper.php, lib/JIT/SuperglobalInit.php

Related

• Web: Runtime-populated superglobals for JIT and AOT (per-request $_GET/$_POST) #49 Runtime superglobals
• Web: Dynamic isset/empty on $_GET and $_POST keys in JIT #70 Dynamic isset/empty