Language: while, do-while, and for loops (CFG → VM → JIT)

[PurHur]

Problem

lib/Compiler.php::compileStmt() only lowers Jump, JumpIf, and Switch_. Any while, do-while, or for statement hits:

LogicException: Unknown Stmt Type: Stmt\While

Web apps use loops for pagination, template rows, retry logic, and route tables. #115 (break/continue) depends on this.

Goal

Support standard PHP loop forms in VM and JIT:

for ($i = 0; $i < count($items); $i++) { /* ... */ }
while ($row = next($rows)) { /* ... */ }
do { /* ... */ } while ($cond);

Tasks

• Add opcodes (or reuse TYPE_JUMP / TYPE_JUMPIF graph) for loop entry, condition, increment, and exit blocks
• Lower PHPCfg\Op\Stmt\While_, For_, DoWhile in compileStmt()
• VM execution in lib/VM.php (block linking + scope for loop variables)
• JIT lowering in lib/JIT.php (phi nodes for loop-carried values)
• PHPT compliance: nested loops, break/continue integration (Language: break and continue for loops and switch #115)
• Document in docs/capabilities.md when matrix lands (DevEx: Builtin capability matrix (VM / JIT / AOT per function) #176)

Acceptance criteria

$s = 0;
for ($i = 0; $i < 5; $i++) { $s += $i; }
echo $s; // 10

Runs identically in bin/vm.php and bin/jit.php.

Dependencies

• Blocks: Language: break and continue for loops and switch #115 break/continue
• Related: Language: Implement foreach (CFG → VM → JIT) #53 foreach (separate iterator lowering)

Files

• lib/Compiler.php, lib/OpCode.php, lib/VM.php, lib/JIT.php
• test/compliance/cases/language/