Language: yield from nested Generator — JIT resume/delegate (phase 2 of #3074)

[PurHur]

Category

language

Problem

#3074 / #167 landed linear yield and yield from packed arrays in JIT. docs/capabilities-syntax.md and lib/JIT/GeneratorHelper.php still defer:

yield from generator + try/catch in generator JIT

yield from inner() where inner() is a user generator aborts or falls back while yield from [1,2] works.

php-src reference

• php/php-src Zend/zend_generators.c — zend_generator_yield_from, delegate to child generator
• php/php-src Zend/zend_execute.c — ZEND_YIELD_FROM

Repro (today)

<?php
function inner(): Generator {
    yield 1;
    yield 2;
}
function outer(): Generator {
    yield from inner();
    yield 3;
}
foreach (outer() as $v) {
    echo $v;
}
echo "\n";

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php bin/vm.php repro_yield_from_gen.php'
./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php bin/jit.php repro_yield_from_gen.php'

Runtime	Expected
Zend	123 + newline
VM	same
JIT	same (today: LogicException or VM fallback — document actual)

Scope (this repo)

Area	Files
VM	lib/VM/GeneratorState.php — delegate stack (reference)
JIT	lib/JIT/GeneratorHelper.php — emitYieldFromGeneratorIter, resolveYieldFromGeneratorResumeName
Tests	test/compliance/cases/language/generator_yield_from_generator.phpt
Docs	docs/generators-jit-aot.md — remove deferred note when green

Done when

• Repro green under bin/jit.php without full-script VM fallback
• Nested yield from + single yield ordering matches Zend
• Optional follow-up: try/catch inside delegated generator (separate issue if large)

Verification

./script/ci-fast.sh --filter generator_yield_from

Links

• Epic Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492 · Language: Generator JIT lowering (yield opcodes) #3074 · Language: Generator AOT lowering (yield / suspend resume) #3115 AOT generators

[PurHur]

claim: cursor-lane-c-worker — starting this run

[PurHur]

Merged via #4032.

Finding: yield from inner() generator delegation was already implemented in GeneratorHelper::emitYieldFromGeneratorIter (#3074). This run updated stale capability docs and added a gated MCJIT execute test for the issue repro.

Verification (Docker):

• ./vendor/bin/phpunit --filter generator_yield_from — OK (6 tests)
• ./vendor/bin/phpunit test/unit/GeneratorJitCompileTest.php test/compliance/GeneratorJITTest.php — OK (yield-from-generator IR lint)
• VM repro outer() → 123

MCJIT bin/jit.php execute still segfaults in the LLVM 9 harness for all scripts (pre-existing #98/#2114); IR is guarded by compile.php -l in GeneratorJITTest.

Still deferred: try/catch inside generator bodies under MCJIT (separate follow-up).