JIT: try/catch/finally lowering phase 2 (#57, after VM #2084)

[PurHur]

Category

language

Problem

#57 tracks VM try/catch/finally lowering; #2084 ✅ adds compliance PHPTs for phase 1. JIT still has no exception unwind model — phpc serve --jit and JIT compliance for caught exceptions remain blocked after VM lands.

#195 throw expressions need a catch target in JIT for 007-ThrowsWeb matrix parity (#2103). VM path for 007 is largely green; JIT column is the gap.

php-src reference

• Zend/zend_compile.c — zend_compile_try(), catch/finally op array layout
• Zend/zend_exceptions.c — zend_throw_exception_internal, unwind stack
• Zend/zend_execute.c — ZEND_HANDLE_EXCEPTION, ZEND_FAST_RET, finally before catch
• LLVM analogue: landing pads / invoke + personality (see docs/capabilities-syntax.md try row)

Repro (today)

<?php
try {
    throw new Exception('boom');
} catch (Exception $e) {
    echo $e->getMessage();
}

# VM — passes (#2084 compliance)
./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php bin/vm.php repro.php'
# → boom

# JIT — gap (VM fallback or LogicException depending on build)
./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php bin/jit.php repro.php'

# Compliance gate
./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && vendor/bin/phpunit test/compliance/JITTest.php --filter try_catch'

Done when JIT repro prints boom without requiring full-VM fallback for this script.

Finally slice:

<?php
try {
    throw new Exception('x');
} finally {
    echo 'fin';
}

Scope

Phase A — VM fallback bridge (fastest slice)

Layer	Files	Notes
JIT	lib/JIT.php	TYPE_TRY / catch: documented VM bridge or requiresVmLowering
Registry	lib/Lint/UnsupportedRegistry.php	Narrow try/catch kinds when bridge exists
Caps	script/capability-syntax.php	JIT row: partial until phase B

Phase B — LLVM landing pads (full parity)

Layer	Files	Notes
Compiler	lib/Compiler.php	Exception edges for JIT EH tables
JIT	lib/JIT.php, lib/JIT/TryCatchHelper.php	Landing pads / invoke-unwind (LLVM 9)
AOT	lib/AOT/	Share EH metadata (#2101)
Tests	test/compliance/cases/php/basic/try_catch_*.phpt	Shared with #2084

Done when

• JIT repro (bin/jit.php repro.php) prints boom for basic try/catch
• vendor/bin/phpunit test/compliance/JITTest.php --filter try_catch green on php-compiler:22.04-dev
• Finally block runs before catch on JIT path (or documented deferral with linked issue)
• docs/capabilities-syntax.md try row JIT = yes (or partial + bridge documented)
• ./script/ci-local.sh LLVM tail includes JIT try/catch when @group llvm runs

Verification

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && vendor/bin/phpunit test/compliance/JITTest.php --filter try_catch'
make test-harness ARGS='--filter try_catch'
./script/ci-fast.sh

Dependencies

• Testing: try/catch compliance PHPT pack (phase 1 of #57) #2084 ✅ PHPT pack merged first
• Language: try/catch/finally lowering #57 VM lowering (parent)
• Language: throw expressions and Exception object propagation #195 throw opcode stable
• JIT: empty user class + throw/catch for 007 ValidationError (serve --jit parity) #2167 — 007 JIT empty-class (parallel)
• Blocks full Web: JIT/AOT mode for bin/serve.php (compile per script on first request) #207 serve--jit with Language: JIT include/require compile-time lowering (#54 follow-up) #475 / JIT: Project include lowering for 003-MiniWebApp (phpc serve --jit blocked on #475) #1770

Links

• ROADMAP 🗺️ ROADMAP: Self-host + web-capable PHP subset (living) #78 Phase 2 language
• Examples: 007-ThrowsWeb — throw/catch presenter app (post-#195/#57) #2076 007-ThrowsWeb · Testing: THROWSWEB_AOT_LINK_GATE + THROWSWEB_AOT_SMOKE_GATE (007-ThrowsWeb) #2101 AOT execute · Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492

[PurHur]

Implementation hints (batch 125 expand)

Unblock order: VM PHPTs (#2084 ✅) → JIT compliance try_catch filter → only then #2101 AOT execute (shared exception runtime).

File map

Area	Path	Starting grep
CFG overlay	lib/Compiler.php	TryCatch, TYPE_TRY, TYPE_CATCH, TYPE_FINALLY
VM unwind	lib/VM.php	executeTry, executeThrow, catch frame
JIT defer	lib/JIT.php	compileTryCatch, PHP_COMPILER_JIT_FALLBACK for uncaught
Unsupported	lib/UnsupportedRegistry.php	remove try/catch once green
Compliance	test/compliance/JITTest.php	--filter try_catch
Registry test	test/unit/UnsupportedRegistryTest.php	assert not listed

Harness verify (no GHA)

./script/docker-runforge.sh -- bash -lc \
  'source script/php-env.sh && vendor/bin/phpunit test/compliance/JITTest.php --filter try_catch'

Dependencies

• Language: throw expressions and Exception object propagation #195 — throw opcode stable (AOT may share lowering)
• JIT: try/catch/finally lowering phase 2 (#57, after VM #2084) #2114 blocks Testing: THROWSWEB_AOT_LINK_GATE + THROWSWEB_AOT_SMOKE_GATE (007-ThrowsWeb) #2101 only if AOT uses same exception tables as JIT
• Parallel: Testing: ExamplesCompileTest test007ThrowsWebAotLink (007-ThrowsWeb) #2143 AOT link gate can land with markTestSkipped until this issue closes

ROADMAP #78 batch 125 · caps #2103 / #2144

[PurHur]

Implementation hints (batch 129)

Unblock order (007 + compliance)

#2084 VM PHPT ✅ → #2114 JIT lowering → #2157 AOT user-class throw/catch → #2167 serve --jit ValidationError

Files (starting points)

Area	Path	Note
VM overlay	lib/VM/TryCatchHelper.php or exception opcodes from #2084	Reuse, do not fork semantics
JIT	lib/JIT.php, lib/JIT/TryCatchHelper.php	Phase 1: interpreter fallback flag; phase 2: LLVM landing pads
Compliance	test/compliance/JITTest.php	--filter try_catch
Caps	script/capability-matrix.php	Pair with #2103

Harness verification (Runforge)

Prefer targeted probe:

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && vendor/bin/phpunit test/compliance/JITTest.php --filter try_catch'

Full gate: make test-harness or ./script/docker-ci-local.sh — not raw docker run -v "$(pwd):/compiler" (empty bind-mount on harness).

Depends: #2084 ✅, #195, blocks #2167 JIT parity for 007-ThrowsWeb.

[PurHur]

claim: worker-lane-c — starting this run

[PurHur]

PR #3156: fix catch-block double-compile in TryCatchHelper (handler pop deferred until TYPE_CATCH/TYPE_FINALLY skip). Adds TryCatchJitExecuteTest for MCJIT when jit-runtime-probe green. bin/jit.php still VM-fallbacks all EH until MCJIT stable in CI.

[PurHur]

claim: runforge-worker-lane-c — continuing PR #3156 this run