Self-host: spine bundle native emit fails — JIT 'Cannot assign to a value' (lib/JIT.php:12225); gen-0 sidecar refresh blocked

[PurHur]

Summary

On current master (d11a1be + spine sync to 4146), the full compiler_lib_spine_smoke bundle no longer compiles through the AOT emit path: bin/compile.php -o … main.php dies with Cannot assign to a value (thrown at lib/JIT.php:12225, the ASSIGN lowering guard). Consequently make bootstrap-gen0-refresh-sidecar cannot produce an honest native emit, and the committed gen-0 sidecar stamp cannot be refreshed — it is already stale on master (stamp e7d7c34b from the 4114-era #16732, spine now 4146).

Isolation so far (pinned container)

• Every recently ADDED lib/ext file (last ~40 commits, 30 files incl. the DOM NamedNodeMap batch, curl_file, ClassUsesRecursive, DatePeriod ISO8601) compiles CLEAN as a mini bundle → the breaker is in a MODIFIED file or a whole-bundle interaction.
• bin/lint.php passes on all suspects individually (lint's LintCompiler pass does not reach this JIT lowering).
• A 4-file mini bundle (3 new ext/dom files + lib/AOT/HelperRuntimeCache.php) compiles but the resulting binary segfaults after c:main_before_php — possibly related, possibly Compiler SIGSEGV: ++/-- lowering crashes on null locals and under the FunctionStatic phpunit filter #16565-class.
• The stale prelinked sidecar fallback binary also crashes (free(): invalid pointer), so the NO_ZEND arm is broken too.

Repro

php bin/compile.php -o /tmp/spine test/selfhost/compiler_lib_spine_smoke/main.php
# → Cannot assign to a value

Impact

• check-selfhost-spine-sidecar-sync is red on master and cannot be healed by refresh until this is fixed.
• Spine-growth PRs can still sync counts/coverage/footnotes but must ship without an honest stamp refresh.

Done when

• Full spine bundle compiles via bin/compile.php (breaker identified — binary-search the 4146 requires from lib/JIT.php:12225 with a debug dump of the offending Op/file)
• make bootstrap-gen0-refresh-sidecar green, stamp matches bundle SHA
• check-selfhost-spine-sidecar-sync green on master

🤖 Generated with Claude Code

[PurHur]

claim: cursor-agent-lane-b — starting this run

[PurHur]

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

[PurHur]

claim: cursor-agent-lane-b — continuing spine bundle JIT ASSIGN fix (prior lane-b claim)

[PurHur]

Merged via #16854.

Fix: prescan global \$name imports before try-merge lowering; handle KIND_VALUE phi operands in assignOperandValue/assignOperand (global imports, native scalars, string concat); null-safe TYPE_ASSIGN alias paths.

Verification:

• php bin/compile.php -o /tmp/aot_test test/fixtures/aot/compile-only/global_foreach_try_after_early_return.php → exit 0
• BootstrapAotJitCompileTest::testGlobalForeachTryAfterEarlyReturnCompiles → OK (Docker/LLVM)
• Full spine: no longer hits Cannot assign to a value / Cannot assignOperandValue to a value; next blocker is Forward reference to class constant DateException::class (separate compile issue for remaining done-when items).