Perf: typed int **102 / pow(n,102) chained smul omit llvm.pow.f64 (#36386)

[PurHur]

Summary

• Part of Performance: v2.0 targets and the codegen roadmap to reach them — typed code ≥ 3x Zend, untyped ≤ 1.5x slower, web request ≥ php-fpm: inline caches for property/method access, escape analysis for arrays/strings, guarded speculation, per-function O1 by default (lib/JIT.php, lib/JIT/Builtin/Type/Object_.php, lib/JIT/Analyzer.php) #36386 (typed fast paths). Lane overflow: CI: php-llvm-structgep-assert.patch fails to apply — blocks north-star5-verify-fast and all bootstrap gates #36143–VM: 1M-iteration loops exit 255 silently — restore compute-suite headroom on bin/vm.php #36148 closed; aot-smoke 9/9 and north-star5-verify-fast green on tip before claim.
• Lower compile-time exponent **102 / pow(n, 102) via (hundredfirst×n) chained smul.with.overflow in JitPowIntegerEmitHigh — omit llvm.pow.f64. Even: (-1)**102 === 1.
• Fold map + unit + differential case + opcode corpus + size budgets.
• No new C ABI. php-src: Zend/zend_operators.c pow_function / zend_pow / mul_function; ext/standard/math.c PHP_FUNCTION(pow).

Part of #36386.

Test plan

• ./script/phpunit.sh --filter 'NoThrowPowHundredsecondMulAotTest|NoThrowPowHundredfirstMulAotTest|NoThrowPowHundredthMulAotTest' → OK (12 tests, 69 assertions)
• ./script/aot-smoke.sh → 9/9
• php script/check-size-budgets.php → OK (156)
• php script/opcode-corpus-md5.php --check → OK (364 files)
• make north-star5-verify-fast → OK (spine 8596/8596)
• script/differential-sweep.sh --aot --repeat 3 → pow_hundredsecond_smul_36386.php 3/3; remaining post-cutoff shard 49/49 ok (exit 0). First-pass log also showed 7 pre-existing DIFF names unrelated to this change (same class as master noise; not introduced here).

Made with Cursor

[PurHur]

Superseded: master already has **102 via #37688 (and **103–**105 via #37691/#37693/#37697). Closing; continuing with **106.