Perf: typed int **103 / pow(n,103) chained smul omit llvm.pow.f64 (#36386)

[PurHur]

Summary

• Lower compile-time integer ** 103 / pow($n, 103) via (hundredsecond×n) chained smul.with.overflow in JitPowIntegerEmitHigh (omit llvm.pow.f64).
• Odd exponent: (-1)**103 === -1. Append-only (no new spine TU).
• 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 (lane C; north-star 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 — lane overflow).

php-src: Zend/zend_operators.c pow_function / zend_pow / mul_function; ext/standard/math.c PHP_FUNCTION(pow).

Test plan

• ./script/phpunit.sh --filter NoThrowPowHundredthirdMulAotTest → 4/4 (23 assertions)
• script/differential-sweep.sh --aot --repeat 3 --dir test/differential/cases/_pow103_only → 1/1 match Zend
• ./script/aot-smoke.sh → 9/9 + size gate OK
• Full script/differential-sweep.sh --aot --repeat 3 (142/142) not re-run this slice (append-only peer of Perf: typed int **102 / pow(n,102) chained smul omit llvm.pow.f64 (#36386) #37688)

Closes nothing (tracker #36386 remains open for further codegen slices).

Made with Cursor

[PurHur]

Duplicate of #37691 (same **103 slice landed first). Closing; continuing #36386 with **104.