Native binary64 execution with narrow semantic operations

Date: 2026-07-19 Area: runtime

GocciaScript continues to represent ECMAScript Number values as the supported compilers' native binary64 Double, retaining ADR 0016's single IEEE-754 representation and rejecting a parallel arithmetic backend. Compilation and execution enter a bounded floating-point scope that saves the host state, establishes the required rounding and exception behaviour, and restores the exact inherited state in finally; this supersedes ADR 0016's engine-lifetime exception-mask guard and forbids permanent process-wide FPU mutation.

Ordinary finite arithmetic uses native Pascal operators and RTL functions. Shared ECMAScript operations add only specification-mandated guards or probe-demonstrated compatibility logic, consistently across compilers. Raw Float16, Float32, and Float64 reinterpretation is owned by NumberBits; canonical stored NaNs are 0x7E00, 0x7FC00000, and 0x7FF8000000000000 respectively. Numeric text conversion follows ADR 0098. Number::remainder is one shared, bit-exact Pascal semantic leaf because neither Pascal mod nor the supported RTL FMod provides the required binary64 contract across the target matrix; interpreter evaluation, constant folding, and bytecode execution call it directly. The same direct-caller rule applies to other shared numeric semantic leaves such as exponentiation and number conversion.

The engine does not import platform libm or another shared/static numerical library to define ECMAScript semantics. When an RTL operation is absent or observably incompatible, GocciaScript uses explicit ECMA-262 guards around a common RTL finite path or a shared pure-Pascal implementation. Compiler-specific branches may adapt syntax or primitive names but may not select different Number semantics. The normative baseline is ECMA-262 ES2026 snapshot 0248456c758431e4bb8e5d26333ff1865123c9cd, including §6.1.6.1.6 Number::remainder.