Remove all user-space asUint/toUint in the libraries. #5194
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We use these in some low-level routines, notably in `RuntimeLong`. Introducing casts avoids unnecessary `AsInstanceOf`s around them.
Instead, we use `Integer.toUnsignedLong(x).toDouble`, which is semantically equivalent. The only remaining use of `x >>> 0` is in the JS-only runtime libraries, notably `RuntimeLong`. We add some optimizations to generate the best possible code on all targets. For JS with `RuntimeLong`, we need to mark `RuntimeLong.toDouble` as fully inline. That is fine, as its body is actually very short (shorter than most methods of `RuntimeLong`). Moreover, we need a tailored rewrite in the optimizer to get rid of a `Double` addition of `0.0 + y` when `y` is provably non-negative. For JS with `bigint`s, we directly fold `(double) <toLongUnsigned>(x)` into `x >>> 0`. Otherwise, we unnecessarily go through a `bigint` with `Number(BigInt(x >>> 0))`. For Wasm, we fold the same shape into a single operation `f64.convert_i32_u`, which we add in `WasmTransients`.
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Instead, we use
Integer.toUnsignedLong(x).toDouble, which is semantically equivalent. The only remaining use ofx >>> 0is in the JS-only runtime libraries, notablyRuntimeLong.We add some optimizations to generate the best possible code on all targets.
For JS with
RuntimeLong, we need to markRuntimeLong.toDoubleas fully inline. That is fine, as its body is actually very short (shorter than most methods ofRuntimeLong). Moreover, we need a tailored rewrite in the optimizer to get rid of aDoubleaddition of0.0 + ywhenyis provably non-negative.For JS with
bigints, we directly fold(double) <toLongUnsigned>(x)intox >>> 0. Otherwise, we unnecessarily go through abigintwithNumber(BigInt(x >>> 0)).For Wasm, we fold the same shape into a single operation
f64.convert_i32_u, which we add inWasmTransients.