Add sign bit tacking for floating points

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Assessment

Difficulty
5/5
Estimated time
Over a week
Newbie friendliness
28/100
Issue type
Feature
Clarity
Mostly clear
Activity status
Stale
Tech stack
cpp, wasm
Domain
compilers, performance

Research direction

Start by locating the existing getMaxBits integer analysis and compare its scope with the LLVM commit linked in the issue. Trace how floating-point facts reach optimizations such as x + 0 and f64.sqrt, then define completion by deterministic sign-bit tracking for floats while preserving the stated NaN caveat and enabling the described optimizations.

Written by the indexing model from the issue text.

Description

Similar to known maximum bits getMaxBits for integers we could track sign for floats. It's quite useful and deterministic (except NaN ofc). This will allow you to do more optimizations for floating points. For example x + 0 -> x if we know x never has sign bits so -0 is not possible. LLVM already do this:
https://github.com/llvm/llvm-project/commit/727a891ec8c42b134dfd9ac8b830fb6072d34ef3

Also f64.sqrt(x) -> sNaN if we know hasSignBit(x) == 1 and etc

Dominant language
WebAssembly
Stars
8.6k
Forks
885
Avg merge
2d 1h
Merged PRs (30d)
70

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