stage2: wasm - Improve @mulWithOverflow implementation
#11605
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When a signed integer is negative, the integer will be stored as a two's complement, rather than its signed value. Instead, we verify the signed bits during arithmetic operations. This fixes signed cases of `@mulWithOverflow`.
As we now store negative signed integers as two's complement, we must also ensure that when truncating a float, its value is wrapped around the integer's size. This also splits `@mulWithOverflow` into its own function to make the code more maintainable and reduce branching.
Luukdegram
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This improves the
@mulWithOverflowimplementation and ensures it passes all tests when bitsize <= 32.To also support integers with bitsize 64, we will need compiler-rt support as Wasm does not have the same capabilities like the native backends with regards to carry bits, etc.
This PR ensures the Wasm backend will comply with #11316