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RE: [Caml-list] 32 bit floats, SSE instructions
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Date: 2004-06-09 (20:03)
From: John Carr <jfc@m...>
Subject: Re: [Caml-list] 32 bit floats, SSE instructions

> I'll add my vote; I find Xavier's occasional comments to be the
> highlight of the mailing list.

I think it's clear where he was headed: a general purpose 32 bit float
type with 32 bit floating point arithmetic is not sufficiently useful
to justify the implementation effort.  As a general rule, on modern
processors operations on 32 bit floats are not faster than operations
on 64 bit floats.  32 bit float scalars do not save much space.

32 bit floats would be useful for three reasons:

1. If vector operations could be done on 32 but not 64 bit
quantities.  Scalar is about the same speed.  SSE could be
helpful but I think you would need significant work in the
code generator.

2. To save space in large data structures.  Bigarray is already
available for this purpose.

3. To save space when many medium-size structures are allocated.
A float32 record/array type would be helpful.

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