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[Caml-list] Pointers needed for optimization problem.
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 Date: -- (:) From: Pal-Kristian Engstad Subject: [Caml-list] Pointers needed for optimization problem.
```Hi,

I'm interested in solving a problem I have with automatically generating
optimal (vector) floating point code. In other words, I want to code a caml
program that transforms the input description into assembly instructions. For
regular floating point operations, a good compiler should be able to optimize
the code:

r := A * x * x + B * x + C

into (if multiplication is more expensive than adds):

t := A * x
t := t + B
t := t * x
t := t + B
since
r := (A * x + B) * x + C

Now, this is fairly trivial to do, but if you have an architecture with SIMD
vector floating point registers and opcodes, a whole range of new interesting
optimizations can be done. With vector registers, I mean registers that have
up to 4 floating point values. For instance, a 4-vector times a 4-by-4 matrix
operation can be coded as:

acc.xyzw := mtxrow[0].xyzw * vec.x
acc.xyzw += mtxrow[1].xyzw * vec.y
acc.xyzw += mtxrow[2].xyzw * vec.z
res.xyzw = acc.xyzw + mtxrow[3].xyzw * vec.w

Here, each line represent one assembly instruction.

So, what I am looking for is basically pointers to literature that deal with
issues like these, and since OCaml is a great language for language
transformations I thought someone on this list would be able to point me in
the right direction. I _have_ been searching on the net, but I guess I don't
know the right keywords to search on.

PKE.
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```