[llvm-dev] [GSoC 2016] [Polly] Implementation of tiling, interchanging and unrolling of specific loops based on the algorithm for the analytical modeling

[Roman Gareev via llvm-dev]

Hi Tobias,

I think that we could split a patch that contains an implementation of
tiling, interchanging and unrolling of specific loops into three
separate patches:

1. The first one adds a class that describes a processor model. It
also adds a new command line parameter that contains all necessary
parameters of a target architecture, which are used to construct
objects of the class.

2. The second one adds methods to the class to compute parameters for
instantiations of the matrix-matrix multiplication. It also implements
tiling, interchanging and unrolling of specific loops.

3. The third one replaces manual passing of parameters of a target
architecture with utilization of information from LLVM.

What do you think about it?

P.S.: I’m not sure whether all necessary parameters of a target
architecture are accessible from LLVM and how it’s better to get them
in our case. Should we ask these questions on the mailing list now?

If I’m not mistaken, we’re interested in the following parameters:

1. Size of double-precision floating-point number.

2. Number of double-precision floating-point numbers that can be hold
by a vector register.

3. Throughput of vector instructions per clock cycle.

4. Latency of instructions (i.e., the minimum number of cycles between
the issuance of two dependent consecutive instructions).

5. Paramaters of cache levels (size of cache lines,  associativity
degrees, sizes).

-- 
                                    Cheers, Roman Gareev.