In case we can not analyze an access function, we do not discard the SCoP, but
assume conservatively that all memory accesses that can be derived from our base
pointer may be accessed.
Patch provided by: Marcello Maggioni <hayarms@gmail.com>
llvm-svn: 146972
To extract a preoptimized LLVM-IR file from a C-file run:
clang -Xclang -load -Xclang LLVMPolly.so -O0 -mllvm -polly file.c -S -emit-llvm
On the generated file you can directly run passes such as:
'opt -view-scops file.s'
llvm-svn: 146560
Previously the scheduler was splitting bands at the level at which it detected
that the splitting of the band is necessary. This may introduce an additional
level of bands, that can be avoided by backtracking and splitting on a higher
level. Additional splits reduce the number of loops that can be tiled, such that
avoiding splits and maximizing the band depth seems preferable.
As a first data point we looked at 2mm and 3mm from the polybench test suite.
For both maximizing the tilable bands results in a significant (5-10x)
performance improvement.
This patch enables the isl scheduler option to maximize the band depth.
llvm-svn: 146557
If larger coefficients appear as part of the input dependences, the schedule
calculation can take a very long time. We observed that the main overhead in
this calculation is due to optimizing the constant coefficients. They are
misused to increase locality by merging several unrelated dimensions into a
single dimension. This unwanted optimization increases the complexity of the
generated code and furthermore slows it down.
We use a new isl scheduler option to bound the values in the constant dimension
by a user defined value (20 in our case). If the right value is choosen, costly
overoptimization is prevented.
This solution works, but requires a specific (here almost randomly choosen)
value by which the constants are bound. For the moment, this is our best
solution, but we hope to to find a more generic one later on.
After these patch the extremly long compile time for simple kernels like 2mm or
3mm is reduced to a reasonable amount of time (Not more than a couple of seconds
even in debug mode).
llvm-svn: 146556
We forgot to include the unistd.h header file that defines the
functions mentioned above. This was not a problem with gnu C++ library,
however it did not work for libc++.
llvm-svn: 145790
Tobias Grosser