As a first step in the direction of assumed invariant loads (loads
that are not written in some context) we now detect and hoist
definitively invariant loads. These invariant loads will be preloaded
in the code generation and used in the optimized version of the SCoP.
If the load is only conditionally executed the preloaded version will
also only be executed under the same condition, hence we will never
access memory that wouldn't have been accessed otherwise. This is also
the most distinguishing feature to licm.
As hoisting can make statements empty we will simplify the SCoP and
remove empty statements that would otherwise cause artifacts in the
code generation.
Differential Revision: http://reviews.llvm.org/D13194
llvm-svn: 248861
This commit basically reverts r246427 but still solves the issue
tackled by that commit. Instead of emitting initialization code in the
beginning of the start block we now generate parallel code in its own
block and thereby guarantee separation. This is necessary as we cannot
generate code for hoisted loads prior to the start block but it still
needs to be placed prior to everything else.
llvm-svn: 248674
There are three possible reasons to add a memory memory access: For explicit load and stores, for llvm::Value defs/uses, and to emulate PHI nodes (the latter two called implicit accesses). Previously MemoryAccess only stored IsPHI. Register accesses could be identified through the isScalar() method if it was no IsPHI. isScalar() determined the number of dimensions of the underlaying array, scalars represented by zero dimensions.
For the work on de-LICM, implicit accesses can have more than zero dimensions, making the distinction of isScalars() useless, hence now stored explicitly in the MemoryAccess. Instead, we replace it by isImplicit() and avoid the term scalar for zero-dimensional arrays as it might be confused with llvm::Value which are also often referred to as scalars (or alternatively, as registers).
No behavioral change intended, under the condition that it was impossible to create explicit accesses to zero-dimensional "arrays".
llvm-svn: 248616
This prepares for a series of patches that merges TempScopInfo into ScopInfo to
reduce Polly's code complexity. Only ScopInfo.{cpp|h} will be left thereafter.
Moving the code of TempScopInfo in one commit makes the mains diffs simpler to
understand.
In detail, merging the following classes is planned:
TempScopInfo into ScopInfo
TempScop into Scop
IRAccess into MemoryAccess
Only moving code, no functional changes intended.
Differential Version: http://reviews.llvm.org/D12693
llvm-svn: 247274
Not all users of our IslNodeBuilder will attach scheduling information to the
AST in the same way IslAstInfo is doing it today. By going through a virtual
function when extracting the schedule of an AST node other users can provide
their own functions for extract scheduling information in case they attach
scheduling information in a different way to the AST nodes.
No functional change for Polly itself intended.
llvm-svn: 247126
Some of the structures are renamed, subfunction introduced to clarify the
individual steps and comments are added describing their functionality.
llvm-svn: 246929
In the common case, the access functions are not modified, hence there is no
need to obtain the IslAstBuild context at all. This should not only be minimally
faster, but this also allows the IslNodeBuilder to work on asts that are not
annotated with isl_ast_builds as long as the memory accesses are not modified.
llvm-svn: 246928
The GlobalMap variable used in BlockGenerator should always reference the same
list througout the entire code generation, hence we can make it a member
variable to avoid passing it around through every function call.
History: Before we switched to the SCEV based code generation the GlobalMap
also contained a mapping form old to new induction variables, hence it was
different for each ScopStmt, which is why we passed it as function argument
to copyStmt. The new SCEV based code generation now uses a separate mapping
called LTS -> LoopToSCEV that maps each original loop to a new loop iteration
variable provided as a SCEVExpr. The GlobalMap is currently mostly used for
OpenMP code generation, where references to parameters in the original function
need to be rewritten to the locations of these variables after they have been
passed to the subfunction.
Suggested-by: Johannes Doerfert <doerfert@cs.uni-saarland.de>
llvm-svn: 246920
Scalar dependences between scop statements have caused troubles during parallel
code generation as we did not pass on the new stack allocation created for such
scalars to the parallel subfunctions. This change now detects all scalar
reads/writes in parallel subfunctions, creates the allocas for these scalar
objects, passes the resulting memory locations to the subfunctions and ensures
that within the subfunction requests for these memory locations will return the
rewritten values.
Johannes suggested as a future optimization to privatizing some of the scalars
in the subfunction.
llvm-svn: 246414
This change allows the BlockGenerator to be reused in contexts where we want to
provide different/modified isl_ast_expressions, which are not only changed to
a different access relation than the original statement, but which may indeed
be different for each code-generated instance of the statement.
We ensure testing of this feature by moving Polly's support to import changed
access functions through a jscop file to use the BlockGenerators support for
generating arbitary access functions if provided.
This commit should not change the behavior of Polly for now. The diff is rather
large, but most changes are due to us passing the NewAccesses hash table through
functions. This style, even though rather verbose, matches what is done
throughout the BlockGenerator with other per-statement properties.
llvm-svn: 246144
To make alias scope metadata generation work in OpenMP mode we now provide
the ScopAnnotator with information about the base pointer rewrite that happens
when passing arrays into the OpenMP subfunction.
llvm-svn: 245451
The SCEVExpander cannot deal with all SCEVs Polly allows in all kinds
of expressions. To this end we introduce a ScopExpander that handles
the additional expressions separatly and falls back to the
SCEVExpander for everything else.
Reviewers: grosser, Meinersbur
Subscribers: #polly
Differential Revision: http://reviews.llvm.org/D12066
llvm-svn: 245288
Instead of flat schedules, we now use so-called schedule trees to represent the
execution order of the statements in a SCoP. Schedule trees make it a lot easier
to analyze, understand and modify properties of a schedule, as specific nodes
in the tree can be choosen and possibly replaced.
This patch does not yet fully move our DependenceInfo pass to schedule trees,
as some additional performance analysis is needed here. (In general schedule
trees should be faster in compile-time, as the more structured representation
is generally easier to analyze and work with). We also can not yet perform the
reduction analysis on schedule trees.
For more information regarding schedule trees, please see Section 6 of
https://lirias.kuleuven.be/handle/123456789/497238
llvm-svn: 242130
Upcoming revisions of isl require us to include header files explicitly, which
have previously been already transitively included. Before we add them, we sort
the existing includes.
Thanks to Chandler for sort_includes.py. A simple, but very convenient script.
llvm-svn: 236930
