Commit Graph

1640 Commits

Author SHA1 Message Date
Michael Kruse d568a3e20d Update test case multidim_indirect_access.ll
This test was written to check the workings of IndependentBlocks on
arrays which doesn't do such transformations anymore. The test itself
is still useful to check that the region is rejected as SCoP.  

llvm-svn: 245353
2015-08-18 21:08:41 +00:00
Michael Kruse acb6ade757 Move early exit to the beginning of the function
If the function exits early there is no reason to enter the loop.

llvm-svn: 245316
2015-08-18 17:25:48 +00:00
Roman Gareev f2bd72e00d Use isl_set_is_subset instead of isl_set_is_equal
It helps to detect correct strides in case of parametric constraints of Stride
in MemoryAccess::isStrideX.

Reviewers: grosser
llvm-svn: 245303
2015-08-18 16:12:05 +00:00
Tobias Grosser c0f8452592 Fix test cases which fail due to changes in isl's set representation
llvm-svn: 245301
2015-08-18 15:28:02 +00:00
Tobias Grosser cf9ebb63d6 Use schedule trees to compute dependences
This patch changes Polly to compute the data-dependences on the schedule tree
instead of a flat schedule representation. Calculating dependences directly on
the schedule tree results in some good compile-time improvements (adi : -23.35%,
3mm : -9.57%), as the structure of the schedule can be exploited for increased
efficiency.

Earlier experiments with schedule tree based dependence analysis in Polly showed
some compile-time regressions. These regressions arose due to the schedule tree
based dependence analysis not taking into account the domain constraints of the
schedule tree. As a result, the computed dependences were different and this
difference caused in some cases the schedule optimizer to take a very long time.
Since isl version fe865996 the schedule tree based dependence analysis takes
domain constraints into account, which fixes the earlier compile-time issues.

Contributed-by: Pratik Bhatu <cs12b1010@iith.ac.in>
llvm-svn: 245300
2015-08-18 15:05:29 +00:00
Roman Gareev 079968e4cf test commit revert
test commit revert

llvm-svn: 245299
2015-08-18 14:56:50 +00:00
Roman Gareev 6753df4bb6 test commit
test commit

llvm-svn: 245298
2015-08-18 14:54:27 +00:00
Michael Kruse d2b0360197 Fix Codegen adding a second exit out of region
executeScopConditionally would destroy a predecessor region if it the
scop's entry was the region's exit block by forking it to polly.start
and thus creating a secnd exit out of the region. This patch "shrinks"
the predecessor region s.t. polly.split_new_and_old is not the 
region's exit anymore. 

llvm-svn: 245294
2015-08-18 13:14:42 +00:00
Johannes Doerfert e69e1141d9 Introduce the ScopExpander as a SCEVExpander replacement
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
2015-08-18 11:56:00 +00:00
Tobias Grosser 77c0f5a3b7 Drop dead and disable code from IndependentBlocks
Since Polly has now support for the code generation of scalar and PHI
dependences this code was unused and is now dropped.

llvm-svn: 245284
2015-08-18 09:30:28 +00:00
Johannes Doerfert d86f2157e5 Add a field to the memory access class for a related value.
The new field in the MemoryAccess allows us to track a value related
  to that access:
    - For real memory accesses the value is the loaded result or the
      stored value.
    - For straigt line scalar accesses it is the access instruction
      itself.
    - For PHI operand accesses it is the operand value.

  We use this value to simplify code which deduced information about the value
  later in the Polly pipeline and was known to be error prone.

Reviewers: grosser, Meinsersbur

Subscribers: #polly

Differential Revision: http://reviews.llvm.org/D12062

llvm-svn: 245213
2015-08-17 10:58:17 +00:00
Tobias Grosser c5bcf246d1 Fix Polly after SCEV port to new pass manager
This fixes compilation after LLVM commit r245193.

llvm-svn: 245211
2015-08-17 10:57:08 +00:00
Johannes Doerfert e1fa6da356 [FIX] Create location if a needed value was not yet demoted
This allows the code generation to continue working even if a needed
  value (that is reloaded anyway) was not yet demoted. Instead of
  failing it will now create the location for future demotion to memory
  and load from that location. The stores will use the same location and
  by construction execute before the load even if the textual order in
  the generated AST is otherwise.

Reviewers: grosser, Meinersbur

Subscribers: #polly

Differential Revision: http://reviews.llvm.org/D12072

llvm-svn: 245203
2015-08-17 09:38:46 +00:00
Tobias Grosser 3278b7cd7c Add 2nd test case for sdiv/srem instructions in a SCEV
llvm-svn: 245186
2015-08-16 19:53:21 +00:00
Johannes Doerfert eca5282dd0 [FIX] Add XFAIL to crashing test case
llvm-svn: 245180
2015-08-16 14:54:16 +00:00
Johannes Doerfert 45545ff782 Build the ScopStmt domain in-place.
This will build the statement domains in-place, hence using the
  ScopStmt::Domain member instead of some intermediate isl_set.

llvm-svn: 245179
2015-08-16 14:36:01 +00:00
Johannes Doerfert c594dc9ed0 Add a crashing test case for the scalar code generation
This test case crashes the scalar code generation as we are not
  consistent with the usage of the assumed context. To be precise, we
  use the assumed context for the dependence analysis but not to
  restrict the domains of the statements.

  A step by step explanation of the problem is given in the test case.

llvm-svn: 245176
2015-08-16 11:12:22 +00:00
Tobias Grosser 8a9c2353f9 Add -polly-context option to provide additional context information
This option allows the user to provide additional information about parameter
values as an isl_set. To specify that N has the value 1024, we can provide
the context -polly-context='[N] -> {: N = 1024}'.

llvm-svn: 245175
2015-08-16 10:19:29 +00:00
Johannes Doerfert ddb83d0f6d Remove trivially true condition
llvm-svn: 245174
2015-08-16 08:35:40 +00:00
Tobias Grosser 234a48270e AST Generation Paper published in TOPLAS
The July issue of TOPLAS contains a 50 page discussion of the AST generation
techniques used in Polly. This discussion gives not only an in-depth
description of how we (re)generate an imperative AST from our polyhedral based
mathematical program description, but also gives interesting insights about:

- Schedule trees: A tree-based mathematical program description that enables us
to perform loop transformations on an abstract level, while issues like the
generation of the correct loop structure and loop bounds will be taken care of
by our AST generator.

- Polyhedral unrolling: We discuss techniques that allow the unrolling of
non-trivial loops in the context of parameteric loop bounds, complex tile
shapes and conditionally executed statements. Such unrolling support enables
the generation of predicated code e.g. in the context of GPGPU computing.

- Isolation for full/partial tile separation: We discuss native support for
handling full/partial tile separation and -- in general -- native support for
isolation of boundary cases to enable smooth code generation for core
computations.

- AST generation with modulo constraints: We discuss how modulo mappings are
lowered to efficient C/LLVM code.

- User-defined constraint sets for run-time checks We discuss how arbitrary
sets of constraints can be used to automatically create run-time checks that
ensure a set of constrainst actually hold. This feature is very useful to
verify at run-time various assumptions that have been taken program
optimization.

Polyhedral AST generation is more than scanning polyhedra
Tobias Grosser, Sven Verdoolaege, Albert Cohen
ACM Transations on Programming Languages and Systems (TOPLAS), 37(4), July 2015

llvm-svn: 245157
2015-08-15 09:34:33 +00:00
Tobias Grosser 4c45542595 Update link to Polly paper
By going through my personal website, people can go directly to the paper.

llvm-svn: 245156
2015-08-15 09:34:28 +00:00
Michael Kruse 82a1c7de09 Make TempScopInfo a RegionPass
This modifies the order in which Polly passes are executed.

Assuming a function has two scops (A and B), the order before was:

FunctionPassManager
  ScopDetection
  IndependentBlocks
  TempScopInfo for A and B
  RegionPassManager
    ScopInfo for A
    DependenceInfo for A
    IslScheduleOptimizer for A
    IslAstInfo for A
    CodeGeneration for A
    ScopInfo for B
    DependenceInfo for B
    IslScheduleOptimizer for B
    IslAstInfo for B
    CodeGeneration for B

After this patch:

FunctionPassManager
  ScopDetection
  IndependentBlocks
  RegionPassManager
    TempScopInfo for A
    ScopInfo for A
    DependenceInfo for A
    IslScheduleOptimizer for A
    IslAstInfo for A
    CodeGeneration for A
    TempScopInfo for B
    ScopInfo for B
    DependenceInfo for B
    IslScheduleOptimizer for B
    IslAstInfo for B
    CodeGeneration for B

TempScopInfo for B might store information and references to the IR
that CodeGeneration for A might modify. Changing the order ensures that
the IR is not modified from the analysis of a region until code
generation.

Reviewers: grosser

Differential Revision: http://reviews.llvm.org/D12014

llvm-svn: 245091
2015-08-14 20:10:27 +00:00
Tobias Grosser bccd1b0af0 Fix test case after recent LLVM changes
llvm-svn: 244954
2015-08-13 21:08:15 +00:00
Tobias Grosser 7e584168ab Manuallt simplify test case
llvm-svn: 244907
2015-08-13 16:33:32 +00:00
Michael Kruse 5a8ddd74a5 Remove unimplemented private method getTempScop
llvm-svn: 244906
2015-08-13 16:28:04 +00:00
Michael Kruse 2da3872a99 Add test case for SCEV synthesizing
CodeGenerator currently tries to generate code for a parameter using
values values that are computed later.

llvm-svn: 244903
2015-08-13 15:53:53 +00:00
Tobias Grosser 0164b8ff70 Enable code generation of scalar dependences from function arguments
This change extends the BlockGenerator to not only allow Instructions as
base elements of scalar dependences, but any llvm::Value. This allows
us to code-generate scalar dependences which reference function arguments, as
they arise when moddeling read-only scalar dependences.

llvm-svn: 244874
2015-08-13 08:07:39 +00:00
Tobias Grosser 72e8f5999e Make sure we increment the reference counter when passing out the isl_pw_aff
llvm-svn: 244758
2015-08-12 15:45:41 +00:00
Tobias Grosser d46fd5ed95 Make the dimension sizes of in ScopArrayInfo available as isl_pw_affs
This makes it easier to reason about the size of an array dimension with isl.

llvm-svn: 244757
2015-08-12 15:27:16 +00:00
Johannes Doerfert 5451544a17 Remove identity operation from SCEVAffinator
llvm-svn: 244736
2015-08-12 10:58:01 +00:00
Johannes Doerfert 33d98a3f45 Revert r244459 'Make StmtSet a list'
llvm-svn: 244735
2015-08-12 10:55:52 +00:00
Johannes Doerfert 3f0a2a325f Add caching to the SCEVAffinator
While the compile time is not affected by this patch much it will
  allow us to look at all translated expressions after the SCoP is build
  in a convenient way. Additionally, bigger SCoPs or SCoPs with
  repeating complicated expressions might benefit from the cache later
  on.

Reviewers: grosser, Meinersbur

Subscribers: #polly

Differential Revision: http://reviews.llvm.org/D11975

llvm-svn: 244734
2015-08-12 10:46:33 +00:00
Johannes Doerfert f363bfb730 [FIX] Typo
llvm-svn: 244733
2015-08-12 10:45:20 +00:00
Johannes Doerfert 916736ef73 Expose the SCEVAffinator and make it a member of a SCoP (cont'd)
Added missing documentation and linked to the correct revision.

Differential Revision: http://reviews.llvm.org/D11974

llvm-svn: 244731
2015-08-12 10:28:45 +00:00
Johannes Doerfert 574182d394 Expose the SCEVAffinator and make it a member of a SCoP.
This change has three major advantages:
    - The ScopInfo becomes smaller.
    - It allows to use the SCEVAffinator from outside the ScopInfo.
    - A member object allows state which in turn allows e.g., caching.

Differential Revision: http://reviews.llvm.org/D9099

llvm-svn: 244730
2015-08-12 10:19:50 +00:00
Johannes Doerfert 9e0daff91e Make arc unit work with ninja builds
In order to find the llvm-obj directory it has to be (or a soft link
  to it) at one of the following locations:

    ${POLLY_SRC_DIR}/build
    ${POLLY_SRC_DIR}.build
    ${POLLY_SRC_DIR}-build
    s/${POLLY_SRC_DIR}/src/build

  Alternatively, the environment variable $POLLY_BIN_DIR can point to it.

llvm-svn: 244727
2015-08-12 09:02:20 +00:00
Johannes Doerfert a7ba98caa2 Adjusted arc linter config for modern version of arcanist
llvm-svn: 244726
2015-08-12 09:01:16 +00:00
Tobias Grosser a77cea49d1 Always model PHI nodes in scop (if not in same nonaffine subregion)
Before we only modeled PHI nodes if at least one incoming basic block was itself
part of the region, now we always model them except if all of their operands are
part of a single non-affine subregion which we model as a black-box.

This change only affects PHI nodes in the entry block, that have exactly one
incoming edge. Before this change, we did not model them and as a result code
generation would not know how to code generate them. With this change, code
generation can code generate them like any other PHI node.

This issue was exposed by r244606. Before this change simplifyRegion would have
moved these PHI nodes out of the SCoP, so we would never have tried to code
generate them. We could implement this behavior again, but changing the IR
after the scop has been modeled and transformed always adds a risk of us
invalidating earlier analysis results. It seems more save and overall also more
consistent to just model and handle this one-entry-edge PHI nodes like any
other PHI node in the scop.

Solution proposed by:  Michael Kruse  <llvm@meinersbur.de>

llvm-svn: 244721
2015-08-12 07:48:54 +00:00
Michael Kruse fba24b3775 Add another test case with trival PHI in entry BB
This one was extracted from the test-suite's pifft and caused a
miscompilation because a scalar was not written to its alloca address.

llvm-svn: 244720
2015-08-12 07:34:55 +00:00
Michael Kruse 4f9caf2b28 Add test case for entry node with trivial PHI
This is a break-down from the test-suite's oggenc where Polly currently
crashes. 

llvm-svn: 244692
2015-08-11 23:09:19 +00:00
Michael Kruse 9c483c5834 Assign regions to all BBs from CodeGeneration
In order to have a valid region analysis, we assign all newly created blocks to the parent of the scop's region. This is correct for any pre-existing regions (including the scop's region and its parent), but does not discover any region inside the generated code. For Polly this is not necessary because we do not want to re-run Polly on its own generated code anyway.

Reviewers: grosser

Part of Differential Revision: http://reviews.llvm.org/D11867

llvm-svn: 244608
2015-08-11 14:47:37 +00:00
Michael Kruse 22370884c4 Revise the simplification of regions
The previous code had several problems:

For newly created BasicBlocks it did not (always) call RegionInfo::setRegionFor in order to update its analysis. At the moment RegionInfo does not verify its BBMap, but will in the future. This is fixed by determining the region new BBs belong to and set it accordingly. The new executeScopConditionally() requires accurate getRegionFor information. 

Which block is created by SplitEdge depends on the incoming and outgoing edges of the blocks it connects, which makes handling its output more difficult than it needs to be. Especially for finding which block has been created an to assign a region to it for the setRegionFor problem above. This patch uses an implementation for splitEdge that always creates a block between the predecessor and successor. simplifyRegion has also been simplified by using SplitBlockPredecessors instead of SplitEdge. Isolating the entries and exits have been refectored into individual functions.

Previously simplifyRegion did more than just ensuring that there is only one entering and one exiting edge. It ensured that the entering block had no other outgoing edge which was necessary for executeScopConditionally(). Now the latter uses the alternative splitEdge implementation which can handle this situation so simplifyRegion really only needs to simplify the region.

Also, executeScopConditionally assumed that there can be no PHI nodes in blocks with one incoming edge. This is wrong and LCSSA deliberately produces such edges. However, previous passes ensured that there can be no such PHIs in exit nodes, but which will no longer hold in the future.

The new code that the property that it preserves the identity of region block (the property that the memory address of the BasicBlock containing the instructions remains the same; new blocks only contain PHI nodes and a terminator), especially the entry block. As a result, there is no need to update the reference to the BasicBlock of ScopStmt that contain its instructions because they have been moved to other basic blocks.

Reviewers: grosser

Part of Differential Revision: http://reviews.llvm.org/D11867 

llvm-svn: 244606
2015-08-11 14:39:21 +00:00
Michael Kruse 23d0e83aa3 Introduce splitBlock and use it in splitEntryBlockForAlloca
RegionInfo::splitBlock did not update RegionInfo correctly. Specifically, it tried to make the new block the entry block if possible. This breaks for nested regions that have edges to the old block. 

We simply do not change the entry block. Updating RegionInfo becomes trivial as both block will always be in the same region.

splitEntryBlockForAlloca makes use of the new splitBlock.

Reviewers: grosser

Part of Differential Revision: http://reviews.llvm.org/D11867

llvm-svn: 244600
2015-08-11 14:04:06 +00:00
Tobias Grosser 6e3ba33b07 Update isl to isl-0.15-117-ge42acfe
Besides other changes this version of isl contains a fundamental fix to memory
corruption issues we have seen with imath-32 backed isl_ints.

This update also contains a fix that ensures that the schedule-tree based
version of isl's dependence analysis takes the domain of the schedule into
account.

llvm-svn: 244585
2015-08-11 11:31:18 +00:00
Tobias Grosser c186ac7aea BlockGenerator: Do not store 'store' statements in BBMap
A store statement has no return value and can consequently not be referenced
from another statement.

llvm-svn: 244576
2015-08-11 08:13:15 +00:00
Michael Kruse 874b5c2197 Correct non-existing past participle of split in filename
llvm-svn: 244478
2015-08-10 18:37:34 +00:00
Johannes Doerfert d6c30160e7 Make StmtSet a list.
With a deque (or any other sequential container) it is not sound to
  take the address of the elements when the container is still under
  construction. With a pointer based container this is save.

llvm-svn: 244459
2015-08-10 16:47:20 +00:00
Michael Kruse 4adb0279a8 Add test case with PHI node in exit block
The PHI node with multiple incoming edges from inside the region.

Thanks Tobias for coming up with the example. 

llvm-svn: 244456
2015-08-10 16:17:59 +00:00
Michael Kruse 1d3c9b54fb Remove leftover comment
The function to which this commit applies has been removed in a
previous commit.

llvm-svn: 244450
2015-08-10 15:07:16 +00:00
Michael Kruse 046dde40c5 [Polly] Refactor buildScop
Summary: The extracted function buildBBScopStmt will be needed later to be invoked individually on the region's exit block.

Reviewers: grosser, jdoerfert

Subscribers: jdoerfert, llvm-commits, pollydev

Projects: #polly

Differential Revision: http://reviews.llvm.org/D11878

llvm-svn: 244443
2015-08-10 13:01:57 +00:00