The patch in http://reviews.llvm.org/D13745 is broken into four parts:
1. New interfaces without functional changes.
2. Use new interfaces in SelectionDAG, while in other passes treat probabilities
as weights.
3. Use new interfaces in all other passes.
4. Remove old interfaces.
This the second patch above. In this patch SelectionDAG starts to use
probability-based interfaces in MBB to add successors but other MC passes are
still using weight-based interfaces. Therefore, we need to maintain correct
weight list in MBB even when probability-based interfaces are used. This is
done by updating weight list in probability-based interfaces by treating the
numerator of probabilities as weights. This change affects many test cases
that check successor weight values. I will update those test cases once this
patch looks good to you.
Differential revision: http://reviews.llvm.org/D14361
llvm-svn: 253965
r243347 was intended to support a change to LSR (r243348). That change
to LSR has since had to be reverted (r243939) because it was buggy, and
now the code added in r243347 is untested and unexercised. Given that,
I think it is appropriate to revert r243347 for now, with the intent of
adding it back in later if I get around to checking in a fixed version
of r243348.
llvm-svn: 252948
SCEVUnionPredicate is copied constructed here: lib/Transforms/Scalar/LoopDistribute.cpp:793
and move assigned (which can use the base class's copy ctor just
fine/without extra cost (I'd add it if it weren't for MSVC's issues
meaning = default is insufficient)) here: lib/Transforms/Utils/LoopVersioning.cpp:46
llvm-svn: 252537
This is a prerequisite for further optimisations of these functions,
which will be commited as a separate patch.
Differential Revision: http://reviews.llvm.org/D14219
llvm-svn: 252535
Summary:
LAA currently generates a set of SCEV predicates that must be checked by users.
In the case of Loop Distribute/Loop Load Elimination, no such predicates could have
been emitted, since we don't allow stride versioning. However, in the future there
could be SCEV predicates that will need to be checked.
This change adds support for SCEV predicate versioning in the Loop Distribute, Loop
Load Eliminate and the loop versioning infrastructure.
Reviewers: anemet
Subscribers: mssimpso, sanjoy, llvm-commits
Differential Revision: http://reviews.llvm.org/D14240
llvm-svn: 252467
Summary:
This change makes the `isImpliedCondition` interface similar to the rest
of the functions in ValueTracking (in that it takes a DataLayout,
AssumptionCache etc.). This is an NFC, intended to make a later diff
less noisy.
Depends on D14369
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D14391
llvm-svn: 252333
The bug: I missed adding break statements in the switch / case.
Original commit message:
[SCEV] Teach SCEV some axioms about non-wrapping arithmetic
Summary:
- A s< (A + C)<nsw> if C > 0
- A s<= (A + C)<nsw> if C >= 0
- (A + C)<nsw> s< A if C < 0
- (A + C)<nsw> s<= A if C <= 0
Right now `C` needs to be a constant, but we can later generalize it to
be a non-constant if needed.
Reviewers: atrick, hfinkel, reames, nlewycky
Subscribers: sanjoy, llvm-commits
Differential Revision: http://reviews.llvm.org/D13686
llvm-svn: 252236
Splits PrintLoopPass into a new-style pass and a PrintLoopPassWrapper,
much like we already do for PrintFunctionPass and PrintModulePass.
llvm-svn: 252085
Summary:
The goal of this pass is to perform store-to-load forwarding across the
backedge of a loop. E.g.:
for (i)
A[i + 1] = A[i] + B[i]
=>
T = A[0]
for (i)
T = T + B[i]
A[i + 1] = T
The pass relies on loop dependence analysis via LoopAccessAnalisys to
find opportunities of loop-carried dependences with a distance of one
between a store and a load. Since it's using LoopAccessAnalysis, it was
easy to also add support for versioning away may-aliasing intervening
stores that would otherwise prevent this transformation.
This optimization is also performed by Load-PRE in GVN without the
option of multi-versioning. As was discussed with Daniel Berlin in
http://reviews.llvm.org/D9548, this is inferior to a more loop-aware
solution applied here. Hopefully, we will be able to remove some
complexity from GVN/MemorySSA as a consequence.
In the long run, we may want to extend this pass (or create a new one if
there is little overlap) to also eliminate loop-indepedent redundant
loads and store that *require* versioning due to may-aliasing
intervening stores/loads. I have some motivating cases for store
elimination. My plan right now is to wait for MemorySSA to come online
first rather than using memdep for this.
The main motiviation for this pass is the 456.hmmer loop in SPECint2006
where after distributing the original loop and vectorizing the top part,
we are left with the critical path exposed in the bottom loop. Being
able to promote the memory dependence into a register depedence (even
though the HW does perform store-to-load fowarding as well) results in a
major gain (~20%). This gain also transfers over to x86: it's
around 8-10%.
Right now the pass is off by default and can be enabled
with -enable-loop-load-elim. On the LNT testsuite, there are two
performance changes (negative number -> improvement):
1. -28% in Polybench/linear-algebra/solvers/dynprog: the length of the
critical paths is reduced
2. +2% in Polybench/stencils/adi: Unfortunately, I couldn't reproduce this
outside of LNT
The pass is scheduled after the loop vectorizer (which is after loop
distribution). The rational is to try to reuse LAA state, rather than
recomputing it. The order between LV and LLE is not critical because
normally LV does not touch scalar st->ld forwarding cases where
vectorizing would inhibit the CPU's st->ld forwarding to kick in.
LoopLoadElimination requires LAA to provide the full set of dependences
(including forward dependences). LAA is known to omit loop-independent
dependences in certain situations. The big comment before
removeDependencesFromMultipleStores explains why this should not occur
for the cases that we're interested in.
Reviewers: dberlin, hfinkel
Subscribers: junbuml, dberlin, mssimpso, rengolin, sanjoy, llvm-commits
Differential Revision: http://reviews.llvm.org/D13259
llvm-svn: 252017
Summary: Will be used by the LoopLoadElimination pass.
Reviewers: hfinkel
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D13258
llvm-svn: 252016
Summary:
The functions use LAI and MemoryDepChecker classes so they need to be
defined after those definitions outside of the Dependence class.
Will be used by the LoopLoadElimination pass.
Reviewers: hfinkel
Subscribers: rengolin, llvm-commits
Differential Revision: http://reviews.llvm.org/D13257
llvm-svn: 252015
Summary:
We now collect all types of dependences including lexically forward
deps not just "interesting" ones.
Reviewers: hfinkel
Subscribers: rengolin, llvm-commits
Differential Revision: http://reviews.llvm.org/D13256
llvm-svn: 251985
Summary:
When the dependence distance in zero then we have a loop-independent
dependence from the earlier to the later access.
No current client of LAA uses forward dependences so other than
potentially hitting the MaxDependences threshold earlier, this change
shouldn't affect anything right now.
This and the previous patch were tested together for compile-time
regression. None found in LNT/SPEC.
Reviewers: hfinkel
Subscribers: rengolin, llvm-commits
Differential Revision: http://reviews.llvm.org/D13255
llvm-svn: 251973
Summary:
SCEV Predicates represent conditions that typically cannot be derived from
static analysis, but can be used to reduce SCEV expressions to forms which are
usable for different optimizers.
ScalarEvolution now has the rewriteUsingPredicate method which can simplify a
SCEV expression using a SCEVPredicateSet. The normal workflow of a pass using
SCEVPredicates would be to hold a SCEVPredicateSet and every time assumptions
need to be made a new SCEV Predicate would be created and added to the set.
Each time after calling getSCEV, the user will call the rewriteUsingPredicate
method.
We add two types of predicates
SCEVPredicateSet - implements a set of predicates
SCEVEqualPredicate - tests for equality between two SCEV expressions
We use the SCEVEqualPredicate to re-implement stride versioning. Every time we
version a stride, we will add a SCEVEqualPredicate to the context.
Instead of adding specific stride checks, LoopVectorize now adds a more
generic SCEV check.
We only need to add support for this in the LoopVectorizer since this is the
only pass that will do stride versioning.
Reviewers: mzolotukhin, anemet, hfinkel, sanjoy
Subscribers: sanjoy, hfinkel, rengolin, jmolloy, llvm-commits
Differential Revision: http://reviews.llvm.org/D13595
llvm-svn: 251800
It looks like this broke the stage 2 builder:
http://lab.llvm.org:8080/green/job/clang-stage2-configure-Rlto/6989/
Original commit message:
AliasSetTracker does not need to convert the access mode to ModRefAccess if the
new visited UnknownInst has only 'REF' modrefinfo to existing pointers in the
sets.
Patch by Andrew Zhogin!
llvm-svn: 251562
This teaches SCEV to compute //max// backedge taken counts for loops
like
for (int i = k; i != 0; i >>>= 1)
whatever();
SCEV yet cannot represent the exact backedge count for these loops, and
this patch does not change that. This is really geared towards teaching
SCEV that loops like the above are *not* infinite.
llvm-svn: 251558
When checking if an indirect global (a global with pointer type) is only assigned by allocation functions, first check if the global is itself initialized. If it is, it's not only assigned by allocation functions.
This fixes PR25309. Thanks to David Majnemer for reducing the test case!
llvm-svn: 251508
Summary: This will allow a later patch to `JumpThreading` use this functionality.
Reviewers: reames
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D13971
llvm-svn: 251488
AliasSetTracker does not need to convert the access mode to ModRefAccess if the
new visited UnknownInst has only 'REF' modrefinfo to existing pointers in the
sets.
Patch by Andrew Zhogin!
llvm-svn: 251451
Summary: This idiom is used elsewhere in LLVM, but was overlooked here.
Reviewers: chandlerc
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D13628
llvm-svn: 251348
Summary:
Replace (const SCEVAddRecExpr *) with cast<SCEVAddRecExpr>.
Rename SCEVApplyRewriter to SCEVLoopAddRecRewriter (which is a more
appropriate name) since the description is "takes a scalar evolution
expression and applies the Map (Loop -> SCEV) to all AddRecExprs."
Subscribers: llvm-commits, sanjoy
Differential Revision: http://reviews.llvm.org/D14065
llvm-svn: 251292
Summary:
Add a SCEVRewriteVisitor class which contains the common
visiting patterns used when rewriting SCEVs.
SCEVParameterRewriter and SCEVApplyRewriter now inherit
from SCEVRewriteVisitor (and are therefore much simpler).
Reviewers: anemet, mzolotukhin, sanjoy
Subscribers: rengolin, llvm-commits, sanjoy
Differential Revision: http://reviews.llvm.org/D13242
llvm-svn: 251283
Instead of playing around with dominance to verify if the possible expansion of
a scop region is indeed a single entry single exit region, we now distinguish
two cases. In case we only append a basic block, all edges entering this basic
block need to have come from within the region that is expanded. In case we join
two regions, the source basic blocks of the edges that end at the entry node of
the region that is appended most be part of either the original region or the
region that is appended.
This change will be tested through Polly.
This fixes llvm.org/PR25242
llvm-svn: 251267
When the target does not support these intrinsics they should be converted to a chain of scalar load or store operations.
If the mask is not constant, the scalarizer will build a chain of conditional basic blocks.
I added isLegalMaskedGather() isLegalMaskedScatter() APIs.
Differential Revision: http://reviews.llvm.org/D13722
llvm-svn: 251237
The loop idiom creating a ConstantRange is repeated twice in the
codebase, time to give it a name and a home.
The loop is also repeated in `rangeMetadataExcludesValue`, but using
`getConstantRangeFromMetadata` there would not be an NFC -- the range
returned by `getConstantRangeFromMetadata` may contain a value that none
of the subranges did.
llvm-svn: 251180
In r251064 I removed a logically unreachable call to `redoLoop`, and
now there aren't any callers of this API at all. Remove the needless
complexity.
llvm-svn: 251067
The insertLoop() API is only used to add new loops, and has confusing
ownership semantics. Simplify it by replacing it with addLoop().
llvm-svn: 251064
Summary:
- A s< (A + C)<nsw> if C > 0
- A s<= (A + C)<nsw> if C >= 0
- (A + C)<nsw> s< A if C < 0
- (A + C)<nsw> s<= A if C <= 0
Right now `C` needs to be a constant, but we can later generalize it to
be a non-constant if needed.
Reviewers: atrick, hfinkel, reames, nlewycky
Subscribers: sanjoy, llvm-commits
Differential Revision: http://reviews.llvm.org/D13686
llvm-svn: 251050
isKnownNonEqual(A, B) returns true if it can be determined that A != B.
At the moment it only knows two facts, that a non-wrapping add of nonzero to a value cannot be that value:
A + B != A [where B != 0, addition is nsw or nuw]
and that contradictory known bits imply two values are not equal.
This patch also hooks this up to InstSimplify; InstSimplify had a peephole for the first fact but not the second so this teaches InstSimplify a new trick too (alas no measured performance impact!)
llvm-svn: 251012
Summary:
If a `CallSite` has operand bundles, then do not peek into the called
function to get a more precise `ModRef` answer.
This is tested using `argmemonly`, `-basicaa` and `-gvn`; but the
functionality is not specific to any of these.
Depends on D13961
Reviewers: reames, chandlerc
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D13962
llvm-svn: 250974
"external" AA wrapper pass.
This is a generic hook that can be used to thread custom code into the
primary AAResultsWrapperPass for the legacy pass manager in order to
allow it to merge external AA results into the AA results it is
building. It does this by threading in a raw callback and so it is
*very* powerful and should serve almost any use case I have come up with
for extending the set of alias analyses used. The only thing not well
supported here is using a *different order* of alias analyses. That form
of extension *is* supportable with the new pass manager, and I can make
the callback structure here more elaborate to support it in the legacy
pass manager if this is a critical use case that people are already
depending on, but the only use cases I have heard of thus far should be
reasonably satisfied by this simpler extension mechanism.
It is hard to test this using normal facilities (the built-in AAs don't
use this for obvious reasons) so I've written a fairly extensive set of
custom passes in the alias analysis unit test that should be an
excellent test case because it models the out-of-tree users: it adds
a totally custom AA to the system. This should also serve as
a reasonably good example and guide for out-of-tree users to follow in
order to rig up their existing alias analyses.
No support in opt for commandline control is provided here however. I'm
really unhappy with the kind of contortions that would be required to
support that. It would fully re-introduce the analysis group
self-recursion kind of patterns. =/
I've heard from out-of-tree users that this will unblock their use cases
with extending AAs on top of the new infrastructure and let us retain
the new analysis-group-free-world.
Differential Revision: http://reviews.llvm.org/D13418
llvm-svn: 250894
Originally I planned to use the same interface for masked gather/scatter and set isConsecutive to "false" in this case.
Now I'm implementing masked gather/scatter and see that the interface is inconvenient. I want to add interfaces isLegalMaskedGather() / isLegalMaskedScatter() instead of using the "Consecutive" parameter in the existing interfaces.
Differential Revision: http://reviews.llvm.org/D13850
llvm-svn: 250686
With r250345 and r250343, we start to observe the following failure
when bootstrap clang with lto and pgo:
PHI node entries do not match predecessors!
%.sroa.029.3.i = phi %"class.llvm::SDNode.13298"* [ null, %30953 ], [ null, %31017 ], [ null, %30998 ], [ null, %_ZN4llvm8dyn_castINS_14ConstantSDNodeENS_7SDValueEEENS_10cast_rettyIT_T0_E8ret_typeERS5_.exit.i.1804 ], [ null, %30975 ], [ null, %30991 ], [ null, %_ZNK4llvm3EVT13getScalarTypeEv.exit.i.1812 ], [ %..sroa.029.0.i, %_ZN4llvm11SmallVectorIiLj8EED1Ev.exit.i.1826 ], !dbg !451895
label %30998
label %_ZNK4llvm3EVTeqES0_.exit19.thread.i
LLVM ERROR: Broken function found, compilation aborted!
I will re-commit this if the bot does not recover.
llvm-svn: 250366
Currently in JumpThreading pass, the branch weight metadata is not updated after CFG modification. Consider the jump threading on PredBB, BB, and SuccBB. After jump threading, the weight on BB->SuccBB should be adjusted as some of it is contributed by the edge PredBB->BB, which doesn't exist anymore. This patch tries to update the edge weight in metadata on BB->SuccBB by scaling it by 1 - Freq(PredBB->BB) / Freq(BB->SuccBB).
This is the third attempt to submit this patch, while the first two led to failures in some FDO tests. After investigation, it is the edge weight normalization that caused those failures. In this patch the edge weight normalization is fixed so that there is no zero weight in the output and the sum of all weights can fit in 32-bit integer. Several unit tests are added.
Differential revision: http://reviews.llvm.org/D10979
llvm-svn: 250345
Summary:
IDFCalculator used a DominatorTree instance for its calculations. Since the PostDominatorTree struct is not a subclass of DominatorTree, it wasn't possible to use PDT in IDFCalculator to compute post-dominance frontiers.
This patch makes IDFCalculator work with a DominatorTreeBase<BasicBlock> instead, which enables PDTs to be utilized.
Patch by Victor Campos (vhscampos@gmail.com)
Reviewers: dberlin
Subscribers: dberlin, llvm-commits
Differential Revision: http://reviews.llvm.org/D13725
llvm-svn: 250320
