Summary:
I'm not planning to check this in at the moment, but feedback is very welcome, in particular how this affects performance.
The feedback obtains here will guide the next steps towards enabling this.
This patch enables the use of MemorySSA in the loop pass manager.
Passes that currently use MemorySSA:
- EarlyCSE
Passes that use MemorySSA after this patch:
- EarlyCSE
- LICM
- SimpleLoopUnswitch
Loop passes that update MemorySSA (and do not use it yet, but could use it after this patch):
- LoopInstSimplify
- LoopSimplifyCFG
- LoopUnswitch
- LoopRotate
- LoopSimplify
- LCSSA
Loop passes that do *not* update MemorySSA:
- IndVarSimplify
- LoopDelete
- LoopIdiom
- LoopSink
- LoopUnroll
- LoopInterchange
- LoopUnrollAndJam
- LoopVectorize
- LoopReroll
- IRCE
Reviewers: chandlerc, george.burgess.iv, davide, sanjoy, gberry
Subscribers: jlebar, Prazek, dmgreen, jdoerfert, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D58311
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For some targets the LICM pass can result in sub-optimal code in some
cases where it would be better not to run the pass, but it isn't
always possible to suppress the transformations heuristically.
Where the front-end has insight into such cases it is beneficial
to attach loop metadata to disable the pass - this change adds the
llvm.licm.disable metadata to enable that.
Differential Revision: https://reviews.llvm.org/D64557
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To avoid duplicates in loop metadata, if the string to add is
already there, just update the value.
Reviewers: reames, Ashutosh
Reviewed By: reames
Subscribers: hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D65265
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Just move the utility function to LoopUtils.cpp to re-use it in loop peeling.
Reviewers: reames, Ashutosh
Reviewed By: reames
Subscribers: hiraditya, asbirlea, llvm-commits
Differential Revision: https://reviews.llvm.org/D65264
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With this patch the getLoopEstimatedTripCount function will
accept also the loops where there are more than one exit but
all exits except latch block should ends up with a call to deopt.
This side exits should not impact the estimated trip count.
Reviewers: reames, mkuper, danielcdh
Reviewed By: reames
Subscribers: fhahn, lebedev.ri, hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D64553
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This patch changes how LLVM handles the accumulator/start value
in the reduction, by never ignoring it regardless of the presence of
fast-math flags on callsites. This change introduces the following
new intrinsics to replace the existing ones:
llvm.experimental.vector.reduce.fadd -> llvm.experimental.vector.reduce.v2.fadd
llvm.experimental.vector.reduce.fmul -> llvm.experimental.vector.reduce.v2.fmul
and adds functionality to auto-upgrade existing LLVM IR and bitcode.
Reviewers: RKSimon, greened, dmgreen, nikic, simoll, aemerson
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D60261
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Instead of passing around fast-math-flags as a parameter, we can set those
using an IRBuilder guard object. This is no-functional-change-intended.
The motivation is to eventually fix the vectorizers to use and set the
correct fast-math-flags for reductions. Examples of that not behaving as
expected are:
https://bugs.llvm.org/show_bug.cgi?id=23116 (should be able to reduce with less than 'fast')
https://bugs.llvm.org/show_bug.cgi?id=35538 (possible miscompile for -0.0)
D61802 (should be able to reduce with IR-level FMF)
Differential Revision: https://reviews.llvm.org/D62272
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Summary:
If `deleteDeadLoop()` is called on such a loop, that has "bad" exit block,
one that e.g. has no terminator instruction, the `DIBuilder::insertDbgValueIntrinsic()`
will be told to insert the Dbg Value Intrinsic after `nullptr`
(since there is no first non-PHI instruction), which will cause it to not insert
those instructions into any basic block. The instructions will be parent-less,
and IR verifier will complain. It is rather obvious to track down the root cause
when that happens, so let's just assert it never happens.
Reviewers: sanjoy, davide, vsk
Reviewed By: vsk
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D61008
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Change from original commit: move test (that uses an X86 triple) into the X86
subdirectory.
Original description:
Gating vectorizing reductions on *all* fastmath flags seems unnecessary;
`reassoc` should be sufficient.
Reviewers: tvvikram, mkuper, kristof.beyls, sdesmalen, Ayal
Reviewed By: sdesmalen
Subscribers: dcaballe, huntergr, jmolloy, mcrosier, jlebar, bixia, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D57728
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This patch accompanies the RFC posted here:
http://lists.llvm.org/pipermail/llvm-dev/2018-October/127239.html
This patch adds a new CallBr IR instruction to support asm-goto
inline assembly like gcc as used by the linux kernel. This
instruction is both a call instruction and a terminator
instruction with multiple successors. Only inline assembly
usage is supported today.
This also adds a new INLINEASM_BR opcode to SelectionDAG and
MachineIR to represent an INLINEASM block that is also
considered a terminator instruction.
There will likely be more bug fixes and optimizations to follow
this, but we felt it had reached a point where we would like to
switch to an incremental development model.
Patch by Craig Topper, Alexander Ivchenko, Mikhail Dvoretckii
Differential Revision: https://reviews.llvm.org/D53765
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DomTreeUpdater depends on headers from Analysis, but is in IR. This is a
layering violation since Analysis depends on IR. Relocate this code from IR
to Analysis to fix the layering violation.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@353265 91177308-0d34-0410-b5e6-96231b3b80d8
LoopVectorize adds llvm.loop.isvectorized, but leaves
llvm.loop.vectorize.enable. Do not consider such a loop for user-forced
vectorization since vectorization already happened -- by prioritizing
llvm.loop.isvectorized except for TM_SuppressedByUser.
Fixes http://llvm.org/PR40546
Differential Revision: https://reviews.llvm.org/D57542
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Summary:
Check the bool value of the attribute in getOptionalBoolLoopAttribute
not just its existance.
Eliminates the warning noise generated when vectorization is explicitly disabled.
Reviewers: Meinersbur, hfinkel, dmgreen
Subscribers: jlebar, sanjoy, llvm-commits
Differential Revision: https://reviews.llvm.org/D57260
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to reflect the new license.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
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The current llvm.mem.parallel_loop_access metadata has a problem in that
it uses LoopIDs. LoopID unfortunately is not loop identifier. It is
neither unique (there's even a regression test assigning the some LoopID
to multiple loops; can otherwise happen if passes such as LoopVersioning
make copies of entire loops) nor persistent (every time a property is
removed/added from a LoopID's MDNode, it will also receive a new LoopID;
this happens e.g. when calling Loop::setLoopAlreadyUnrolled()).
Since most loop transformation passes change the loop attributes (even
if it just to mark that a loop should not be processed again as
llvm.loop.isvectorized does, for the versioned and unversioned loop),
the parallel access information is lost for any subsequent pass.
This patch unlinks LoopIDs and parallel accesses.
llvm.mem.parallel_loop_access metadata on instruction is replaced by
llvm.access.group metadata. llvm.access.group points to a distinct
MDNode with no operands (avoiding the problem to ever need to add/remove
operands), called "access group". Alternatively, it can point to a list
of access groups. The LoopID then has an attribute
llvm.loop.parallel_accesses with all the access groups that are parallel
(no dependencies carries by this loop).
This intentionally avoid any kind of "ID". Loops that are clones/have
their attributes modifies retain the llvm.loop.parallel_accesses
attribute. Access instructions that a cloned point to the same access
group. It is not necessary for each access to have it's own "ID" MDNode,
but those memory access instructions with the same behavior can be
grouped together.
The behavior of llvm.mem.parallel_loop_access is not changed by this
patch, but should be considered deprecated.
Differential Revision: https://reviews.llvm.org/D52116
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The actual type of the first argument of the @dbg intrinsic
doesn't really matter as we're setting it to `undef`, but the
bitcode reader is picky about `void` types.
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When loops are deleted, we don't keep track of variables modified inside
the loops, so the DI will contain the wrong value for these.
e.g.
int b() {
int i;
for (i = 0; i < 2; i++)
;
patatino();
return a;
-> 6 patatino();
7 return a;
8 }
9 int main() { b(); }
(lldb) frame var i
(int) i = 0
We mark instead these values as unavailable inserting a
@llvm.dbg.value(undef to make sure we don't end up printing an incorrect
value in the debugger. We could consider doing something fancier,
for, e.g. constants, in the future.
PR39868.
rdar://problem/46418795)
Differential Revision: https://reviews.llvm.org/D55299
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When multiple loop transformation are defined in a loop's metadata, their order of execution is defined by the order of their respective passes in the pass pipeline. For instance, e.g.
#pragma clang loop unroll_and_jam(enable)
#pragma clang loop distribute(enable)
is the same as
#pragma clang loop distribute(enable)
#pragma clang loop unroll_and_jam(enable)
and will try to loop-distribute before Unroll-And-Jam because the LoopDistribute pass is scheduled after UnrollAndJam pass. UnrollAndJamPass only supports one inner loop, i.e. it will necessarily fail after loop distribution. It is not possible to specify another execution order. Also,t the order of passes in the pipeline is subject to change between versions of LLVM, optimization options and which pass manager is used.
This patch adds 'followup' attributes to various loop transformation passes. These attributes define which attributes the resulting loop of a transformation should have. For instance,
!0 = !{!0, !1, !2}
!1 = !{!"llvm.loop.unroll_and_jam.enable"}
!2 = !{!"llvm.loop.unroll_and_jam.followup_inner", !3}
!3 = !{!"llvm.loop.distribute.enable"}
defines a loop ID (!0) to be unrolled-and-jammed (!1) and then the attribute !3 to be added to the jammed inner loop, which contains the instruction to distribute the inner loop.
Currently, in both pass managers, pass execution is in a fixed order and UnrollAndJamPass will not execute again after LoopDistribute. We hope to fix this in the future by allowing pass managers to run passes until a fixpoint is reached, use Polly to perform these transformations, or add a loop transformation pass which takes the order issue into account.
For mandatory/forced transformations (e.g. by having been declared by #pragma omp simd), the user must be notified when a transformation could not be performed. It is not possible that the responsible pass emits such a warning because the transformation might be 'hidden' in a followup attribute when it is executed, or it is not present in the pipeline at all. For this reason, this patche introduces a WarnMissedTransformations pass, to warn about orphaned transformations.
Since this changes the user-visible diagnostic message when a transformation is applied, two test cases in the clang repository need to be updated.
To ensure that no other transformation is executed before the intended one, the attribute `llvm.loop.disable_nonforced` can be added which should disable transformation heuristics before the intended transformation is applied. E.g. it would be surprising if a loop is distributed before a #pragma unroll_and_jam is applied.
With more supported code transformations (loop fusion, interchange, stripmining, offloading, etc.), transformations can be used as building blocks for more complex transformations (e.g. stripmining+stripmining+interchange -> tiling).
Reviewed By: hfinkel, dmgreen
Differential Revision: https://reviews.llvm.org/D49281
Differential Revision: https://reviews.llvm.org/D55288
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LoopUtils.cpp contains a utility that splits an loop exit block, so that the new block contains only edges coming from the loop. In the case of nested loops, the exit path for the inner loop might also be the back-edge of the outer loop. The new block which is inserted on this path, is now a latch for the outer loop, and it needs to hold the loop metadata for the outer loop. (The test case gives a more concrete view of the situation.)
Patch by Chang Lin (clin1)
Differential Revision: https://reviews.llvm.org/D53876
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Summary:
The InductionDescriptor and RecurrenceDescriptor classes basically analyze the IR to identify the respective IVs. So, it is better to have them in the "Analysis" directory instead of the "Transforms" directory.
The rationale for this is to make the Induction and Recurrence descriptor classes available for analysis passes. Currently including them in an analysis pass produces link error (http://lists.llvm.org/pipermail/llvm-dev/2018-July/124456.html).
Induction and Recurrence descriptors are moved from Transforms/Utils/LoopUtils.h|cpp to Analysis/IVDescriptors.h|cpp.
Reviewers: dmgreen, llvm-commits, hfinkel
Reviewed By: dmgreen
Subscribers: mgorny
Differential Revision: https://reviews.llvm.org/D51153
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Summary:
Move InductionDescriptor::transform() routine from LoopUtils to its only uses in LoopVectorize.cpp.
Specifically, the function is renamed as InnerLoopVectorizer::emitTransformedIndex().
This is a child to D51153.
Reviewers: dmgreen, llvm-commits
Reviewed By: dmgreen
Differential Revision: https://reviews.llvm.org/D51837
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Summary:
This patch is the second in a series of patches related to the [[ http://lists.llvm.org/pipermail/llvm-dev/2018-June/123883.html | RFC - A new dominator tree updater for LLVM ]].
It converts passes (e.g. adce/jump-threading) and various functions which currently accept DDT in local.cpp and BasicBlockUtils.cpp to use the new DomTreeUpdater class.
These converted functions in utils can accept DomTreeUpdater with either UpdateStrategy and can deal with both DT and PDT held by the DomTreeUpdater.
Reviewers: brzycki, kuhar, dmgreen, grosser, davide
Reviewed By: brzycki
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D48967
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The DEBUG() macro is very generic so it might clash with other projects.
The renaming was done as follows:
- git grep -l 'DEBUG' | xargs sed -i 's/\bDEBUG\s\?(/LLVM_DEBUG(/g'
- git diff -U0 master | ../clang/tools/clang-format/clang-format-diff.py -i -p1 -style LLVM
- Manual change to APInt
- Manually chage DOCS as regex doesn't match it.
In the transition period the DEBUG() macro is still present and aliased
to the LLVM_DEBUG() one.
Differential Revision: https://reviews.llvm.org/D43624
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We've been running doxygen with the autobrief option for a couple of
years now. This makes the \brief markers into our comments
redundant. Since they are a visual distraction and we don't want to
encourage more \brief markers in new code either, this patch removes
them all.
Patch produced by
for i in $(git grep -l '\\brief'); do perl -pi -e 's/\\brief //g' $i & done
Differential Revision: https://reviews.llvm.org/D46290
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Without the fast math flags, the llvm.experimental.vector.reduce.fadd/fmul intrinsic expansions must be expanded in order.
This patch scalarizes the reduction, applying the accumulator at the start of the sequence: ((((Acc + Scl[0]) + Scl[1]) + Scl[2]) + ) ... + Scl[NumElts-1]
Differential Revision: https://reviews.llvm.org/D45366
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Next step is to actually merge the implementations and get both implementations tested through the new printer.
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This builds on the work from https://reviews.llvm.org/D44287. It turned out supporting fcmp was much easier than I realized, so let's do that now.
As an aside, our -O3 handling of a floating point IVs leaves a lot to be desired. We do convert the float IV to an integer IV, but do so late enough that many other optimizations are missed (e.g. we don't vectorize).
Differential Revision: https://reviews.llvm.org/D44542
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It is common to have conditional exits within a loop which are known not to be taken on some iterations, but not necessarily all. This patches extends our reasoning around guaranteed to execute (used when establishing whether it's safe to dereference a location from the preheader) to handle the case where an exit is known not to be taken on the first iteration and the instruction of interest *is* known to be taken on the first iteration.
This case comes up in two major ways:
* If we have a range check which we've been unable to eliminate, we frequently know that it doesn't fail on the first iteration.
* Pass ordering. We may have a check which will be eliminated through some sequence of other passes, but depending on the exact pass sequence we might never actually do so or we might miss other optimizations from passes run before the check is finally eliminated.
The initial version (here) is implemented via InstSimplify. At the moment, it catches a few cases, but misses a lot too. I added test cases for missing cases in InstSimplify which I'll follow up on separately. Longer term, we should probably wire SCEV through to here to get much smarter loop aware simplification of the first iteration predicate.
Differential Revision: https://reviews.llvm.org/D44287
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Move computeLoopSafetyInfo, defined in Transforms/Utils/LoopUtils.h,
into the corresponding LoopUtils.cpp, as opposed to LICM where it resides
at the moment. This will allow other functions from Transforms/Utils
to reference it.
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The type-shrinking logic in reduction detection, although narrow in scope, is
also rather ad-hoc, which has led to bugs (e.g., PR35734). This patch modifies
the approach to rely on the demanded bits and value tracking analyses, if
available. We currently perform type-shrinking separately for reductions and
other instructions in the loop. Long-term, we should probably think about
computing minimal bit widths in a more complete way for the loops we want to
vectorize.
PR35734
Differential Revision: https://reviews.llvm.org/D42309
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This is a fix for PR35884.
When we want to delete dead loop we must clean uses in unreachable blocks
otherwise we'll get an assert during deletion of instructions from the loop.
Reviewers: anna, davide
Reviewed By: anna
Subscribers: llvm-commits, lebedev.ri
Differential Revision: https://reviews.llvm.org/D41943
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