Reductions with intermediate stores currently need to be fixed in order
of their intermediate stores. Instead of doing this at fixup time after
code has been generated, sort the reductions in adjustRecipesForReductions.
This makes the order explicit in VPlan and will enable removing
fixReductions with modeling computing the final reduction result in
VPlan, followed by also modeling the intermediate stores explicitly.
This patch enables scalable vectors in the VPlan-native path.
If a vectorization factor is specified via loop vectorization hints,
that factor is used. If no vectorization factor is specified, but the
target preferes scalable vectorization, a scalable vectorization factor
is selected.
Reviewed By: fhahn
Differential Revision: https://reviews.llvm.org/D157484
This reverts commit e4ea0997486000b460c4875a00301b73b3c0d6a7.
The recommit fixes a reported crash by adding a missing check to make
sure the cast recipes are only introduced when vectorizing.
Test coverage added in 3cac608fbd0811b2f5c59c6e13148162ccd8543e.
Original commit message:
Update the code to create Trunc/Ext recipes directly in
adjustRecipesForReductions instead of fixing it up later in
fixReductions.
This explicitly models the required conversions and also makes sure they
are generated at the right place (instead of after the exit condition),
hence the changes in a few tests.
Update the code to create Trunc/Ext recipes directly in
adjustRecipesForReductions instead of fixing it up later in
fixReductions.
This explicitly models the required conversions and also makes sure they
are generated at the right place (instead of after the exit condition),
hence the changes in a few tests.
This patch is based off of
https://github.com/llvm/llvm-project/pull/67543.
We are currently using the exact trip count to make decisions regarding
the maximum VF. We can instead use the upper bound TC, which will be the
same as the constant trip count when that is known.
LoopVectorize currently queries VFDatabase repeatedly for each CI,
and each query to VFDatabase rescans all vector variants.
This patch instead makes a decision for each call once per VF based
on the cost of scalarization vs. function call to a vector variant
of the function vs. a vector intrinsic, then caches the decision
along with relevant info for use in planning and plan execution.
There's no need to repeatedly query and reset the state for
LoopExitInstDef. This removes one of the last uses of
VPTransformState::reset, by use a vector to store and update the
results. No other code should try to retrieve the result from State
outside the fixReductionCall.
Since the getMaximisedVFForTarget function is called twice, once for fixed-width and once for scalable, it adds no value to always return a fixed-width VF. Instead, when we are tail-folding, we can use either fixed-width or scalable vectors.
This patch updates the mask creation code to always create compares of
the form (ICMP_ULE, wide canonical IV, backedge-taken-count) up front
when tail folding and introduce active-lane-mask as later
transformation.
This effectively makes (ICMP_ULE, wide canonical IV, backedge-taken-count)
the canonical form for tail-folding early on. Introducing more specific
active-lane-mask recipes is treated as a VPlan-to-VPlan optimization.
This has the advantage of keeping the logic (and complexity) of
introducing active-lane-mask recipes in a single place, instead of
spreading the logic out across multiple functions. It also simplifies
initial VPlan construction and enables treating introducing EVL as
similar optimization.
Reviewed By: Ayal
Differential Revision: https://reviews.llvm.org/D158779
Partial progress towards removing in-tree uses of `getPointerTo()`,
by employing the following options:
* Drop the call entirely if the sole purpose of it is to support a no-op
bitcast (remove the no-op bitcast as well).
* Replace with `PointerType::get()`/`PointerType::getUnqual()`
This is a NFC cleanup effort.
Reviewed By: barannikov88
Differential Revision: https://reviews.llvm.org/D155232
Now that VPInstruction can manage fast math flags via
VPRecipeWithIRFlags, use them directly to model the fast-math flags of
the select created for the final reduction value instead of adding them
late.
After f108c6c, (mul x, 1) is simplified to x, which can cause the select
for the final reduction value when tail-folding to use the reduction
value for both options. Relax the assertion to make sure this case is
allowed.
Note that the reduction is now redundant itself and could be further
simplified.
Fixes#66895.
Continuing the patch series to get rid of debug intrinsics [0], instruction
insertion needs to be done with iterators rather than instruction pointers,
so that we can communicate information in the iterator class. This patch
adds an iterator-taking insertBefore method and converts various call sites
to take iterators. These are all sites where such debug-info needs to be
preserved so that a stage2 clang can be built identically; it's likely that
many more will need to be changed in the future.
At this stage, this is just changing the spelling of a few operations,
which will eventually become signifiant once the debug-info bearing
iterator is used.
[0] https://discourse.llvm.org/t/rfc-instruction-api-changes-needed-to-eliminate-debug-intrinsics-from-ir/68939
Differential Revision: https://reviews.llvm.org/D152537
The return value of the function is only used to get the debug location.
Directly return the debug location, as this avoids an extra null
check in the caller.
This patch removes the member TTI from VPReductionRecipe, as the
generation of reduction operations no longer requires TTI.
Reviewed By: fhahn
Differential Revision: https://reviews.llvm.org/D158148
Extend VPRecipeWithIRFlags to also manage predicates for compares. This
allows removing the custom ICmpULE opcode from VPInstruction which was a
workaround for missing proper predicate handling.
This simplifies the code a bit while also allowing compares with any
predicates. It also fixes a case where the compare predixcate wasn't
printed properly for VPReplicateRecipes.
Discussed/split off from D150398.
Reviewed By: Ayal
Differential Revision: https://reviews.llvm.org/D158992
When a loop has multiple reductions, each with an intermediate invariant
store, the order in which those reductions are processed is not considered.
This can result in the invariant stores outside the loop not preserving the
original order.
This patch sorts VPReductionPHIRecipes by the order in which they have
stores in the original loop before running
`InnerLoopVectorizer::fixReduction` function, and it helps to maintain
the correct order of stores.
Fixes https://github.com/llvm/llvm-project/issues/64047
Differential Revision: https://reviews.llvm.org/D157631
Split off from D150398 to avoid builder-related diff changes there.
Using IRBuilder to create ICmps simplifies the result if both operands
are constants.
Reviewed By: Ayal
Differential Revision: https://reviews.llvm.org/D158332
Suppose we have a nested loop like this:
void foo(int32_t *dst, int32_t *src, int m, int n) {
for (int i = 0; i < m; i++) {
for (int j = 0; j < n; j++) {
dst[(i * n) + j] += src[(i * n) + j];
}
}
}
We currently generate runtime memory checks as a precondition for
entering the vectorised version of the inner loop. However, if the
runtime-determined trip count for the inner loop is quite small
then the cost of these checks becomes quite expensive. This patch
attempts to mitigate these costs by adding a new option to
expand the memory ranges being checked to include the outer loop
as well. This leads to runtime checks that can then be hoisted
above the outer loop. For example, rather than looking for a
conflict between the memory ranges:
1. &dst[(i * n)] -> &dst[(i * n) + n]
2. &src[(i * n)] -> &src[(i * n) + n]
we can instead look at the expanded ranges:
1. &dst[0] -> &dst[((m - 1) * n) + n]
2. &src[0] -> &src[((m - 1) * n) + n]
which are outer-loop-invariant. As with many optimisations there
is a trade-off here, because there is a danger that using the
expanded ranges we may never enter the vectorised inner loop,
whereas with the smaller ranges we might enter at least once.
I have added a HoistRuntimeChecks option that is turned off by
default, but can be enabled for workloads where we know this is
guaranteed to be of real benefit. In future, we can also use
PGO to determine if this is worthwhile by using the inner loop
trip count information.
When enabling this option for SPEC2017 on neoverse-v1 with the
flags "-Ofast -mcpu=native -flto" I see an overall geomean
improvement of ~0.5%:
SPEC2017 results (+ is an improvement, - is a regression):
520.omnetpp: +2%
525.x264: +2%
557.xz: +1.2%
...
GEOMEAN: +0.5%
I didn't investigate all the differences to see if they are
genuine or noise, but I know the x264 improvement is real because
it has some hot nested loops with low trip counts where I can
see this hoisting is beneficial.
Tests have been added here:
Transforms/LoopVectorize/runtime-checks-hoist.ll
Differential Revision: https://reviews.llvm.org/D152366
Split off mask creation for tail folding and proactively create the mask for
the header block.
This simplifies createBlockInMask.
Reviewed By: Ayal
Differential Revision: https://reviews.llvm.org/D157037
Split off independent suggestion from D157037. This simplifies the
condition to decide if a recipe needs to be inserted to the header phi
section or simply appended.
The assertion has been updated to allow cases where the first non-phi
recipe is the end of the block, in which case inserting before this
point is equivalent to appending.
All dependencies on code from LoopVectorize.cpp have been
removed/refactored. Move the ::execute implementations to other recipe
definitions in VPlanRecipes.cpp
This commit refactors the implementation of VPReductionRecipe to use
reference instead of pointer for member RdxDesc. Because the member
RdxDesc in VPReductionRecipe should not be a nullptr, using a reference
will provide clearer semantics.
Reviewed By: fhahn
Differential Revision: https://reviews.llvm.org/D158058
Address post-commit simplification suggestion for 8a56179bcd8c:
Store operator only for floating point inductions (i.e. the binary op is
a FPMathOperator).
Address post-commit simplification suggestion for 8a56179bcd8c: Replace
IsTruncated by conditionally setting TruncResultTy only if truncation
is required.
VPlan has become an integral part of the inner loop vectorizer pipeline
that has been actively developed over the previous years. Let's move
VectorizationPlan.rst from the proposal stage to bring the docs in line
and to avoid confusion when reading the docs.
Reviewed By: rengolin
Differential Revision: https://reviews.llvm.org/D157593
Explicitly pass InductionKind and InductionBinOp to
emitTransformedIndex. Only those values are needed from the induction
descriptor. This makes explicit what is needed for the function and
allows future use cases where the a full induction descriptor object is
not available.
Update VPInstruction to use VPRecipeWithIRFlags to manage FMFs for
VPInstruction.
Reviewed By: Ayal
Differential Revision: https://reviews.llvm.org/D157144
Model wrap flags directly using VPRecipeWithIRFlags and clean up the
duplicated *NUW opcodes.
D157144 will build on this and also model FMFs for VPInstruction.
Reviewed By: Ayal
Differential Revision: https://reviews.llvm.org/D157194
Replace ConditionalAssume set by treating conditional assumes like other
predicated instructions (i.e. create a VPReplicateRecipe with a mask)
and later remove any assume recipes with masks during VPlan cleanup.
This reduces coupling of VPlan construction and Legal by removing a
shared set between the 2 and results in a cleaner code structure
overall.
Reviewed By: Ayal
Differential Revision: https://reviews.llvm.org/D157034
Split up tryToBuildVPlanWithVPRecipes into intial plan creation and
optimizations, by introducing a VPLanTransform::optimize helper.
Depends on D154640.
Reviewed By: Ayal
Differential Revision: https://reviews.llvm.org/D154644
