Process dead interleave pointer ops in reverse order. This also catches
cases where the same base pointer is used by multiple different
interleave groups.
This fixes another case where the legacy cost model inaccuarately
estimates cost, surfaced by b841e2eca3b5c8.
For the Neoverse V2 we would like to prefer fixed width over scalable
vectorisation if the cost-model assigns an equal cost to both for certain
loops. This improves 7 kernels from TSVC-2 and several production kernels by
about 2x, and does not affect SPEC21017 INT and FP. This also adds a new TTI
hook that can steer the loop vectorizater to preferring fixed width
vectorization, which can be set per CPU. For now, this is only enabled for the
Neoverse V2.
There are 3 reasons why preferring NEON might be better in the case the
cost-model is a tie and the SVE vector size is the same as NEON (128-bit):
architectural reasons, micro-architecture reasons, and SVE codegen reasons. The
latter will be improved over time, so the more important reasons are the former
two. I.e., (micro) architecture reason is the use of LPD/STP instructions which
are not available in SVE2 and it avoids predication.
For what it is worth: this codegen strategy to generate more NEON is inline
with GCC's codegen strategy, which is actually even more aggressive in
generating NEON when no predication is required. We could be smarter about the
decision making, but this seems to be a first good step in the right direction,
and we can always revise this later (for example make the target hook more
general).
This change allows to consider compare instructions in the loop with
multiple use inside the loop and outside.
This change allows to vectorise this loop:
int foo(float* a, int n) {
_Bool any = 0;
_Bool all = 1;
for (int i = 0; i < n; i++) {
if (a[i] < 0.0f) {
any = 1;
} else {
all = 0;
}
}
return all ? 1 : any ? 2 : 3;
}
Resume and exit values for inductions are currently still created
outside of VPlan and independent of the induction recipes. Don't add
live-outs for now, as the additional unneeded users can pessimize other
anlysis.
Fixes https://github.com/llvm/llvm-project/issues/98660.
When collecting candidates to pre-compute cost for operands of exit
conditions, skip users outside the loop when checking if they are in
ExistInstrs. The users outside the loop should be ignored, as they won't
make a value live in the VPlan.
This fixes a failure when building for X86 with sanitizers on macOS
after b841e2eca3b5c
(https://green.lab.llvm.org/job/llvm.org/job/clang-stage2-cmake-RgSan/287/)
This patch introduces a new ResumePhi VPInstruction which creates a phi
in a leaf block of a VPlan. The first use is to create the phi node for
fixed-order recurrence resume values in the scalar preheader.
The VPInstruction takes 2 operands: 1) the incoming value from the
middle-block and a default value to be used for all other incoming
blocks.
In follow-up changes, it will also be used to create phis for reduction
and induction resume values.
Depends on https://github.com/llvm/llvm-project/pull/92651
PR: https://github.com/llvm/llvm-project/pull/94760
This patch implements limited loop vectorization support for the 'all-in-one' histogram intrinsic. The feature is disabled by default, and when enabled will only vectorize if there are no other users of values in the gather-modify-scatter sequence.
If an extend is truncated, it will be removed if the result type is <=
the source type, as there is nothing to extend. Return a cost of 0.
This was caught by the first step to perform cost-modeling based on
VPlan (b841e2e), as the legacy cost model would query the cost of an
invalid extend, while the extend has been folded away by VPlan
transforms.
Fixes https://github.com/llvm/llvm-project/issues/98413.
Adjusting the name of the recurrence phi in the scalar loop is a bit
inconsistent, as we do not adjust any other names in the scalar loops
(including other phis).
Remove this adjustment in preparation for
https://github.com/llvm/llvm-project/pull/94760/ and as discussed there.
This reverts commit 6f538f6a2d3224efda985e9eb09012fa4275ea92.
A number of crashes have been fixed by separate fixes, including
ttps://github.com/llvm/llvm-project/pull/96622. This version of the
PR also pre-computes the costs for branches (except the latch) instead
of computing their costs as part of costing of replicate regions, as
there may not be a direct correspondence between original branches and
number of replicate regions.
Original message:
This adds a new interface to compute the cost of recipes, VPBasicBlocks,
VPRegionBlocks and VPlan, initially falling back to the legacy cost model
for all recipes. Follow-up patches will gradually migrate recipes to
compute their own costs step-by-step.
It also adds getBestPlan function to LVP which computes the cost of all
VPlans and picks the most profitable one together with the most
profitable VF.
The VPlan selected by the VPlan cost model is executed and there is an
assert to catch cases where the VPlan cost model and the legacy cost
model disagree. Even though I checked a number of different build
configurations on AArch64 and X86, there may be some differences
that have been missed.
Additional discussions and context can be found in @arcbbb's
https://github.com/llvm/llvm-project/pull/67647 and
https://github.com/llvm/llvm-project/pull/67934 which is an earlier
version of the current PR.
PR: https://github.com/llvm/llvm-project/pull/92555
Port collectEphemeralValues to VPlan as collectEphemeralRecipesForVPlan,
use it in willGenerateVectors. This fixes a regression caused by
29b8b72117 for loops where the only vector values are ephemeral.
Update buildPlainCFG to re-use the vector and latch VPBBs created as
part of the initial skeleton in 72937203dd3b.
This should fix the leak sanitizer failure discovered by
https://lab.llvm.org/buildbot/#/builders/52/builds/619.
Introduce new canFoldTail helper which only checks if tail-folding is
possible, but without modifying MaskedOps.
Just because tail-folding is possible doesn't mean the tail will be
folded; that's up to the cost-model to decide. Separating the check if
tail-folding is possible and preparing for tail-folding makes sure that
MaskedOps is only populated when tail-folding is actually selected.
PR: https://github.com/llvm/llvm-project/pull/77612
Add tests with loops with ephemeral values that are widened.
After 29b8b72117, @ephemeral_load_and_compare_another_load_used_outside
is vectorized even though the only vector values that are generated are
ephemeral.
This patch moves the check if any vector instructions will be generated
from getInstructionCost to be based on VPlan. This simplifies
getInstructionCost, is more accurate as we check the final result and
also allows us to exit early once we visit a recipe that generates
vector instructions.
The helper can then be re-used by the VPlan-based cost model to match
the legacy selectVectorizationFactor behavior, this fixing a crash and
paving the way to recommit
https://github.com/llvm/llvm-project/pull/92555.
PR: https://github.com/llvm/llvm-project/pull/96622
LoopVectorize already always preserves DT, LI and SCEV. If any changes
get made to the CFG, cached LAA info for loops are cleared.
LoopAccessAnalysis also implements ::invalidate to clear the analysis if
SE, DT or LI gets invalidated. Hence it should be safe to preserve LAA
and save a small amount of compile-time.
This patch moves branch condition creation to enter the scalar epilogue
loop to VPlan. Modeling the branch in the middle block also requires
modeling the successor blocks. This is done using the recently
introduced VPIRBasicBlock.
Note that the middle.block is still created as part of the skeleton and
then patched in during VPlan execution. Unfortunately the skeleton needs
to create the middle.block early on, as it is also used for induction
resume value creation and is also needed to properly update the
dominator tree during skeleton creation.
After this patch lands, I plan to move induction resume value and phi
node creation in the scalar preheader to VPlan. Once that is done, we
should be able to create the middle.block in VPlan directly.
This is a re-worked version based on the earlier
https://reviews.llvm.org/D150398 and the main change is the use of
VPIRBasicBlock.
Depends on https://github.com/llvm/llvm-project/pull/92525
PR: https://github.com/llvm/llvm-project/pull/92651
Previously we only handled the `L0 == R0` case if both `L1` and `R1`
where constant.
We can get more out of the analysis using general constant ranges
instead.
For example, `X u> Y` implies `X != 0`.
In general, any strict comparison on `X` implies that `X` is not equal
to the boundary value for the sign and constant ranges with/without
sign bits can be useful in deducing implications.
Closes#85557
Simplify the arms of a select based on the KnownBits implied by its condition.
For now this only handles the case where the select arm folds to a constant,
but this can be generalized to handle other patterns by using
SimplifyDemandedBits instead (in that case we would also have to limit to
non-undef conditions).
This is implemented by adding a new member to SimplifyQuery that can be used
to inject an additional condition. The affected values are pre-computed and
we don't call computeKnownBits() if the select arms don't contain affected
values. This reduces the cost in some pathological cases.
This is a small canonicalization for `gep i32, p, (mul x, C)` -> `gep
i8, p, (mul x, C*4)`, so that the mul can combine both of the constant
multiplications, and we take a small step towards canonicalizing more
geps to i8.
It currently doesn't attempt to check for multiple uses on the mul, but
that should be possible if it sounds better. Let me know what you think
of the idea in general.
Previously isElementTypeLegalForScalableVector returned false for i1
types, which also prevented vectorisation of loops with i1 reductions.
This is overkill - we only need to disable vectorisation for loads
and/or stores of i1 types. I've added i1 as a legal type, but changed
the cost model to return an invalid cost for loads and stores.
Introduce a Loop::getLocStr stolen from LoopVectorize's static function
getDebugLocString in order to have uniform debug output headers across
LoopVectorize, LoopAccessAnalysis, and LoopDistribute. The motivation
for this change is to have UpdateTestChecks recognize the headers and
automatically generate CHECK lines for debug output, with minimal
special-casing.
At the moment, vectorization is only enabled in streaming(-compatible)
mode when enabled through an option. But the interfaces should check
more than just 'hasSVE()', because a function with +sme in streaming
mode should also vectorize with the option enabled.
Additionally, a streaming-compatible function should only be able to use
fixed-length autovec if SVE is available, otherwise the vector code will
be scalarised by the backend.
In some cases, no vector VPlans can be constructed due to failing VPlan
legality checks (e.g. unable to perform sinking for first order
recurrences or plans being incompatible with EVL).
There's no need to compute costs in those cases, so check directly if
there are no vector plans.
This reverts commit 242cc200ccb24e22eaf54aed7b0b0c84cfc54c0b and
eea150c84053035163f307b46549a2997a343ce9, as it is causing a build bot
failure and there have been a number of crashes reported at
https://github.com/llvm/llvm-project/pull/92555
In WebAssembly, costs != 0 are assigned to be backedge and induction
phis, so make sure we include those costs in the VPlan-based cost model.
This fixes a downstream crash with WebAssembly after 242cc200ccb
(https://github.com/llvm/llvm-project/pull/92555)
This reverts commit 6f538f6a2d3224efda985e9eb09012fa4275ea92.
Extra tests for crashes discovered when building Chromium have been
added in fb86cb7ec157689e, 3be7312f81ad2.
Original message:
This adds a new interface to compute the cost of recipes, VPBasicBlocks,
VPRegionBlocks and VPlan, initially falling back to the legacy cost model
for all recipes. Follow-up patches will gradually migrate recipes to
compute their own costs step-by-step.
It also adds getBestPlan function to LVP which computes the cost of all
VPlans and picks the most profitable one together with the most
profitable VF.
The VPlan selected by the VPlan cost model is executed and there is an
assert to catch cases where the VPlan cost model and the legacy cost
model disagree. Even though I checked a number of different build
configurations on AArch64 and X86, there may be some differences
that have been missed.
Additional discussions and context can be found in @arcbbb's
https://github.com/llvm/llvm-project/pull/67647 and
https://github.com/llvm/llvm-project/pull/67934 which is an earlier
version of the current PR.
PR: https://github.com/llvm/llvm-project/pull/92555
Use VPIRBasicBlock to wrap the middle block and implement patching up
branches in predecessors in VPIRBasicBlock::execute. The IR middle block
is only created after skeleton creation. Initially a regular
VPBasicBlock is created, which will later be replaced by a
VPIRBasicBlock once the middle IR basic block has been created.
Note that this slightly changes the order of instructions created in the
middle block; code generated by recipe execution in the middle block
will now be inserted before the terminator (and in between the compare
to used by the terminator). The original order will be restored in
https://github.com/llvm/llvm-project/pull/92651.
PR: https://github.com/llvm/llvm-project/pull/95816
