If we identify an instruction as uniform after vectorization, we know that we
should only use the value corresponding to the first vector lane of each unroll
iteration. However, when scalarizing such instructions, we still produce values
for the other vector lanes. This patch prevents us from generating the unused
scalars.
Differential Revision: https://reviews.llvm.org/D24275
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@282087 91177308-0d34-0410-b5e6-96231b3b80d8
This patch moves the processing of pointer induction variables in
collectLoopUniforms from the consecutive pointer phase of the analysis to the
phi node phase. Previously, if a pointer induction variable was used by both a
scalarized non-memory instruction as well as a vectorized memory instruction,
we would incorrectly identify the pointer as uniform. Pointer induction
variables should be treated the same as other phi nodes. That is, they are
uniform if all users of the induction variable and induction variable update
are uniform.
Differential Revision: https://reviews.llvm.org/D24511
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@281485 91177308-0d34-0410-b5e6-96231b3b80d8
The test case included in r280979 wasn't checking what it was supposed to be
checking for the predicated store case. Fixing the test revealed that the
multi-use case (when a pointer is used by both vectorized and scalarized memory
accesses) wasn't being handled properly. We can't skip over
non-consecutive-like pointers since they may have looked consecutive-like with
a different memory access.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@280992 91177308-0d34-0410-b5e6-96231b3b80d8
Previously, all consecutive pointers were marked uniform after vectorization.
However, if a consecutive pointer is used by a memory access that is eventually
scalarized, the pointer won't remain uniform after all. An example is
predicated stores. Even though a predicated store may be consecutive, it will
still be scalarized, making it's pointer operand non-uniform.
This patch updates the logic in collectLoopUniforms to consider the cases where
a memory access may be scalarized. If a memory access may be scalarized, its
pointer operand is not marked uniform. The determination of whether a given
memory instruction will be scalarized or not has been moved into a common
function that is used by the vectorizer, cost model, and legality analysis.
Differential Revision: https://reviews.llvm.org/D24271
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@280979 91177308-0d34-0410-b5e6-96231b3b80d8
For uniform instructions, we're only required to generate a scalar value for
the first vector lane of each unroll iteration. Thus, if we have a reverse
interleaved group, computing the member index off the scalar GEP corresponding
to the last vector lane of its pointer operand technically makes the GEP
non-uniform. We should compute the member index off the first scalar GEP
instead.
I've added the updated member index computation to the existing reverse
interleaved group test.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@280497 91177308-0d34-0410-b5e6-96231b3b80d8
We can now maintain scalar values in VectorLoopValueMap. Thus, we no longer
have to create temporary vectors with insertelement instructions when handling
pointer induction variables. This case was mistakenly missed from r279649 when
refactoring the other scalarization code.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@280405 91177308-0d34-0410-b5e6-96231b3b80d8
This patch moves the allocation of VectorParts for PHI nodes into the actual
PHI widening code. Previously, we allocated these VectorParts in
vectorizeBlockInLoop, and passed them by reference to widenPHIInstruction. Upon
returning, we would then map the VectorParts in VectorLoopValueMap. This
behavior is problematic for the cases where we only want to generate a scalar
version of a PHI node. For example, if in the future we only generate a scalar
version of an induction variable, we would end up inserting an empty vector
entry into the map once we return to vectorizeBlockInLoop. We now no longer
need to pass VectorParts to the various PHI widening functions, and we can keep
VectorParts allocation as close as possible to the point at which they are
actually mapped in VectorLoopValueMap.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@280390 91177308-0d34-0410-b5e6-96231b3b80d8
After r279649 when getting a vector value from VectorLoopValueMap, we create an
insertelement sequence on-demand if the value has been scalarized instead of
vectorized. We previously inserted this insertelement sequence before the
value's first vector user. However, this insert location is problematic if that
user is the phi node of a first-order recurrence. With this patch, we move the
insertelement sequence after the last scalar instruction we created when
scalarizing the value. Thus, the value's vector definition in the new loop will
immediately follow its scalar definitions. This should fix PR30183.
Reference: https://llvm.org/bugs/show_bug.cgi?id=30183
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This patch unifies the data structures we use for mapping instructions from the
original loop to their corresponding instructions in the new loop. Previously,
we maintained two distinct maps for this purpose: WidenMap and ScalarIVMap.
WidenMap maintained the vector values each instruction from the old loop was
represented with, and ScalarIVMap maintained the scalar values each scalarized
induction variable was represented with. With this patch, all values created
for the new loop are maintained in VectorLoopValueMap.
The change allows for several simplifications. Previously, when an instruction
was scalarized, we had to insert the scalar values into vectors in order to
maintain the mapping in WidenMap. Then, if a user of the scalarized value was
also scalar, we had to extract the scalar values from the temporary vector we
created. We now aovid these unnecessary scalar-to-vector-to-scalar conversions.
If a scalarized value is used by a scalar instruction, the scalar value is used
directly. However, if the scalarized value is needed by a vector instruction,
we generate the needed insertelement instructions on-demand.
A common idiom in several locations in the code (including the scalarization
code), is to first get the vector values an instruction from the original loop
maps to, and then extract a particular scalar value. This patch adds
getScalarValue for this purpose along side getVectorValue as an interface into
VectorLoopValueMap. These functions work together to return the requested
values if they're available or to produce them if they're not.
The mapping has also be made less permissive. Entries can be added to
VectorLoopValue map with the new initVector and initScalar functions.
getVectorValue has been modified to return a constant reference to the mapped
entries.
There's no real functional change with this patch; however, in some cases we
will generate slightly different code. For example, instead of an insertelement
sequence following the definition of an instruction, it will now precede the
first use of that instruction. This can be seen in the test case changes.
Differential Revision: https://reviews.llvm.org/D23169
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@279649 91177308-0d34-0410-b5e6-96231b3b80d8
div/rem instructions in basic blocks that require predication currently prevent
vectorization. This patch extends the existing mechanism for predicating stores
to handle other instructions and leverages it to predicate divs and rems.
Differential Revision: https://reviews.llvm.org/D22918
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@279620 91177308-0d34-0410-b5e6-96231b3b80d8
Summary: I later (after r278573) found that LoopIterator.h has some overlapping with LoopBodyTraits. It's good to use LoopBodyTraits because a *Traits struct is algorithm independent.
Reviewers: anemet, nadav, mkuper
Subscribers: mzolotukhin, llvm-commits
Differential Revision: https://reviews.llvm.org/D23529
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@278996 91177308-0d34-0410-b5e6-96231b3b80d8
If the result of the find is only used to compare against end(), just
use is_contained instead.
No functionality change is intended.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@278469 91177308-0d34-0410-b5e6-96231b3b80d8
Shifts with a uniform but non-constant count were considered very expensive to
vectorize, because the splat of the uniform count and the shift would tend to
appear in different blocks. That made the splat invisible to ISel, and we'd
scalarize the shift at codegen time.
Since r201655, CodeGenPrepare sinks those splats to be next to their use, and we
are able to select the appropriate vector shifts. This updates the cost model to
to take this into account by making shifts by a uniform cheap again.
Differential Revision: https://reviews.llvm.org/D23049
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@277782 91177308-0d34-0410-b5e6-96231b3b80d8
This patch enables the vectorizer to generate both scalar and vector versions
of an integer induction variable for a given loop. Previously, we only
generated a scalar induction variable if we knew all its users were going to be
scalar. Otherwise, we generated a vector induction variable. In the case of a
loop with both scalar and vector users of the induction variable, we would
generate the vector induction variable and extract scalar values from it for
the scalar users. With this patch, we now generate both versions of the
induction variable when there are both scalar and vector users and select which
version to use based on whether the user is scalar or vector.
Differential Revision: https://reviews.llvm.org/D22869
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@277474 91177308-0d34-0410-b5e6-96231b3b80d8
Adam Nemet
Matthew Simpson
Elena Demikhovsky
Michael Kuperstein
Gil Rapaport
Benjamin Kramer
Tim Shen
David Majnemer
Wei Mi