Commit Graph

3096 Commits

Author SHA1 Message Date
Paulo Matos 4facbf213c [WebAssembly] Implementation of global.get/set for reftypes in LLVM IR
Reland of 31859f896.

This change implements new DAG notes GLOBAL_GET/GLOBAL_SET, and
lowering methods for load and stores of reference types from IR
globals. Once the lowering creates the new nodes, tablegen pattern
matches those and converts them to Wasm global.get/set.

Differential Revision: https://reviews.llvm.org/D104797
2021-07-02 09:46:28 +02:00
David Green 2887f14639 [ISel] Port AArch64 SABD and UABD to DAGCombine
This ports the AArch64 SABD and USBD over to DAG Combine, where they can be
used by more backends (notably MVE in a follow-up patch). The matching code
has changed very little, just to handle legal operations and types
differently. It selects from (ABS (SUB (EXTEND a), (EXTEND b))), producing
a ubds/abdu which is zexted to the original type.

Differential Revision: https://reviews.llvm.org/D91937
2021-06-26 19:34:16 +01:00
David Green b8c8bb0769 [DAG] Fold neg(splat(neg(x)) -> splat(x)
This add as a fold of sub(0, splat(sub(0, x))) -> splat(x). This can
come up in the lowering of right shifts under AArch64, where we generate
a shift left of a negated number.

Differential Revision: https://reviews.llvm.org/D103755
2021-06-25 19:53:29 +01:00
Jinsong Ji c125af82a5 [DAGCombine] Check reassoc flags in aggressive fsub fusion
The is from discussion in https://reviews.llvm.org/D104247#inline-993387

The contract and reassoc flags shouldn't imply each other .

All the aggressive fsub fusion reassociate operations,
we should guard them with reassoc flag check.

Reviewed By: mcberg2017

Differential Revision: https://reviews.llvm.org/D104723
2021-06-23 13:59:40 +00:00
Jinsong Ji 3996311ee1 [DAGCombine] reassoc flag shouldn't enable contract
According to IR LangRef, the FMF flag:

contract
Allow floating-point contraction (e.g. fusing a multiply followed by an
addition into a fused multiply-and-add).

reassoc
Allow reassociation transformations for floating-point instructions.
This may dramatically change results in floating-point.

My understanding is that these two flags shouldn't imply each other,
as we might have a SDNode that can be reassociated with others, but
not contractble.

eg: We may want following fmul/fad/fsub to freely reassoc, but don't
want fma being generated here.

   %F = fmul reassoc double %A, %B         ; <double> [#uses=1]
   %G = fmul reassoc double %C, %D         ; <double> [#uses=1]
   %H = fadd reassoc double %F, %G         ; <double> [#uses=1]
   %I = fsub reassoc double %H, %E         ; <double> [#uses=1]

Before https://reviews.llvm.org/D45710, `reassoc` flag actually
did not imply isContratable either.

The current implementation also only check the flag in fadd node,
ignoring fmul node, this patch update that as well.

Reviewed By: spatel, qiucf

Differential Revision: https://reviews.llvm.org/D104247
2021-06-21 21:15:43 +00:00
Saleem Abdulrasool 5b5833b9e0 SelectionDAG: repair the Windows build
6e5628354e regressed the Windows build as
the return type no longer matched in both branches for the return value
type deduction.  This uses a bit more compiler magic to deal with that.
2021-06-14 08:25:36 -07:00
Roman Lebedev 0f94c3c80d
[NFC][DAGCombine] Extract getFirstIndexOf() lambda back into a function
Not all supported compilers like such lambdas, at least one buildbot is unhappy.
2021-06-14 16:25:59 +03:00
Roman Lebedev 6e5628354e
[DAGCombine] reduceBuildVecToShuffle(): sort input vectors by decreasing size
The sorting, obviously, must be stable, else we will have random assembly fluctuations.

Apparently there was no test coverage that would benefit from that,
so i've added one test.

The sorting consists of two parts - just sort the input vectors,
and recompute the shuffle mask -> input vector mapping.
I don't believe we need to do anything else.

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D104187
2021-06-14 16:18:37 +03:00
Carl Ritson cfbb92441f [SDAG] Fix pow2 assumption when splitting vectors
When reducing vector builds to shuffles it possible that
the DAG combiner may try to extract invalid subvectors.

This happens as the existing code assumes vectors will be power
of 2 sizes, which is already untrue, but becomes more noticable
with v6 and v7 types.
Specifically the existing code assumes that half PowerOf2Ceil of
a given vector index will fit twice into a given vector.

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D103880
2021-06-11 08:58:16 +09:00
David Spickett 64de8763aa Revert "Implementation of global.get/set for reftypes in LLVM IR"
This reverts commit 31859f896c.

Causing SVE and RISCV-V test failures on bots.
2021-06-10 10:11:17 +00:00
Paulo Matos 31859f896c Implementation of global.get/set for reftypes in LLVM IR
This change implements new DAG notes GLOBAL_GET/GLOBAL_SET, and
lowering methods for load and stores of reference types from IR
globals. Once the lowering creates the new nodes, tablegen pattern
matches those and converts them to Wasm global.get/set.

Reviewed By: tlively

Differential Revision: https://reviews.llvm.org/D95425
2021-06-10 10:07:45 +02:00
Sanjay Patel dd763ac791 [SDAG] fix miscompile from merging stores of different sizes
As shown in:
https://llvm.org/PR50623
...and the similar tests here, we were not accounting for
store merging of different sizes that do not cover the
entire range of the wide value to be stored.

This is the easy fix: just make sure that all of the
original stores are the same size, so when we calculate
the wide width, it's a simple N * M check.

This still allows all of the motivating optimizations from:
D86420 / 54a5dd485c
D87112 / 7a06b166b1

We could enhance this code to track individual bytes and
allow merging multiple sizes.
2021-06-09 09:51:39 -04:00
Simon Pilgrim 61a2d6bfe4 [DAG] foldShuffleOfConcatUndefs - ensure shuffles of upper (undef) subvector elements is undef (PR50609)
shuffle(concat(x,undef),concat(y,undef)) -> concat(shuffle(x,y),shuffle(x,y))

If the original shuffle references any of the upper (undef) subvector elements, ensure the split shuffle masks uses undef instead of an out-of-bounds value.

Fixes PR50609
2021-06-08 15:49:41 +01:00
Sanjay Patel 0718ac706d [SDAG] allow cast folding for vector sext-of-setcc with signed compare
This extends 434c8e013a and ede3982792 to handle signed
predicates by sign-extending the setcc operands.

This is not shown directly in https://llvm.org/PR50055 ,
but the pattern is visible by changing the unsigned convert
to signed in the source code.
2021-06-02 15:05:02 -04:00
Sanjay Patel ede3982792 [SDAG] allow more cast folding for vector sext-of-setcc
This is a follow-up to D103280 that eases the use restrictions,
so we can handle the motivating case from:
https://llvm.org/PR50055

The loop code is adapted from similar use checks in
ExtendUsesToFormExtLoad() and SliceUpLoad(). I did not see an
easier way to filter out non-chain uses of load values.

Differential Revision: https://reviews.llvm.org/D103462
2021-06-02 13:14:49 -04:00
Sanjay Patel 1b14f3951a [SDAG] add helper function for sext-of-setcc folds; NFC
Try to make this easier to read as noted in D103280
2021-06-01 08:07:17 -04:00
Sanjay Patel 63fe4cb082 [SDAG] add check to sext-of-setcc fold to bypass changing a legal op
I accidentaly pushed a draft of D103280 that was discussed
during the review, but it was not supposed to be the final
version.

Rather than revert and recommit, I'm updating the existing
code. This way we have a record of the codegen diff that
would result if we decide to remove this predicate in the
future.
2021-05-31 08:58:11 -04:00
Sanjay Patel 434c8e013a [SDAG] try harder to fold casts into vector compare
sext (vsetcc X, Y) --> vsetcc (zext X), (zext Y) --
(when the zexts are free and a bunch of other conditions)

We have a couple of similar folds to this already for vector selects,
but this pattern slips through because it is only a setcc.

The tests are based on the motivating case from:
https://llvm.org/PR50055
...but we need extra logic to get that example, so I've left that as
a TODO for now.

Differential Revision: https://reviews.llvm.org/D103280
2021-05-31 07:14:01 -04:00
Florian Hahn 126f90b252
[DAGCombine] Poison-prove scalarizeExtractedVectorLoad.
extractelement is poison if the index is out-of-bounds, so just
scalarizing the load may introduce an out-of-bounds load, which is UB.

To avoid introducing new UB, we can mask the index so it only contains
valid indices.

Fixes PR50382.

Reviewed By: efriedma

Differential Revision: https://reviews.llvm.org/D103077
2021-05-30 11:40:55 +01:00
Fraser Cormack b7101e218c [DAGCombine][RISCV] Don't try to trunc-store combined vector stores
DAGCombine's `mergeStoresOfConstantsOrVecElts` optimization is told
whether it's to use vector types and also whether it's to issue a
truncating store. However, the truncating store code path assumes a
scalar integer `ConstantSDNode`, and when using vector types it creates
either a `BUILD_VECTOR` or `CONCAT_VECTORS` to store: neither of which
is a constant.

The `riscv64` target is able to expose a crash here because it switches
on both code paths at the same time. The `f32` is stored as `i32` which
must be promoted to `i64`, necessitating a truncating store.
It also decides later that it prefers a vector store of `v2f32`.

While vector truncating stores are legal, this combine is not able to
emit them. We also don't have a test case. This patch adds an assert to
catch this case more gracefully, and updates one of the caller functions
to the function to turn off the use of truncating stores when preferring
vectors.

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D103173
2021-05-27 14:16:32 +01:00
Fraser Cormack 85e31eddf2 [DAGCombiner] Relax an assertion to an early return
The select-of-constants transform was asserting that its constant vector
inputs did not implicitly truncate their input without that as an
explicit precondition to the function. This patch relaxes that assertion
into an early return to skip the optimization.

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D102393
2021-05-17 09:15:55 +01:00
Sanjay Patel 9dfd7f9b67 [SDAG] reduce code duplication for extend_vec_inreg combines; NFC
These are identical so far, and I was looking at adding a fold
for a pattern with scalar_to_vector which would also nd up duplicated.
2021-05-14 08:29:57 -04:00
Hendrik Greving 762ac725bf [DAGCombiner] Fix DAG combine store elimination, different address space.
Fixes a bug in the DAG combiner that eliminates the stores because it missed
to inspect the address space of the pointers.

%v = load %ptr_as1
// no chain side effect
store %v, %ptr_as2

As well as

store %v, %ptr_as1
store %v, %ptr_as2

Fixes a test for above in X86.

Differential Revision: https://reviews.llvm.org/D102096
2021-05-12 07:14:22 -07:00
Bradley Smith 635164b95a [AArch64][SVE] Improve SVE codegen for fixed length BITCAST
Expanding a fixed length operation involves wrapping the operation in an
insert/extract subvector pair, as such, when this is done to bitcast we
end up with an extract_subvector of a bitcast. DAGCombine tries to
convert this into a bitcast of an extract_subvector which restores the
initial fixed length bitcast, causing an infinite loop of legalization.

As part of this patch, we must make sure the above DAGCombine does not
trigger after legalization if the created bitcast would not be legal.

Differential Revision: https://reviews.llvm.org/D101990
2021-05-10 14:43:53 +01:00
Craig Topper 0c330afdfa [RISCV] Enable SPLAT_VECTOR for fixed vXi64 types on RV32.
This replaces D98479.

This allows type legalization to form SPLAT_VECTOR_PARTS so we don't
lose the splattedness when the scalar type is split.

I'm handling SPLAT_VECTOR_PARTS for fixed vectors separately so
we can continue using non-VL nodes for scalable vectors.

I limited to RV32+vXi64 because DAGCombiner::visitBUILD_VECTOR likes
to form SPLAT_VECTOR before seeing if it can replace the BUILD_VECTOR
with other operations. Especially interesting is a splat BUILD_VECTOR of
the extract_vector_elt which can become a splat shuffle, but won't if
we form SPLAT_VECTOR first. We either need to reorder visitBUILD_VECTOR
or add visitSPLAT_VECTOR.

Reviewed By: frasercrmck

Differential Revision: https://reviews.llvm.org/D100803
2021-04-29 08:20:09 -07:00
Jun Ma 978eb3f168 [DAGCombiner] Allow operand of step_vector to be negative.
It is proper to relax non-negative limitation of step_vector.
Also this patch adds more combines for step_vector:
(sub X, step_vector(C)) -> (add X,  step_vector(-C))

Differential Revision: https://reviews.llvm.org/D100812
2021-04-22 20:58:03 +08:00
Fraser Cormack c141bd3cf9 [DAGCombiner] Support all-ones/all-zeros SPLAT_VECTOR in more combines
This patch adds incrementally-better support for SPLAT_VECTOR in a
handful of vector combines by changing a few more
isBuildVectorAllOnes/isBuildVectorAllZeros to the equivalent
isConstantSplatVectorAllOnes/Zeros calls.

Reviewed By: paulwalker-arm

Differential Revision: https://reviews.llvm.org/D100851
2021-04-21 11:05:37 +01:00
Jun Ma 1ef5699d1a [DAGCombiner] Support fold zero scalar vector.
This patch changes ISD::isBuildVectorAllZeros to
ISD::isConstantSplatVectorAllZeros which handles zero sclar vector.

TestPlan: check-llvm

Differential Revision: https://reviews.llvm.org/D100813
2021-04-20 16:28:43 +08:00
David Sherwood 83f5fa519e [CodeGen] Improve code generation for clamping of constant indices with scalable vectors
When trying to clamp a constant index into a scalable vector we can
test if the index is less than the minimum number of elements in the
vector. If so, we can simply return the index because we know it is
guaranteed to fit inside the vector.

Differential Revision: https://reviews.llvm.org/D100639
2021-04-19 08:34:17 +01:00
Jun Ma 7e1422c1e4 [DAGCombiner] Fold step_vector with add/mul/shl
This patch implements some DAG combines for STEP_VECTOR:
add step_vector(C1), step_vector(C2) -> step_vector(C1+C2)
add (add X step_vector(C1)), step_vector(C2) -> add X step_vector(C1+C2)
mul step_vector(C1), C2 -> step_vector(C1*C2)
shl step_vector(C1), C2 -> step_vector(C1<<C2)

TestPlan: check-llvm

Differential Revision: https://reviews.llvm.org/D100088
2021-04-15 18:06:35 +08:00
dfukalov d066079728 [NFC][AA] Prepare to convert AliasResult to class with PartialAlias offset.
Main reason is preparation to transform AliasResult to class that contains
offset for PartialAlias case.

Reviewed By: asbirlea

Differential Revision: https://reviews.llvm.org/D98027
2021-04-09 12:54:22 +03:00
Simon Pilgrim 77d625f8d8 [DAG] MergeInnerShuffle with BinOps - sometimes accept undef mask elements
If the inner shuffle already contains undef elements, then accept them in the merged shuffle as well.

This helps some X86 HADD/SUB patterns where slow targets were ending up with HADD/SUB because the (un)merged shuffles were stuck either side of the ADD/SUB - meaning we ended up with a total cost much higher than the "2*shuffle+add" that a slow target usually expands a HADD/SUB to.
2021-04-01 14:33:00 +01:00
Florian Hahn eb3d9f2eb6
[SelDag] Add isIntOrFPConstant helper function.
This patch adds a new isIntOrFPConstant  helper function to check if a
SDValue is a integer of FP constant. This pattern is used in various
places.

There also are places that incorrectly just check for integer constants,
e.g. D99384, so hopefully this helper will help people avoid that issue.

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D99428
2021-03-28 12:48:58 +01:00
Craig Topper 30080b003e [DAGCombiner] Minor compile time improvement to (sext_in_reg (sign_extend_vector_inreg x)) optimization.
Don't bother calling ComputeNumSignBits if N00Bits < ExtVTBits. No
matter what answer we get back this will be true:
(N00Bits - DAG.ComputeNumSignBits(N00, DemandedSrcElts)) < ExtVTBits)

So we might as well save the computation. This makes the code more
consistent with the similar (sext_in_reg (sext x)) handling above.
2021-03-21 11:16:41 -07:00
Simon Pilgrim 64c2641c89 [DAG] Limit (sext_in_reg (zero_extend_vector_inreg x)) to exact sign extension
As commented by @craig.topper on rG1ba5c550d418, we can't guarantee that we'll be extending zero bits, just sign bit. So, revert to the old code for zero_extend_vector_inreg cases.
2021-03-21 14:01:37 +00:00
Simon Pilgrim ffb2887103 [DAG] Fold shuffle(bop(shuffle(x,y),shuffle(z,w)),undef) -> bop(shuffle'(x,y),shuffle'(z,w))
Followup to D96345, handle unary shuffles of binops (as well as binary shuffles) if we can merge the shuffle with inner operand shuffles.

Differential Revision: https://reviews.llvm.org/D98646
2021-03-19 14:14:56 +00:00
Craig Topper 182b831aeb [DAGCombiner][RISCV] Teach visitMGATHER/MSCATTER to remove gather/scatters with all zeros masks that use SPLAT_VECTOR.
Previously only all zeros BUILD_VECTOR was recognized.
2021-03-18 15:34:14 -07:00
Simon Pilgrim 1ba5c550d4 [DAG] Improve folding (sext_in_reg (*_extend_vector_inreg x)) -> (sext_vector_inreg x)
Extend this to support ComputeNumSignBits of the (used) source vector elements so that we can handle more than just the case where we're sext_in_reg from the source element signbit.

Noticed while investigating the poor codegen in D98587.
2021-03-18 15:34:53 +00:00
Craig Topper 5b825433d7 [DAGCombiner] Optimize 1-bit smulo to AND+SETNE.
A 1-bit smulo overflows is both inputs are -1 since the result
should be +1 which can't be represented in a signed 1 bit value.

We can detect this with an AND and a setcc. The multiply result
can also use the same AND.

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D97634
2021-03-13 09:39:36 -08:00
Craig Topper 2ea7014089 [DAGCombiner] Use isConstantSplatVectorAllZeros/Ones instead of isBuildVectorAllZeros/Ones in visitMSTORE and visitMLOAD.
This allows us to optimize when the mask is a splat_vector in
addition to build_vector.
2021-03-12 12:14:56 -08:00
Sanjay Patel 415c67ba4c [SDAG] allow partial undef vector constants with select->logic folds
This is an enhancement suggested in the original review/commit:
D97730 / 7fce3322a2
2021-03-02 14:29:15 -05:00
Sanjay Patel 7fce3322a2 [SDAG] allow vector types for select->logic folds
This prepares codegen for a change that will remove the identical
folds from IR because they are not poison-safe. See
D93065 / D97360
for details.

We already generically support scalar types, and there are various
target-specific transforms that overlap the vector folds. For example,
x86 recognizes the and patterns, but not or. We can end up with 1
extra instruction there, but I think that is still preferred over the
blendv alternative that loads a constant vector.

If this is not optimal, then it should be fixed with a later transform
(this change is not expected to result in any regressions because
InstCombine currently does the same thing).

Removing custom code and supporting undefs in constant-pattern-matching
can be follow-up changes.

Differential Revision: https://reviews.llvm.org/D97730
2021-03-02 09:25:10 -05:00
Simon Pilgrim c0d4b44e6a [DAG] DAGCombiner::tryStoreMergeOfLoads - remove unused StartAddress variable. NFCI.
Noticed in "initialization is never read" clang-tidy warning - the only StartAddress set/used is inside the load combine loop.
2021-03-02 13:29:31 +00:00
Sanjay Patel 154c47dc06 [SDAG] add helper for select->logic folds; NFC
This set of transforms should be extended to handle vector types.
2021-03-01 16:24:15 -05:00
Simon Pilgrim 9dd83f5ee8 [DAG] visitVECTOR_SHUFFLE - attempt to match commuted shuffles with MergeInnerShuffle.
Try to match "shuffle(C, shuffle(A, B, M0), M1) -> shuffle(A, B, M2)" etc. by using MergeInnerShuffle's commuted inner shuffle mode.
2021-03-01 10:42:11 +00:00
Simon Pilgrim 64c41301ce [DAG] visitVECTOR_SHUFFLE - move shuffle canonicalization/merges all under the same legality test. NFCI.
Minor cleanup to move related combines closer together to make it more coherent, without changing the ordering.
2021-03-01 09:42:00 +00:00
Craig Topper 5de09ef02e [DAGCombiner][X86] Don't peek through ANDs on the shift amount in matchRotateSub when called from MatchFunnelPosNeg.
Peeking through AND is only valid if the input to both shifts is
the same. If the inputs are different, then the original pattern
ORs the two values when the masked shift amount is 0. This is ok
if the values are the same since the OR would be a NOP which is
why its ok for rotate.

Fixes PR49365 and reverts PR34641

Differential Revision: https://reviews.llvm.org/D97637
2021-02-28 12:58:00 -08:00
Craig Topper ca5247bb17 [DAGCombiner] Don't skip no overflow check on UMULO if the first computeKnownBits call doesn't return any 0 bits.
Even if the first computeKnownBits call doesn't have any zero
bits it is possible the other operand has bitwidth-1 leading zero.
In that case overflow is still impossible. So always call computeKnownBits
for both operands.
2021-02-28 08:26:22 -08:00
Craig Topper eea53b142d [DAGCombiner] Optimize SMULO/UMULO if we can prove that overflow is impossible.
Using ComputeNumSignBits or computeKnownBits we might be able
to determine that overflow is impossible.

This especially helps after type legalization if the type was
promoted from a type with half the bits or more. Type legalization
conservatively creates a promoted smulo/umulo and an overflow
check for the promoted bits. The overflow from the promoted
smulo/umulo is ORed with the result of the promoted bits
overflow check. Proving that the promoted smulo/umulo can never
overflow will leave us with just the promoted bits overflow check.

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D97160
2021-02-26 14:50:03 -08:00
Simon Pilgrim 9490b9f14b [DAG] Move simplification of SADDSAT/SSUBSAT/UADDSAT/USUBSAT of vXi1 to getNode()
As discussed on D97276 we should be able to always do this in node creation, we don't need a combine.
2021-02-25 17:49:26 +00:00
Simon Pilgrim 8082bfe7e5 [DAG] Add basic mul-with-overflow constant folding support
As noticed on D97160
2021-02-24 11:09:02 +00:00
Simon Pilgrim 38ab47c813 [DAG] Match USUBSAT patterns through zext/trunc
This patch handles usubsat patterns hidden through zext/trunc and uses the getTruncatedUSUBSAT helper to determine if the USUBSAT can be correctly performed in the truncated form:

zext(x) >= y ? x - trunc(y) : 0 --> usubsat(x,trunc(umin(y,SatLimit)))
zext(x) >  y ? x - trunc(y) : 0 --> usubsat(x,trunc(umin(y,SatLimit)))

Based on original examples:

void foo(unsigned short *p, int max, int n) {
    int i;
    unsigned m;
    for (i = 0; i < n; i++) {
        m = *--p;
        *p = (unsigned short)(m >= max ? m-max : 0);
    }
}

Differential Revision: https://reviews.llvm.org/D25987
2021-02-21 15:26:54 +00:00
Simon Pilgrim 761bbed264 [DAG] foldSubToUSubSat - fold sub(a,trunc(umin(zext(a),b))) -> usubsat(a,trunc(umin(b,SatLimit)))
This moves the last custom x86 USUBSAT fold to generic DAGCombine.

Completes PR40111

Differential Revision: https://reviews.llvm.org/D96703
2021-02-20 12:02:07 +00:00
Simon Pilgrim 5d3930bb8f [DAG] visitTRUNCATE - attempt to truncate USUBSAT
Fold trunc(usubsat(zext(x),y)) -> usubsat(x,trunc(umin(y,satlimit)))
2021-02-19 14:26:05 +00:00
Simon Pilgrim 53e83afcaf [DAG] getTruncatedUSUBSAT - always truncate operands. NFCI.
As noticed on D96703, we're always truncating the operands so should use getNode(ISD::TRUNCATE) instead of getZExtOrTrunc.
2021-02-18 21:28:55 +00:00
Guozhi Wei 66f2d09ebf [DAGCombiner] Transform (zext (select c, load1, load2)) -> (select c, zextload1, zextload2)
If extload is legal, following transform
    (zext (select c, load1, load2)) -> (select c, zextload1, zextload2)
can save one ext instruction.

Differential Revision: https://reviews.llvm.org/D95086
2021-02-18 13:15:20 -08:00
Bradley Smith 8bad8a43c3 [AArch64][SVE] Add patterns to generate FMLA/FMLS/FNMLA/FNMLS/FMAD
Adjust generateFMAsInMachineCombiner to return false if SVE is present
in order to combine fmul+fadd into fma. Also add new pseudo instructions
so as to select the most appropriate of FMLA/FMAD depending on register
allocation.

Depends on D96599

Differential Revision: https://reviews.llvm.org/D96424
2021-02-18 16:55:16 +00:00
Simon Pilgrim 87fbc06d06 [DAG] Pull out getTruncatedUSUBSAT helper from foldSubToUSubSat. NFCI.
This will simplify an incoming generic implementation of D25987.

I'll rebase D96703 shortly to support this.
2021-02-17 12:17:08 +00:00
Simon Pilgrim 05c64ea672 [DAG] Fold shuffle(bop(shuffle(x,y),shuffle(z,w)),bop(shuffle(a,b),shuffle(c,d))) (REAPPLIED)
Fold shuffle(bop(shuffle(x,y),shuffle(z,w)),bop(shuffle(a,b),shuffle(c,d))) -> bop(shuffle(x,y),shuffle(z,w)),bop(shuffle(a,b),shuffle(c,d))

Attempt to fold from a shuffle of a pair of binops to a binop of shuffles, as long as one/both of the binop sources are also shuffles that can be merged with the outer shuffle. This should guarantee that we remove one binop without introducing any additional shuffles.

Technically there's potential for a merged shuffle's lowering to be poorer than the original shuffle, but it could also be better, and I'm not seeing any regressions as long as we keep the 'don't merge splats' rule already present in MergeInnerShuffle.

This expands and generalizes an existing X86 combine and attempts to merge either of each binop's sources (with an on-the-fly commutation of the shuffle mask) - we couldn't do that in the x86 version as it had to stay in a form that DAGCombine's MergeInnerShuffle would still recognise.

Fixes issue raised by @saugustine in rG5aa8f4c0843a where we were failing to replace null shuffle operands from MergeInnerShuffle to UNDEFs.

Differential Revision: https://reviews.llvm.org/D96345
2021-02-17 11:42:43 +00:00
Sterling Augustine 5aa8f4c084 Revert "[DAG] Fold shuffle(bop(shuffle(x,y),shuffle(z,w)),bop(shuffle(a,b),shuffle(c,d)))"
This reverts commit 5dfba562dd.

That commit causes an assertion failure with the following repro:

typedef long b __attribute__((__vector_size__(16)));
b *d;
b e;
b __attribute__((__always_inline__)) c(b h, b i) {
  return (__attribute__((__vector_size__(8 * sizeof(short)))) short)h + i;
}
j() {
  b k, l, m, n, o[6], p, q;
  m = d[5];
  b r = m;
  b s = f(r, 8);
  q = s;
  l = d[1];
  p = l;
  t(q);
  n = c(m, l);
  o[1] = c(s, f(p, 8));
  k = __builtin_shufflevector(n, o[1], 0, 2);
  e = __builtin_ia32_psrlwi128(k, j);
}

./bin/clang -cc1 -triple x86_64-grtev4-linux-gnu -emit-obj -O1 -std=c99 test.c
2021-02-16 12:48:15 -08:00
Simon Pilgrim 5dfba562dd [DAG] Fold shuffle(bop(shuffle(x,y),shuffle(z,w)),bop(shuffle(a,b),shuffle(c,d)))
Fold shuffle(bop(shuffle(x,y),shuffle(z,w)),bop(shuffle(a,b),shuffle(c,d))) -> bop(shuffle(x,y),shuffle(z,w)),bop(shuffle(a,b),shuffle(c,d))

Attempt to fold from a shuffle of a pair of binops to a binop of shuffles, as long as one/both of the binop sources are also shuffles that can be merged with the outer shuffle. This should guarantee that we remove one binop without introducing any additional shuffles.

Technically there's potential for a merged shuffle's lowering to be poorer than the original shuffle, but it could also be better, and I'm not seeing any regressions as long as we keep the 'don't merge splats' rule already present in MergeInnerShuffle.

This expands and generalizes an existing X86 combine and attempts to merge either of each binop's sources (with an on-the-fly commutation of the shuffle mask) - we couldn't do that in the x86 version as it had to stay in a form that DAGCombine's MergeInnerShuffle would still recognise.

Differential Revision: https://reviews.llvm.org/D96345
2021-02-16 15:46:34 +00:00
Simon Pilgrim e47f21da61 [DAG] visitVSELECT - move OpLHS == LHS into inner if() in USUBSAT matching. NFCI.
This will be necessary for the update of D25987 where we'll need to match OpLHS against other ops.
2021-02-15 18:27:00 +00:00
Simon Pilgrim 6f5a805bbb [DAG] Fold i1/vXi1 saddsat/uaddsat(x,y) -> or(x,y)
Alive2: https://alive2.llvm.org/ce/z/FzcrpH
2021-02-13 15:02:01 +00:00
Simon Pilgrim 0df15e5eff [DAG] Fold i1/vXi1 ssubsat/usubsat(x,y) -> and(x,~y)
Alive2: https://alive2.llvm.org/ce/z/4nkNGh
2021-02-13 13:21:15 +00:00
Simon Pilgrim 4841a225b7 [DAG] Move basic USUBSAT pattern matches from X86 to DAGCombine
Begin transitioning the X86 vector code to recognise sub(umax(a,b) ,b) or sub(a,umin(a,b)) USUBSAT patterns to make it more generic and available to all targets.

This initial patch just moves the basic umin/umax patterns to DAG, removing some vector-only checks on the way - these are some of the patterns that the legalizer will try to expand back to so we can be reasonably relaxed about matching these pre-legalization.

We can handle the trunc(sub(..))) variants as well, which helps with patterns where we were promoting to a wider type to detect overflow/saturation.

The remaining x86 code requires some cleanup first - some of it isn't actually tested etc. I also need to resurrect D25987.

Differential Revision: https://reviews.llvm.org/D96413
2021-02-12 18:22:57 +00:00
Simon Pilgrim 5beebf9c58 [DAG] foldLogicOfSetCCs - Generalize and/or (setcc X, CMax, ne), (setcc X, CMin, ne/eq) fold. NFCI.
Prep work to add support for non-uniform vectors - replace APInt values with using the SDValue ops directly.
2021-02-11 17:09:01 +00:00
Luís Marques acac29ca42 [DAGCombiner] Don't fold FCOPYSIGN vector sign operand casts
Avoid doing the following combine for vector types:

```
copysign(x, fp_extend(y)) -> copysign(x, y)
copysign(x, fp_round(y)) -> copysign(x, y)
```

That combine seemed to impede the selection of vector instruction and cause
a mess in some circumstances.

Differential Revision: https://reviews.llvm.org/D96037
2021-02-10 14:25:24 +00:00
Kazu Hirata 7e75f6fc1d [SelectionDAG] Use range-based for loops (NFC) 2021-02-09 22:14:30 -08:00
Nemanja Ivanovic a5222aa085 [DAGCombine] Do not remove masking argument to FP16_TO_FP for some targets
As of commit 284f2bffc9, the DAG Combiner gets rid of the masking of the
input to this node if the mask only keeps the bottom 16 bits. This is because
the underlying library function does not use the high order bits. However, on
PowerPC's ELFv2 ABI, it is the caller that is responsible for clearing the bits
from the register. Therefore, the library implementation of __gnu_h2f_ieee will
return an incorrect result if the bits aren't cleared.

This combine is desired for ARM (and possibly other targets) so this patch adds
a query to Target Lowering to check if this zeroing needs to be kept.

Fixes: https://bugs.llvm.org/show_bug.cgi?id=49092

Differential revision: https://reviews.llvm.org/D96283
2021-02-09 06:33:48 -06:00
Simon Pilgrim c5c690a835 [DAG] visitVECTOR_SHUFFLE - move shuffle legality check into MergeInnerShuffle lamda. NFCI.
This is going to be necessary for a future reuse of MergeInnerShuffle
2021-02-08 14:25:16 +00:00
Huihui Zhang 1b81117f88 [DAGCombiner][SVE] Fix invalid use of getVectorNumElements() in visitSRA.
Make sure scalable property is preserved by using getVectorElementCount().

Reviewed By: paulwalker-arm

Differential Revision: https://reviews.llvm.org/D95967
2021-02-05 09:56:49 -08:00
Craig Topper 34da12dd1f [DAGCombiner] Remove (sra (shl X, C), C) if X has more than C sign bits.
If sext_inreg is supported, we will turn this into sext_inreg. That
will then remove it if there are enough sign bits. But if sext_inreg
isn't supported, we can still remove the shift pair based on sign
bits.

Split from D95890.
2021-02-03 10:18:40 -08:00
Fraser Cormack fde2466171 [SelectionDAG] Support scalable-vector splats in more cases
This patch adds support for scalable-vector splats in DAGCombiner's
`isConstantOrConstantVector` and `ISD::matchUnaryPredicate` functions,
which enable the SelectionDAG div/rem-by-constant optimizations for
scalable vector types.

It also fixes up one case where the UDIV optimization was generating a
SETCC without first consulting the target for its preferred SETCC result
type.

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D94501
2021-01-25 10:58:15 +00:00
QingShan Zhang ffc3e800c6 [NFC] [DAGCombine] Correct the result for sqrt even the iteration is zero
For now, we correct the result for sqrt if iteration > 0. This doesn't make
sense as they are not strict relative.

Reviewed By: dmgreen, spatel, RKSimon

Differential Revision: https://reviews.llvm.org/D94480
2021-01-25 04:02:44 +00:00
Kazu Hirata 16baad8f4e [llvm] Use pop_back_val (NFC) 2021-01-24 12:18:57 -08:00
Simon Pilgrim 5dbe5d2c91 [DAG] Commute shuffle(splat(A,u), shuffle(C,D)) -> shuffle'(shuffle(C,D), splat(A,u))
We only merge shuffles if the inner (LHS) shuffle is a non-splat, so commute these shuffles to improve merging of multiple shuffles.
2021-01-22 11:43:18 +00:00
Simon Pilgrim 69bc0990a9 [DAGCombiner] Enable SimplifyDemandedBits vector support for TRUNCATE (REAPPLIED).
Add DemandedElts support inside the TRUNCATE analysis.

REAPPLIED - this was reverted by @hans at rGa51226057fc3 due to an issue with vector shift amount types, which was fixed in rG935bacd3a724 and an additional test case added at rG0ca81b90d19d

Differential Revision: https://reviews.llvm.org/D56387
2021-01-21 13:01:34 +00:00
Simon Pilgrim bc9ab9a5cd [DAG] CombineToPreIndexedLoadStore - use const APInt& for getAPIntValue(). NFCI.
Cleanup some code to use auto* properly from cast, and use const APInt& for getAPIntValue() to avoid an unnecessary copy.
2021-01-21 11:04:09 +00:00
Hans Wennborg a51226057f Revert "[DAGCombiner] Enable SimplifyDemandedBits vector support for TRUNCATE"
It caused "Vector shift amounts must be in the same as their first arg"
asserts in Chromium builds. See the code review for repro instructions.

> Add DemandedElts support inside the TRUNCATE analysis.
>
> Differential Revision: https://reviews.llvm.org/D56387

This reverts commit cad4275d69.
2021-01-20 20:06:55 +01:00
Simon Pilgrim cad4275d69 [DAGCombiner] Enable SimplifyDemandedBits vector support for TRUNCATE
Add DemandedElts support inside the TRUNCATE analysis.

Differential Revision: https://reviews.llvm.org/D56387
2021-01-20 15:39:58 +00:00
Kazu Hirata b023cdeacc [llvm] Use llvm::all_of (NFC) 2021-01-19 20:19:17 -08:00
Kazu Hirata 8857202489 [llvm] Use llvm::find (NFC) 2021-01-19 20:19:14 -08:00
Simon Pilgrim 207f32948b [DAG] SimplifyDemandedBits - use KnownBits comparisons to remove ISD::UMIN/UMAX ops
Use the KnownBits icmp comparisons to determine when a ISD::UMIN/UMAX op is unnecessary should either op be known to be ULT/ULE or UGT/UGE than the other.

Differential Revision: https://reviews.llvm.org/D94532
2021-01-18 10:29:23 +00:00
Simon Pilgrim 46aa3c6c33 [DAG] visitVECTOR_SHUFFLE - MergeInnerShuffle - improve shuffle(shuffle(x,y),shuffle(x,y)) merging
MergeInnerShuffle currently attempts to merge shuffle(shuffle(x,y),z) patterns into a single shuffle, using 1 or 2 of the x,y,z ops.

However if we already match 2 ops we might be able to handle the third op if its also a shuffle that references one of the previous ops, allowing us to handle some cases like:

shuffle(shuffle(x,y),shuffle(x,y))
shuffle(shuffle(shuffle(x,z),y),z)
shuffle(shuffle(x,shuffle(x,y)),z)
etc.

This isn't an exhaustive match and is dependent on the order the candidate ops are encountered - if one of the matched ops was a shuffle that was peek-able we don't go back and try to split that, I haven't found much need for that amount of analysis yet.

This is a preliminary patch that will allow us to later improve x86 HADD/HSUB matching - but needs to be reviewed separately as its in generic code and affects existing Thumb2 tests.

Differential Revision: https://reviews.llvm.org/D94671
2021-01-15 15:08:31 +00:00
Simon Pilgrim 7c30c05ff7 [DAG] visitVECTOR_SHUFFLE - MergeInnerShuffle - reset shuffle ops and reorder early-out and second op matching. NFCI.
I'm hoping to reuse MergeInnerShuffle in some other folds - so ensure the candidate ops/mask are reset at the start of each run.

Also, move the second op matching before bailing to make it simpler to try to match other things afterward.
2021-01-14 11:55:20 +00:00
Simon Pilgrim af8d27a7a8 [DAG] visitVECTOR_SHUFFLE - pull out shuffle merging code into lambda helper. NFCI.
Make it easier to reuse in a future patch.
2021-01-14 11:05:19 +00:00
Kazu Hirata 5c1c39e8d8 [llvm] Use *Set::contains (NFC) 2021-01-13 19:14:41 -08:00
Simon Pilgrim 993c488ed2 [DAG] visitVECTOR_SHUFFLE - use all_of to check for all-undef shuffle mask. NFCI. 2021-01-13 17:19:41 +00:00
Juneyoung Lee 25eb7b08ba [DAGCombiner] Fold BRCOND(FREEZE(COND)) to BRCOND(COND)
This patch resolves the suboptimal codegen described in http://llvm.org/pr47873 .
When CodeGenPrepare lowers select into a conditional branch, a freeze instruction is inserted.
It is then translated to `BRCOND(FREEZE(SETCC))` in SelDag.
The `FREEZE` in the middle of `SETCC` and `BRCOND` was causing a suboptimal code generation however.
This patch adds `BRCOND(FREEZE(cond))` -> `BRCOND(cond)` fold to DAGCombiner to remove the `FREEZE`.

To make this optimization sound, `BRCOND(UNDEF)` simply should nondeterministically jump to the branch or not, rather than raising UB.
It wasn't clear what happens when the condition was undef according to the comments in ISDOpcodes.h, however.
I updated the comments of `BRCOND` to make it explicit (as well as `BR_CC`, which is also a conditional branch instruction).

Note that it diverges from the semantics of `br` instruction in IR, which is explicitly UB.
Since the UB semantics was necessary to explain optimizations that use branching conditions, and SelDag doesn't seem to have such optimization, I think this divergence is okay.

Reviewed By: spatel

Differential Revision: https://reviews.llvm.org/D92015
2021-01-13 09:36:52 +09:00
Craig Topper df74c001fa [DAGCombiner] Replace static helper function isConstantFPBuildVectorOrConstantFP with the identical version in SelectionDAG. NFC 2021-01-11 23:41:40 -08:00
Joe Ellis 007358239d [DAGCombiner] Use getVectorElementCount inside visitINSERT_SUBVECTOR
This avoids TypeSize-/ElementCount-related warnings.

Differential Revision: https://reviews.llvm.org/D92747
2021-01-11 14:15:11 +00:00
QingShan Zhang 7539c75bb4 [DAGCombine] Remove the check for unsafe-fp-math when we are checking the AFN
We are checking the unsafe-fp-math for sqrt but not for fpow, which behaves inconsistent.
As the direction is to remove this global option, we need to remove the unsafe-fp-math
check for sqrt and update the test with afn fast-math flags.

Reviewed By: Spatel

Differential Revision: https://reviews.llvm.org/D93891
2021-01-11 02:25:53 +00:00
Craig Topper 4ef91f5871 [DAGCombiner] Don't speculatively create an all ones constant in visitREM that might not be used.
This looks to have been done to save some duplicated code under
two different if statements, but it ends up being harmful to D94073.
This speculative constant can be called on a scalable vector type
with i64 element size when i64 scalars aren't legal. The code tries
and fails to find a vector type with i32 elements that it can use.

So only create the node when we know it will be used.
2021-01-05 12:45:57 -08:00
Cameron McInally 92be640bd7 [FPEnv][AMDGPU] Disable FSUB(-0,X)->FNEG(X) DAGCombine when subnormals are flushed
This patch disables the FSUB(-0,X)->FNEG(X) DAG combine when we're flushing subnormals. It requires updating the existing AMDGPU tests to use the fneg IR instruction, in place of the old fsub(-0,X) canonical form, since AMDGPU is the only backend currently checking the DenormalMode flags.

Note that this will require follow-up optimizations to make sure the FSUB(-0,X) form is handled appropriately

Differential Revision: https://reviews.llvm.org/D93243
2021-01-04 14:44:10 -06:00
Layton Kifer d29f93bda5 [DAGCombiner] Don't create sexts of deleted xors when they were in-visit replaced
Fixes a bug introduced by D91589.

When folding `(sext (not i1 x)) -> (add (zext i1 x), -1)`, we try to replace the not first when possible. If we replace the not in-visit, then the now invalidated node will be returned, and subsequently we will return an invalid sext. In cases where the not is replaced in-visit we can simply return SDValue, as the not in the current sext should have already been replaced.

Thanks @jgorbe, for finding the below reproducer.

The following reduced test case crashes clang when built with `clang -O1 -frounding-math`:

```
template <class> class a {
  int b() { return c == 0.0 ? 0 : -1; }
  int c;
};
template class a<long>;
```

A debug build of clang produces this "assertion failed" error:
```
clang: /home/jgorbe/code/llvm/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:264: void {anonymous}::DAGCombiner::AddToWorklist(llvm::
SDNode*): Assertion `N->getOpcode() != ISD::DELETED_NODE && "Deleted Node added to Worklist"' failed.
```

Reviewed By: spatel

Differential Revision: https://reviews.llvm.org/D93274
2020-12-23 16:16:26 -08:00
Layton Kifer 385e9a2a04 [DAGCombiner] Improve shift by select of constant
Clean up a TODO, to support folding a shift of a constant by a
select of constants, on targets with different shift operand sizes.

Reviewed By: RKSimon, lebedev.ri

Differential Revision: https://reviews.llvm.org/D90349
2020-12-18 02:21:42 +00:00
Kerry McLaughlin 05edfc5475 [SVE][CodeGen] Add DAG combines for s/zext_masked_gather
This patch adds the following DAGCombines, which apply if isVectorLoadExtDesirable() returns true:
 - fold (and (masked_gather x)) -> (zext_masked_gather x)
 - fold (sext_inreg (masked_gather x)) -> (sext_masked_gather x)

LowerMGATHER has also been updated to fetch the LoadExtType associated with the
gather and also use this value to determine the correct masked gather opcode to use.

Reviewed By: sdesmalen

Differential Revision: https://reviews.llvm.org/D92230
2020-12-09 11:53:19 +00:00
Kerry McLaughlin 4519ff4b6f [SVE][CodeGen] Add the ExtensionType flag to MGATHER
Adds the ExtensionType flag, which reflects the LoadExtType of a MaskedGatherSDNode.
Also updated SelectionDAGDumper::print_details so that details of the gather
load (is signed, is scaled & extension type) are printed.

Reviewed By: sdesmalen

Differential Revision: https://reviews.llvm.org/D91084
2020-12-09 11:19:08 +00:00
Huihui Zhang 8e6fc1f97e [AArch64][SVE] Add lowering for llvm.maxnum|minnum for scalable type.
LLVM intrinsic llvm.maxnum|minnum is overloaded intrinsic, can be used on any
floating-point or vector of floating-point type.
This patch extends current infrastructure to support scalable vector type.

This patch also fix a warning message of incorrect use of EVT::getVectorNumElements()
for scalable type, when DAGCombiner trying to split scalable vector.

Reviewed By: sdesmalen

Differential Revision: https://reviews.llvm.org/D92607
2020-12-08 09:35:53 -08:00
Kai Luo 44bd8ea167 [DAGCombine][PowerPC] Simplify nabs by using legal `smin` operation
Convert `0 - abs(x)` to `smin (x, -x)` if `smin` is a legal operation.

Verification: https://alive2.llvm.org/ce/z/vpquFR

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D92637
2020-12-08 03:24:07 +00:00