Commit Graph

3019 Commits

Author SHA1 Message Date
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
Simon Pilgrim b6e847c396 [DAG] Cleanup by folding some single use VT.getScalarSizeInBits() calls into its comparison. NFCI. 2020-12-07 18:23:54 +00:00
Kerry McLaughlin 111f559bbd [SVE][CodeGen] Call refineIndexType & refineUniformBase from visitMGATHER
The refineIndexType & refineUniformBase functions added by D90942 can also be used to
improve CodeGen of masked gathers.

These changes were split out from D91092

Reviewed By: sdesmalen

Differential Revision: https://reviews.llvm.org/D92319
2020-12-07 13:20:19 +00:00
Bing1 Yu eee30a6dce [CodeGen] Modify the refineIndexType(...)'s code to fix a bug in D90942.
In previous code, when refineIndexType(...) is called and Index is undef, Index.getOperand(0) will raise a assertion fail.

Reviewed By: pengfei

Differential Revision: https://reviews.llvm.org/D92548
2020-12-07 08:49:07 +08:00
Layton Kifer ac522f8700 [DAGCombiner] Fold (sext (not i1 x)) -> (add (zext i1 x), -1)
Move fold of (sext (not i1 x)) -> (add (zext i1 x), -1) from X86 to DAGCombiner to improve codegen on other targets.

Differential Revision: https://reviews.llvm.org/D91589
2020-12-06 11:52:10 -05:00
Simon Pilgrim 6f4ee6f870 [DAGCombiner] Use const APInt& for getConstantOperandAPInt results. NFCI.
Avoid unnecessary instantiation.

Noticed while removing unnecessary autos
2020-12-04 09:44:58 +00:00
dfukalov 2ce38b3f03 [NFC] Reduce include files dependency.
1. Removed #include "...AliasAnalysis.h" in other headers and modules.
2. Cleaned up includes in AliasAnalysis.h.

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D92489
2020-12-03 18:25:05 +03:00
Joe Ellis 78c0ea54a2 [DAGCombine] Fix TypeSize warning in DAGCombine::visitLIFETIME_END
Bail out early if we encounter a scalable store.

Reviewed By: peterwaller-arm

Differential Revision: https://reviews.llvm.org/D92392
2020-12-03 12:12:41 +00:00
Layton Kifer d7fec38f05
[DAGCombiner][NFC] Replace duplicate implementation flipBoolean with DAG.getLogicalNOT
Reviewed By: lebedev.ri

Differential Revision: https://reviews.llvm.org/D92246
2020-12-01 22:23:04 +03:00
Benjamin Kramer 107e92dff8 [DAG] Remove unused variable. NFC. 2020-12-01 16:29:02 +01:00
Simon Pilgrim 1b209ff9e3 [DAG] Move vselect(icmp_ult, 0, sub(x,y)) -> usubsat(x,y) to DAGCombine (PR40111)
Move the X86 VSELECT->USUBSAT fold to DAGCombiner - there's nothing target specific about these folds.
2020-12-01 14:25:29 +00:00
Simon Pilgrim 6dbd0d36a1 [DAG] Move vselect(icmp_ult, -1, add(x,y)) -> uaddsat(x,y) to DAGCombine (PR40111)
Move the X86 VSELECT->UADDSAT fold to DAGCombiner - there's nothing target specific about these folds.

The SSE42 test diffs are relatively benign - its avoiding an extra constant load in exchange for an extra xor operation - there are extra register moves, which is annoying as all those operations should commute them away.

Differential Revision: https://reviews.llvm.org/D91876
2020-12-01 11:56:26 +00:00
QingShan Zhang 4d83aba422 [DAGCombine] Adding a hook to improve the precision of fsqrt if the input is denormal
For now, we will hardcode the result as 0.0 if the input is denormal or 0. That will
have the impact the precision. As the fsqrt added belong to the cold path of the
cmp+branch, it won't impact the performance for normal inputs for PowerPC, but improve
the precision if the input is denormal.

Reviewed By: Spatel

Differential Revision: https://reviews.llvm.org/D80974
2020-11-27 02:10:55 +00:00
QingShan Zhang 9c588f53fc [DAGCombine] Add hook to allow target specific test for sqrt input
PowerPC has instruction ftsqrt/xstsqrtdp etc to do the input test for software square root.
LLVM now tests it with smallest normalized value using abs + setcc. We should add hook to
target that has test instructions.

Reviewed By: Spatel, Chen Zheng, Qiu Chao Fang

Differential Revision: https://reviews.llvm.org/D80706
2020-11-25 05:37:15 +00:00
Kai Luo 5931be60b5 [DAGCombine][PowerPC] Convert negated abs to trivial arithmetic ops
This patch converts `0 - abs(x)` to `Y = sra (X, size(X)-1); sub (Y, xor (X, Y))` for better codegen.

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D91120
2020-11-24 09:43:35 +00:00
Kerry McLaughlin 306c8ab208 [SVE][CodeGen] Improve codegen of scalable masked scatters
If the scatter store is able to perform the sign/zero extend of
its index, this is folded into the instruction with refineIndexType().
Additionally, refineUniformBase() will return the base pointer and index
from an add + splat_vector.

Reviewed By: sdesmalen

Differential Revision: https://reviews.llvm.org/D90942
2020-11-13 11:19:36 +00:00
Francesco Petrogalli fc2fe6817e [llvm][AArch64] Simplify (and (sign_extend..) #bitmask).
Fold

    VT = (and (sign_extend NarrowVT to VT) #bitmask)

into

    VT = (zero_extend NarrowVT)

With this combine, the test replaces a sign extended load + an
unsigned extention with a zero extended load to render one of the
operands of the last multiplication.

  BEFORE                       |  AFTER
    f_i16_i32:                 |    f_i16_i32:
         .fnstart              |           .fnstart
         ldrsh   r0, [r0]      |           ldrh    r1, [r1]
         ldrsh   r1, [r1]      |           ldrsh   r0, [r0]
         smulbb  r0, r1, r0    |           smulbb  r0, r0, r1
         uxth    r1, r1        |           mul     r0, r0, r1
         mul     r0, r0, r1    |           bx      lr
         bx      lr            |

Reviewed By: resistor

Differential Revision: https://reviews.llvm.org/D90605
2020-11-09 12:53:36 +00:00
Fraser Cormack f99580c1e5 [DAGCombine] Fix bug in load scalarization
Summary:
For vector element types which are not byte-sized, we would generate
incorrect scalar offsets and produce incorrect codegen.

This optimization could potentially be supported in the future, e.g. by
loading in bytes, then shifting and masking out the remaining bits of
the vector element. However, without an upstream target to test against
it's best to avoid the bad codegen in the simplest possible way.

Related to this bug:

  https://bugs.llvm.org/show_bug.cgi?id=27600

Reviewed by: foad

Differential Revision: https://reviews.llvm.org/D78568
2020-11-04 19:02:40 +00:00
Kerry McLaughlin f2412d372d [SVE][CodeGen] Lower scalable integer vector reductions
This patch uses the existing LowerFixedLengthReductionToSVE function to also lower
scalable vector reductions. A separate function has been added to lower VECREDUCE_AND
& VECREDUCE_OR operations with predicate types using ptest.

Lowering scalable floating-point reductions will be addressed in a follow up patch,
for now these will hit the assertion added to expandVecReduce() in TargetLowering.

Reviewed By: paulwalker-arm

Differential Revision: https://reviews.llvm.org/D89382
2020-11-04 11:38:49 +00:00
Simon Pilgrim f53d7f55f1 [DAG] Move canFoldInAddressingMode before foldBinOpIntoSelect. NFC.
Reduces the diff in D90113.
2020-10-28 12:16:05 +00:00
Peter Waller 5b742a0c10 [SVE][CodeGen][DAGCombiner] Fix TypeSize warning in redundant store elimination
The modified code in visitSTORE was missing a scalable vector check, and still
using the now deprecated implicit cast of TypeSize to uint64_t through the
overloaded operator. This patch fixes these issues.

This brings the logic in line with the comment on the context line immediately
above the added precondition.

Add a test in sve-redundant-store.ll that the warning is not triggered.

Differential Revision: https://reviews.llvm.org/D89701
2020-10-26 16:37:48 +00:00
Peter Waller 6536d6040f Revert "[SVE][CodeGen][DAGCombiner] Fix TypeSize warning in redundant store elimination"
This reverts commit 4604441386.

Reverting because it was not the intended version of the patch, which
follows this patch.
2020-10-26 16:37:00 +00:00
Peter Waller 4604441386 [SVE][CodeGen][DAGCombiner] Fix TypeSize warning in redundant store elimination
The modified code in visitSTORE was missing a scalable vector check, and still
using the now deprecated implicit cast of TypeSize to uint64_t through the
overloaded operator. This patch fixes these issues.

This brings the logic in line with the comment on the context line immediately
above the added precondition.

Add a test in Redundantstores.ll that the warning is not triggered.
2020-10-26 16:23:42 +00:00
Qiu Chaofan 1b2fe71ecf [DAGCombiner] Tighten reasscociation of visitFMA
From LangRef, FMF contract should not enable reassociating to form
arbitrary contractions. So it should not help rearrange nodes like
(fma (fmul x, c1), c2, y) into (fma x, c1*c2, y).

Reviewed By: spatel

Differential Revision: https://reviews.llvm.org/D89527
2020-10-20 10:13:01 +08:00
Amy Kwan 6a946fd06f [DAGCombiner][PowerPC] Remove isMulhCheaperThanMulShift TLI hook, Use isOperationLegalOrCustom directly instead.
MULH is often expanded on targets.
This patch removes the isMulhCheaperThanMulShift hook and uses
isOperationLegalOrCustom instead.

Differential Revision: https://reviews.llvm.org/D80485
2020-10-19 12:23:04 -05:00
David Sherwood 3945b69e81 [SVE][CodeGen] Replace more TypeSize comparison operators with their scalar equivalents
In certain places in llvm/lib/CodeGen we were relying upon the TypeSize
comparison operators when in fact the code was only ever expecting
either scalar values or fixed width vectors. This patch changes a few
functions that were always expecting to work on scalar or fixed width
types:

1. DAGCombiner::mergeTruncStores - deals with scalar integers only.
2. DAGCombiner::ReduceLoadWidth - not valid for vectors.
3. DAGCombiner::createBuildVecShuffle - should only be used for
   fixed width vectors.
4. SelectionDAGLegalize::ExpandFCOPYSIGN and
   SelectionDAGLegalize::getSignAsIntValue - only work on scalars.

Differential Revision: https://reviews.llvm.org/D88562
2020-10-19 08:38:50 +01:00
David Sherwood 35a531fb45 [SVE][CodeGen][NFC] Replace TypeSize comparison operators with their scalar equivalents
In certain places in llvm/lib/CodeGen we were relying upon the TypeSize
comparison operators when in fact the code was only ever expecting
either scalar values or fixed width vectors. I've changed some of these
places to use the equivalent scalar operator.

Differential Revision: https://reviews.llvm.org/D88482
2020-10-19 08:30:31 +01:00
David Sherwood f693f915a0 [SVE][CodeGen] Replace uses of TypeSize comparison operators
In certain places in the code we can never end up in a situation where
we're mixing fixed width and scalable vector types. For example,
we can't have truncations and extends that change the lane count. Also,
in other places such as GenWidenVectorStores and GenWidenVectorLoads we
know from the behaviour of FindMemType that we can never choose a vector
type with a different scalable property.

In various places I have used EVT::bitsXY functions instead of
TypeSize::isKnownXY, where it probably makes sense to keep an assert
that scalable properties match.

Differential Revision: https://reviews.llvm.org/D88654
2020-10-19 08:08:41 +01:00
Craig Topper 1687a8d83b [X86][SelectionDAG] Add SADDO_CARRY and SSUBO_CARRY to support multipart signed add/sub overflow legalization.
This passes existing X86 test but I'm not sure if it handles all type
legalization cases it needs to.

Alternative to D89200

Reviewed By: efriedma

Differential Revision: https://reviews.llvm.org/D89222
2020-10-12 23:18:29 -07:00
David Sherwood c5ba0d33cc [SVE] Make ElementCount and TypeSize use a new PolySize class
I have introduced a new template PolySize class, where the template
parameter determines the type of quantity, i.e. for an element
count this is just an unsigned value. The ElementCount class is
now just a simple derivation of PolySize<unsigned>, whereas TypeSize
is more complicated because it still needs to contain the uint64_t
cast operator, since there are still many places in the code that
rely upon this implicit cast. As such the class also still needs
some of it's own operators.

I've tried to minimise the amount of code in the base PolySize
class, which led to a couple of changes:

1. In some places we were relying on '==' operator comparisons
between ElementCounts and the scalar value 1. I didn't put this
operator in the new PolySize class, and thought it was actually
clearer to use the isScalar() function instead.
2. I removed the isByteSized function and replaced it with calls
to isKnownMultipleOf(8).

I've also renamed NextPowerOf2 to be coefficientNextPowerOf2 so
that it's more consistent with coefficientDivideBy.

Differential Revision: https://reviews.llvm.org/D88409
2020-10-12 08:23:38 +01:00
Esme-Yi e9fd8823ba [DAGCombiner] Add decomposition patterns for Mul-by-Imm.
Summary: This patch is derived from D87384.
In this patch we expand the existing decomposition of mul-by-constant to be more general by implementing 2 patterns:
```
  mul x, (2^N + 2^M) --> (add (shl x, N), (shl x, M))
  mul x, (2^N - 2^M) --> (sub (shl x, N), (shl x, M))
```
The conversion will be trigged if the multiplier is a big constant that the target can't use a single multiplication instruction to handle. This is controlled by the hook `decomposeMulByConstant`.
More over, the conversion benefits from an ILP improvement since the instructions are independent. A case with the sequence like following also gets benefit since a shift instruction is saved.

```
*res1 = a * 0x8800;
*res2 = a * 0x8080;
```

Reviewed By: spatel

Differential Revision: https://reviews.llvm.org/D88201
2020-10-09 08:51:40 +00:00
David Sherwood 4ed47d50ea [SVE][CodeGen] Fix DAGCombiner::ForwardStoreValueToDirectLoad for scalable vectors
In DAGCombiner::ForwardStoreValueToDirectLoad I have fixed up some
implicit casts from TypeSize -> uint64_t and replaced calls to
getVectorNumElements() with getVectorElementCount(). There are some
simple cases of forwarding that we can definitely support for
scalable vectors, i.e. when the store and load are both scalable
vectors and have the same size. I have added tests for the new
code paths here:

  CodeGen/AArch64/sve-forward-st-to-ld.ll

Differential Revision: https://reviews.llvm.org/D87098
2020-10-06 08:04:03 +01:00
Craig Topper 1127662c6d [SelectionDAG] Make sure FMF are propagated when getSetcc canonicalizes FP constants to RHS.
getNode handling for ISD:SETCC calls FoldSETCC which can canonicalize
FP constants to the RHS. When this happens we should create the node
with the FMF that was requested. By using FlagInserter when can ensure
any calls to getNode/getSetcc during canonicalization will also get the flags.

Differential Revision: https://reviews.llvm.org/D88063
2020-10-05 14:55:23 -07:00
Sanjay Patel 2ccbf3dbd5 [SDAG] fold x * 0.0 at node creation time
In the motivating case from https://llvm.org/PR47517
we create a node that does not get constant folded
before getNegatedExpression is attempted from some
other node, and we crash.

By moving the fold into SelectionDAG::simplifyFPBinop(),
we get the constant fold sooner and avoid the problem.
2020-10-04 11:31:57 -04:00
David Sherwood bafdd11326 [SVE] Replace / operator in TypeSize/ElementCount with divideCoefficientBy
After some recent upstream discussion we decided that it was best
to avoid having the / operator for both ElementCount and TypeSize,
since this could give the impression that these classes can be used
in the same way as basic integer integer types. However, division
for scalable types is a bit odd because we are only dividing the
minimum quantity by a value, as opposed to something like:

  (MinSize * Vscale) / SomeValue

This is why when performing division it's important the caller
first establishes whether the operation makes sense, perhaps by
calling isKnownMultipleOf() prior to division. The caller must now
explictly call divideCoefficientBy() on the class to perform the
operation.

Differential Revision: https://reviews.llvm.org/D87700
2020-09-28 08:03:00 +01:00
Simon Pilgrim a61272a900 [DAG] Fold vector mul(x,0)/mul(x,1) to a clearing mask
If we're multiplying all elements of a vector by '0' or '1' then we can more efficiently perform this as a clearing mask (that is likely to further simplify to a shuffle blend).

This was noticed when reviewing D87502 but seems to help idiv/irem by constant cases even more as '0'/'1' values are often used for 'passthrough' cases.

Differential Revision: https://reviews.llvm.org/D88225
2020-09-26 14:31:57 +01:00
Qiu Chaofan c0f8e4c06c [SelectionDAG] Add guard to automatically insert flags
This is like FastMathFlagGuard in IR. Since we use SDAG instance to get
values, it's with SelectionDAG. By creating a FlagInserter in current
scope, all values created by getNode will get the flags if no Flags
argument provided.

In this patch, I applied it to floating point operations folding part in
DAG combiner, and removed Flags passing to getNode to show its effect.
Other places in DAG combiner and other helper methods similar to getNode
also need this. They can be done in follow-up patches.

Reviewed By: spatel

Differential Revision: https://reviews.llvm.org/D87361
2020-09-26 13:57:52 +08:00
David Sherwood e077367a28 [SVE] Make EVT::getScalarSizeInBits and others consistent with Type::getScalarSizeInBits
An existing function Type::getScalarSizeInBits returns a uint64_t
instead of a TypeSize class because the caller is requesting a
scalar size, which cannot be scalable. This patch makes other
similar functions requesting a scalar size consistent with that,
thereby eliminating more than 1000 implicit TypeSize -> uint64_t
casts.

Differential revision: https://reviews.llvm.org/D87889
2020-09-23 09:20:08 +01:00
Craig Topper e30371d99d [DAGCombiner] Teach visitMSTORE to replace an all ones mask with an unmasked store.
Similar to what done in D87788 for MLOAD.

Again I've skipped indexed, truncating, and compressing stores.
2020-09-16 16:42:22 -07:00
Craig Topper 89ee4c0314 [DAGCombiner] Teach visitMLOAD to replace an all ones mask with an unmasked load
If we have an all ones mask, we can just a regular masked load. InstCombine already gets this in IR. But the all ones mask can appear after type legalization.

Only avx512 test cases are affected because X86 backend already looks for element 0 and the last element being 1. It replaces this with an unmasked load and blend. The all ones mask is a special case of that where the blend will be removed. That transform is only enabled on avx2 targets. I believe that's because a non-zero passthru on avx2 already requires a separate blend so its more profitable to handle mixed constant masks.

This patch adds a dedicated all ones handling to the target independent DAG combiner. I've skipped extending, expanding, and index loads for now. X86 doesn't use index so I don't know much about it. Extending made me nervous because I wasn't sure I could trust the memory VT had the right element count due to some weirdness in vector splitting. For expanding I wasn't sure if we needed different undef handling.

Differential Revision: https://reviews.llvm.org/D87788
2020-09-16 13:21:16 -07:00
Simon Pilgrim 3f682611ab [DAG] Remover getOperand() call. NFCI. 2020-09-16 11:18:58 +01:00
Craig Topper c193a689b4 [SelectionDAG] Use Align/MaybeAlign in calls to getLoad/getStore/getExtLoad/getTruncStore.
The versions that take 'unsigned' will be removed in the future.

I tried to use getOriginalAlign instead of getAlign in some
places. getAlign factors in the minimum alignment implied by
the offset in the pointer info. Since we're also passing the
pointer info we can use the original alignment.

Reviewed By: arsenm

Differential Revision: https://reviews.llvm.org/D87592
2020-09-14 13:54:50 -07:00
Nikita Popov 8e69c3cde8 [DAGCombiner] Fold fmin/fmax with INF / FLT_MAX
Similar to D87415, this folds the various float min/max opcodes
with a constant INF or -INF operand, or FLT_MAX / -FLT_MAX operand
if the ninf flag is set. Some of the folds are only possible under
nnan.

The fminnum(X, INF) with nnan and fmaxnum(X, -INF) with nnan cases
are needed to improve the VECREDUCE_FMIN/FMAX lowerings on X86,
the rest is here for the sake of completeness.

Differential Revision: https://reviews.llvm.org/D87571
2020-09-14 19:59:33 +02:00
Craig Topper 56b33391d3 [SelectionDAG] Move ISD:PARITY formation from DAGCombine to SimplifyDemandedBits.
Previously, we formed ISD::PARITY by looking for (and (ctpop X), 1)
but the AND might be separated from the ctpop. For example if the
parity result is multiplied by 2, we'll pull the AND through the
shift.

So to handle more cases, move to SimplifyDemandedBits where we
can handle more cases that result in only the LSB of the CTPOP
being used.
2020-09-13 21:04:13 -07:00
Qiu Chaofan a4c5351986 [DAGCombiner] Propagate FMF flags in FMA folding
DAG combiner folds (fma a 1.0 b) into (fadd a b) but the flag isn't
propagated into new fadd. This patch fixes that.

Some code in visitFMA is redundant and such support for vector constants
is missing. Need follow-up patch to clean.

Reviewed By: spatel

Differential Revision: https://reviews.llvm.org/D87037
2020-09-14 00:19:06 +08:00
Craig Topper ad3d6f993d [SelectionDAG][X86][ARM][AArch64] Add ISD opcode for __builtin_parity. Expand it to shifts and xors.
Clang emits (and (ctpop X), 1) for __builtin_parity. If ctpop
isn't natively supported by the target, this leads to poor codegen
due to the expansion of ctpop being more complex than what is needed
for parity.

This adds a DAG combine to convert the pattern to ISD::PARITY
before operation legalization. Type legalization is updated
to handled Expanding and Promoting this operation. If after type
legalization, CTPOP is supported for this type, LegalizeDAG will
turn it back into CTPOP+AND. Otherwise LegalizeDAG will emit a
series of shifts and xors followed by an AND with 1.

I've avoided vectors in this patch to avoid more legalization
complexity for this patch.

X86 previously had a custom DAG combiner for this. This is now
moved to Custom lowering for the new opcode. There is a minor
regression in vector-reduce-xor-bool.ll, but a follow up patch
can easily fix that.

Fixes PR47433

Reviewed By: efriedma

Differential Revision: https://reviews.llvm.org/D87209
2020-09-12 11:42:18 -07:00
Nikita Popov 0a5dc7effb [DAGCombiner] Fold fmin/fmax of NaN
fminnum(X, NaN) is X, fminimum(X, NaN) is NaN. This mirrors the
behavior of existing InstSimplify folds.

This is expected to improve the reduction lowerings in D87391,
which use NaN as a neutral element.

Differential Revision: https://reviews.llvm.org/D87415
2020-09-09 23:53:32 +02:00
Ulrich Weigand 1a25133bcd [DAGCombine] Skip re-visiting EntryToken to avoid compile time explosion
During the main DAGCombine loop, whenever a node gets replaced, the new
node and all its users are pushed onto the worklist.  Omit this if the
new node is the EntryToken (e.g. if a store managed to get optimized
out), because re-visiting the EntryToken and its users will not uncover
any additional opportunities, but there may be a large number of such
users, potentially causing compile time explosion.

This compile time explosion showed up in particular when building the
SingleSource/UnitTests/matrix-types-spec.cpp test-suite case on any
platform without SIMD vector support.

Reviewed By: arsenm
Differential Revision: https://reviews.llvm.org/D86963
2020-09-09 19:13:46 +02:00
Craig Topper b1e68f885b [SelectionDAGBuilder] Pass fast math flags to getNode calls rather than trying to set them after the fact.:
This removes the after the fact FMF handling from D46854 in favor of passing fast math flags to getNode. This should be a superset of D87130.

This required adding a SDNodeFlags to SelectionDAG::getSetCC.

Now we manage to contant fold some stuff undefs during the
initial getNode that we don't do in later DAG combines.

Differential Revision: https://reviews.llvm.org/D87200
2020-09-08 15:27:21 -07:00
Sanjay Patel 7a06b166b1 [DAGCombiner] allow more store merging for non-i8 truncated ops
This is a follow-up suggested in D86420 - if we have a pair of stores
in inverted order for the target endian, we can rotate the source
bits into place.
The "be_i64_to_i16_order" test shows a limitation of the current
function (which might be avoided if we integrate this function with
the other cases in mergeConsecutiveStores). In the earlier
"be_i64_to_i16" test, we skip the first 2 stores because we do not
match the full set as consecutive or rotate-able, but then we reach
the last 2 stores and see that they are an inverted pair of 16-bit
stores. The "be_i64_to_i16_order" test alters the program order of
the stores, so we miss matching the sub-pattern.

Differential Revision: https://reviews.llvm.org/D87112
2020-09-07 14:12:36 -04:00
Paul Walker f72121254d [SVE] Don't reorder subvector/binop sequences when the resulting binop is not legal.
When lowering fixed length vector operations for SVE the subvector
operations are used extensively to marshall data between scalable
and fixed-length vectors. This means that sequences like:

  extract_subvec(binop(insert_subvec(a), insert_subvec(b)))

are very common. DAGCombine only checks if the resulting binop is
legal or can be custom lowered when undoing such sequences. When
it's custom lowering that is introducing them the result is an
infinite legalise->combine->legalise loop.

This patch extends the isOperationLegalOr... functions to include
a "LegalOnly" parameter to restrict the check to legal operations
only. Although isOperationLegal could be used it's common for
the affected code paths to be visited pre and post legalisation,
so the extra parameter keeps the code tidy.

Differential Revision: https://reviews.llvm.org/D86450
2020-09-02 11:01:33 +01:00
Cameron McInally cfe2b81710 [SVE] Update INSERT_SUBVECTOR DAGCombine to use getVectorElementCount().
A small piece of the project to replace getVectorNumElements() with getVectorElementCount().

Differential Revision: https://reviews.llvm.org/D86894
2020-09-01 16:51:44 -05:00
Sam Tebbs 15e880a04f [DAGCombiner] Fold an AND of a masked load into a zext_masked_load
This patch folds an AND of a masked load and build vector into a zero
extended masked load.

Differential Revision: https://reviews.llvm.org/D86789
2020-09-01 17:02:07 +01:00
Qiu Chaofan 5475154865 [NFC] [DAGCombiner] Refactor bitcast folding within fabs/fneg
fabs and fneg share a common transformation:

(fneg (bitconvert x)) -> (bitconvert (xor x sign))
(fabs (bitconvert x)) -> (bitconvert (and x ~sign))

This patch separate the code into a single method.

Reviewed By: spatel

Differential Revision: https://reviews.llvm.org/D86862
2020-09-01 00:48:12 +08:00
Qiu Chaofan eb2a405c18 [NFC] [DAGCombiner] Remove unnecessary negation in visitFNEG
In visitFNEG of DAGCombiner, the folding of (fneg (fsub c, x)) is
redundant since getNegatedExpression already handles it.
2020-09-01 00:35:01 +08:00
Sanjay Patel 1c9a09f42e [DAGCombiner] skip reciprocal divisor optimization for x/sqrt(x), better
I tried to fix this in:
rG716e35a0cf53
...but that patch depends on the order that we encounter the
magic "x/sqrt(x)" expression in the combiner's worklist.

This patch should improve that by waiting until we walk the
user list to decide if there's a use to skip.

The AArch64 test reveals another (existing) ordering problem
though - we may try to create an estimate for plain sqrt(x)
before we see that it is part of a 1/sqrt(x) expression.
2020-08-31 09:35:59 -04:00
Sanjay Patel 716e35a0cf [DAGCombiner] skip reciprocal divisor optimization for x/sqrt(x)
In general, we probably want to try the multi-use reciprocal
transform before sqrt transforms, but x/sqrt(x) is a special-case
because that will always reduce to plain sqrt(x) or an estimate.

The AArch64 tests show that the transform is limited by TLI
hook to patterns where there are 3 or more uses of the divisor.
So this change can result in an extra division compared to
what we had, but that's the intended behvior based on the
current setting of that hook.
2020-08-30 10:55:45 -04:00
Kai Luo b904324788 [DAGCombiner] Enhance (zext(setcc))
Current `v:t = zext(setcc x,y,cc)` will be transformed to `select x, y, 1:t, 0:t, cc`. It misses some opportunities if x's type size is less than `t`'s size. This patch enhances the above transformation.

Reviewed By: spatel

Differential Revision: https://reviews.llvm.org/D86687
2020-08-29 03:37:41 +00:00
David Sherwood f4257c5832 [SVE] Make ElementCount members private
This patch changes ElementCount so that the Min and Scalable
members are now private and can only be accessed via the get
functions getKnownMinValue() and isScalable(). In addition I've
added some other member functions for more commonly used operations.
Hopefully this makes the class more useful and will reduce the
need for calling getKnownMinValue().

Differential Revision: https://reviews.llvm.org/D86065
2020-08-28 14:43:53 +01:00
Drew Wock 0ec098e22b [FPEnv] Allow fneg + strict_fadd -> strict_fsub in DAGCombiner
This is the first of a set of DAGCombiner changes enabling strictfp
optimizations. I want to test to waters with this to make sure changes
like these are acceptable for the strictfp case- this particular change
should preserve exception ordering and result precision perfectly, and
many other possible changes appear to be able to as well.

Copied from regular fadd combines but modified to preserve ordering via
the chain, this change allows strict_fadd x, (fneg y) to become
struct_fsub x, y and strict_fadd (fneg x), y to become strict_fsub y, x.

Differential Revision: https://reviews.llvm.org/D85548
2020-08-27 08:17:01 -04:00
Sanjay Patel 54a5dd485c [DAGCombiner] allow store merging non-i8 truncated ops
We have a gap in our store merging capabilities for shift+truncate
patterns as discussed in:
https://llvm.org/PR46662

I generalized the code/comments for this function in earlier commits,
so we only need ease the type restriction and adjust the address/endian
checking to make this work.

AArch64 lets us switch endian to make sure that patterns are matched
either way.

Differential Revision: https://reviews.llvm.org/D86420
2020-08-26 15:23:08 -04:00
Venkataramanan Kumar 62e91bf563 [DAGCombine]: Fold X/Sqrt(X) to Sqrt(X)
With FMF ( "nsz" and " reassoc") fold X/Sqrt(X) to Sqrt(X).

This is done after targets have the chance to produce a
reciprocal sqrt estimate sequence because that expansion
is probably more efficient than an expansion of a
non-reciprocal sqrt. That is also why we deferred doing
this transform in IR (D85709).

Differential Revision: https://reviews.llvm.org/D86403
2020-08-24 18:16:13 -04:00
Sanjay Patel 1d0fa79824 [DAGCombiner] restrict store merge of truncs to early combining
The pattern matching does not account for truncating stores,
so it is unlikely to work at later stages. So we are likely
wasting compile-time with no hope of improvement by running
this later.
2020-08-23 10:44:23 -04:00
Sanjay Patel 79cb289a95 [DAGCombiner] add early exit for store merging of truncs
This should be NFC in terms of output because the endian
check further down would bail out too, but we are wasting
time by waiting to that point to give up. If we generalize
that function to deal with more than i8 types, we should
not have to deal with the degenerate case.
2020-08-22 16:25:16 -04:00
Sanjay Patel 2fc7c85201 [DAGCombiner] clean up merge of truncated stores; NFC
This code handles the special-case of i8 stores,
but it could be generalized to deal with other types.
2020-08-22 09:23:32 -04:00
Sanjay Patel f925fd3304 [DAGCombiner] give magic number a name in getStoreMergeCandidates; NFC 2020-08-17 15:37:55 -04:00
Sanjay Patel 046b4a550a [DAGCombiner] reduce code duplication in getStoreMergeCandidates; NFC 2020-08-17 15:37:55 -04:00
Sanjay Patel 20c85fd1ab [DAGCombiner] simplify bool return in getStoreMergeCandidates; NFC 2020-08-17 15:37:55 -04:00
Sanjay Patel 52cd8f1ecb [DAGCombiner] clean up getStoreMergeCandidates(); NFC
1. Move bailouts and local var declarations.
2. Convert if-chain to switch on StoreSource with unreachable default.
2020-08-17 15:37:54 -04:00
Sanjay Patel 27708db3e3 [DAGCombiner] convert StoreSource if-chain to switch; NFC
The "isa" checks were less constrained because they allow
target constants, but the later matching code would bail
out on those anyway, so this should be slightly more
efficient.
2020-08-17 15:37:54 -04:00
Kerry McLaughlin 30af595f05 [SVE][CodeGen] Legalisation of EXTRACT_VECTOR_ELT for scalable vectors
This patch changes SplitVecOp_EXTRACT_VECTOR_ELT to work correctly
for scalable vectors and also fixes an a bug in DAGCombiner where
the scalable property is dropped in visitTRUNCATE when attempting
to fold an extract + a truncate.

Reviewed By: efriedma

Differential Revision: https://reviews.llvm.org/D85754
2020-08-13 12:32:59 +01:00
David Sherwood 3ec3fcb97a [CodeGen] In narrowExtractedVectorLoad bail out for scalable vectors
In narrowExtractedVectorLoad there is an optimisation that tries to
combine extract_subvector with a narrowing vector load. At the moment
this produces warnings due to the incorrect calls to
getVectorNumElements() for scalable vector types. I've got this
working for scalable vectors too when the extract subvector index
is a multiple of the minimum number of elements. I have added a
new variant of the function:

  MachineFunction::getMachineMemOperand

that copies an existing MachineMemOperand, but replaces the pointer
info with a null version since we cannot currently represent scaled
offsets.

I've added a new test for this particular case in:

  CodeGen/AArch64/sve-extract-subvector.ll

Differential Revision: https://reviews.llvm.org/D83950
2020-08-13 10:46:18 +01:00
Kerry McLaughlin 85c7e89f3b [CodeGen] Refactor getMemBasePlusOffset & getObjectPtrOffset to accept a TypeSize
Changes the Offset arguments to both functions from int64_t to TypeSize
& updates all uses of the functions to create the offset using TypeSize::Fixed()

Reviewed By: efriedma

Differential Revision: https://reviews.llvm.org/D85220
2020-08-11 12:17:10 +01:00
Sanjay Patel f22ac1d15b [DAGCombiner] reassociate reciprocal sqrt expression to eliminate FP division, part 2
Follow-up to D82716 / rGea71ba11ab11
We do not have the fabs removal fold in IR yet for the case
where the sqrt operand is repeated, so that's another potential
improvement.
2020-08-08 10:38:06 -04:00
Simon Pilgrim 4aaf301fb8 [DAG] Fold vector (aext (load x)) -> (zext (truncate (zextload x)))
We currently don't do anything to fold any_extend vector loads as no target has such an instruction.

Instead I've added support for folding to a zextload, SimplifyDemandedBits does a good job of adjusting the zext(truncate(()) stages as required later on.

We still need the custom scalar extload handling instead of using the tryToFoldExtOfLoad helper as it has different legality tests - we can probably tweak that to reduce most of the code duplication.

Fixes the regression I mentioned in rG99a971cadff7

Differential Revision: https://reviews.llvm.org/D85129
2020-08-05 11:22:23 +01:00
Sam Tebbs 276ed5f7e4 [DAGCombiner] Fold sext_inreg of a masked load into a sign extended masked load
This patch adds a DAG combine fold for a sext(masked_load) into a sign extended masked load.

Differential Revision: https://reviews.llvm.org/D84332
2020-07-30 10:34:02 +01:00
David Sherwood 2078771759 [SVE][CodeGen] Add simple integer add tests for SVE tuple types
I have added tests to:

  CodeGen/AArch64/sve-intrinsics-int-arith.ll

for doing simple integer add operations on tuple types. Since these
tests introduced new warnings due to incorrect use of
getVectorNumElements() I have also fixed up these warnings in the
same patch. These fixes are:

1. In narrowExtractedVectorBinOp I have changed the code to bail out
early for scalable vector types, since we've not yet hit a case that
proves the optimisations are profitable for scalable vectors.
2. In DAGTypeLegalizer::WidenVecRes_CONCAT_VECTORS I have replaced
calls to getVectorNumElements with getVectorMinNumElements in cases
that work with scalable vectors. For the other cases I have added
asserts that the vector is not scalable because we should not be
using shuffle vectors and build vectors in such cases.

Differential revision: https://reviews.llvm.org/D84016
2020-07-29 13:32:10 +01:00
Changpeng Fang 9162b70e51 DADCombiner: Don't simplify the token factor if the node's number of operands already exceeds TokenFactorInlineLimit
Summary:
  In parallelizeChainedStores, a TokenFactor was created with the size greater than 3000.
We found that DAGCombiner::visitTokenFactor will consume a huge amount of time on
such nodes. Since the number of operands already exceeds TokenFactorInlineLimit, we propose
to give up simplification with the consideration of compile time.

Reviewers:
  @spatel, @arsenm

Differential Revision:
  https://reviews.llvm.org/D84204
2020-07-25 21:20:59 -07:00