When SelectionDAG merges consecutive stores and loads in MergeConsecutiveStores, it does not set dereferenceable flag for a created load instruction. This results in an assertion failure if SelectionDAG commonizes this load instruction with other load instructions, as well as it may miss optimization opportunities.
This patch sat dereferenceable flag for the newly created load instruction if all the load instructions to be merged are dereferenceable.
Differential Revision: https://reviews.llvm.org/D34679
llvm-svn: 306404
Move GlobalAddress Offset decomposition from initial match into
comparision check and removing the possibility of constructing a new
offseted global address when examining addresses.
llvm-svn: 305917
Add support for combining a build vector to a shuffle.
When the build vector is of extracted elements from 2 vectors (vec1, vec2) where vec2 is 2 times smaller than vec1.
llvm-svn: 305883
As all store merges checks are based on the memory operation
performed, allow use of truncated stores and extended loads as valid
input candidates for merging.
Relanding after fixing selection between truncated and normal store.
llvm-svn: 305701
In preparation for doing storemerge post-legalization, reorder
visitSTORE passes to move pre/post-index combining after store
merge. Reordered passes other than store merge are unaffected.
llvm-svn: 305473
As all store merges checks are based on the memory operation
performed, allow use of truncated stores and extended loads as valid
input candidates for merging.
llvm-svn: 305468
This step is just intended to reduce code duplication rather than change any functionality.
A follow-up would be to replace PPCTargetLowering::spliceIntoChain() usage with this new helper.
Differential Revision: https://reviews.llvm.org/D33649
llvm-svn: 305192
Summary: UADDO has 2 result, and one must check the result no before doing any kind of combine. Without it, the transform is invalid.
Reviewers: joerg
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D34088
llvm-svn: 305162
When considering merging stores values are the results of loads only
consider stores whose values come from loads from the same base.
This fixes much of the longer compile times in PR33330.
llvm-svn: 304934
Other calls to DAGCombiner::*PromoteOperand check the result, but here it could cause an assertion in getNode.
Falling back to any extend in this case instead of failing outright seems correct to me.
No test case because:
The failure was triggered by an out of tree backend. In order to trigger it, a backend would need to overload
TargetLowering::IsDesirableToPromoteOp to return true for a type for which ISD::SIGN_EXTEND_INREG is marked
illegal. In tree, only X86 overloads and sometimes returns true for MVT::i16 yet it marks
setOperationAction(ISD::SIGN_EXTEND_INREG, MVT::i16 , Legal);.
Patch by Jacob Young!
Differential Revision: https://reviews.llvm.org/D33633
llvm-svn: 304723
Summary:
This is a problem uncovered by stage2 testing. ADDCARRY end up being generated on target that do not support it.
The patch that introduced the problem has other patches layed on top of it, so we want to fix the issue rather than revert it to avoid creating a lor of churn.
A regression test will be added shortly, but this is committed as this in order to get the build back to green promptly.
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D33770
llvm-svn: 304409
Summary:
This is a continuation of the work started in D29872 . Passing the carry down as a value rather than as a glue allows for further optimizations. Introducing setcccarry makes the use of addc/subc unecessary and we can start the removal process.
This patch only introduce the optimization strictly required to get the same level of optimization as was available before nothing more.
Reviewers: jyknight, nemanjai, mkuper, spatel, RKSimon, zvi, bkramer
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D33374
llvm-svn: 304404
Summary: This pattern is no very useful per se, but it exposes optimization for toehr patterns that wouldn't kick in otherwize. It's very common and worth optimizing for.
Reviewers: jyknight, nemanjai, mkuper, spatel, RKSimon, zvi, bkramer
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D32756
llvm-svn: 304402
Correct references to alignment of store which may be deleted in a
previous iteration of merge. Instead use first store that would be
merged.
Corrects pr33172's use-after-poison caught by ASan.
Reviewers: spatel, hfinkel, RKSimon
Reviewed By: RKSimon
Subscribers: thegameg, javed.absar, llvm-commits
Differential Revision: https://reviews.llvm.org/D33686
llvm-svn: 304299
The extending load possibility was missed in:
https://reviews.llvm.org/rL304072
We might want to handle this cases as a follow-up, but bailing out for now
to avoid miscompiling.
llvm-svn: 304153
If we have (extract_subvector(load wide vector)) with no other users,
that can just be (load narrow vector). This is intentionally conservative.
Follow-ups may loosen the one-use constraint to account for the extract cost
or just remove the one-use check.
The memop chain updating is based on code that already exists multiple times
in x86 lowering, so that should be pulled into a helper function as a follow-up.
Background: this is a potential improvement noticed via regressions caused by
making x86's peekThroughBitcasts() not loop on consecutive bitcasts (see
comments in D33137).
Differential Revision: https://reviews.llvm.org/D33578
llvm-svn: 304072
In the best case:
extract (binop (concat X1, X2), (concat Y1, Y2)), N --> binop XN, YN
...we kill all of the extract/concat and just have narrow binops remaining.
If only one of the binop operands is amenable, this transform is still
worthwhile because we kill some of the extract/concat.
Optional bitcasting makes the code more complicated, but there doesn't
seem to be a way to avoid that.
The TODO about extending to more than bitwise logic is there because we really
will regress several x86 tests including madd, psad, and even a plain
integer-multiply-by-2 or shift-left-by-1. I don't think there's anything
fundamentally wrong with this patch that would cause those regressions; those
folds are just missing or brittle.
If we extend to more binops, I found that this patch will fire on at least one
non-x86 regression test. There's an ARM NEON test in
test/CodeGen/ARM/coalesce-subregs.ll with a pattern like:
t5: v2f32 = vector_shuffle<0,3> t2, t4
t6: v1i64 = bitcast t5
t8: v1i64 = BUILD_VECTOR Constant:i64<0>
t9: v2i64 = concat_vectors t6, t8
t10: v4f32 = bitcast t9
t12: v4f32 = fmul t11, t10
t13: v2i64 = bitcast t12
t16: v1i64 = extract_subvector t13, Constant:i32<0>
There was no functional change in the codegen from this transform from what I
could see though.
For the x86 test changes:
1. PR32790() is the closest call. We don't reduce the AVX1 instruction count in that case,
but we improve throughput. Also, on a core like Jaguar that double-pumps 256-bit ops,
there's an unseen win because two 128-bit ops have the same cost as the wider 256-bit op.
SSE/AVX2/AXV512 are not affected which is expected because only AVX1 has the extract/concat
ops to match the pattern.
2. do_not_use_256bit_op() is the best case. Everyone wins by avoiding the concat/extract.
Related bug for IR filed as: https://bugs.llvm.org/show_bug.cgi?id=33026
3. The SSE diffs in vector-trunc-math.ll are just scheduling/RA, so nothing real AFAICT.
4. The AVX1 diffs in vector-tzcnt-256.ll are all the same pattern: we reduced the instruction
count by one in each case by eliminating two insert/extract while adding one narrower logic op.
https://bugs.llvm.org/show_bug.cgi?id=32790
Differential Revision: https://reviews.llvm.org/D33137
llvm-svn: 303997
Summary:
While this makes some case better and some case worse - so it's unclear if it is a worthy combine just by itself - this is a useful canonicalisation.
As per discussion in D32756 .
Reviewers: jyknight, nemanjai, mkuper, spatel, RKSimon, zvi, bkramer
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D32916
llvm-svn: 303441
Summary:
In SelectionDAG, when a store is immediately chained to another store
to the same address, elide the first store as it has no observable
effects. This is causes small improvements dealing with intrinsics
lowered to stores.
Test notes:
* Many testcases overwrite store addresses multiple times and needed
minor changes, mainly making stores volatile to prevent the
optimization from optimizing the test away.
* Many X86 test cases optimized out instructions associated with
associated with va_start.
* Note that test_splat in CodeGen/AArch64/misched-stp.ll no longer has
dependencies to check and can probably be removed and potentially
replaced with another test.
Reviewers: rnk, john.brawn
Subscribers: aemerson, rengolin, qcolombet, jyknight, nemanjai, nhaehnle, javed.absar, llvm-commits
Differential Revision: https://reviews.llvm.org/D33206
llvm-svn: 303198
Summary:
Eli pointed out that it's unsafe to combine the shifts to ISD::SHL etc.,
because those are not defined for b > sizeof(a) * 8, even after some of
the combiners run.
However, PPCISD::SHL defines that behavior (as the instructions themselves).
Move the combination to the backend.
The tests in shift_mask.ll still pass.
Reviewers: echristo, hfinkel, efriedma, iteratee
Subscribers: nemanjai, llvm-commits
Differential Revision: https://reviews.llvm.org/D33076
llvm-svn: 302937
This reverts r302712.
The change fails with ASAN enabled:
ERROR: AddressSanitizer: use-after-poison on address ... at ...
READ of size 2 at ... thread T0
#0 ... in llvm::SDNode::getNumValues() const <snip>/include/llvm/CodeGen/SelectionDAGNodes.h:855:42
#1 ... in llvm::SDNode::hasAnyUseOfValue(unsigned int) const <snip>/lib/CodeGen/SelectionDAG/SelectionDAG.cpp:7270:3
#2 ... in llvm::SDValue::use_empty() const <snip> include/llvm/CodeGen/SelectionDAGNodes.h:1042:17
#3 ... in (anonymous namespace)::DAGCombiner::MergeConsecutiveStores(llvm::StoreSDNode*) <snip>/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:12944:7
Reviewers: niravd
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D33081
llvm-svn: 302746
Summary:
Allow consecutive stores whose values come from consecutive loads to
merged in the presense of other uses of the loads. Previously this was
disallowed as in general the merged load cannot be shared with the
other uses. Merging N stores into 1 may cause as many as N redundant
loads. However in the context of caching this should have neglible
affect on memory pressure and reduce instruction count making it
almost always a win.
Fixes PR32086.
Reviewers: spatel, jyknight, andreadb, hfinkel, efriedma
Reviewed By: efriedma
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D30471
llvm-svn: 302712
Before r247167, the pass manager builder controlled which AA
implementations were used, exporting them all in the AliasAnalysis
analysis group.
Now, AAResultsWrapperPass always uses BasicAA, but still uses other AA
implementations if made available in the pass pipeline.
But regardless, SDAGISel is required at O0, and really doesn't need to
be doing fancy optimizations based on useful AA results.
Don't require AA at CodeGenOpt::None, and only use it otherwise.
This does have a functional impact (and one testcase is pessimized
because we can't reuse a load). But I think that's desirable no matter
what.
Note that this alone doesn't result in less DT computations: TwoAddress
was previously able to reuse the DT we computed for SDAG. That will be
fixed separately.
Differential Revision: https://reviews.llvm.org/D32766
llvm-svn: 302611
Remove an extra canonicalization step if ISD::ABS is going to be used anyway.
Updated x86 abs combine to check that we are lowering from both canonicalizations.
llvm-svn: 302337
Summary: Do the transform when the carry isn't used. It's a pattern exposed when legalizing large integers.
Reviewers: jyknight, nemanjai, mkuper, spatel, RKSimon, zvi, bkramer
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D32755
llvm-svn: 302047
Summary:
This is the corresponding llvm change to D28037 to ensure no performance
regression.
Reviewers: bogner, kbarton, hfinkel, iteratee, echristo
Subscribers: nemanjai, llvm-commits
Differential Revision: https://reviews.llvm.org/D28329
llvm-svn: 301990
Summary: This is a common pattern that arise when legalizing large integers operations. Only do it when Y + 1 cannot overflow as this would change the carry behavior of uaddo .
Reviewers: jyknight, nemanjai, mkuper, spatel, RKSimon, zvi, bkramer
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D32687
llvm-svn: 301922
Summary: Common pattern when legalizing large integers operations. Similar to D32687, when the carry isn't used.
Reviewers: jyknight, nemanjai, mkuper, spatel, RKSimon, zvi, bkramer
Differential Revision: https://reviews.llvm.org/D32738
llvm-svn: 301919
The existing code only looks at half of the tree when matching bswap + rol patterns ending in an OR tree (as opposed to a cascade).
Patch originally introduced by Jim Lewis.
Submitted on the behalf of Dinar Temirbulatov.
Differential Revision: https://reviews.llvm.org/D32039
llvm-svn: 301907
We discussed shrinking/widening of selects in IR in D26556, and I'll try to get back to that
patch eventually. But I'm hoping that this transform is less iffy in the DAG where we can check
legality of the select that we want to produce.
A few things to note:
1. We can't wait until after legalization and do this generically because (at least in the x86
tests from PR14657), we'll have PACKSS and bitcasts in the pattern.
2. This might benefit more of the SSE codegen if we lifted the legal-or-custom requirement, but
that requires a closer look to make sure we don't end up worse.
3. There's a 'vblendv' opportunity that we're missing that results in andn/and/or in some cases.
That should be fixed next.
4. I'm assuming that AVX1 offers the worst of all worlds wrt uneven ISA support with multiple
legal vector sizes, but if there are other targets like that, we should add more tests.
5. There's a codegen miracle in the multi-BB tests from PR14657 (the gcc auto-vectorization tests):
despite IR that is terrible for the target, this patch allows us to generate the optimal loop
code because something post-ISEL is hoisting the splat extends above the vector loops.
Differential Revision: https://reviews.llvm.org/D32620
llvm-svn: 301781
Summary: As per discution on how to get better codegen an large int legalization, it became clear that using a glue for the carry was preventing several desirable optimizations. Passing the carry down as a value allow for more flexibility.
Reviewers: jyknight, nemanjai, mkuper, spatel, RKSimon, zvi, bkramer
Subscribers: igorb, llvm-commits
Differential Revision: https://reviews.llvm.org/D29872
llvm-svn: 301775
This patch replaces the separate APInts for KnownZero/KnownOne with a single KnownBits struct. This is similar to what was done to ValueTracking's version recently.
This is largely a mechanical transformation from KnownZero to Known.Zero.
Differential Revision: https://reviews.llvm.org/D32569
llvm-svn: 301620
This patch uses various APInt methods to reduce the number of temporary APInts. These were all found while working through converting SelectionDAG's computeKnownBits to also use the KnownBits struct recently added to the ValueTracking version.
llvm-svn: 301618
Besides better codegen, the motivation is to be able to canonicalize this pattern
in IR (currently we don't) knowing that the backend is prepared for that.
This may also allow removing code for special constant cases in
DAGCombiner::foldSelectOfConstants() that was added in D30180.
Differential Revision: https://reviews.llvm.org/D31944
llvm-svn: 301457
While we use BaseIndexOffset in FindBetterNeighborChains to
appropriately realize they're almost the same address and should be
improved concurrently we do not use it in isAlias using the non-index
understanding FindBaseOffset instead. Adding a BaseIndexOffset check
in isAlias like should allow indexed stores to be merged.
FindBaseOffset to be excised in subsequent patch.
Reviewers: jyknight, aditya_nandakumar, bogner
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D31987
llvm-svn: 301187
This reverts commit r301105, 4, 3 and 1, as a follow up of the previous
revert, which broke even more bots.
For reference:
Revert "[APInt] Use operator<<= where possible. NFC"
Revert "[APInt] Use operator<<= instead of shl where possible. NFC"
Revert "[APInt] Use ashInPlace where possible."
PR32754.
llvm-svn: 301111
getSignBit is a static function that creates an APInt with only the sign bit set. getSignMask seems like a better name to convey its functionality. In fact several places use it and then store in an APInt named SignMask.
Differential Revision: https://reviews.llvm.org/D32108
llvm-svn: 300856
I've changed one of the tests to not fold away, but we didn't and still don't do the transform
that the comment claims we do (and I don't know why we'd want to do that).
Follow-up to:
https://reviews.llvm.org/rL300725https://reviews.llvm.org/rL300763
llvm-svn: 300772
This allows forming more 'not' ops, so we get improvements for ISAs that have and-not.
Follow-up to:
https://reviews.llvm.org/rL300725
llvm-svn: 300763
The patch itself is simple: stop discriminating against vectors in visitAnd() and again in
SimplifyDemandedBits().
Some notes for reference:
1. We're not consistent about calls to SimplifyDemandedBits in the various visitXXX functions.
Sometimes, we check if the RHS is a constant first. Other times (like here), we just dive in.
2. I'd like to break the vector shackles in steps for the sake of risk minimization, but we could
make similar simultaneous changes in other places if we think that would be better.
3. I don't know what the intent of the changed tests in this patch was supposed to be, but since
they wiggled in a positive way, I'm just going with that. :)
4. In the rotate tests, note that we can see through non-splat constants. This is a result of D24253.
5. My motivation for being here now is to make D31944 look better, so this is step 1 of N towards
improving the vector codegen in that patch without writing any actual new code.
Differential Revision: https://reviews.llvm.org/D32230
llvm-svn: 300725
This patch uses lshrInPlace to replace code where the object that lshr is called on is being overwritten with the result.
This adds an lshrInPlace(const APInt &) version as well.
Differential Revision: https://reviews.llvm.org/D32155
llvm-svn: 300566
Remove non-consecutive stores from store merge candidate search as
they cannot be merged and will prevent us from finding subsequent
mergeable store cases.
Reviewers: jyknight, bogner, javed.absar, spatel
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D32086
llvm-svn: 300561
This is a follow-on to r299096 which added support for fmadd.
Subtract does not have the case where with two multiply operands we commute in
order to fuse with the multiply with the fewer uses.
llvm-svn: 299572
This is a generic combine enabled via target hook to reduce icmp logic as discussed in:
https://bugs.llvm.org/show_bug.cgi?id=32401
It's likely that other targets will want to enable this hook for scalar transforms,
and there are probably other patterns that can use bitwise logic to reduce comparisons.
Note that we are missing an IR canonicalization for these patterns, and we will probably
prefer the pair-of-compares form in IR (shorter, more likely to fold).
Differential Revision: https://reviews.llvm.org/D31483
llvm-svn: 299542
This reverts commit r299047 which is incorrect because the
simplification may result in incorrect propogation of undefs to users of
the folded shuffle.
Thanks to Andrea Di Biagio for pointing this out.
llvm-svn: 299368
This moves the isMask and isShiftedMask functions to be class methods. They now use the MathExtras.h function for single word size and leading/trailing zeros/ones or countPopulation for the multiword size. The previous implementation made multiple temorary memory allocations to do the bitwise arithmetic operations to match the MathExtras.h implementation.
Differential Revision: https://reviews.llvm.org/D31565
llvm-svn: 299362
The code already allowed vector types in via "isInteger" (which might want
a more specific name), so use splat-friendly constant predicates to match
those types.
llvm-svn: 299304
This can only happen when we have a mix of zero and undef elements and the two vectors have a different arrangement of zeros/undefs. The shuffle should eventually be constant folded to all zeros.
Fixes PR32484.
llvm-svn: 299291
(and (setlt X, 0), (setlt Y, 0)) --> (setlt (and X, Y), 0)
We have 7 similar folds, but this one got away. The fact that the
x86 test with a branch didn't change is probably a separate bug. We
may also be missing this and the related folds in instcombine.
llvm-svn: 299252
Now alternatively to the TargetOption.AllowFPOpFusion global flag, FMUL->FADD
can also use the per operation FMF to allow fusion.
The idea here is not to port everything to the new scheme (e.g. fused
multiply-and-sub will be ported later) but that this work all the way from
clang.
The transformation is conditionalized on *both* the FADD and the FMUL having
the FMF contract flag.
Differential Revision: https://reviews.llvm.org/D31169
llvm-svn: 299096
Deal with case that initial node is deleted during dag-combine leading
to an assertional failure in promoteIntShiftOp.
Fixes PR32420.
Reviewers: spatel, RKSimon
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D31403
llvm-svn: 298931
Reorder work in PromoteIntBinOp to prevent stale (deleted) nodes from
being used.
Fixes PR32340 and PR32345.
Reviewers: hfinkel, dbabokin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D31148
llvm-svn: 298923
Summary:
This class is a list of AttributeSetNodes corresponding the function
prototype of a call or function declaration. This class used to be
called ParamAttrListPtr, then AttrListPtr, then AttributeSet. It is
typically accessed by parameter and return value index, so
"AttributeList" seems like a more intuitive name.
Rename AttributeSetImpl to AttributeListImpl to follow suit.
It's useful to rename this class so that we can rename AttributeSetNode
to AttributeSet later. AttributeSet is the set of attributes that apply
to a single function, argument, or return value.
Reviewers: sanjoy, javed.absar, chandlerc, pete
Reviewed By: pete
Subscribers: pete, jholewinski, arsenm, dschuff, mehdi_amini, jfb, nhaehnle, sbc100, void, llvm-commits
Differential Revision: https://reviews.llvm.org/D31102
llvm-svn: 298393
Don't scalarize VSELECT->SETCC when operands/results needs to be widened,
or when the type of the SETCC operands are different from those of the VSELECT.
(VSELECT SETCC) and (VSELECT (AND/OR/XOR (SETCC,SETCC))) are handled.
The previous splitting of VSELECT->SETCC in DAGCombiner::visitVSELECT() is
no longer needed and has been removed.
Updated tests:
test/CodeGen/ARM/vuzp.ll
test/CodeGen/NVPTX/f16x2-instructions.ll
test/CodeGen/X86/2011-10-19-widen_vselect.ll
test/CodeGen/X86/2011-10-21-widen-cmp.ll
test/CodeGen/X86/psubus.ll
test/CodeGen/X86/vselect-pcmp.ll
Review: Eli Friedman, Simon Pilgrim
https://reviews.llvm.org/D29489
llvm-svn: 297930
Reduced version of D26357 - based on the discussion on llvm-dev about canonicalization of UMIN/UMAX/SMIN/SMAX as well as ABS I've reduced that patch to just the ABS ISD node (with x86/sse support) to improve basic combines and lowering.
ARM/AArch64, Hexagon, PowerPC and NVPTX all have similar instructions allowing us to make this a generic opcode and move away from the hard coded tablegen patterns which makes it tricky to match more complex patterns.
At the moment this patch doesn't attempt legalization as we only create an ABS node if its legal/custom.
Differential Revision: https://reviews.llvm.org/D29639
llvm-svn: 297780
Recommiting with compiler time improvements
Recommitting after fixup of 32-bit aliasing sign offset bug in DAGCombiner.
* Simplify Consecutive Merge Store Candidate Search
Now that address aliasing is much less conservative, push through
simplified store merging search and chain alias analysis which only
checks for parallel stores through the chain subgraph. This is cleaner
as the separation of non-interfering loads/stores from the
store-merging logic.
When merging stores search up the chain through a single load, and
finds all possible stores by looking down from through a load and a
TokenFactor to all stores visited.
This improves the quality of the output SelectionDAG and the output
Codegen (save perhaps for some ARM cases where we correctly constructs
wider loads, but then promotes them to float operations which appear
but requires more expensive constant generation).
Some minor peephole optimizations to deal with improved SubDAG shapes (listed below)
Additional Minor Changes:
1. Finishes removing unused AliasLoad code
2. Unifies the chain aggregation in the merged stores across code
paths
3. Re-add the Store node to the worklist after calling
SimplifyDemandedBits.
4. Increase GatherAllAliasesMaxDepth from 6 to 18. That number is
arbitrary, but seems sufficient to not cause regressions in
tests.
5. Remove Chain dependencies of Memory operations on CopyfromReg
nodes as these are captured by data dependence
6. Forward loads-store values through tokenfactors containing
{CopyToReg,CopyFromReg} Values.
7. Peephole to convert buildvector of extract_vector_elt to
extract_subvector if possible (see
CodeGen/AArch64/store-merge.ll)
8. Store merging for the ARM target is restricted to 32-bit as
some in some contexts invalid 64-bit operations are being
generated. This can be removed once appropriate checks are
added.
This finishes the change Matt Arsenault started in r246307 and
jyknight's original patch.
Many tests required some changes as memory operations are now
reorderable, improving load-store forwarding. One test in
particular is worth noting:
CodeGen/PowerPC/ppc64-align-long-double.ll - Improved load-store
forwarding converts a load-store pair into a parallel store and
a memory-realized bitcast of the same value. However, because we
lose the sharing of the explicit and implicit store values we
must create another local store. A similar transformation
happens before SelectionDAG as well.
Reviewers: arsenm, hfinkel, tstellarAMD, jyknight, nhaehnle
llvm-svn: 297695
Summary: This essentially does the same transform as for ADC.
Reviewers: jyknight, nemanjai, mkuper, spatel, RKSimon, zvi, bkramer
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D30417
llvm-svn: 297416
Summary: This essentially does the same transform as for SUBC.
Reviewers: jyknight, nemanjai, mkuper, spatel, RKSimon, zvi, bkramer
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D30437
llvm-svn: 297404
As discussed in the review thread for rL297026, this is actually 2 changes that
would independently fix all of the test cases in the patch:
1. Return undef in FoldConstantArithmetic for div/rem by 0.
2. Move basic undef simplifications for div/rem (simplifyDivRem()) before
foldBinopIntoSelect() as a matter of efficiency.
I will handle the case of vectors with any zero element as a follow-up. That change
is the DAG sibling for D30665 + adding a check of vector elements to FoldConstantVectorArithmetic().
I'm deleting the test for PR30693 because it does not test for the actual bug any more
(dangers of using bugpoint).
Differential Revision:
https://reviews.llvm.org/D30741
llvm-svn: 297384
This helps in cases involving bitfields where an AND is exposed by
legalization.
Differential Revision: https://reviews.llvm.org/D30472
llvm-svn: 297249
This is known incomplete and not called in the right order relative to
other folds, but that's the current behavior. I'm just trying to clean
this up before making actual functional changes to make the patch smaller.
The logic here should mimic the IR equivalents that are in InstSimplify's
simplifyDivRem().
llvm-svn: 297086
Refactoring of duplicated code and more fixes to follow.
This is motivated by the post-commit comments for r296699:
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20170306/435182.html
Ie, we can crash if we're missing obvious simplifications like this that
exist in the IR simplifier or if these occur later than expected.
The x86 change for non-splat division shows a potential opportunity to improve
vector codegen: we assumed that since only one lane had meaningful results, we
should do the math in scalar. But that means moving back and forth from vector
registers.
llvm-svn: 297026
select Cond, C +/- 1, C --> add(ext Cond), C -- with a target hook.
This is part of the ongoing process to obsolete D24480. The motivation is to
canonicalize to select IR in InstCombine whenever possible, so we need to have a way to
undo that easily in codegen.
PowerPC is an obvious winner for this kind of transform because it has fast and complete
bit-twiddling abilities but generally lousy conditional execution perf (although this might
have changed in recent implementations).
x86 also sees some wins, but the effect is limited because these transforms already mostly
exist in its target-specific combineSelectOfTwoConstants(). The fact that we see any x86
changes just shows that that code is a mess of special-case holes. We may be able to remove
some of that logic now.
My guess is that other targets will want to enable this hook for most cases. The likely
follow-ups would be to add value type and/or the constants themselves as parameters for the
hook. As the tests in select_const.ll show, we can transform any select-of-constants to
math/logic, but the general transform for any 2 constants needs one more instruction
(multiply or 'and').
ARM is one target that I think may not want this for most cases. I see infinite loops there
because it wants to use selects to enable conditionally executed instructions.
Differential Revision: https://reviews.llvm.org/D30537
llvm-svn: 296977
This patch causes compile times for some patterns to explode. I have
a (large, unreduced) test case that slows down by more than 20x and
several test cases slow down by 2x. I'm sending some of the test cases
directly to Nirav and following up with more details in the review log,
but this should unblock anyone else hitting this.
llvm-svn: 296862
Summary:
Currently, when 't1: i1 = setcc t2, t3, cc' followed by 't4: i1 = xor t1, Constant:i1<-1>' is folded into 't5: i1 = setcc t2, t3 !cc', SDLoc of newly created SDValue 't5' follows SDLoc of 't4', not 't1'. However, as the opcode of newly created SDValue is 'setcc', it make more sense to take DebugLoc from 't1' than 't4'. For the code below
```
extern int bar();
extern int baz();
int foo(int x, int y) {
if (x != y)
return bar();
else
return baz();
}
```
, following is the bitcode representation of 'foo' at the end of llvm-ir level optimization:
```
define i32 @foo(i32 %x, i32 %y) !dbg !4 {
entry:
tail call void @llvm.dbg.value(metadata i32 %x, i64 0, metadata !9, metadata !11), !dbg !12
tail call void @llvm.dbg.value(metadata i32 %y, i64 0, metadata !10, metadata !11), !dbg !13
%cmp = icmp ne i32 %x, %y, !dbg !14
br i1 %cmp, label %if.then, label %if.else, !dbg !16
if.then: ; preds = %entry
%call = tail call i32 (...) @bar() #3, !dbg !17
br label %return, !dbg !18
if.else: ; preds = %entry
%call1 = tail call i32 (...) @baz() #3, !dbg !19
br label %return, !dbg !20
return: ; preds = %if.else, %if.then
%retval.0 = phi i32 [ %call, %if.then ], [ %call1, %if.else ]
ret i32 %retval.0, !dbg !21
}
!14 = !DILocation(line: 5, column: 9, scope: !15)
!16 = !DILocation(line: 5, column: 7, scope: !4)
```
As you can see, in 'entry' block, 'icmp' instruction and 'br' instruction have different debug locations. However, with current implementation, there's no distinction between debug locations of these two when they are lowered to asm instructions. This is because 'icmp' and 'br' become 'setcc' 'xor' and 'brcond' in SelectionDAG, where SDLoc of 'setcc' follows the debug location of 'icmp' but SDLOC of 'xor' and 'brcond' follows the debug location of 'br' instruction, and SDLoc of 'xor' overwrites SDLoc of 'setcc' when they are folded. This patch addresses this issue.
Reviewers: atrick, bogner, andreadb, craig.topper, aprantl
Reviewed By: andreadb
Subscribers: jlebar, mkuper, jholewinski, andreadb, llvm-commits
Differential Revision: https://reviews.llvm.org/D29813
llvm-svn: 296825
This bug was introduced with:
https://reviews.llvm.org/rL296699
There may be a way to loosen the restriction, but for now just bail out
on any opaque constant.
The tests show that opacity is target-specific. This goes back to cost
calculations in ConstantHoisting based on TTI->getIntImmCost().
llvm-svn: 296768
This is part of the ongoing attempt to improve select codegen for all targets and select
canonicalization in IR (see D24480 for more background). The transform is a subset of what
is done in InstCombine's FoldOpIntoSelect().
I first noticed a regression in the x86 avx512-insert-extract.ll tests with a patch that
hopes to convert more selects to basic math ops. This appears to be a general missing DAG
transform though, so I added tests for all standard binops in rL296621
(PowerPC was chosen semi-randomly; it has scripted FileCheck support, but so do ARM and x86).
The poor output for "sel_constants_shl_constant" is tracked with:
https://bugs.llvm.org/show_bug.cgi?id=32105
Differential Revision: https://reviews.llvm.org/D30502
llvm-svn: 296699
Add check that deleted nodes do not get added to worklist. This can
occur when a node's operand is simplified to an existing node.
This fixes PR32108.
Reviewers: jyknight, hfinkel, chandlerc
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D30506
llvm-svn: 296668
Resubmit r295336 after the bug with non-zero offset patterns on BE targets is fixed (r296336).
Support {a|s}ext, {a|z|s}ext load nodes as a part of load combine patters.
Reviewed By: filcab
Differential Revision: https://reviews.llvm.org/D29591
llvm-svn: 296651
Recommiting after fixup of 32-bit aliasing sign offset bug in DAGCombiner.
* Simplify Consecutive Merge Store Candidate Search
Now that address aliasing is much less conservative, push through
simplified store merging search and chain alias analysis which only
checks for parallel stores through the chain subgraph. This is cleaner
as the separation of non-interfering loads/stores from the
store-merging logic.
When merging stores search up the chain through a single load, and
finds all possible stores by looking down from through a load and a
TokenFactor to all stores visited.
This improves the quality of the output SelectionDAG and the output
Codegen (save perhaps for some ARM cases where we correctly constructs
wider loads, but then promotes them to float operations which appear
but requires more expensive constant generation).
Some minor peephole optimizations to deal with improved SubDAG shapes (listed below)
Additional Minor Changes:
1. Finishes removing unused AliasLoad code
2. Unifies the chain aggregation in the merged stores across code
paths
3. Re-add the Store node to the worklist after calling
SimplifyDemandedBits.
4. Increase GatherAllAliasesMaxDepth from 6 to 18. That number is
arbitrary, but seems sufficient to not cause regressions in
tests.
5. Remove Chain dependencies of Memory operations on CopyfromReg
nodes as these are captured by data dependence
6. Forward loads-store values through tokenfactors containing
{CopyToReg,CopyFromReg} Values.
7. Peephole to convert buildvector of extract_vector_elt to
extract_subvector if possible (see
CodeGen/AArch64/store-merge.ll)
8. Store merging for the ARM target is restricted to 32-bit as
some in some contexts invalid 64-bit operations are being
generated. This can be removed once appropriate checks are
added.
This finishes the change Matt Arsenault started in r246307 and
jyknight's original patch.
Many tests required some changes as memory operations are now
reorderable, improving load-store forwarding. One test in
particular is worth noting:
CodeGen/PowerPC/ppc64-align-long-double.ll - Improved load-store
forwarding converts a load-store pair into a parallel store and
a memory-realized bitcast of the same value. However, because we
lose the sharing of the explicit and implicit store values we
must create another local store. A similar transformation
happens before SelectionDAG as well.
Reviewers: arsenm, hfinkel, tstellarAMD, jyknight, nhaehnle
llvm-svn: 296476
DAGCombiner already supports peeking thorough shuffles to improve vector element extraction, but legalization often leaves us in situations where we need to extract vector elements after shuffles have already been lowered.
This patch adds support for VECTOR_EXTRACT_ELEMENT/PEXTRW/PEXTRB instructions to attempt to handle target shuffles as well. I've covered some basic scenarios including handling shuffle mask scaling and the implicit zero-extension of PEXTRW/PEXTRB, there is more that could be done here (that I've mentioned in TODOs) but I haven't found many cases where its worth it.
Differential Revision: https://reviews.llvm.org/D30176
llvm-svn: 296381
This pattern is essentially a i16 load from p+1 address:
%p1.i16 = bitcast i8* %p to i16*
%p2.i8 = getelementptr i8, i8* %p, i64 2
%v1 = load i16, i16* %p1.i16
%v2.i8 = load i8, i8* %p2.i8
%v2 = zext i8 %v2.i8 to i16
%v1.shl = shl i16 %v1, 8
%res = or i16 %v1.shl, %v2
Current implementation would identify %v1 load as the first byte load and would mistakenly emit a i16 load from %p1.i16 address. This patch adds a check that the first byte is loaded from a non-zero offset of the first load address. This way this address can be used as the base address for the combined value. Otherwise just give up combining.
llvm-svn: 296336
Nirav Dave