Since we have distinct types for pointers and scalars, G_INTTOPTRs can sometimes
obstruct attempts to find constant source values. These usually come about when
try to do some kind of null pointer check. Teaching getConstantVRegValWithLookThrough
about this operation allows the CBZ/CBNZ optimization to catch more cases.
This change also improves the case where we can't find a constant source at all.
Previously we would emit a cmp, cset and tbnz for that. Now we try to just emit
a cmp and conditional branch, saving an instruction.
The cumulative code size improvement of this change plus D64354 is 5.5% geomean
on arm64 CTMark -O0.
Differential Revision: https://reviews.llvm.org/D64377
llvm-svn: 365690
Some minor cleanup.
This function in Utils does the same thing as `findMIFromReg`. It also looks
through copies, which `findMIFromReg` didn't.
Delete `findMIFromReg` and use `getOpcodeDef` instead. This only happens in
`tryOptVectorDup` right now.
Update opt-shuffle-splat to show that we can look through the copies now, too.
Differential Revision: https://reviews.llvm.org/D64520
llvm-svn: 365684
There are a few places where we walk over copies throughout
AArch64InstructionSelector.cpp. In Utils, there's a function that does exactly
this which we can use instead.
Note that the utility function works with the case where we run into a COPY
from a physical register. We've run into bugs with this a couple times, so using
it should defend us from similar future bugs.
Also update opt-fold-compare.mir to show that we still handle physical registers
properly.
Differential Revision: https://reviews.llvm.org/D64513
llvm-svn: 365683
If we have an icmp->brcond->br sequence where the brcond just branches to the
next block jumping over the br, while the br takes the false edge, then we can
modify the conditional branch to jump to the br's target while inverting the
condition of the incoming icmp. This means we can eliminate the br as an
unconditional branch to the fallthrough block.
Differential Revision: https://reviews.llvm.org/D64354
llvm-svn: 365510
Porting over the part of `emitComparison` in AArch64ISelLowering where we use
TST to represent a compare.
- Rename `tryOptCMN` to `tryFoldIntegerCompare`, since it now also emits TSTs
when possible.
- Add a utility function for emitting a TST with register operands.
- Rename opt-fold-cmn.mir to opt-fold-compare.mir, since it now also tests the
TST fold as well.
Differential Revision: https://reviews.llvm.org/D64371
llvm-svn: 365404
Instead of just stopping to see if we have a G_CONSTANT, instead, look through
G_TRUNCs, G_SEXTs, and G_ZEXTs.
This gives an average ~1.3% code size improvement on CINT2000 at -O3.
Differential Revision: https://reviews.llvm.org/D64108
llvm-svn: 365063
There are two main issues preventing us from generating immediate form shifts:
1) We have partial SelectionDAG imported support for G_ASHR and G_LSHR shift
immediate forms, but they currently don't work because the amount type is
expected to be an s64 constant, but we only legalize them to have homogenous
types.
To deal with this, first we introduce a custom legalizer to *only* custom legalize
s32 shifts which have a constant operand into a s64.
There is also an additional artifact combiner to fold zexts(g_constant) to a
larger G_CONSTANT if it's legal, a counterpart to the anyext version committed
in an earlier patch.
2) For G_SHL the importer can't cope with the pattern. For this I introduced an
early selection phase in the arm64 selector to select these forms manually
before the tablegen selector pessimizes it to a register-register variant.
Differential Revision: https://reviews.llvm.org/D63910
llvm-svn: 364994
This teaches `tryOptSelect` to handle folding G_ICMP, and removes the
requirement that the G_SELECT we're dealing with is floating point.
Some refactoring to make this work nicely as well:
- Factor out the scalar case from the selection code for G_ICMP into
`emitIntegerCompare`.
- Make `tryOptCMN` return a MachineInstr* instead of a bool.
- Make `tryOptCMN` not modify the instruction being selected.
- Factor out the CMN emission into `emitCMN` for readability.
By doing this this way, we can get all of the compare selection optimizations
in select emission.
Differential Revision: https://reviews.llvm.org/D64084
llvm-svn: 364961
The new switch lowering code that tries to generate jump tables and range checks
were tested at -O0 on arm64, but on -O3 the generic switch lowering code goes to
town on trying to generate optimized lowerings, e.g. multiple jump tables, range
checks etc. This exposed bugs in the way PHI nodes are handled because the CFG
looks even stranger after all of this is done.
llvm-svn: 364613
Change the interface of CallLowering::lowerCall to accept several
virtual registers for each argument, instead of just one. This is a
follow-up to D46018.
CallLowering::lowerReturn was similarly refactored in D49660 and
lowerFormalArguments in D63549.
With this change, we no longer pack the virtual registers generated for
aggregates into one big lump before delegating to the target. Therefore,
the target can decide itself whether it wants to handle them as separate
pieces or use one big register.
ARM and AArch64 have been updated to use the passed in virtual registers
directly, which means we no longer need to generate so many
merge/extract instructions.
NFCI for AMDGPU, Mips and X86.
Differential Revision: https://reviews.llvm.org/D63551
llvm-svn: 364512
Change the interface of CallLowering::lowerCall to accept several
virtual registers for the call result, instead of just one. This is a
follow-up to D46018.
CallLowering::lowerReturn was similarly refactored in D49660 and
lowerFormalArguments in D63549.
With this change, we no longer pack the virtual registers generated for
aggregates into one big lump before delegating to the target. Therefore,
the target can decide itself whether it wants to handle them as separate
pieces or use one big register.
ARM and AArch64 have been updated to use the passed in virtual registers
directly, which means we no longer need to generate so many
merge/extract instructions.
NFCI for AMDGPU, Mips and X86.
Differential Revision: https://reviews.llvm.org/D63550
llvm-svn: 364511
Change the interface of CallLowering::lowerFormalArguments to accept
several virtual registers for each formal argument, instead of just one.
This is a follow-up to D46018.
CallLowering::lowerReturn was similarly refactored in D49660. lowerCall
will be refactored in the same way in follow-up patches.
With this change, we forward the virtual registers generated for
aggregates to CallLowering. Therefore, the target can decide itself
whether it wants to handle them as separate pieces or use one big
register. We also copy the pack/unpackRegs helpers to CallLowering to
facilitate this.
ARM and AArch64 have been updated to use the passed in virtual registers
directly, which means we no longer need to generate so many
merge/extract instructions.
AArch64 seems to have had a bug when lowering e.g. [1 x i8*], which was
put into a s64 instead of a p0. Added a test-case which illustrates the
problem more clearly (it crashes without this patch) and fixed the
existing test-case to expect p0.
AMDGPU has been updated to unpack into the virtual registers for
kernels. I think the other code paths fall back for aggregates, so this
should be NFC.
Mips doesn't support aggregates yet, so it's also NFC.
x86 seems to have code for dealing with aggregates, but I couldn't find
the tests for it, so I just added a fallback to DAGISel if we get more
than one virtual register for an argument.
Differential Revision: https://reviews.llvm.org/D63549
llvm-svn: 364510
With this we can now fully code generate jump tables, which is important for code size.
Differential Revision: https://reviews.llvm.org/D63223
llvm-svn: 364086
This change makes use of the newly refactored SwitchLoweringUtils code from
SelectionDAG to in order to generate jump tables and range checks where appropriate.
Much of this code is ported from SDAG with some modifications. We generate
G_JUMP_TABLE and G_BRJT instructions when JT opportunities are found. This means
that targets which previously relied on the naive one MBB per case stmt
translation will now start falling back until they add support for the new opcodes.
For range checks, we don't generate any previously unused operations. This
just recognizes contiguous ranges of case values and generates a single block per
range. Single case value blocks are just a special case of ranges so we get that
support almost for free.
There are still some optimizations missing that I haven't ported over, and
bit-tests are also unimplemented. This patch series is already complex enough.
Actual arm64 support for selection of jump tables is coming in a later patch.
Differential Revision: https://reviews.llvm.org/D63169
llvm-svn: 364085
We sometimes get poor code size because constants of types < 32b are legalized
as 32 bit G_CONSTANTs with a truncate to fit. This works but means that the
localizer can no longer sink them (although it's possible to extend it to do so).
On AArch64 however s8 and s16 constants can be selected in the same way as s32
constants, with a mov pseudo into a W register. If we make s8 and s16 constants
legal then we can avoid unnecessary truncates, they can be CSE'd, and the
localizer can sink them as normal.
There is a caveat: if the user of a smaller constant has to widen the sources,
we end up with an anyext of the smaller typed G_CONSTANT. This can cause
regressions because of the additional extend and missed pattern matching. To
remedy this, there's a new artifact combiner to generate the wider G_CONSTANT
if it's legal for the target.
Differential Revision: https://reviews.llvm.org/D63587
llvm-svn: 364075
G_INTTOPTR can prevent the localizer from moving G_CONSTANTs, but since it's
essentially a side effect free cast instruction we can remat both instructions.
This patch changes the localizer to enable localization of the chains by
iterating over the entry block instructions in reverse order. That way, uses will
localized first, and then the defs are free to be localized as well.
This also changes the previous SmallPtrSet of localized instructions to use a
SetVector instead. We're dealing with pointers and need deterministic iteration
order.
Overall, this change improves ARM64 -O0 CTMark code size by around 0.7% geomean.
Differential Revision: https://reviews.llvm.org/D63630
llvm-svn: 364001
This allows targets to make more decisions about reserved registers
after isel. For example, now it should be certain there are calls or
stack objects in the frame or not, which could have been introduced by
legalization.
Patch by Matthias Braun
llvm-svn: 363757
Inter-block localization is the same as what currently happens, except now it
only runs on the entry block because that's where the problematic constants with
long live ranges come from.
The second phase is a new intra-block localization phase which attempts to
re-sink the already localized instructions further right before one of the
multiple uses.
One additional change is to also localize G_GLOBAL_VALUE as they're constants
too. However, on some targets like arm64 it takes multiple instructions to
materialize the value, so some additional heuristics with a TTI hook have been
introduced attempt to prevent code size regressions when localizing these.
Overall, these changes improve CTMark code size on arm64 by 1.2%.
Full code size results:
Program baseline new diff
------------------------------------------------------------------------------
test-suite...-typeset/consumer-typeset.test 1249984 1217216 -2.6%
test-suite...:: CTMark/ClamAV/clamscan.test 1264928 1232152 -2.6%
test-suite :: CTMark/SPASS/SPASS.test 1394092 1361316 -2.4%
test-suite...Mark/mafft/pairlocalalign.test 731320 714928 -2.2%
test-suite :: CTMark/lencod/lencod.test 1340592 1324200 -1.2%
test-suite :: CTMark/kimwitu++/kc.test 3853512 3820420 -0.9%
test-suite :: CTMark/Bullet/bullet.test 3406036 3389652 -0.5%
test-suite...ark/tramp3d-v4/tramp3d-v4.test 8017000 8016992 -0.0%
test-suite...TMark/7zip/7zip-benchmark.test 2856588 2856588 0.0%
test-suite...:: CTMark/sqlite3/sqlite3.test 765704 765704 0.0%
Geomean difference -1.2%
Differential Revision: https://reviews.llvm.org/D63303
llvm-svn: 363632
Summary: This case is related to D63405 in that we need to be propagating FMF on negates.
Reviewers: volkan, spatel, arsenm
Reviewed By: arsenm
Subscribers: wdng, javed.absar
Differential Revision: https://reviews.llvm.org/D63458
llvm-svn: 363631
Summary:
Change the way we deal with iterator invalidation in the extload combines as it
was still possible to neglect to visit a use. Even worse, it happened in the
in-tree test cases and the checks weren't good enough to detect it.
We now take a cheap copy of the use list before iterating over it. This
prevents iterator invalidation from occurring and has the nice side effect
of making the existing schedule-for-erase/schedule-for-insert mechanism
moot.
Reviewers: aditya_nandakumar
Reviewed By: aditya_nandakumar
Subscribers: rovka, kristof.beyls, javed.absar, volkan, Petar.Avramovic, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D61813
llvm-svn: 363616
Basically porting over the behaviour in AArch64ISelLowering to GISel. See
emitComparison for reference.
When we have something like this:
```
lhs = G_SUB 0, y
...
G_ICMP lhs, rhs
```
We can fold away the G_SUB and produce a cmn instead, given that we produce
the same value in NZCV.
Add a test showing that the transformation works, and also showing that we
don't perform the transformation when it's unsafe.
Also factor out the CSet emission into emitCSetForICMP.
Differential Revision: https://reviews.llvm.org/D63163
llvm-svn: 363596
This patch changes MIR stack-id from an integer to an enum,
and adds printing/parsing support for this in MIR files. The default
stack-id '0' is now renamed to 'default'.
This should make MIR tests that have stack objects with different stack-ids
more descriptive. It also clarifies code operating on StackID.
Reviewers: arsenm, thegameg, qcolombet
Reviewed By: arsenm
Differential Revision: https://reviews.llvm.org/D60137
llvm-svn: 363533
This is a branch opcode that takes a jump table pointer, jump table index and an
index into the table to do an indirect branch.
We pass both the table pointer and JTI to allow targets like ARM64 to more
easily use the existing jump table compression optimization without having to
walk up the block to find a paired G_JUMP_TABLE.
Differential Revision: https://reviews.llvm.org/D63159
llvm-svn: 363434
Constants, including G_GLOBAL_VALUE, are all emitted into the entry block which
lets us use the vreg def assuming it dominates all other users. However, it can
cause jumpy debug behaviour since the DebugLoc attached to these MIs are from
a user instruction that could be in a different block.
Fixes PR40887.
Differential Revision: https://reviews.llvm.org/D63286
llvm-svn: 363331
If the source is undef, then just don't do anything.
This matches SelectionDAG's behaviour in SelectionDAG.cpp.
Also add a test showing that we do the right thing here.
(irtranslator-memfunc-undef.ll)
Differential Revision: https://reviews.llvm.org/D63095
llvm-svn: 362989
We already get support for G_ZEXTLOAD to s32 from the importer, but it can't
deal with the SUBREG_TO_REG in the pattern. Tweaking the existing manual
selection code for G_LOAD to handle an additional SUBREG_TO_REG when dealing
with G_ZEXTLOAD isn't much work.
Also add tests to check the imported pattern selections to s32 work.
llvm-svn: 362681
When looking through copies, make sure to not try to find the vreg def of a physreg.
Normally getVRegDef will return nullptr in this case, but if there happens to be
multiple defs then it will assert.
This fixes PR42129.
llvm-svn: 362666
Although we had the support in the prelegalizer combiner to generate the
G_SEXTLOAD or G_ZEXTLOAD ops, the legalizer definitions for arm64 had them as
lowering back to separate ops.
llvm-svn: 362553
Instead of emitting all of the test stuff for a compare when it's only used by
a select, instead, just emit the compare + select. The select will use the
value of NZCV correctly, so we don't need to emit all of the test instructions
etc.
For now, only support fp selects which use G_FCMP. Also only support condition
codes which will only require one select to represent.
Also add a test.
Differential Revision: https://reviews.llvm.org/D62695
llvm-svn: 362446
Add support for selecting FCMPSri and FCMPDri when comparing against 0.0, and
factor out opcode selection for G_FCMP into its own function.
Add a test to show that we don't do this with other immediates.
Differential Revision: https://reviews.llvm.org/D62539
llvm-svn: 361888
In a few places in getInstrMapping, we check if use/def instructions for the
instruction we're mapping have floating point constraints.
We can improve this check and reduce the number of copies in GISel-compiled code
if we make a couple observations:
- For a def instruction, it only matters if the def instruction must always
output a value stored on a FPR
- For a use instruction, it only matters if the use instruction must always
only take in values stored in FPRs
This adds two new functions:
- onlyUsesFP
- onlyDefinesFP
Then we can use those when we're checking the uses/defs instead.
Without this patch, the load, unmerge, store, and select in the added test
would have unnecessary copies.
Differential Revision: https://reviews.llvm.org/D62426
llvm-svn: 361679
The fcsel and csel instructions differ in only the register banks they work on.
So, they're entirely interchangeable otherwise.
With this in mind, this does two things:
- Teach AArch64RegisterBankInfo to consider the inputs to G_SELECT as well as
the outputs.
- Teach it to choose the best register bank mapping based off the constraints
of the inputs and outputs.
The "best" in this case means the one that requires the smallest number of
copies to properly emit a fcsel/csel.
For example, if the inputs are all already going to be on FPRs, we should
emit a fcsel, even if the output is a GPR. This costs one copy to produce the
result, but saves us from copying the inputs into GPRs.
Also update the regbank-select.mir to check that we end up with the right
select instruction.
Differential Revision: https://reviews.llvm.org/D62267
llvm-svn: 361665
swifterror marks an argument as a register pretending to be a pointer, so we
need a guaranteed mem2reg-like analysis of its uses. Fortunately most of the
infrastructure can be reused from the DAG world.
llvm-svn: 361608
After support for dealing with types that need to be extended in some way was
added in r358032 we didn't correctly handle <1 x T> return types. These types
don't have a GISel direct representation, instead we just see them as scalars.
When we need to pad them into <2 x T> types however we need to use a
G_BUILD_VECTOR instead of trying to do a G_CONCAT_VECTOR.
This fixes PR41738.
llvm-svn: 360068
This saves us some unnecessary copies.
If the inputs to a G_SELECT are floating point, we should use fcsel rather than
csel.
Changes here are...
- Teach selectCopy about s1-to-s1 copies across register banks.
- AArch64RegisterBankInfo about G_SELECT in general.
- Teach the instruction selector about the FCSEL instructions.
Also add two tests:
- select-select.mir to show that we get the expected FCSEL
- regbank-select.mir (unfortunately named) to show the register banks on
G_SELECT are properly preserved
And update fast-isel-select.ll to show that we do the same thing as other
instruction selectors in these cases.
llvm-svn: 359940
We use to incorrectly use the store size instead of the alloc size when
creating the stack slot for allocas.
On aarch64 this can be demonstrated by allocating weirdly sized types.
For instance, in the added test case, we use an alloca for i19. We used
to allocate a slot of size 24-bit (19 rounded up to the next byte),
whereas we really want to use a full 32-bit slot for this type.
llvm-svn: 359856
This adds support for using fmov rather than a standard mov to materialize
G_FCONSTANT when it's safe to do so.
Update arm64-fast-isel-materialize.ll and select-constant.mir to show that the
selection is correct.
llvm-svn: 359734
getConstantVRegValWithLookThrough does the same thing as the
getConstantValueForReg function, and has more visibility across GISel. Plus, it
supports looking through G_TRUNC, G_SEXT, and G_ZEXT. So, we get better code
reuse and more functionality for free by using it.
Add some test cases to select-extract-vector-elt.mir to show that we can now
look through those instructions.
llvm-svn: 359351
There are instructions for these, so mark them as legal. Select the correct
instruction in AArch64InstructionSelector.cpp.
Update select-bswap.mir and arm64-rev.ll to reflect the changes.
llvm-svn: 359331
The code was using the alignment of a pointer to the value, not the
alignment of the constant itself.
Maybe we got away with it so far because the pointer alignment is
fairly high, but we did end up under-aligning <16 x i8> vectors,
which was caught in the Chromium build after lld stopped over-aligning
the .rodata.cst16 section in r356428. (See crbug.com/953815)
Differential revision: https://reviews.llvm.org/D61124
llvm-svn: 359287
Douglas Yung