Commit Graph

49446 Commits

Author SHA1 Message Date
Krasimir Georgiev 547d824da6 Revert "[WebAssembly] LSDA info generation"
This reverts commit r344575.
Newly introduced test eh-lsda.ll.test fails with use-after-free under
ASAN build.

llvm-svn: 344639
2018-10-16 18:50:09 +00:00
Evandro Menezes c98decf864 [PATCH] [NFC][AArch64] Fix refactoring of macro fusion
Fix compiler error.

llvm-svn: 344632
2018-10-16 17:41:45 +00:00
Evandro Menezes 46eadcff9c [NFC][ARM] Refactor macro fusion
Simplify code for wildcards.

llvm-svn: 344625
2018-10-16 17:19:51 +00:00
Evandro Menezes de655c6d3a [NFC][AArch64] Refactor macro fusion
Simplify API of checking functions.

llvm-svn: 344624
2018-10-16 17:19:28 +00:00
Simon Pilgrim 7d27cfdcb2 [X86] Fix Skylake ReadAfterLd for PADDrm etc.
Missed in rL343868 as due to their custom InstrRW.

llvm-svn: 344600
2018-10-16 09:50:16 +00:00
Aleksandar Beserminji a5949439ca [mips][micromips] Fix how values in .gcc_except_table are calculated
When a landing pad is calculated in a program that is compiled
for micromips, it will point to an even address. Such an error will
cause a segmentation fault, as the instructions in micromips are
aligned on odd addresses. This patch sets the last bit of the offset
where a landing pad is, to 1, which will effectively be
an odd address and point to the instruction exactly.

Differential Revision: https://reviews.llvm.org/D52985

llvm-svn: 344591
2018-10-16 08:27:28 +00:00
Heejin Ahn 0981eaab47 [WebAssembly] LSDA info generation
Summary:
This adds support for LSDA (exception table) generation for wasm EH.
Wasm EH mostly follows the structure of Itanium-style exception tables,
with one exception: a call site table entry in wasm EH corresponds to
not a call site but a landing pad.

In wasm EH, the VM is responsible for stack unwinding. After an
exception occurs and the stack is unwound, the control flow is
transferred to wasm 'catch' instruction by the VM, after which the
personality function is called from the compiler-generated code. (Refer
to WasmEHPrepare pass for more information on this part.)

This patch:
- Changes wasm.landingpad.index intrinsic to take a token argument, to
make this 1:1 match with a catchpad instruction
- Stores landingpad index info and catch type info MachineFunction in
before instruction selection
- Lowers wasm.lsda intrinsic to an MCSymbol pointing to the start of an
exception table
- Adds WasmException class with overridden methods for table generation
- Adds support for LSDA section in Wasm object writer

Reviewers: dschuff, sbc100, rnk

Subscribers: mgorny, jgravelle-google, sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D52748

llvm-svn: 344575
2018-10-16 00:09:12 +00:00
Craig Topper e70c560b6d [X86] Remove some isel patterns that shouldn't be possible.
These included a bitcast of a load from v4f32 to v2f64, but DAG combine should have already changed the type of the load to remove the cast.

llvm-svn: 344573
2018-10-15 23:34:58 +00:00
Craig Topper 2909a3d9d0 [X86] Fix a bad bitcast in the load form of vXi16 uniform shift patterns for EVEX encoded instructions.
llvm-svn: 344563
2018-10-15 21:51:32 +00:00
Simon Pilgrim 095a7fe635 [AARCH64] Improve vector popcnt lowering with ADDLP
AARCH64 equivalent to D53257 - uses widening pairwise adds on vXi8 CTPOP to support i16/i32/i64 vectors.

This is a blocker for generic vector CTPOP expansion (P32655) - this will remove the aarch64 diff from D53258.

Differential Revision: https://reviews.llvm.org/D53259

llvm-svn: 344554
2018-10-15 21:15:58 +00:00
Konstantin Zhuravlyov 94dfcc2eb2 AMDGPU: Generate .amdgcn_target for object code v3
Differential Revision: https://reviews.llvm.org/D53221

llvm-svn: 344552
2018-10-15 20:37:47 +00:00
Aleksandar Beserminji 81eb440772 [mips][micromips] Fix overlaping FDEs error
When compiling static executable for micromips, CFI symbols
are incorrectly labeled as MICROMIPS, which cause
".eh_frame_hdr refers to overlapping FDEs." error.

This patch does not label CFI symbols as MICROMIPS, and FDEs do not
overlap anymore. This patch also exposes another bug, which is fixed
here: https://reviews.llvm.org/D52985

Differential Revision: https://reviews.llvm.org/D52987

llvm-svn: 344516
2018-10-15 14:39:12 +00:00
Aleksandar Beserminji 585f55bb8b [mips][micromips] Revert "Fix overlaping FDEs error"
This reverts r344511.

llvm-svn: 344515
2018-10-15 14:36:48 +00:00
Simon Pilgrim 5abb607ebe [ARM][NEON] Improve vector popcnt lowering with PADDL (PR39281)
As I suggested on PR39281, this patch uses PADDL pairwise addition to widen from the vXi8 CTPOP result to the target vector type.

This is a blocker for moving more x86 code to generic vector CTPOP expansion (P32655 + D53258) - ARM's vXi64 CTPOP currently expands, which would generate a vXi64 MUL but ARM's custom lowering expands the general MUL case and vectors aren't well handled in LegalizeDAG - improving the CTPOP lowering was a lot easier than fixing the MUL lowering for this one case......

Differential Revision: https://reviews.llvm.org/D53257

llvm-svn: 344512
2018-10-15 13:20:41 +00:00
Aleksandar Beserminji 10ec5c8c28 [mips][micromips] Fix overlaping FDEs error
When compiling static executable for micromips, CFI symbols
are incorrectly labeled as MICROMIPS, which cause
".eh_frame_hdr refers to overlapping FDEs." error.

This patch does not label CFI symbols as MICROMIPS, and FDEs do not
overlap anymore. This patch also exposes another bug, which is fixed
here: https://reviews.llvm.org/D52985

Differential Revision: https://reviews.llvm.org/D52987

llvm-svn: 344511
2018-10-15 12:59:17 +00:00
Chandler Carruth edb12a838a [TI removal] Make variables declared as `TerminatorInst` and initialized
by `getTerminator()` calls instead be declared as `Instruction`.

This is the biggest remaining chunk of the usage of `getTerminator()`
that insists on the narrow type and so is an easy batch of updates.
Several files saw more extensive updates where this would cascade to
requiring API updates within the file to use `Instruction` instead of
`TerminatorInst`. All of these were trivial in nature (pervasively using
`Instruction` instead just worked).

llvm-svn: 344502
2018-10-15 10:04:59 +00:00
Craig Topper 06aea1720a [X86] Move promotion of vector and/or/xor from legalization to DAG combine
Summary:
I've noticed that the bitcasts we introduce for these make computeKnownBits and computeNumSignBits not work well in LegalizeVectorOps. LegalizeVectorOps legalizes bottom up while LegalizeDAG legalizes top down. The bottom up strategy for LegalizeVectorOps means operands are legalized before their uses. So we promote and/or/xor before we legalize the operands that use them making computeKnownBits/computeNumSignBits in places like LowerTruncate suboptimal. I looked at changing LegalizeVectorOps to be top down as well, but that was more disruptive and caused some regressions. I also looked at just moving promotion of binops to LegalizeDAG, but that had a few issues one around matching AND,ANDN,OR into VSELECT because I had to create ANDN as vXi64, but the other nodes hadn't legalized yet, I didn't look too hard at fixing that.

This patch seems to produce better results overall than my other attempts. We now form broadcasts of constants better in some cases. For at least some of them the AND was being introduced in LegalizeDAG, promoted to vXi64, and the BUILD_VECTOR was also legalized there. I think we got bad ordering of that. Now the promotion is out of the legalizer so we handle this better.

In the longer term I think we really should evaluate whether we should be doing this promotion at all. It's really there to reduce isel pattern count, but I'm wondering if we'd be better served just eating the pattern cost or doing C++ based isel for vector and/or/xor in X86ISelDAGToDAG. The masked and/or/xor will definitely be difficult in patterns if a bitcast gets between the vselect and the and/or/xor node. That becomes a lot of permutations to cover.

Reviewers: RKSimon, spatel

Reviewed By: RKSimon

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D53107

llvm-svn: 344487
2018-10-15 01:51:58 +00:00
Craig Topper 671779456a [X86] Add 128 MOVDDUP to the constant pool printing in X86AsmPrinter::EmitInstruction.
We use this instruction to broadcast a single 64-bit value to a v2i64/v2f64 vector.

llvm-svn: 344486
2018-10-15 01:51:53 +00:00
Simon Pilgrim 861cd0ba44 [X86][AVX] Enable lowerVectorShuffleAsLanePermuteAndPermute v16i16/v32i8 shuffle lowering
Extends D53148 from v4f64 now that we have test coverage for v16i16/v32i8 shuffles.

llvm-svn: 344481
2018-10-14 17:34:20 +00:00
Dorit Nuzman 38bbf81ade recommit 344472 after fixing build failure on ARM and PPC.
llvm-svn: 344475
2018-10-14 08:50:06 +00:00
Dorit Nuzman 5118c68cde revert 344472 due to failures.
llvm-svn: 344473
2018-10-14 07:21:20 +00:00
Dorit Nuzman 8174368955 [IAI,LV] Add support for vectorizing predicated strided accesses using masked
interleave-group

The vectorizer currently does not attempt to create interleave-groups that
contain predicated loads/stores; predicated strided accesses can currently be
vectorized only using masked gather/scatter or scalarization. This patch makes
predicated loads/stores candidates for forming interleave-groups during the
Loop-Vectorizer's analysis, and adds the proper support for masked-interleave-
groups to the Loop-Vectorizer's planning and transformation stages. The patch
also extends the TTI API to allow querying the cost of masked interleave groups
(which each target can control); Targets that support masked vector loads/
stores may choose to enable this feature and allow vectorizing predicated
strided loads/stores using masked wide loads/stores and shuffles.

Reviewers: Ayal, hsaito, dcaballe, fhahn, javed.absar

Reviewed By: Ayal

Differential Revision: https://reviews.llvm.org/D53011

llvm-svn: 344472
2018-10-14 07:06:16 +00:00
Craig Topper 20fa085d74 [X86] Fix bad indentation. NFC
llvm-svn: 344471
2018-10-14 04:01:40 +00:00
Craig Topper ec4b75f47a [X86] Type legalize v2f32 stores by widening to v4f32, casting to v2f64, extracting f64 and storing.
Summary: This is similar to what D52528 did for loads. It should match what generic type legalization does in 64-bit mode where it uses a v2i64 cast and an i64 store.

Reviewers: RKSimon, spatel

Reviewed By: RKSimon

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D53173

llvm-svn: 344470
2018-10-14 03:36:27 +00:00
Benjamin Kramer c55e997556 Move some helpers from the global namespace into anonymous ones.
llvm-svn: 344468
2018-10-13 22:18:22 +00:00
Thomas Lively ffde98de21 [WebAssembly][NFC] Fix signed/unsigned comparison warning
llvm-svn: 344459
2018-10-13 16:58:03 +00:00
Simon Pilgrim c5d7c6e5f6 [X86][SSE] Remove most of vector CTTZ custom lowering and use LegalizeDAG instead.
There is one remnant - AVX1 custom splitting of 256-bit vectors - which is due to a regression where the X86ISD::ANDNP is still performed as a YMM.

I've also tightened the CTLZ or CTPOP lowering in SelectionDAGLegalize::ExpandBitCount to require a legal CTLZ - it doesn't affect existing users and fixes an issue with AVX512 codegen.

llvm-svn: 344457
2018-10-13 16:11:15 +00:00
Simon Pilgrim 1c2051ead7 [X86][SSE] Begin removing vector CTTZ custom lowering and use LegalizeDAG instead.
Adds CTTZ vector legalization support and begins the removal of the X86/SSE custom lowering. 

llvm-svn: 344453
2018-10-13 15:16:55 +00:00
Simon Pilgrim 1c6d320351 [X86][SSE] combineIncDecVector - use isConstantSplat
Use isConstantSplat instead of ISD::isConstantSplatVector to let us us peek through to illegal types (in this case for i686 targets to recognise i64 constants)

llvm-svn: 344452
2018-10-13 14:45:44 +00:00
Simon Pilgrim a03379527a [X86] Pull out target constant splat helper function. NFCI.
The code in LowerScalarImmediateShift is just a more powerful version of ISD::isConstantSplatVector.

llvm-svn: 344451
2018-10-13 14:28:40 +00:00
Simon Pilgrim 10434cbae1 Pull out repeated getOperand(). NFCI.
llvm-svn: 344450
2018-10-13 13:33:32 +00:00
Simon Pilgrim bc141724c0 Remove unused variable. NFCI.
llvm-svn: 344449
2018-10-13 13:30:10 +00:00
Simon Pilgrim f64e654d62 [X86][SSE] Improve CTTZ lowering when CTLZ is legal
If we have better CTLZ support than CTPOP, then use cttz(x) = width - ctlz(~x & (x - 1)) - and remove the CTTZ_ZERO_UNDEF handling as it no longer gives better codegen.

Similar to rL344447, this is also closer to LegalizeDAG's approach

llvm-svn: 344448
2018-10-13 13:05:19 +00:00
Simon Pilgrim afead139cf [X86][SSE] Change CTTZ vector lowering to cttz(x) = ctpop(~x & (x - 1))
This patch changes the vector CTTZ lowering from:

cttz(x) = ctpop((x & -x) - 1)

to:

cttz(x) = ctpop(~x & (x - 1))

Not only does this make better use of the PANDN instruction, but it also matches the LegalizeDAG method which should allow us to remove the x86 specific code at some point in the future (we need to fix some issues with the bitcasted logic ops and CTPOP lowering first).

Differential Revision: https://reviews.llvm.org/D53214

llvm-svn: 344447
2018-10-13 12:12:06 +00:00
Simon Pilgrim f3952413f7 [X86][AVX] Add lowerVectorShuffleAsLanePermuteAndPermute for v4f64 shuffles (PR39161)
Add shuffle lowering for the case where we can shuffle the lanes into place followed by an in-lane permute.

This is mainly for cases where we can have non-repeating permutes in each lane, but for now I've just enabled it for v4f64 unary shuffles to fix PR39161 - there is no test coverage for other shuffles that might benefit yet.

We now have several cross-lane shuffle lowering methods that all do something similar - I've looked at merging some of these (notably by making the repeated mask mechanism in lowerVectorShuffleByMerging128BitLanes optional), but there is a lot of assertions/assumptions in the way that makes this tricky - I ended up going for adding yet another relatively simple method instead.

Differential Revision: https://reviews.llvm.org/D53148

llvm-svn: 344446
2018-10-13 11:38:10 +00:00
Arnaud A. de Grandmaison 162435e7b5 [AArch64] Swap comparison operands if that enables some folding.
Summary:
AArch64 can fold some shift+extend operations on the RHS operand of
comparisons, so swap the operands if that makes sense.

This provides a fix for https://bugs.llvm.org/show_bug.cgi?id=38751

Reviewers: efriedma, t.p.northover, javed.absar

Subscribers: mcrosier, kristof.beyls, llvm-commits

Differential Revision: https://reviews.llvm.org/D53067

llvm-svn: 344439
2018-10-13 07:43:56 +00:00
Thomas Lively 3afc346dd0 [WebAssembly] SIMD min and max
Summary: Depends on D52324 and D52764.

Reviewers: aheejin, dschuff

Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D52325

llvm-svn: 344438
2018-10-13 07:26:10 +00:00
Thomas Lively 0ff82ac154 [WebAssembly][NFC] Unify ARGUMENT classes
Reviewers: aheejin, dschuff

Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D53172

llvm-svn: 344436
2018-10-13 07:09:10 +00:00
Alex Bradbury 748d080e62 [RISCV] Eliminate unnecessary masking of promoted shift amounts
SelectionDAGBuilder::visitShift will always zero-extend a shift amount when it
is promoted to the ShiftAmountTy. This results in zero-extension (masking)
which is unnecessary for RISC-V as the shift operations only read the lower 5
or 6 bits (RV32 or RV64).

I initially proposed adding a getExtendForShiftAmount hook so the shift amount
can be any-extended (D52975). @efriedma explained this was unsafe, so I have
instead eliminate the unnecessary and operations at instruction selection time
in a manner similar to X86InstrCompiler.td.

Differential Revision: https://reviews.llvm.org/D53224

llvm-svn: 344432
2018-10-12 23:18:52 +00:00
Craig Topper 3e76b2d736 [X86] Improve type legalization of (v2i32/v4i16/v8i16 (bitcast (v2f32))) to avoid a stack stack temporary.
llvm-svn: 344425
2018-10-12 22:00:04 +00:00
Craig Topper c693a23025 [X86] Simplify the end of custom type legalization for (v2i32/v4i16/v8i8 (bitcast (f64))) by just emitting an EXTRACT_SUBVECTOR instead of a BUILD_VECTOR.
Generic legalization should be able to finish legalizing the EXTRACT_SUBVECTOR probably by turning it into a BUILD_VECTOR. But we should emit the simplest sequence.

llvm-svn: 344424
2018-10-12 22:00:00 +00:00
Craig Topper a8a44f1bec [X86] Skip (v2i32/v4i16/v8i8 (bitcast (f64))) handling in ReplaceNodeResults if the dest type can be widened by generic legalization. NFCI
The algorithm we would do previously was identical to generic legalization. If we ever switch to legalizing integer vectors via widening we'll be able to kill off the code since it now only runs for promotion.

llvm-svn: 344423
2018-10-12 21:59:58 +00:00
Sanjay Patel e28c8ecd72 [x86] add and use fast horizontal vector math subtarget feature
This is the planned follow-up to D52997. Here we are reducing horizontal vector math codegen 
by default. AMD Jaguar (btver2) should have no difference with this patch because it has 
fast-hops. (If we want to set that bit for other CPUs, let me know.)

The code changes are small, but there are many test diffs. For files that are specifically 
testing for hops, I added RUNs to distinguish fast/slow, so we can see the consequences 
side-by-side. For files that are primarily concerned with codegen other than hops, I just 
updated the CHECK lines to reflect the new default codegen.

To recap the recent horizontal op story:

1. Before rL343727, we were producing hops for all subtargets for a variety of patterns. 
   Hops were likely not optimal for all targets though.
2. The IR improvement in r343727 exposed a hole in the backend hop pattern matching, so 
   we reduced hop codegen for all subtargets. That was bad for Jaguar (PR39195).
3. We restored the hop codegen for all targets with rL344141. Good for Jaguar, but 
   probably bad for other CPUs.
4. This patch allows us to distinguish when we want to produce hops, so everyone can be 
   happy. I'm not sure if we have the best predicate here, but the intent is to undo the 
   extra hop-iness that was enabled by r344141.

Differential Revision: https://reviews.llvm.org/D53095

llvm-svn: 344361
2018-10-12 16:41:02 +00:00
Eric Liu 55ab86b72b Fix unused variable warning after r344348
llvm-svn: 344350
2018-10-12 15:01:11 +00:00
Simon Pilgrim 78b5a3c3ef [X86][SSE] LowerVectorCTPOP - pull out repeated byte sum stage.
Pull out repeated byte sum stage for popcount of vector elements > 8bits.

This allows us to simplify the LUT/BITMATH popcnt code to always assume vXi8 vectors, and also improves avx512bitalg codegen which only has access to vpopcntb/vpopcntw.

llvm-svn: 344348
2018-10-12 14:18:47 +00:00
Hiroshi Inoue 9552dd187a [PowerPC] avoid masking already-zero bits in BitPermutationSelector
The current BitPermutationSelector generates a code to build a value by tracking two types of bits: ConstZero and Variable.
ConstZero means a bit we need to mask off and Variable is a bit we copy from an input value.

This patch add third type of bits VariableKnownToBeZero caused by AssertZext node or zero-extending load node.
VariableKnownToBeZero means a bit comes from an input value, but it is known to be already zero. So we do not need to mask them.
VariableKnownToBeZero enhances flexibility to group bits, since we can avoid redundant masking for these bits.

This patch also renames "HasZero" to "NeedMask" since now we may skip masking even when we have zeros (of type VariableKnownToBeZero).

Differential Revision: https://reviews.llvm.org/D48025

llvm-svn: 344347
2018-10-12 14:02:20 +00:00
Simon Pilgrim 29279f29c8 [X86][SSE] Add extract_subvector(PSHUFB) -> PSHUFB(extract_subvector()) combine
Fixes PR32160 by reducing the size of PSHUFB if we only use one of the lanes.

This approach can probably be generalized to handle any target shuffle (and any subvector index) but we have no test coverage at the moment.

llvm-svn: 344336
2018-10-12 12:10:34 +00:00
Andrea Di Biagio 6eebbe0a97 [tblgen][llvm-mca] Add the ability to describe move elimination candidates via tablegen.
This patch adds the ability to identify instructions that are "move elimination
candidates". It also allows scheduling models to describe processor register
files that allow move elimination.

A move elimination candidate is an instruction that can be eliminated at
register renaming stage.
Each subtarget can specify which instructions are move elimination candidates
with the help of tablegen class "IsOptimizableRegisterMove" (see
llvm/Target/TargetInstrPredicate.td).

For example, on X86, BtVer2 allows both GPR and MMX/SSE moves to be eliminated.
The definition of 'IsOptimizableRegisterMove' for BtVer2 looks like this:

```
def : IsOptimizableRegisterMove<[
  InstructionEquivalenceClass<[
    // GPR variants.
    MOV32rr, MOV64rr,

    // MMX variants.
    MMX_MOVQ64rr,

    // SSE variants.
    MOVAPSrr, MOVUPSrr,
    MOVAPDrr, MOVUPDrr,
    MOVDQArr, MOVDQUrr,

    // AVX variants.
    VMOVAPSrr, VMOVUPSrr,
    VMOVAPDrr, VMOVUPDrr,
    VMOVDQArr, VMOVDQUrr
  ], CheckNot<CheckSameRegOperand<0, 1>> >
]>;
```

Definitions of IsOptimizableRegisterMove from processor models of a same
Target are processed by the SubtargetEmitter to auto-generate a target-specific
override for each of the following predicate methods:

```
bool TargetSubtargetInfo::isOptimizableRegisterMove(const MachineInstr *MI)
const;
bool MCInstrAnalysis::isOptimizableRegisterMove(const MCInst &MI, unsigned
CPUID) const;
```

By default, those methods return false (i.e. conservatively assume that there
are no move elimination candidates).

Tablegen class RegisterFile has been extended with the following information:
 - The set of register classes that allow move elimination.
 - Maxium number of moves that can be eliminated every cycle.
 - Whether move elimination is restricted to moves from registers that are
   known to be zero.

This patch is structured in three part:

A first part (which is mostly boilerplate) adds the new
'isOptimizableRegisterMove' target hooks, and extends existing register file
descriptors in MC by introducing new fields to describe properties related to
move elimination.

A second part, uses the new tablegen constructs to describe move elimination in
the BtVer2 scheduling model.

A third part, teaches llm-mca how to query the new 'isOptimizableRegisterMove'
hook to mark instructions that are candidates for move elimination. It also
teaches class RegisterFile how to describe constraints on move elimination at
PRF granularity.

llvm-mca tests for btver2 show differences before/after this patch.

Differential Revision: https://reviews.llvm.org/D53134

llvm-svn: 344334
2018-10-12 11:23:04 +00:00
Simon Pilgrim c844bc84dd [X86] Ignore float/double non-temporal loads (PR39256)
Scalar non-temporal loads were asserting instead of just being ignored.

Reduced from https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=10895

llvm-svn: 344331
2018-10-12 10:20:16 +00:00
Stefan Maksimovic 285c0f4fdc [mips] Mark fmaxl as a long double emulation routine
Failure was discovered upon running
projects/compiler-rt/test/builtins/Unit/divtc3_test.c
in a stage2 compiler build.

When compiling projects/compiler-rt/lib/builtins/divtc3.c,
a call to fmaxl within the divtc3 implementation had its
return values read from registers $2 and $3 instead of $f0 and $f2.
Include fmaxl in the list of long double emulation routines
to have its return value correctly interpreted as f128.

Almost exact issue here: https://reviews.llvm.org/D17760

Differential Revision: https://reviews.llvm.org/D52649

llvm-svn: 344326
2018-10-12 08:18:38 +00:00