91 Commits

Author SHA1 Message Date
David Majnemer
7ebb7ed7d0 [MC] Switch static const to an enum to silence MSVC linker warnings
Integral class statics are handled oddly in MSVC, we don't need them in
this case, use an enum instead.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241945 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-10 21:50:04 +00:00
Pete Cooper
f89e1bdc1a Pack MCSymbol::Flags in to the bitfield with other members. NFC.
All file formats only needed 16-bits right now which is enough to fit
in to the padding with other fields.

This reduces the size of MCSymbol to 24-bytes on a 64-bit system.  The
layout is now

   0 | class llvm::MCSymbol
   0 |   class llvm::PointerIntPair SectionOrFragmentAndHasName
   0 |     intptr_t Value
     |   [sizeof=8, dsize=8, align=8
     |    nvsize=8, nvalign=8]

   8 |   unsigned int IsTemporary
   8 |   unsigned int IsRedefinable
   8 |   unsigned int IsUsed
   8 |   _Bool IsRegistered
   8 |   unsigned int IsExternal
   8 |   unsigned int IsPrivateExtern
   8 |   unsigned int Kind
   9 |   unsigned int IsUsedInReloc
   9 |   unsigned int SymbolContents
   9 |   unsigned int CommonAlignLog2
  10 |   uint32_t Flags
  12 |   uint32_t Index
  16 |   union
  16 |     uint64_t Offset
  16 |     uint64_t CommonSize
  16 |     const class llvm::MCExpr * Value
     |   [sizeof=8, dsize=8, align=8
     |    nvsize=8, nvalign=8]

     | [sizeof=24, dsize=24, align=8
     |  nvsize=24, nvalign=8]

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241196 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-01 21:57:51 +00:00
Pete Cooper
f77ca9f85f Encode MCSymbol alignment as log2(align).
Given that alignments are always powers of 2, just encode it this way.

This matches how we encode alignment on IR GlobalValue's for example.

This compresses the CommonAlign member down to 5 bits which allows it
to pack better with the surrounding fields.

Reviewed by Duncan Exon Smith.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241189 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-01 21:07:03 +00:00
Pete Cooper
8cdbab9dd6 Pack MCSymbol::HasName in to a spare bit in the section/fragment union.
This is part of an effort to pack the average MCSymbol down to 24 bytes.

The HasName bit was pushing the size of the bitfield over to another word,
so this change uses a PointerIntPair to fit in it to unused bits of a
PointerUnion.

Reviewed by Rafael Espíndola

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241115 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-30 20:54:21 +00:00
Pete Cooper
8b4b91acd8 Move MCSymbol Value in to the union of Offset and CommonSize.
This is a reapplication of r239440 which was reverted in r239441.
There are no changes to this patch from then, but this had instead exposed
a bug in .thumb_set which was fixed in r240318.  Having fixed that bug, it
is now safe to re-apply this code.

Original commit message below:

It wasn't possible to have a variable Symbol with offset or 'isCommon' so
this just enables better packing of the MCSymbol class.

Reviewed by Rafael Espindola.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@240320 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-22 19:57:33 +00:00
Rafael Espindola
a1e31b45cc Move IsUsedInReloc from MCSymbolELF to MCSymbol.
There is a free bit is MCSymbol and MachO needs the same information.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239933 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-17 20:08:20 +00:00
Pete Cooper
51be69023d Remove unnecessary MCExpr.h include from MCSymbol.h
MCSymbol.h already forwards declares MCExpr and only uses MCExpr* so doesn't
need to include the header.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239626 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-12 18:07:34 +00:00
Pete Cooper
dbb0802eb6 Revert "Move MCSymbol Value in to the union of Offset and CommonSize."
This reverts commit 2e449ec5bcdf67b52b315b16c2128aaf25d5b73c.

This was svn r239440.  Its currently failing an ARM test so reverting while I work out
what to do next.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239441 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-09 22:35:55 +00:00
Pete Cooper
c11f1d8ae8 Move MCSymbol Value in to the union of Offset and CommonSize.
It wasn't possible to have a variable Symbol with offset or 'isCommon' so
this just enables better packing of the MCSymbol class.

Reviewed by Rafael Espindola.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239440 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-09 22:21:37 +00:00
Pete Cooper
38f72d04ea Reduce duplication in MCSymbol Name handling. NFC>
Based on feedback to r239428 by David Blaikie, use const_cast to reduce
duplication of the const and non-const versions of getNameEntryPtr.

Also have that method return the pointer to the name directly instead
of users having to then get the name from the union.

Finally, add a FIXME that we should use a static_assert once available in
the new operator.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239429 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-09 20:41:08 +00:00
Pete Cooper
5c8a22f11b Make MCSymbol::Name be a union of uint64_t and a pointer.
This should hopefully fix the 32-bit bots which were allocating space for a pointer
but needed to be aligned to 64-bits.

Now we allocate enough space for a uint64_t and a pointer and cast to the appropriate storage

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239428 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-09 19:56:05 +00:00
Pete Cooper
79e04c5844 Allocate space for MCSymbol::Name only if required.
Similarly to User which allocates a number of Use's prior to the this pointer,
allocate space for the Name* for MCSymbol only when we need a name.

Given that an MCSymbol is 48-bytes on 64-bit systems, this saves a decent % of space.

Given the verify_uselistorder test case with debug info and llc, 50k symbols have names
out of 700k so this optimises for the common case of temporary unnamed symbols.

Reviewed by David Blaikie.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239423 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-09 18:36:13 +00:00
Matt Arsenault
d99ce2f630 MC: Add target hook to control symbol quoting
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239370 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-09 00:31:39 +00:00
Reid Kleckner
dea5078cde [MC] Use unsigned for the Kind bitfield in MCSymbol
Fixes most of the test suite on Windows with clang-cl.

I'm not sure why the test suite was passing with MSVC 2013. Maybe they
changed their behavior and we are emulating their old sign extension
behavior. I think this deserves more investigation, but I want to green
the bot first.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239357 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-08 22:12:44 +00:00
Pete Cooper
d354befbbb Use a PointerUnion in MCSymbol for Section and Fragment. NFC.
The Fragment and Section, and a bool for HasFragment were all used to create
a PointerUnion.  Just use a pointer union instead.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239324 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-08 18:41:57 +00:00
Pete Cooper
1a8319cbef Make flags get/set method protected so that all flags have to be managed by subclasses.
All of ELF, COFF and MachO now manipulate the flags in helpers so we don't need
anyone to read the flags directly, but instead via those helpers.

Reviewed by Rafael Espíndola.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239317 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-08 17:17:30 +00:00
Pete Cooper
62f764a6c9 Change MCSymbol IsELF to an enum to support future MCSymbolCOFF and MCSymbolMachO.
Reviewed by Rafael Espíndola.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239311 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-08 17:17:09 +00:00
Colin LeMahieu
2ca8f0f5d6 [MC] Common symbols weren't being checked for redeclaration which allowed an assembly file to generate an assertion in setCommon(): !isCommon(). This change allows redeclaration as long as the size and alignment match exactly, otherwise report a fatal error.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239227 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-06 20:12:40 +00:00
Rafael Espindola
f7e0685b9a Create a MCSymbolELF.
This create a MCSymbolELF class and moves SymbolSize since only ELF
needs a size expression.

This reduces the size of MCSymbol from 56 to 48 bytes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238801 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-02 00:25:12 +00:00
Rafael Espindola
ba9e3285d0 The fragment implies the section, don't store both.
This reduces MCSymbol from 64 to 56 bytes on x86_64.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238747 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-01 14:34:40 +00:00
Rafael Espindola
223e58b67d Rename HasData to IsRegistered.
There is no MCSectionData, so the old name is now meaningless.

Also remove some asserts/checks that were there just because the information
they used was in MCSectionData.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238708 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-01 01:52:18 +00:00
Rafael Espindola
2e20fdbfcb Use a 32 bit field for the symbol index.
Even 64 ELF uses a 32 bit field to refer to symbols.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238704 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-01 00:58:31 +00:00
Benjamin Kramer
bfe3365795 [MC] Reorder MCSymbol members to reduce padding.
sizeof(MCSymbol) goes from 72 to 64 bytes on x86_64.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238655 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-30 13:52:30 +00:00
Jim Grosbach
586c0042da MC: Clean up MCExpr naming. NFC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238634 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-30 01:25:56 +00:00
Rafael Espindola
cfac75ad0e Remove getData.
This completes the mechanical part of merging MCSymbol and MCSymbolData.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238617 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-29 21:45:01 +00:00
Rafael Espindola
5760c5fe31 Remove the MCSymbolData typedef.
The getData member function is next.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238611 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-29 20:41:47 +00:00
Rafael Espindola
63e7baf8f6 Merge MCSymbol and MCSymbolData.
As a transition hack leave MCSymbolData as a typedef of MCSymbol. I will be
removing that in a second.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238609 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-29 20:31:23 +00:00
Rafael Espindola
071c3df378 Move Flags from MCSymbolData to MCSymbol.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238598 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-29 19:07:51 +00:00
Rafael Espindola
f021547d33 Use an explicitly defaulted constructor.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238591 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-29 18:31:17 +00:00
Rafael Espindola
82fdcc0e7f Move common symbol related information from MCSectionData to MCSymbol.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238583 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-29 17:48:04 +00:00
Rafael Espindola
28afbf2421 Move SymbolSize from MCSymbolData to MCSymbol.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238580 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-29 17:24:52 +00:00
Duncan P. N. Exon Smith
f5e0674d06 MC: Shave a pointer off of MCSymbol::Name
Shave a pointer off of `MCSymbolName` by storing `StringMapEntry<bool>*`
instead of `StringRef`.  This brings `sizeof(MCSymbol)` down to 64 on
64-bit platforms, a nice round number.  My profile showed memory
dropping from 914 MB down to 908 MB, roughly 0.7%.  Other than memory
usage, no functionality change here.

(I'm looking at `llc` memory usage on `verify-uselistorder.lto.opt.bc`;
see r236629 for details.)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238005 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-22 06:04:42 +00:00
Duncan P. N. Exon Smith
005bf5f8b0 MC: Pack MCSymbol::Index in with the bitfield in MCSymbol
Save a pointer for each `MCSymbol`, bringing `llc` memory usage down
from 920 MB to 914 MB, around ~0.6%.

(I'm looking at `llc` memory usage on `verify-uselistorder.lto.opt.bc`;
see r236629 for details.)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238003 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-22 05:59:05 +00:00
Duncan P. N. Exon Smith
6c3a7cbe54 MC: Lift MCSymbolData::Index up to MCSymbol::Index, NFC
Lift `MCSymbolData::Index` up a level to `MCSymbol`, as preparation for
packing it into the bitfield in `MCSymbol`.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238001 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-22 05:54:01 +00:00
Rafael Espindola
7521964d28 Move alignment from MCSectionData to MCSection.
This starts merging MCSection and MCSectionData.

There are a few issues with the current split between MCSection and
MCSectionData.

* It optimizes the the not as important case. We want the production
of .o files to be really fast, but the split puts the information used
for .o emission in a separate data structure.

* The ELF/COFF/MachO hierarchy is not represented in MCSectionData,
leading to some ad-hoc ways to represent the various flags.

* It makes it harder to remember where each item is.

The attached patch starts merging the two by moving the alignment from
MCSectionData to MCSection.

Most of the patch is actually just dropping 'const', since
MCSectionData is mutable, but MCSection was not.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237936 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-21 19:20:38 +00:00
Duncan P. N. Exon Smith
1d4f2ba509 MC: Initialize MCSymbolData::Offset directly
Try to fix miscompile after r237873.  Looks like this union
initialization isn't legal (or at least not supported).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237875 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-21 01:59:58 +00:00
Duncan P. N. Exon Smith
4652459f64 MC: Simplify MCSymbolData initialization and remove MCSymbol pointer
Finally remove the `MCSymbolData::Symbol` pointer.  It was still being
used to track whether `MCSymbolData` had been initialized, but this is
better tracked by the bitfield in `MCSymbol`.

The only caller of `MCSymbolData::initialize()` was `MCAssembler`, which
(other than `Symbol`) passed in all-0 values.  Replace all that
indirection with a default constructor.

The main point is a cleanup (and there's more cleanup to do), but there
are also some small memory savings.  I measured ~989 MB down to ~975 MB,
cutting a little over 1% off the top of `llc`.

(I'm looking at `llc` memory usage on `verify-uselistorder.lto.opt.bc`;
see r236629 for details.)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237873 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-21 01:33:03 +00:00
Duncan P. N. Exon Smith
549a742ba4 MC: Make MCSymbolData::Symbol private
Make the back-pointer from `MCSymbolData` to `MCSymbol` private,
preparing to remove the back pointer entirely.  I've already updated all
the users, although for now it's still used to indicate whether
`MCSymbol::Data` has been initialized.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237868 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-21 00:49:09 +00:00
Duncan P. N. Exon Smith
c5f2ba0401 MC: Merge MCSymbol and MCSymbolData
Turn `MCSymbolData` into a field inside of `MCSymbol`.  Keep all the old
API alive for now, so that consumers can be updated in a later commit.
This means we still temporarily need the back pointer from
`MCSymbolData` to `MCSymbol`, but I'll remove it in a follow-up.

This optimizes for object emission over assembly emission.  By removing
the `DenseMap` in `MCAssembler`, llc memory usage drops from around 1040
MB to 1001 MB (3.8%).

(I'm looking at `llc` memory usage on `verify-uselistorder.lto.opt.bc`;
see r236629 for details.)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237490 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-16 00:03:06 +00:00
Duncan P. N. Exon Smith
b42b9f8563 MC: Move MCSymbolData to MCSymbol.h, NFC
Prepare for always including symbol data in MCSymbol.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237489 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-16 00:03:00 +00:00
Duncan P. N. Exon Smith
da645e31a7 MC: clang-format MCSymbol.h, NFC
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237297 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-13 21:41:14 +00:00
Jim Grosbach
c8a51b01aa MC: Tidy up comments and clean up formatting a bit. NFC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236368 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-02 00:44:14 +00:00
Jim Grosbach
000564c01a Fix spelling.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236367 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-02 00:44:07 +00:00
Matt Arsenault
b638e142b4 Revert accidentally committed "MC: Allow targets to stop symbol name quoting"
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235672 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-23 23:34:51 +00:00
Matt Arsenault
6ec2992aca MC: Allow targets to stop symbol name quoting
Currently symbol names are printed in quotes if it contains something
outside of the arbitrary set of characters that isAcceptableChar tests
for. On somem targets, it is never OK to print a symbol name in quotes
so allow targets to opt out of this behavior.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235670 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-23 23:34:05 +00:00
Rafael Espindola
db244041cd Move AliasedSymbol to MachObjectWriter.
It was only used by MachO.
Part of pr19627.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235185 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-17 12:28:43 +00:00
Peter Collingbourne
c39f5dd0e2 MC: For variable symbols, maintain MCSymbol::Section as a cache.
Fixes PR19582.

Previously, when an asm assignment (.set or =) was created, we would look up
the section immediately in MCSymbol::setVariableValue. This caused symbols
to receive the wrong section if the RHS of the assignment had not been seen
yet. This had a knock-on effect in the object file emitters, causing them
to emit extra symbols, or to give symbols the wrong visibility or the wrong
section. For example, in the following asm:

.data
.Llocal:

.text
leaq .Llocal1(%rip), %rdi
.Llocal1 = .Llocal2
.Llocal2 = .Llocal

the first assignment would give .Llocal1 a null section, which would never get
fixed up by the second assignment. This would cause the ELF object file emitter
to consider .Llocal1 to be an undefined symbol and give it external linkage,
even though .Llocal1 should not have been emitted at all in the object file.

Or in the following asm:

alias_to_local = Ltmp0
Ltmp0:

the Mach-O object file emitter would give the alias_to_local symbol a n_type
of N_SECT and a n_sect of 0.  This is invalid under the Mach-O specification,
which requires N_SECT symbols to receive a non-zero section number if the
symbol is defined in a section in the object file.

https://developer.apple.com/library/mac/documentation/DeveloperTools/Conceptual/MachORuntime/#//apple_ref/c/tag/nlist

After this change we do not look up the section when the assignment is created,
but instead look it up on demand and store it in Section, which is treated
as a cache if the symbol is a variable symbol.

This change also fixes a bug in MCExpr::FindAssociatedSection. Previously,
if we saw a subtraction, we would return the first referenced section, even in
cases where we should have been returning the absolute pseudo-section. Now we
always return the absolute pseudo-section for expressions that subtract two
section-derived expressions. This isn't always correct (e.g. if one of the
sections ends up being laid out at an absolute address), but it's probably
the best we can do without more context.

This allows us to remove code in two places where we appear to have been
working around this bug, in MachObjectWriter::markAbsoluteVariableSymbols
and in X86AsmPrinter::EmitStartOfAsmFile.

Re-applies r233595 (aka D8586), which was reverted in r233898.

Differential Revision: http://reviews.llvm.org/D8798

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233995 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-03 01:46:11 +00:00
Peter Collingbourne
a8432640e8 Revert r233595, "MC: For variable symbols, maintain MCSymbol::Section as a cache."
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233898 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-02 07:02:51 +00:00
Peter Collingbourne
07ee8d2fc1 MC: For variable symbols, maintain MCSymbol::Section as a cache.
This fixes the visibility of symbols in certain edge cases involving aliases
with multiple levels of indirection.

Fixes PR19582.

Differential Revision: http://reviews.llvm.org/D8586

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233595 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-30 20:41:21 +00:00
Aaron Ballman
66981fe208 Removing LLVM_DELETED_FUNCTION, as MSVC 2012 was the last reason for requiring the macro. NFC; LLVM edition.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229340 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-15 22:54:22 +00:00