Commit Graph

229 Commits

Author SHA1 Message Date
Serge Guelton 52d777fc4f Tentative fix for r351701 and gcc 6.2 build on ubuntu
llvm-svn: 351728
2019-01-21 07:44:52 +00:00
Chandler Carruth 2946cd7010 Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00
Fangrui Song fe36417f6e [ELF] .gnu.hash bloom filter: use Shift2 = 26 instead of 6
Summary:
For the 2-bit bloom filter, we currently pick the bits Hash%64 and Hash>>6%64 (Shift2=6), but bits [6:...] are also used to select a word, causing a loss of precision.

In this patch, we choose Shift2=26, with is suggested by Ambrose Feinstein.

Note, Shift2 is computed as maskbitslog2 in bfd/elflink.c and gold/dynobj.cc
It is varying with the number of dynamic symbols but we don't
necessarily copy its rule.

Reviewers: ruiu, espindola

Reviewed By: ruiu

Subscribers: emaste, arichardson, llvm-commits

Differential Revision: https://reviews.llvm.org/D55971

llvm-svn: 349966
2018-12-21 21:59:34 +00:00
Rui Ueyama 63d397ea6e Simplify Symbol::getPltVA.
This patch also makes getPltEntryOffset a non-member function because
it doesn't depend on any private members of the TargetInfo class.

I tried a few different ideas, and it seems this change fits in best to me.

Differential Revision: https://reviews.llvm.org/D54981

llvm-svn: 347781
2018-11-28 17:42:59 +00:00
George Rimar 0e0cd5be40 [LLD][ELF] - Add llvm_unreachable. NFC.
We never should call writeTo() for BSS section.

llvm-svn: 347540
2018-11-26 10:07:10 +00:00
Sean Fertile 614dc11ca8 [PPC64] Long branch thunks.
On PowerPC64, when a function call offset is too large to encode in a call
instruction the address is stored in a table in the data segment. A thunk is
used to load the branch target address from the table relative to the
TOC-pointer and indirectly branch to the callee. When linking position-dependent
code the addresses are stored directly in the table, for position-independent
code the table is allocated and filled in at load time by the dynamic linker.

For position-independent code the branch targets could have gone in the .got.plt
but using the .branch_lt section for both position dependent and position
independent binaries keeps it consitent and helps keep this PPC64 specific logic
seperated from the target-independent code handling the .got.plt.

Differential Revision: https://reviews.llvm.org/D53408

llvm-svn: 346877
2018-11-14 17:56:43 +00:00
Fangrui Song 0736461b24 [ELF] Rename NameTypeEntry to NameAttrEntry and its field "Type" to CuIndexAndAttrs
Summary:
NameTypeEntry::Type is a bit-packed value of CU index+attributes (https://sourceware.org/gdb//onlinedocs/gdb/Index-Section-Format.html), which is named cu_index_and_attrs in a local variable in gdb/dwarf2read.c:dw2_symtab_iter_next

The new name CuIndexAndAttrs is more meaningful.

Reviewers: ruiu, dblaikie, espindola

Reviewed By: dblaikie

Subscribers: emaste, aprantl, arichardson, JDevlieghere, arphaman, llvm-commits

Differential Revision: https://reviews.llvm.org/D54481

llvm-svn: 346794
2018-11-13 20:25:51 +00:00
George Rimar 4cb05713de [ELF] - Remove unused variable. NFC.
It triggered a bot failture somehow today:
http://lab.llvm.org:8011/builders/lld-perf-testsuite/builds/7993

llvm-svn: 344344
2018-10-12 13:39:35 +00:00
George Rimar fa91327b51 [ELF] - Remove dead declaration. NFC.
MipsGotSection::FileGot::isOverflow()
was a dead declararion.

llvm-svn: 344342
2018-10-12 13:25:25 +00:00
Rui Ueyama e28c146423 Avoid unnecessary buffer allocation and memcpy for compressed sections.
Previously, we uncompress all compressed sections before doing anything.
That works, and that is conceptually simple, but that could results in
a waste of CPU time and memory if uncompressed sections are then
discarded or just copied to the output buffer.

In particular, if .debug_gnu_pub{names,types} are compressed and if no
-gdb-index option is given, we wasted CPU and memory because we
uncompress them into newly allocated bufers and then memcpy the buffers
to the output buffer. That temporary buffer was redundant.

This patch changes how to uncompress sections. Now, compressed sections
are uncompressed lazily. To do that, `Data` member of `InputSectionBase`
is now hidden from outside, and `data()` accessor automatically expands
an compressed buffer if necessary.

If no one calls `data()`, then `writeTo()` directly uncompresses
compressed data into the output buffer. That eliminates the redundant
memory allocation and redundant memcpy.

This patch significantly reduces memory consumption (20 GiB max RSS to
15 Gib) for an executable whose .debug_gnu_pub{names,types} are in total
5 GiB in an uncompressed form.

Differential Revision: https://reviews.llvm.org/D52917

llvm-svn: 343979
2018-10-08 16:58:59 +00:00
Rui Ueyama 12ef7a9575 De-template VersionDefinitionSection. NFC.
When we write a struct to a mmap'ed buffer, we usually use
write16/32/64, but we didn't for VersionDefinitionSection, so
we needed to template that class.

llvm-svn: 343024
2018-09-25 20:37:51 +00:00
Rui Ueyama 4e247522ac Reset input section pointers to null on each linker invocation.
Previously, if you invoke lld's `main` more than once in the same process,
the second invocation could fail or produce a wrong result due to a stale
pointer values of the previous run.

Differential Revision: https://reviews.llvm.org/D52506

llvm-svn: 343009
2018-09-25 19:26:58 +00:00
Rui Ueyama 970573776a Rename GdbIndex.{cpp,h} -> DWARF.{cpp,h}.
These files used to contain classes and functions for .gdb_index,
but they are moved to SyntheticSections.{cpp,h}, so the name is now
irrelevant.

llvm-svn: 342299
2018-09-14 23:51:05 +00:00
Petr Hosek c6a233a68a [ELF] Don't emit .relr.dyn section if there are no relocs
This resolves PR38875.

Differential Revision: https://reviews.llvm.org/D51834

llvm-svn: 341870
2018-09-10 21:54:56 +00:00
Rui Ueyama 025bb56a86 Always add a .note.GNU-stack section if -r.
With this patch, lld creates a .note.GNU_stack and adds that to an
output file if it is creating a re-linkable object file (i.e. if -r
is given). If we don't do this, and if you use GNU linkers as a final
linker, they create an executable whose stack area is executable,
which is considered pretty bad these days.

Differential Revision: https://reviews.llvm.org/D51400

llvm-svn: 340902
2018-08-29 07:27:09 +00:00
George Rimar 88863a5f62 [ELF] - Get rid of SyntheticSection::postThunkContents(). NFCI.
It turns out that postThunkContents() is only used for
sorting symbols in .symtab.

Though we can instead move the logic to SymbolTableBaseSection::finalizeContents(),
postpone calling it and then get rid of postThunkContents completely.

Differential revision: https://reviews.llvm.org/D49547

llvm-svn: 339413
2018-08-10 07:24:18 +00:00
George Rimar 9524dee72e [ELF] - Implement SHT_SYMTAB_SHNDX (.symtab_shndxr) section.
This is relative to https://bugs.llvm.org//show_bug.cgi?id=38119.

SHT_SYMTAB section is able to keep symbols with output section indices
up to 0xff00 (SHN_LORESERVE). But if we have indices that are greater
than that (PR shows that it might happen), we need to use
SHT_SYMTAB_SHNDX extended section. It was not supported by LLD.

Description of the SHT_SYMTAB_SHNDX section is here:
https://docs.oracle.com/cd/E19683-01/817-3677/chapter6-94076/index.html.

Differential revision: https://reviews.llvm.org/D49541

llvm-svn: 338247
2018-07-30 12:39:54 +00:00
Fangrui Song a66d77b22b [ELF] Check eh_frame_hdr overflow with PC offsets instead of PC absolute addresses
Reviewers: grimar, ruiu, espindola

Subscribers: emaste, arichardson, llvm-commits

Differential Revision: https://reviews.llvm.org/D49607

llvm-svn: 337610
2018-07-20 20:27:42 +00:00
George Rimar cb17fdbe3c [ELF] - Add classof() member for ARMExidxSentinelSection.
Or code uses constructions like isa<ARMExidxSentinelSection>:
https://github.com/llvm-mirror/lld/blob/master/ELF/Writer.cpp#L1428
https://github.com/llvm-mirror/lld/blob/master/ELF/SyntheticSections.cpp#L2944

That is confusing, because without ARMExidxSentinelSection::classof()
these lines are equal to isa<SyntheticSection> and the code does not really do
the same what it expected to. I found no good way to break it though, but it is not nice.

Patch adds ARMExidxSentinelSection::classof().

llvm-svn: 336813
2018-07-11 15:11:13 +00:00
Rui Ueyama eca0e633d1 Remove dead code.
llvm-svn: 336791
2018-07-11 11:52:13 +00:00
Rui Ueyama f3731d4e9c Refactor GdbIndexSection. NFC.
This patch merges createGdbIndex function and GdbIndexSection's
constructor into a single static member function of the class.

This patch also change how we keep CU vectors. Previously, CuVector
and GdbSymbols were parallel arrays, but there's no reason to choose that
design. Now, CuVector is a member of GdbSymbol class.

A lot of members are removed from GdbIndexSection. Previously, it has
members that need to be kept in sync over several phases. I belive the new
design is less error-prone, and the new code is much easier to read
than before.

llvm-svn: 336743
2018-07-10 23:48:27 +00:00
Rui Ueyama 2b9b85f2bf Initialize a variable properly to fix buildbots.
llvm-svn: 336700
2018-07-10 16:26:15 +00:00
Rui Ueyama 09b373845a Make a struct type declaration private. NFC.
llvm-svn: 336690
2018-07-10 15:57:25 +00:00
Rui Ueyama 7f112ea26d Reduce memory usage when creating .gdb_index. NFC.
.gdb_index sections can be very large. When you are compiling
multi-gibibyte executables, they can be larger than 1 GiB. The previous
implementation of .gdb_index seems to consume too much memory.

This patch reduces memory consumption by eliminating temporary objects.
In one experiment, memory consumption of GdbIndexSection class is
reduced from 962 MiB to 228 MiB when creating a .gdb_index of 1350 GiB.

Differential Revision: https://reviews.llvm.org/D49094

llvm-svn: 336672
2018-07-10 13:49:13 +00:00
Rui Ueyama 2a3036fb1d Report an error for an extremely large .gdb_index section.
I believe the only way to test this functionality is to create extremely
large object files and attempt to create a .gdb_index that is greater
than 4 GiB. But I think that's too much for most environments and buildbots,
so I'm commiting this without a test that actually triggers the new
error condition.

llvm-svn: 336631
2018-07-10 01:22:25 +00:00
Rui Ueyama 11479daf2f lld: add experimental support for SHT_RELR sections.
Patch by Rahul Chaudhry!

This change adds experimental support for SHT_RELR sections, proposed
here: https://groups.google.com/forum/#!topic/generic-abi/bX460iggiKg

Pass '--pack-dyn-relocs=relr' to enable generation of SHT_RELR section
and DT_RELR, DT_RELRSZ, and DT_RELRENT dynamic tags.

Definitions for the new ELF section type and dynamic array tags, as well
as the encoding used in the new section are all under discussion and are
subject to change. Use with caution!

Pass '--use-android-relr-tags' with '--pack-dyn-relocs=relr' to use
SHT_ANDROID_RELR section type instead of SHT_RELR, as well as
DT_ANDROID_RELR* dynamic tags instead of DT_RELR*. The generated
section contents are identical.

'--pack-dyn-relocs=android+relr --use-android-relr-tags' enables both
'--pack-dyn-relocs=android' and '--pack-dyn-relocs=relr': lld will
encode the relative relocations in a SHT_ANDROID_RELR section, and pack
the rest of the dynamic relocations in a SHT_ANDROID_REL(A) section.

Differential Revision: https://reviews.llvm.org/D48247

llvm-svn: 336594
2018-07-09 20:08:55 +00:00
Simon Atanasyan 00d8843fa3 [ELF] Pass a pointer to InputFile to the getRelocTargetVA to escape dereferencing of nullptr. NFC
llvm-svn: 334392
2018-06-11 08:37:19 +00:00
Simon Atanasyan ed9ee69ccf [ELF][MIPS] Multi-GOT implementation
Almost all entries inside MIPS GOT are referenced by signed 16-bit
index. Zero entry lies approximately in the middle of the GOT. So the
total number of GOT entries cannot exceed ~16384 for 32-bit architecture
and ~8192 for 64-bit architecture. This limitation makes impossible to
link rather large application like for example LLVM+Clang. There are two
workaround for this problem. The first one is using the -mxgot
compiler's flag. It enables using a 32-bit index to access GOT entries.
But each access requires two assembly instructions two load GOT entry
index to a register. Another workaround is multi-GOT. This patch
implements it.

Here is a brief description of multi-GOT for detailed one see the
following link https://dmz-portal.mips.com/wiki/MIPS_Multi_GOT.

If the sum of local, global and tls entries is less than 64K only single
got is enough. Otherwise, multi-got is created. Series of primary and
multiple secondary GOTs have the following layout:
```
- Primary GOT
    Header
    Local entries
    Global entries
    Relocation only entries
    TLS entries

- Secondary GOT
    Local entries
    Global entries
    TLS entries
...
```

All GOT entries required by relocations from a single input file
entirely belong to either primary or one of secondary GOTs. To reference
GOT entries each GOT has its own _gp value points to the "middle" of the
GOT. In the code this value loaded to the register which is used for GOT
access.

MIPS 32 function's prologue:
```
lui     v0,0x0
0: R_MIPS_HI16  _gp_disp
addiu   v0,v0,0
4: R_MIPS_LO16  _gp_disp
```

MIPS 64 function's prologue:
```
lui     at,0x0
14: R_MIPS_GPREL16  main
```

Dynamic linker does not know anything about secondary GOTs and cannot
use a regular MIPS mechanism for GOT entries initialization. So we have
to use an approach accepted by other architectures and create dynamic
relocations R_MIPS_REL32 to initialize global entries (and local in case
of PIC code) in secondary GOTs. But ironically MIPS dynamic linker
requires GOT entries and correspondingly ordered dynamic symbol table
entries to deal with dynamic relocations. To handle this problem
relocation-only section in the primary GOT contains entries for all
symbols referenced in global parts of secondary GOTs. Although the sum
of local and normal global entries of the primary got should be less
than 64K, the size of the primary got (including relocation-only entries
can be greater than 64K, because parts of the primary got that overflow
the 64K limit are used only by the dynamic linker at dynamic link-time
and not by 16-bit gp-relative addressing at run-time.

The patch affects common LLD code in the following places:

- Added new hidden -mips-got-size flag. This flag required to set low
maximum size of a single GOT to be able to test the implementation using
small test cases.

- Added InputFile argument to the getRelocTargetVA function. The same
symbol referenced by GOT relocation from different input file might be
allocated in different GOT. So result of relocation depends on the file.

- Added new ctor to the DynamicReloc class. This constructor records
settings of dynamic relocation which used to adjust address of 64kb page
lies inside a specific output section.

With the patch LLD is able to link all LLVM+Clang+LLD applications and
libraries for MIPS 32/64 targets.

Differential revision: https://reviews.llvm.org/D31528

llvm-svn: 334390
2018-06-11 07:24:31 +00:00
Rafael Espindola bd4d2acb11 Don't create a temporary DenseMap for each input .eh_frame.
These maps are small, but we are creating an destroying one for each
input .eh_frame.

This patch reduces the total memory allocation from 765.54MB to
749.19MB. The peak is still the same: 563.7MB.

llvm-svn: 331075
2018-04-27 20:19:28 +00:00
Rafael Espindola f1652d4c60 Split .eh_frame sections in parellel.
We can now split them in the same spot we split merge sections.

llvm-svn: 331064
2018-04-27 18:17:36 +00:00
Rafael Espindola 9bf1006278 Split merge sections early.
Now that getSectionPiece is fast (uses a hash) it is probably OK to
split merge sections early.

The reason I want to do this is to split eh_frame sections in the same
place.

This does mean that we have to decompress early. Given that the only
compressed sections are debug info, I don't think we are missing much.

It is a small improvement: 0.5% on the geometric mean.

llvm-svn: 331058
2018-04-27 16:29:57 +00:00
Rafael Espindola ab0cce5f1f Replace SharedSymbols with Defined when creating copy relocations.
This is slightly simpler to read IMHO. Now if a symbol has a position
in the file, it is Defined.

The main motivation is that with this a SharedSymbol doesn't need a
section, which reduces the size of SymbolUnion.

With this the peak allocation when linking chromium goes from 568.1 to
564.2 MB.

llvm-svn: 330966
2018-04-26 17:58:58 +00:00
Rafael Espindola ea2c78369c Reduce code duplication.
getVA was already implemented in the base class.

llvm-svn: 330036
2018-04-13 16:07:27 +00:00
Simon Atanasyan 1ba194212a [ELF][MIPS] Support linking of PIE for MIPS
MIPS ABI requires creation of the MIPS_RLD_MAP dynamic tag for non-PIE
executables only and MIPS_RLD_MAP_REL tag for both PIE and non-PIE
executables. The patch skips definition of the MIPS_RLD_MAP for PIE
files and defines MIPS_RLD_MAP_REL.

The MIPS_RLD_MAP_REL tag stores the offset to the .rld_map section
relative to the address of the tag itself.

Differential Revision: https://reviews.llvm.org/D43347

llvm-svn: 329996
2018-04-13 08:15:01 +00:00
Peter Collingbourne c5391ce51e ELF: Allow thunks to change size. NFCI.
Differential Revision: https://reviews.llvm.org/D44962

llvm-svn: 328841
2018-03-29 22:32:13 +00:00
Peter Collingbourne cebab4a639 ELF: Make required Thunk methods pure virtual and remove an unused argument. NFC.
Also make certain Thunk methods non-const as this will be required for
an upcoming change.

Differential Revision: https://reviews.llvm.org/D44961

llvm-svn: 328732
2018-03-28 21:33:31 +00:00
Rafael Espindola 816127ea17 Initialize OffsetMap in a known location.
This is a small optimization and avoids the need to use call_once.

llvm-svn: 328686
2018-03-28 03:20:18 +00:00
Rui Ueyama ba32e739b2 Remove GnuHashTableSection::getShift2().
Choosing a Shift2 value based on wordsize is cargo-culted from gold.
Assuming that djb hash is a good hash function, choosing bits [4,9]
shouldn't be any worse or better than choosing bits [5,10]. We shouldn't
have copied that behavior that we can't justify in the first place.

Differential Revision: https://reviews.llvm.org/D44547

llvm-svn: 327921
2018-03-19 23:04:13 +00:00
Peter Smith 3d044f57d4 [ELF] Recommit 327248 with Arm using the .got for _GLOBAL_OFFSET_TABLE_
This is the same as 327248 except Arm defining _GLOBAL_OFFSET_TABLE_ to
be the base of the .got section as some existing code is relying upon it.

For most Targets the _GLOBAL_OFFSET_TABLE_ symbol is expected to be at
the start of the .got.plt section so that _GLOBAL_OFFSET_TABLE_[0] =
reserved value that is by convention the address of the dynamic section.
Previously we had defined _GLOBAL_OFFSET_TABLE_ as either the start or end
of the .got section with the intention that the .got.plt section would
follow the .got. However this does not always hold with the current
default section ordering so _GLOBAL_OFFSET_TABLE_[0] may not be consistent
with the reserved first entry of the .got.plt.

X86, X86_64 and AArch64 will use the .got.plt. Arm, Mips and Power use .got

Fixes PR36555

Differential Revision: https://reviews.llvm.org/D44259

llvm-svn: 327823
2018-03-19 06:52:51 +00:00
Peter Collingbourne 5c902845e5 Revert r327248, "For most Targets the _GLOBAL_OFFSET_TABLE_ symbol is expected to be at"
This change broke ARM code that expects to be able to add
_GLOBAL_OFFSET_TABLE_ to the result of an R_ARM_REL32.

I will provide a reproducer on llvm-commits.

llvm-svn: 327688
2018-03-16 01:01:44 +00:00
Rui Ueyama a5c1ed340f [ELF] Add .eh_frame pieces to map file
This patch is a simplified version of https://reviews.llvm.org/D42960
written by Andrew Ng.

Differential Revision: https://reviews.llvm.org/D44168

llvm-svn: 327574
2018-03-14 21:18:18 +00:00
Peter Smith 18aa0be36e For most Targets the _GLOBAL_OFFSET_TABLE_ symbol is expected to be at
the start of the .got.plt section so that _GLOBAL_OFFSET_TABLE_[0] =
reserved value that is by convention the address of the dynamic section.
Previously we had defined _GLOBAL_OFFSET_TABLE_ as either the start or end
of the .got section with the intention that the .got.plt section would
follow the .got. However this does not always hold with the current
default section ordering so _GLOBAL_OFFSET_TABLE_[0] may not be consistent
with the reserved first entry of the .got.plt.

X86, X86_64, Arm and AArch64 will use the .got.plt. Mips and Power use .got

Fixes PR36555

Differential Revision: https://reviews.llvm.org/D44259

llvm-svn: 327248
2018-03-11 20:58:18 +00:00
Alexander Richardson 048e2508ad Rename DynamicReloc::getAddend() to computeAddend(). NFC
Summary:
Before the name of the function sounded like it was just a getter for the
private class member Addend. However, it actually calculates the final
value for the r_addend field in Elf_Rela that is used when writing the
.rela.dyn section. I also added a comment to the UseSymVA member to
explain how it interacts with computeAddend().

Differential Revision: https://reviews.llvm.org/D43161

llvm-svn: 325485
2018-02-19 11:00:15 +00:00
Rafael Espindola b960325989 Simplify RelocationBaseSection::addReloc.
Now that we have R_ADDEND, UseSymVA was redundant. We only want to
write the symbol virtual address when using an expression other than
R_ADDEND.

llvm-svn: 325360
2018-02-16 16:53:04 +00:00
Alexander Richardson cfb6093379 Ensure that Elf_Rel addends are always written for dynamic relocations
Summary:
This follows up on r321889 where writing of Elf_Rel addends was partially
moved to RelocationBaseSection. This patch ensures that the addends are
always written to the output section when a input section uses RELA but the
output is REL.

Differential Revision: https://reviews.llvm.org/D42843

llvm-svn: 325328
2018-02-16 10:01:17 +00:00
Rafael Espindola d49866edba Use RelType in a few more places. NFC.
llvm-svn: 325017
2018-02-13 16:06:11 +00:00
Rafael Espindola 35cf8bbe36 Add a simpler version of addReloc. NFC.
Extracted from a patch by Alexander Richardson!

llvm-svn: 325016
2018-02-13 16:03:52 +00:00
Alexander Richardson 59aaf1ae33 Use RelType instead of uint32_t in DynamicReloc. NFC
llvm-svn: 324821
2018-02-10 18:14:34 +00:00
Rui Ueyama e2dfdbf0aa Do not pass an argument that can be easily inferred from other argument.
llvm-svn: 322416
2018-01-12 22:29:29 +00:00
George Rimar 9fc2c64b35 [ELF] - Do not use HeaderSize for conditions in PltSection.
Previously we checked (HeaderSize == 0) to find out if
PltSection section is IPLT or PLT. Some targets does not set
HeaderSize though. For example PPC64 has no lazy binding implemented
and does not set PltHeaderSize constant.

Because of that using of both IPLT and PLT relocations worked
incorrectly there (testcase is provided).

Patch fixes the issue.

Differential revision: https://reviews.llvm.org/D41613

llvm-svn: 322362
2018-01-12 09:35:57 +00:00