Commit Graph

5594 Commits

Author SHA1 Message Date
Fangrui Song abc068fc59 [ELF] Fix typo: .symtab_shndxr -> .symtab_shndx
The typo was introduced to llvm MC in rL204769 (fixed in rL358247) and then to lld.

Also, for relocatable-many-sections.s, the size of .symtab changed at some point and the formula needs update.

llvm-svn: 358248
2019-04-12 02:20:52 +00:00
Rui Ueyama 3a8bb7cd2c Discard debuginfo for object files empty after GC
Patch by Robert O'Callahan.

Rust projects tend to link in all object files from all dependent
libraries and rely on --gc-sections to strip unused code and data.
Unfortunately --gc-sections doesn't currently strip any debuginfo
associated with GC'ed sections, so lld links in the full debuginfo from
all dependencies even if almost all that code has been discarded. See
https://github.com/rust-lang/rust/issues/56068 for some details.

Properly stripping debuginfo for discarded sections would be difficult,
but a simple approach that helps significantly is to mark debuginfo
sections as live only if their associated object file has at least one
live code/data section. This patch does that. In a (contrived but not
totally artificial) Rust testcase linked above, it reduces the final
binary size from 46MB to 5.1MB.

Differential Revision: https://reviews.llvm.org/D54747

llvm-svn: 358069
2019-04-10 10:37:10 +00:00
Rui Ueyama 0c01607bbf Rename a variable and add a comment.
llvm-svn: 358049
2019-04-10 06:32:05 +00:00
Chih-Mao Chen 949570ce39 [RISCV] Fix range check for HI20/LO12/RVC_LUI relocations
The code previously specified a 32-bit range for R_RISCV_HI20 and
R_RISCV_LO12_[IS], however this is incorrect as the maximum offset on
RV64 that can be formed from the immediate of lui and the displacement
of an I-type or S-type instruction is -0x80000800 to 0x7ffff7ff. There
is also the same issue with a c.lui and LO12 pair, whose actual
addressable range should be -0x20800 to 0x1f7ff.

The tests will be included in the next patch that converts all RISC-V
tests to use llvm-mc instead of yaml2obj, as assembler support has
matured enough to write tests in them.

Differential Revision: https://reviews.llvm.org/D60414

llvm-svn: 357995
2019-04-09 11:39:23 +00:00
Rui Ueyama f432fa6eee De-template SymbolTable::addShared.
Because of r357925, this member function doesn't have to be a
template of ELFT.

llvm-svn: 357982
2019-04-09 08:52:00 +00:00
Peter Collingbourne d3e207057f ELF: Move verneed tracking data structures out of VersionNeedSection.
For partitions I intend to use the same set of version indexes in
each partition for simplicity. Since each partition will need its own
VersionNeedSection this will require moving the verneed tracking out of
VersionNeedSection. The way I've done this is to move most of the tracking
into SharedFile. What will eventually become the per-partition tracking
still lives in VersionNeedSection.

As a bonus the code gets a little simpler and more consistent with how we
handle verdef.

Differential Revision: https://reviews.llvm.org/D60307

llvm-svn: 357926
2019-04-08 17:48:05 +00:00
Peter Collingbourne cc1618e668 ELF: De-template SharedFile. NFCI.
Differential Revision: https://reviews.llvm.org/D60305

llvm-svn: 357925
2019-04-08 17:35:55 +00:00
Rui Ueyama 4af8d47d05 Fix -emit-reloc against local symbols.
Previously, we drop symbols starting with .L from the symbol table, so
if there is a relocation that refers a .L symbol, it ended up
referencing a null -- which happened to be interpreted as an absolute
symbol.

This patch copies all symbols including local ones if -emit-reloc is
given.

Fixes https://bugs.llvm.org/show_bug.cgi?id=41385

Differential Revision: https://reviews.llvm.org/D60306

llvm-svn: 357885
2019-04-08 06:45:07 +00:00
Peter Collingbourne 883ab235ee ELF: De-template ELFFileBase. NFCI.
Differential Revision: https://reviews.llvm.org/D60304

llvm-svn: 357806
2019-04-05 20:16:26 +00:00
Peter Collingbourne ad4376e8af ELF: Simplify. NFCI.
Differential Revision: https://reviews.llvm.org/D60299

llvm-svn: 357739
2019-04-05 01:31:40 +00:00
Rui Ueyama 7c28937baf Remove redundant parameters. NFC.
llvm-svn: 357738
2019-04-05 01:30:09 +00:00
Peter Collingbourne 8238604259 ELF: Move SymtabSHNDX and getSectionIndex() to ObjFile. NFCI.
Differential Revision: https://reviews.llvm.org/D60244

llvm-svn: 357670
2019-04-04 03:13:51 +00:00
Peter Collingbourne a9e847238e ELF: Perform per-section .ARM.exidx processing during combineEhFrameSections(). NFCI.
And rename the function to combineEhSections(). This makes the processing
of .ARM.exidx even more similar to .eh_frame and means that we can avoid an
additional loop over InputSections.

Differential Revision: https://reviews.llvm.org/D60026

llvm-svn: 357417
2019-04-01 18:01:18 +00:00
Fangrui Song d83fb24533 [ELF] Rename SyntheticSection::empty to more appropriate isNeeded() with opposite meaning
Summary:
Some synthetic sections can be empty while still being needed, thus they
can't be removed by removeUnusedSyntheticSections(). Rename this member
function to more appropriate isNeeded() with the opposite meaning.

No functional change intended.

Reviewers: ruiu, espindola

Reviewed By: ruiu

Subscribers: jhenderson, grimar, emaste, arichardson, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59982

llvm-svn: 357377
2019-04-01 08:16:08 +00:00
Rui Ueyama a77ea59c4d Simplify. NFC.
llvm-svn: 357373
2019-04-01 00:25:17 +00:00
Rui Ueyama 68b9f45fee Replace `typedef A B` with `using B = A`. NFC.
I did this using Perl.

Differential Revision: https://reviews.llvm.org/D60003

llvm-svn: 357372
2019-04-01 00:11:24 +00:00
Fangrui Song 8048fe2b8c [ELF][MachO][wasm] Simplify range-style std::find{,_if} with STLExtras.h utilities. NFC
llvm-svn: 357269
2019-03-29 16:21:16 +00:00
Rui Ueyama 6528f2eac9 Remove a duplicate assignment. NFC.
llvm-svn: 357223
2019-03-28 23:53:38 +00:00
Rui Ueyama f28825bc06 Create an instance of Target after reading all input files. NFC.
This change itself doesn't mean anything, but it helps D59780 because
in patch, we don't know whether we need to create a CET-aware PLT or
not until we read all input files.

llvm-svn: 357194
2019-03-28 17:38:53 +00:00
Rui Ueyama 8521ba37d7 Make a member function a non-member function.
Since this member function doesn't use anything in the class,
it doesn't have to be a member of the class.

llvm-svn: 357193
2019-03-28 17:35:00 +00:00
Rui Ueyama 676d25ab94 De-template X86_64TargetInfo. NFC.
llvm-svn: 357191
2019-03-28 17:31:12 +00:00
Rui Ueyama c694633a12 Make TargetInfo const. NFC.
We do not mutate a TargetInfo instance after creating it. This change
makes it explicit.

llvm-svn: 357185
2019-03-28 17:05:09 +00:00
Peter Smith 3ce9af9370 [ELF][ARM] Recommit Redesign of .ARM.exidx handling to use a SyntheticSection
Recommit r356666 with fixes for buildbot failure, as well as handling for
--emit-relocs, which we decide not to emit any relocation sections as the
table is already position independent and an offline tool can deduce the
relocations.

Instead of creating extra Synthetic .ARM.exidx sections to account for
gaps in the table, create a single .ARM.exidx SyntheticSection that can
derive the contents of the gaps from a sorted list of the executable
InputSections. This has the benefit of moving the ARM specific code for
SyntheticSections in SHF_LINK_ORDER processing and the table merging code
into the ARM specific SyntheticSection. This also makes it easier to create
EXIDX_CANTUNWIND table entries for executable InputSections that don't
have an associated .ARM.exidx section.

Fixes pr40277

Differential Revision: https://reviews.llvm.org/D59216

llvm-svn: 357160
2019-03-28 11:10:20 +00:00
Rui Ueyama a0a50a7a5b Inline a trivial function. NFC.
I found that hiding this particular actual expression doesn't help
readers understand the code. So I remove and inline that function.

llvm-svn: 357140
2019-03-28 01:37:48 +00:00
Rui Ueyama 432030e843 [ELF] Dump symbols ordered by profiled guided section layout to file.
Patch by Tiancong Wang.

In D36351, Call-Chain Clustering (C3) heuristic is implemented with
option --call-graph-ordering-file <file>.
This patch adds a flag --print-symbol-order=<file> to LLD, and when
specified, it prints out the symbols ordered by the heuristics to the
file. The symbols printout is helpful to those who want to understand
the heuristics and want to reproduce the ordering with
--symbol-ordering-file in later pass.

Differential Revision: https://reviews.llvm.org/D59311

llvm-svn: 357133
2019-03-27 23:52:22 +00:00
Fangrui Song 210949a221 [ELF] Change GOT*_FROM_END (relative to end(.got)) to GOTPLT* (start(.got.plt))
Summary:
This should address remaining issues discussed in PR36555.

Currently R_GOT*_FROM_END are exclusively used by x86 and x86_64 to
express relocations types relative to the GOT base. We have
_GLOBAL_OFFSET_TABLE_ (GOT base) = start(.got.plt) but end(.got) !=
start(.got.plt)

This can have problems when _GLOBAL_OFFSET_TABLE_ is used as a symbol, e.g.
glibc dl_machine_dynamic assumes _GLOBAL_OFFSET_TABLE_ is start(.got.plt),
which is not true.

  extern const ElfW(Addr) _GLOBAL_OFFSET_TABLE_[] attribute_hidden;
  return _GLOBAL_OFFSET_TABLE_[0]; // R_X86_64_GOTPC32

In this patch, we

* Change all GOT*_FROM_END to GOTPLT* to fix the problem.
* Add HasGotPltOffRel to denote whether .got.plt should be kept even if
  the section is empty.
* Simplify GotSection::empty and GotPltSection::empty by setting
  HasGotOffRel and HasGotPltOffRel according to GlobalOffsetTable early.

The change of R_386_GOTPC makes X86::writePltHeader simpler as we don't
have to compute the offset start(.got.plt) - Ebx (it is constant 0).

We still diverge from ld.bfd (at least in most cases) and gold in that
.got.plt and .got are not adjacent, but the advantage doing that is
unclear.

Reviewers: ruiu, sivachandra, espindola

Subscribers: emaste, mehdi_amini, arichardson, dexonsmith, jdoerfert, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59594

llvm-svn: 356968
2019-03-25 23:46:19 +00:00
Rui Ueyama e6c24299d2 Use a class instead of lambda-based callbacks to organize garbage collector.
lld's mark-sweep garbage collector was written in the visitor pattern.
There are functions that traverses a given graph, and the functions calls
callback functions to dispatch according to node type.

The code was originaly pretty simple, and lambdas worked pretty
well. However, as we add more features to the garbage collector, that became
more like a callback hell. We now have a callback function that wraps
another callback function, for example. It is not easy to follow the flow of
the control.

This patch rewrites it as a regular class. What was once a lambda is now a
regular class member function. I think this change fixes the readability
issue.

No functionality change intended.

Differential Revision: https://reviews.llvm.org/D59800

llvm-svn: 356966
2019-03-25 23:28:47 +00:00
Rui Ueyama d2e0ed7755 Simplify PltSection.
Previously, `Entries` contains pairs of symbols and their indices.
The indices are always 0, x, 2x, 3x, ..., where x is the size of
relocation entry. We didn't have to store that values because we can
compute them when we consume them.

llvm-svn: 356812
2019-03-22 21:17:25 +00:00
Fangrui Song dc6c0cf94d [DWARF] Refactor RelocVisitor and fix computation of SHT_RELA-typed relocation entries
Summary: This is the lld-side change of D57939

Reviewers: echristo, dblaikie, ruiu, espindola

Reviewed By: echristo, ruiu

Subscribers: jdoerfert, emaste, arichardson, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D57940

llvm-svn: 356730
2019-03-22 02:43:17 +00:00
Peter Smith 54dab70bb7 [ELF][ARM] Revert Redesign of .ARM.exidx handling to use a SyntheticSection
There is a reproducible buildbot failure (segfault) on the 2 stage
clang-cmake-armv8-lld bot. Reverting while I investigate.

Differential Revision: https://reviews.llvm.org/D59216

llvm-svn: 356684
2019-03-21 17:17:54 +00:00
Peter Smith d3511a214e [ELF][ARM] Redesign of .ARM.exidx handling to use a SyntheticSection
Instead of creating extra Synthetic .ARM.exidx sections to account for
gaps in the table, create a single .ARM.exidx SyntheticSection that can
derive the contents of the gaps from a sorted list of the executable
InputSections. This has the benefit of moving the ARM specific code for
SyntheticSections in SHF_LINK_ORDER processing and the table merging code
into the ARM specific SyntheticSection. This also makes it easier to create
EXIDX_CANTUNWIND table entries for executable InputSections that don't
have an associated .ARM.exidx section.

Fixes pr40277

Differential Revision: https://reviews.llvm.org/D59216

llvm-svn: 356666
2019-03-21 14:06:40 +00:00
Fangrui Song 1092fc9057 [ELF] Allow sh_entsize to be unrelated to sh_addralign and not a power of 2
Summary:
This implements Rui Ueyama's idea in PR39044.
I've checked that ld.bfd and gold do not have the power-of-2 requirement
and do not require sh_entsize to be a multiple of sh_align.

Now on the updated test merge-entsize.s, all the 3 linkers happily
create .rodata that is not 3-byte aligned.

This has a use case in Linux arch/x86/crypto/sha512-avx2-asm.S
It uses sh_entsize of 640, which is not a power of 2.
See https://github.com/ClangBuiltLinux/linux/issues/417

Reviewers: ruiu, espindola

Reviewed By: ruiu

Subscribers: nickdesaulniers, E5ten, emaste, arichardson, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59478

llvm-svn: 356428
2019-03-18 23:49:18 +00:00
Siva Chandra 1915e2be93 [ELF] Emit weak-undef symbols in .dynsym of a PIE binary only if linked against shared libs.
Reviewers: espindola

Subscribers: emaste, arichardson, MaskRay, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59275

llvm-svn: 356374
2019-03-18 15:32:57 +00:00
Fangrui Song 6778b53e95 [ELF] De-virtualize findOrphanPos, excludeLibs and handleARMTlsRelocation
llvm-svn: 356331
2019-03-17 13:53:42 +00:00
Fangrui Song f9695e166b [ELF] Delete unused forward declarations and unused DynamicReloc::getInputSec(). NFC
llvm-svn: 356239
2019-03-15 07:16:39 +00:00
Fangrui Song 76a7ecb3ae [ELF] De-template wrapSymbols, isReserved and addGotEntry. NFC
llvm-svn: 356237
2019-03-15 06:58:23 +00:00
Fangrui Song e8710ef1fb [ELF] Split RW PT_LOAD on the PT_GNU_RELRO boundary
Summary:
Based on Peter Collingbourne's suggestion in D56828.

Before D56828: PT_LOAD(.data PT_GNU_RELRO(.data.rel.ro .bss.rel.ro) .bss)
Old:           PT_LOAD(PT_GNU_RELRO(.data.rel.ro .bss.rel.ro) .data .bss)
New:           PT_LOAD(PT_GNU_RELRO(.data.rel.ro .bss.rel.ro)) PT_LOAD(.data. .bss)

The new layout reflects the runtime memory mappings.
By having two PT_LOAD segments, we can utilize the NOBITS part of the
first PT_LOAD and save bytes for .bss.rel.ro.

.bss.rel.ro is currently small and only used by copy relocations of
symbols in read-only segments, but it can be used for other purposes in
the future, e.g. if a relro section's statically relocated data is all
zeros, we can move it to .bss.rel.ro.

Reviewers: espindola, ruiu, pcc

Reviewed By: ruiu

Subscribers: nemanjai, jvesely, nhaehnle, javed.absar, kbarton, emaste, arichardson, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D58892

llvm-svn: 356226
2019-03-15 01:29:57 +00:00
Rui Ueyama cc8e4e839f Make a hack for LTO work only when you are actually doing LTO.
We allow an archive file without symbol table as a linker input as a
workaround for a very common error in LTO build. But that logic worked
even for an archive file containing non-bitcode files, which is not
expected. This patch limits that workaround to one that contains only
bitcode files.

Differential Revision: https://reviews.llvm.org/D59373

llvm-svn: 356186
2019-03-14 18:21:32 +00:00
Fangrui Song 07f8daf05e [ELF] Simplify RelRo, TLS, NOBITS section ranks and make RW PT_LOAD start with RelRo
Old: PT_LOAD(.data | PT_GNU_RELRO(.data.rel.ro .bss.rel.ro) | .bss)
New: PT_LOAD(PT_GNU_RELRO(.data.rel.ro .bss.rel.ro) | .data .bss)

The placement of | indicates page alignment caused by PT_GNU_RELRO. The
new layout has simpler rules and saves space for many cases.

Old size: roundup(.data) + roundup(.data.rel.ro)
New size: roundup(.data.rel.ro + .bss.rel.ro) + .data

Other advantages:

* At runtime the 3 memory mappings decrease to 2.
* start(PT_TLS) = start(PT_GNU_RELRO) = start(RW PT_LOAD). This
  simplifies binary manipulation tools.
  GNU strip before 2.31 discards PT_GNU_RELRO if its
  address is not equal to the start of its associated PT_LOAD.
  This has been fixed by https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=f2731e0c374e5323ce4cdae2bcc7b7fe22da1a6f
  But with this change, we will be compatible with GNU strip before 2.31
* Before, .got.plt (non-relro by default) was placed before .got (relro
  by default), which made it impossible to have _GLOBAL_OFFSET_TABLE_
  (start of .got.plt on x86-64) equal to the end of .got (R_GOT*_FROM_END)
  (https://bugs.llvm.org/show_bug.cgi?id=36555). With the new ordering, we
  can improve on this regard if we'd like to.

Reviewers: ruiu, espindola, pcc

Subscribers: emaste, arichardson, llvm-commits, joerg, jdoerfert

Differential Revision: https://reviews.llvm.org/D56828

llvm-svn: 356117
2019-03-14 03:47:45 +00:00
Simon Atanasyan 2e855675eb [mips] Remove redundant setup of less-significant bit. NFC
The less-significant bit for microMIPS symbols configured
in the `getSymVA` function. Do not need to setup it once again.

llvm-svn: 356058
2019-03-13 16:00:35 +00:00
Francis Visoiu Mistrih dd42236c6c Reland "[Remarks] Add -foptimization-record-passes to filter remark emission"
Currently we have -Rpass for filtering the remarks that are displayed as
diagnostics, but when using -fsave-optimization-record, there is no way
to filter the remarks while generating them.

This adds support for filtering remarks by passes using a regex.
Ex: `clang -fsave-optimization-record -foptimization-record-passes=inline`

will only emit the remarks coming from the pass `inline`.

This adds:

* `-fsave-optimization-record` to the driver
* `-opt-record-passes` to cc1
* `-lto-pass-remarks-filter` to the LTOCodeGenerator
* `--opt-remarks-passes` to lld
* `-pass-remarks-filter` to llc, opt, llvm-lto, llvm-lto2
* `-opt-remarks-passes` to gold-plugin

Differential Revision: https://reviews.llvm.org/D59268

Original llvm-svn: 355964

llvm-svn: 355984
2019-03-12 21:22:27 +00:00
Peter Collingbourne 8a28673a2e ELF: Don't add .dynamic strings to .dynstr early.
This does not appear to be necessary because StringTableSection does not
need to be finalized, which also means that we can remove the call to
finalizeSynthetic on .dynstr.

Differential Revision: https://reviews.llvm.org/D59240

llvm-svn: 355977
2019-03-12 20:58:34 +00:00
Francis Visoiu Mistrih 1d6c47ad2b Revert "[Remarks] Add -foptimization-record-passes to filter remark emission"
This reverts commit 20fff32b7d.

llvm-svn: 355976
2019-03-12 20:54:18 +00:00
Peter Collingbourne e2b8c40a77 ELF: Use bump pointer allocator for uncompressed section buffers. NFCI.
This shaves another word off SectionBase and makes it possible to clone a
section using the implicit copy constructor.

This basically reverts r311056, which removed the mutex in order to
make the code easier to understand. On balance I think it's probably more
straightforward to have a mutex here than to have an unusual copy constructor
in SectionBase.

Differential Revision: https://reviews.llvm.org/D59269

llvm-svn: 355966
2019-03-12 20:32:30 +00:00
Francis Visoiu Mistrih 20fff32b7d [Remarks] Add -foptimization-record-passes to filter remark emission
Currently we have -Rpass for filtering the remarks that are displayed as
diagnostics, but when using -fsave-optimization-record, there is no way
to filter the remarks while generating them.

This adds support for filtering remarks by passes using a regex.
Ex: `clang -fsave-optimization-record -foptimization-record-passes=inline`

will only emit the remarks coming from the pass `inline`.

This adds:

* `-fsave-optimization-record` to the driver
* `-opt-record-passes` to cc1
* `-lto-pass-remarks-filter` to the LTOCodeGenerator
* `--opt-remarks-passes` to lld
* `-pass-remarks-filter` to llc, opt, llvm-lto, llvm-lto2
* `-opt-remarks-passes` to gold-plugin

Differential Revision: https://reviews.llvm.org/D59268

llvm-svn: 355964
2019-03-12 20:28:50 +00:00
Peter Collingbourne 2da7b32684 ELF: Simplify. NFCI.
We don't need to take a slice of SectionCommands in addOrphanSections()
because it is not modified until the end of the function.

Differential Revision: https://reviews.llvm.org/D59239

llvm-svn: 355954
2019-03-12 19:19:23 +00:00
George Rimar 43b6689e64 [LLD][ELF] - Show symbols visibility in "undefined symbol..." error messages.
This teaches LLD to report visibility when showing undefined symbol errors
and fixes https://bugs.llvm.org/show_bug.cgi?id=40770.

Differential revision: https://reviews.llvm.org/D58577

llvm-svn: 355909
2019-03-12 11:10:29 +00:00
Peter Collingbourne b5a307fa24 ELF: Remove dead code. NFCI.
The Live bit is already set to false by SectionBase.

Differential Revision: https://reviews.llvm.org/D59052

llvm-svn: 355893
2019-03-12 02:18:03 +00:00
Eli Friedman 3751ae4a94 [ELF] Print a better error for an archive containing a non-ELF file.
Hopefully gives a more readable error message for the most obvious
mistake.

Differential Revision: https://reviews.llvm.org/D59170

llvm-svn: 355888
2019-03-12 01:24:39 +00:00
Rui Ueyama 033c4d2126 Include an archive file name in an error message for a corrupted file.
Differential Revision: https://reviews.llvm.org/D59212

llvm-svn: 355886
2019-03-12 00:24:34 +00:00