Commit Graph

12154 Commits

Author SHA1 Message Date
Peter Collingbourne ba2816be82 ELF: Add basic partition data structures and behaviours.
This change causes us to read partition specifications from partition
specification sections and split output sections into partitions according
to their reachability from partition entry points.

This is only the first step towards a full implementation of partitions. Later
changes will add additional synthetic sections to each partition so that
they can be loaded independently.

Differential Revision: https://reviews.llvm.org/D60353

llvm-svn: 361925
2019-05-29 03:55:20 +00:00
Peter Collingbourne 31fda09b2d Add IR support, ELF section and user documentation for partitioning feature.
The partitioning feature was proposed here:
http://lists.llvm.org/pipermail/llvm-dev/2019-February/130583.html

This is mostly just documentation. The feature itself will be contributed
in subsequent patches.

Differential Revision: https://reviews.llvm.org/D60242

llvm-svn: 361923
2019-05-29 03:29:01 +00:00
Fangrui Song 719322411c [ELF] Implement General Dynamic style TLSDESC for x86-64
This handles two initial relocation types R_X86_64_GOTPC32_TLSDESC and
R_X86_64_TLSDESC_CALL, as well as the GD->LE and GD->IE relaxations.

Reviewed By: ruiu

Differential Revision: https://reviews.llvm.org/D62513

llvm-svn: 361911
2019-05-29 02:03:56 +00:00
Alexandre Ganea ccc1fa5e1d Revert r361842 as it breaks LLDB :: tools/lldb-mi/exec/exec-finish.test
llvm-svn: 361876
2019-05-28 20:57:56 +00:00
Reid Kleckner f612b18720 [COFF] Add ImportChunkThunk, simplify, deduplicate
Removes the isHotPatchable faux-virtual and virtual methods.  Follow-up to
D62362.

Reviewers: aganea

Differential Revision: https://reviews.llvm.org/D62422

llvm-svn: 361851
2019-05-28 17:38:04 +00:00
Alexandre Ganea ebe22a1774 [LLD][COFF] Early load PDB type server files
We need to have all input files ready before doing debuginfo type merging.
This patch is moving the late PDB type server discovery much earlier in the process, when the explicit inputs (OBJs, LIBs) are loaded.
The short term goal is to parallelize type merging.

Differential Revision: https://reviews.llvm.org/D60095

llvm-svn: 361842
2019-05-28 15:35:23 +00:00
Alexandre Ganea 756565d470 Fix 'warning: comparison is always true due to limited range of data type [-Wtype-limits]' with GCC 7.3
llvm-svn: 361840
2019-05-28 15:32:11 +00:00
Fangrui Song 5d3b3188f7 Reland D61583 [ELF] Error on relocations to STT_SECTION symbols if the sections were discarded
This is implemented by creating Undefined (instead of Defined) for such
local STT_SECTION symbols. It allows us to catch errors when there are
relocations to such discarded sections (e.g. in PR41693, ld.bfd and gold
error but we don't). Updated comdat-discarded-error.s checks we emit
friendly error message.

For relocatable-eh-frame.s, ld.lld -r a.o a.o will now error
"STT_SECTION symbol should be defined" because the section .eh_frame
refers to is now an Undefined instead of a Defined.
So I have to change `error()` to `warn()` to retain the output.

rLLD361144 inadvertently enabled the error for --gdb-index
(in LLDDwarfObj<ELFT>::findAux()).

Relocations from .debug_info (not in comdat) to .text.* (in comdat) for
DW_AT_low_pc are common. If an .text.* was discarded, rLLD361144 would error,
which was unexpected. (Note, if we don't error as this patch does,
InputSection::relocateNonAlloc() will resolve such relocations).

llvm-svn: 361830
2019-05-28 14:34:28 +00:00
Nico Weber 833c5abbce Add release note entries for recent typo correction changes
Differential Revision: https://reviews.llvm.org/D62523

llvm-svn: 361824
2019-05-28 14:04:48 +00:00
Haojian Wu 241dcb386e Revert [ELF] Error on relocations to STT_SECTION symbols if the sections were discarded
This reverts r361792 (git commit cfca5095df), the
revision causes link errors internally, will share more details with the
author.

llvm-svn: 361806
2019-05-28 11:21:59 +00:00
Fangrui Song 173a68f1fb [ELF] Replace two addSymbol() call sites with Symbol::resolve(). NFC
If we have a handle of the symbol, insert() called by addSymbol() is
redundant. Just call resolve().

llvm-svn: 361802
2019-05-28 10:12:06 +00:00
Fangrui Song cfca5095df [ELF] Error on relocations to STT_SECTION symbols if the sections were discarded
This is implemented by creating Undefined (instead of Defined) for such
local STT_SECTION symbols. It allows us to catch errors when there are
relocations to such discarded sections (e.g. in PR41693, ld.bfd and gold
error but we don't). Updated comdat-discarded-error.s checks we emit
friendly error message.

For relocatable-eh-frame.s, ld.lld -r a.o a.o will now error
"STT_SECTION symbol should be defined" because the section .eh_frame
refers to is now an Undefined instead of a Defined.
So I have to change `error()` to `warn()` to retain the output.

Reviewed By: ruiu

Differential Revision: https://reviews.llvm.org/D61583

llvm-svn: 361792
2019-05-28 06:34:52 +00:00
Rui Ueyama d8f8abbd4a Use SymbolTable::insert() to implement --trace.
Differential Revision: https://reviews.llvm.org/D62381

llvm-svn: 361791
2019-05-28 06:33:06 +00:00
Rui Ueyama 92069605bf Merge ELFFileBase::{initSymtab,parseHeader} as ELFFileBase:init. NFC.
This patch simplifies ELFFile instance initialization by merging
two similar functions into a single function and call it from the
ctor.

llvm-svn: 361789
2019-05-28 05:17:21 +00:00
Rui Ueyama 76737f4d19 Remove elf::createSharedFile and move its code to SharedFile's ctor. NFC.
llvm-svn: 361747
2019-05-27 07:26:13 +00:00
Sam Clegg 59f959ff33 [WebAssembly] Relax signature checking for undefined functions that are not called directly
When function signatures don't match and the undefined function is not
called directly (i.e. only has its address taken) we don't issue a
warning or create a runtime thunk for the undefined function.

Instead in this case we simply use the defined version of the function.
This is possible since checking signatures of dynamic calls happens
at runtime so any invalid usage will still result in a runtime error.

This is needed to allow C++ programs to link without generating
warnings.  Its not uncommon in C++ for vtables to be populated by
function address whee the signature of the function is not known in the
compilation unit.  In this case clang declares the method as void(void)
and relies on the vtable caller casting the data back to the correct
signature.

Fixes: https://bugs.llvm.org/show_bug.cgi?id=40412

Differential Revision: https://reviews.llvm.org/D62153

llvm-svn: 361678
2019-05-24 22:45:08 +00:00
Reid Kleckner a431dd7ae7 [COFF] De-virtualize Chunk and SectionChunk
Shaves another pointer off of SectionChunk, reducing the size from 96 to
88 bytes, down from 144 before I started working on this. Combined with
D62356, this reduced peak memory usage when linking chrome_child.dll
from 713MB to 675MB, or 5%.

Create NonSectionChunk to provide virtual dispatch to the rest of the
chunk types.

Reviewers: ruiu, aganea

Differential Revision: https://reviews.llvm.org/D62362

llvm-svn: 361667
2019-05-24 20:25:40 +00:00
Reid Kleckner 56bee1a90a [COFF] Replace OutputSection* with uint16_t index in Chunk
Shaves another 8 bytes off of SectionChunk, the most commonly allocated
type in LLD.

These indices are only valid after we've assigned chunks to output
sections and removed empty sections, so do that in a new pass.

Reviewers: ruiu, aganea

Differential Revision: https://reviews.llvm.org/D62356

llvm-svn: 361657
2019-05-24 18:25:49 +00:00
Sam Clegg a5ca34e6b3 [WebAssebmly] Add support for --wrap
The code for implementing this features is taken almost verbatim
from the ELF backend.

Fixes: https://bugs.llvm.org/show_bug.cgi?id=41681

Differential Revision: https://reviews.llvm.org/D62380

llvm-svn: 361639
2019-05-24 14:14:25 +00:00
Sam Clegg 7991b68284 [lld] Trace all references with lld --trace-symbol
Previously undefined symbol references were only traced if they were
seen before that definition.

Fixes https://bugs.llvm.org/show_bug.cgi?id=41878

Differential Revision: https://reviews.llvm.org/D61929

llvm-svn: 361636
2019-05-24 13:29:17 +00:00
Sam Clegg 35be7ff80c [WebAssembly] Add support for -emit-relocs
This can be useful for post-link tools and for testing.  Sometimes
it can be useful to produces a regular executable but with relocations
preserved.

Differential Revision: https://reviews.llvm.org/D62378

llvm-svn: 361635
2019-05-24 13:28:27 +00:00
Rui Ueyama 74de6203ef [LLD][COFF] Implement /filealign parameter
Patch by Stefan Schmidt.

This adds the /filealign parameter to lld, which allows to specify the
section alignment in the output file (as it does on Microsoft's
link.exe).

This is required to be able to load dynamically linked libraries on the
original Xbox, where the debugger monitor expects the section alignment
in the file to be the same as in memory.

llvm-svn: 361634
2019-05-24 12:42:36 +00:00
Simon Atanasyan 8362cbe13b [llvm-readobj] Implement GNU-style output for dynamic table
GNU readelf tool prints slightly different dynamic table "header" and
surrounds dynamic tag names by brackets. This patch implements the same
formatting for GNU-style output of the `llvm-readobj`.

LLVM
```
DynamicSection [ (13 entries)
  Tag        Type                 Name/Value
  0x00000006 SYMTAB               0x168
  ...
]
```

GNU
```
Dynamic section at offset 0x1d0 contains 13 entries:
  Tag        Type                 Name/Value
  0x00000006 (SYMTAB)             0x168
  ...
```

Differential Revision: https://reviews.llvm.org/D62256

llvm-svn: 361633
2019-05-24 12:22:53 +00:00
Fangrui Song 7d4a67852d [ELF] Fix a doc typo. NFC
llvm-svn: 361617
2019-05-24 09:53:25 +00:00
Fangrui Song 7f1ff68a16 [ELF] Deleted unused forward declarations. NFC
llvm-svn: 361614
2019-05-24 09:25:47 +00:00
Reid Kleckner 11c141eb68 [COFF] Remove finalizeContents virtual method from Chunk, NFC
This only needs to be done for MergeChunks, so just do that in a
separate pass in the Writer.

This is one small step towards eliminating the vtable in Chunk.

llvm-svn: 361573
2019-05-24 00:02:00 +00:00
Peter Collingbourne ca6a8ae0bf ELF: Remove a comparison against In.EhFrame. NFCI.
This won't work once we have multiple .eh_frame sections.

Differential Revision: https://reviews.llvm.org/D62280

llvm-svn: 361556
2019-05-23 21:30:30 +00:00
Reid Kleckner 14f4ff6e89 [COFF] Move KeepUnique bit from Chunk to SectionChunk, NFC
The KeepUnique bit is used during ICF, which only operates on
SectionChunks, so only SectionChunks need it. This frees up a byte in
Chunk, which I plan to use in a follow-up change.

llvm-svn: 361549
2019-05-23 20:26:41 +00:00
Nico Weber 9b2830b46e lld-link, clang: Treat non-existent input files as possible spellos for option flags
OptTable treats arguments starting with / that aren't a known option
as filenames. This means lld-link's and clang-cl's typo correction for
unknown flags didn't do spell checking for misspelled options that start
with /.

I first tried changing OptTable, but that got pretty messy, see PR41787
comments 2 and 3.

Instead, let lld-link's and clang's (including clang-cl's) "file not
found" diagnostic check if a non-existent file looks like it could be a
mis-spelled option, and if so add a "did you mean" suggestion to the
"file not found" diagnostic.

While here, make formatting of a few diagnostics a bit more
self-consistent.

Fixes PR41787.

Differential Revision: https://reviews.llvm.org/D62276

llvm-svn: 361518
2019-05-23 17:58:33 +00:00
Rui Ueyama f5d9d23905 Simplify InputFile::fetch().
We don't have to return a value from the function. Instead, we can
directly call parseFile from the functions.

llvm-svn: 361478
2019-05-23 10:15:12 +00:00
Rui Ueyama 821a1ac050 Remove LazyObjFile::AddedToLink.
Instead we can just clear a MemoryBuffer so that we cannot get the
same buffer more than once.

llvm-svn: 361477
2019-05-23 10:08:56 +00:00
Sam Clegg 4bce63a0e7 Reland: [WebAssembly] Add __start_/_stop_ symbols for data sections
This is a reland of rL361235.

Fixes https://bugs.llvm.org/show_bug.cgi?id=41565

Differential Revision: https://reviews.llvm.org/D61876

llvm-svn: 361476
2019-05-23 10:06:03 +00:00
Rui Ueyama 7f7d2b2e62 Move code for symbol resolution from SymbolTable.cpp to Symbols.cpp.
My recent commits separated symbol resolution from the symbol table,
so the functions to resolve symbols are now in a somewhat wrong file.
This patch moves it to Symbols.cpp.

The functions are now member functions of the symbol.

This is code move change. I modified function names so that they are
appropriate as member functions, though. No functionality change
intended.

Differential Revision: https://reviews.llvm.org/D62290

llvm-svn: 361474
2019-05-23 09:58:08 +00:00
Rui Ueyama 4254840313 Speed up --start-lib and --end-lib.
--{start,end}-lib give files grouped by the options the archive file
semantics. That is, each object file between them acts as if it were
in an archive file whose sole member is the file.

Therefore, files between --{start,end}-lib are linked to the final
output only if they are needed to resolve some undefined symbols.

Previously, the feature was implemented this way:

 1. We read a symbol table and insert defined symbols to the symbol
    table as lazy symbols.

 2. If an undefind symbol is resolved to a lazy symbol, that lazy
    symbol instantiate ObjFile class for that symbol, which re-insert
    all defined symbols to the symbol table.

So, if an ObjFile is instantiated, defined symbols are inserted to the
symbol table twice. Since inserting long symbol names is not cheap,
there's a room to optimize here.

This patch optimzies it. Now, LazyObjFile remembers symbol handles and
passed them over to a new ObjFile instance, so that the ObjFile
doesn't insert the same strings.

Here is a quick benchmark to link clang. "Original" is the original
lld with unmodified command line options. For "Case 1" and "Case 2", I
extracted all files from archive files and replace .a's in a command
line with .o's wrapped with --{start,end}-lib. I used the original lld
for Case 1" and use this patch for Case 2.

  Original: 5.892
    Case 1: 6.001 (+1.8%)
    Case 2: 5.701 (-3.2%)

So, interestingly, --{start,end}-lib are now faster than the regular
linking scheme with archive files. That's perhaps not too surprising,
though, because for regular archive files, we look up the symbol table
with the same string twice.

Differential Revision: https://reviews.llvm.org/D62188

llvm-svn: 361473
2019-05-23 09:53:30 +00:00
George Rimar 77b4f0abb8 [LLD][ELF] - Improve diagnostic about unrecognized relocations.
This is a minor improvement inspired by https://bugs.llvm.org/show_bug.cgi?id=38303.

A person reported that he observed message complaining about unsupported R_ARM_V4BX:
error: can't create dynamic relocation R_ARM_V4BX against local symbol in readonly segment; recompile object files with -fPIC

But with -z notext he only saw a relocation number, what is not convenient:
error: ../../gfx/cairo/libpixman/src/pixman-arm-neon-asm-bilinear.o:(.text+0x4F0): unrecognized reloc 40

Also, in the error messages we use relocation but not reloc.

With this patch we start to print one of the following messages:
error: file.o: unrecognized relocation Unknown(999)
error: file.o: unrecognized relocation R_X_KNOWN_BY_LLVM_BUT_UNSUPPORTED_BY_LLD_NAME

There is no way to write a test for that I believe.

Differential revision: https://reviews.llvm.org/D62237

llvm-svn: 361472
2019-05-23 09:50:18 +00:00
Sam Clegg b9889bbacb [WebAssembly] Seal imports section before counting imports
Summary:
Before we can assign entries in the function of global index space
we need to know the total number of function and global imports
respectively.

To avoid programmer error this change seals that imports section before
assigned function and global index space.  Any attempt to add an import
after the section is sealed will assert.

The lack this such as check caused  https://reviews.llvm.org/D61876
to be reverted.  I'm also trying to craft a test case the this
failure.

Subscribers: dschuff, jgravelle-google, aheejin, sunfish, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62240

llvm-svn: 361470
2019-05-23 09:41:03 +00:00
Rui Ueyama 0baaf45be7 Move SymbolTable::addCombinedLTOObject() to LinkerDriver.
Also renames it LinkerDriver::compileBitcodeFiles.

The function doesn't logically belong to SymbolTable. We added this
function to the symbol table because symbol table used to be a
container of input files. This is no longer the case.

Differential Revision: https://reviews.llvm.org/D62291

llvm-svn: 361469
2019-05-23 09:26:27 +00:00
Reid Kleckner ee4e0a2942 Re-land r361206 "[COFF] Store alignment in log2 form, NFC"
The previous patch lost the call to PowerOf2Ceil, which causes LLD to
crash when handling common symbols with a non-power-of-2 size. I tweaked
the existing common.test to make the bsspad16 common symbol be 15 bytes
to add coverage for this case.

llvm-svn: 361426
2019-05-22 20:21:52 +00:00
Simon Atanasyan 74b791b4f7 [mips] Use GNU-style output to make tests smaller. NFC
llvm-svn: 361394
2019-05-22 15:03:52 +00:00
Simon Atanasyan 84f929d00c [mips] Replace multiple `-check-prefix` by single `-check-prefixes`. NFC
llvm-svn: 361393
2019-05-22 15:03:42 +00:00
Rui Ueyama ecf6eb515f Copy symbol length when we replace a symbol.
Symbol's NameSize is computed lazily. Currently, when we replace a symbol,
a cached length value can be discarded. This patch propagates that value.

Differential Revision: https://reviews.llvm.org/D62234

llvm-svn: 361364
2019-05-22 09:19:30 +00:00
Fangrui Song b72b091389 [ELF] Improve error message for relocations to symbols defined in discarded sections
Rather than report "undefined symbol: ", give more informative message
about the object file that defines the discarded section.

In particular, PR41133, if the section is a discarded COMDAT, print the
section group signature and the object file with the prevailing
definition. This is useful to track down some ODR issues.

We need to
* add `uint32_t DiscardedSecIdx` to Undefined for this feature.
* make ComdatGroups public and change its type to DenseMap<CachedHashStringRef, const InputFile *>

Reviewed By: ruiu

Differential Revision: https://reviews.llvm.org/D59649

llvm-svn: 361359
2019-05-22 09:06:42 +00:00
Rui Ueyama 33e74d9f62 Simplify the logic to instantiate Symbols. Should be NFC.
llvm-svn: 361350
2019-05-22 04:56:25 +00:00
Fangrui Song b372259ace [docs] Fix troff macro (.F1 -> .Fl) in ld.lld.1
llvm-svn: 361345
2019-05-22 02:15:25 +00:00
Richard Smith 32591ca4e2 Fix test to put its outputs into the temp directory.
llvm-svn: 361297
2019-05-21 19:41:19 +00:00
Sam Clegg c0a4f45bcb Revert "[WebAssembly] Add __start_/_stop_ symbols for data sections"
This reverts commit 7804dbddcc.

This change broke a bunch of tests of the WebAssembly waterfall.
Will hopefully reland with increased test coverage.

llvm-svn: 361273
2019-05-21 17:16:33 +00:00
Fangrui Song 5ea0d06e81 [ELF] Deleted unused ComdatGroups member variable left by D61854
llvm-svn: 361266
2019-05-21 14:40:38 +00:00
Rui Ueyama d3f27f2bf4 Fix test failure.
I forgot to submit a last-minute change to the last patch.

llvm-svn: 361249
2019-05-21 12:01:16 +00:00
Rui Ueyama 35150bb534 [WebAssembly] Add --reproduce.
--reproduce is a convenient option for debugging. If you invoke lld
with `--reproduce=repro.tar`, it creates `repro.tar` with all input
files and the command line options given to the linker, so that it is
very easy to run lld with the exact same inputs.

ELF and Windows lld have this option.

This patch add that option to lld/wasm.

Differential Revision: https://reviews.llvm.org/D62170

llvm-svn: 361244
2019-05-21 11:52:14 +00:00
Sam Clegg 7804dbddcc [WebAssembly] Add __start_/_stop_ symbols for data sections
Fixes https://bugs.llvm.org/show_bug.cgi?id=41565

Differential Revision: https://reviews.llvm.org/D61876

llvm-svn: 361236
2019-05-21 10:07:30 +00:00
Sam Clegg 8fcf012693 [WebAssembly] Refactor synthetic sections and relocation processing. NFC.
Major refactor to better match the structure of the ELF linker.

- Split out relocation processing into scanRelocations
- Split out synthetic sections into their own classes.

Differential Revision: https://reviews.llvm.org/D61811

llvm-svn: 361233
2019-05-21 09:13:09 +00:00
Fangrui Song ecf4c9e13c [ELF] Don't advance position in a memory region when assigning to the Dot
For memory5.test, ld.bfd appears to ignore `. += 0x2000;`, so the test was testing
a wrong behavior. After deleting the code added in rLLD336335, we match ld.bfd and thus fix PR41357.

PR37836 (memory4.test) seems to have been fixed by another change.

Reviewed By: ruiu

Differential Revision: https://reviews.llvm.org/D62177

llvm-svn: 361228
2019-05-21 08:21:44 +00:00
Fangrui Song 547e3e930c [ELF] Error on relocations to local undefined symbols
For a reference to a local symbol, ld.bfd and gold error if the symbol
is defined in a discarded section but accept it if the symbol is
undefined. This inconsistent behavior seems unnecessary for us (it
probably makes sense for them as they differentiate local/global
symbols, the error would mean more code).

Catch such errors. Symbol index 0 may be used by marker relocations,
e.g. R_*_NONE R_ARM_V4BX. Don't error on them.

The difference from D61563 (which caused msan failure) is we don't call
Sym.computeBinding() on local symbols - VersionId is uninitialized.

llvm-svn: 361213
2019-05-21 02:38:11 +00:00
Nico Weber 67510fac36 Revert r361206 "[COFF] Store alignment in log2 form, NFC"
Makes the linker crash when linking nasm.exe.

llvm-svn: 361212
2019-05-21 02:06:59 +00:00
Reid Kleckner 1a5cc629de [COFF] Store alignment in log2 form, NFC
Summary:
Valid section or chunk alignments are powers of 2 in the range [1,
8192]. These can be stored more canonically in log2 form to free up some
bits in Chunk. Combined with D61696, SectionChunk gets 8 bytes smaller.

Reviewers: ruiu, aganea

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D61698

llvm-svn: 361206
2019-05-20 22:57:52 +00:00
Tiancong Wang a5d8d01d6f [ELF][Driver] Fix precedence of symbol ordering file and CGProfile
This patch is a fix for https://bugs.llvm.org/show_bug.cgi?id=41804.
We try to solve the precedence of user-specified symbol ordering file and C3 ordering provided as call graph. It deals with two case:
(1) When both --symbol-ordering-file=<file> and --call-graph-order-file=<file> are present, whichever flag comes later will take precedence.
(2) When only --symbol-ordering-file=<file> is present, it takes precedence over implicit call graph (CGProfile) generated by CGProfilePass enabled in new pass manager.

llvm-svn: 361190
2019-05-20 19:13:34 +00:00
Tiancong Wang af4219adf5 Test commit, add an empty line.
llvm-svn: 361186
2019-05-20 18:46:25 +00:00
Fangrui Song 055906e1e5 [ELF] -z combreloc: sort dynamic relocations by (!is_relative,symbol_index,r_offset)
We currently sort dynamic relocations by (!is_relative,symbol_index).
Add r_offset as the third key. This makes `readelf -r` debugging easier
(relocations to the same symbol are ordered by r_offset).

Refactor the test combreloc.s (renamed from combrelocs.s) to check
R_X86_64_RELATIVE, and delete --expand-relocs.

The difference from the reverted D61477 is that we keep !is_relative as
the first key. In local dynamic TLS model, DTPMOD (e.g.
R_ARM_TLS_DTPMOD32 R_X86_64_DTPMOD and R_PPC{,64}_DTPMOD) may use 0 as
the symbol index.

Reviewed By: grimar

Differential Revision: https://reviews.llvm.org/D62141

llvm-svn: 361164
2019-05-20 15:25:01 +00:00
Dmitri Gribenko 0429fddc9d Revert "[ELF] Error on relocations to local undefined symbols"
This reverts commit r361144.  It causes a use-of-uninitialized-value in
maybeReportUndefined at llvm/tools/lld/ELF/Relocations.cpp:682, as
detected by MemorySanitizer when local-undefined-symbol.s test is run.

llvm-svn: 361162
2019-05-20 15:04:08 +00:00
Dmitri Gribenko a2fbe2bcda Revert "[ELF] -z combreloc: sort dynamic relocations by (symbol_index,r_offset)"
This reverts commit r361125.  This linker change breaks shared libraries
in some subtle way on x86_64.  (Specifically, gold segfaults when
loading the LLVMgold.so plugin linked with lldb with this patch.)

llvm-svn: 361150
2019-05-20 13:05:55 +00:00
Fangrui Song 2109572464 [ELF] Fix getRelocTargetVA formulae of R_TLS and R_NEG_TLS
For R_TLS:
1) Delete Sym.isTls() . The assembler ensures the symbol is STT_TLS.
   If not (the input is broken), we would crash (dereferencing null Out::TlsPhdr).
2) Change Sym.isUndefWeak() to Sym.isUndefined(), otherwise with --noinhibit-exec
   we would still evaluate the symbol and crash.
3) Return A if the symbol is undefined. This is PR40570.
   The case is probably unrealistic but returning A matches R_ABS and the
   behavior of several dynamic loaders.

R_NEG_TLS is obsoleted Sun TLS we don't fully support, but
R_RELAX_TLS_GD_TO_LE_NEG is still used by GD->LE relaxation (subl $var@tpoff,%eax).

They should add the addend. Unfortunately I can't test it as compilers don't seem to generate non-zero implicit addends.

Reviewed By: ruiu

Differential Revision: https://reviews.llvm.org/D62098

llvm-svn: 361146
2019-05-20 11:47:31 +00:00
Fangrui Song 7c7425483a [ELF] Error on relocations to local undefined symbols
For a reference to a local symbol, ld.bfd and gold error if the symbol
is defined in a discarded section but accept it if the symbol is
undefined. This inconsistent behavior seems unnecessary for us (it
probably makes sense for them as they differentiate local/global
symbols, the error would mean more code).

Weaken the condition to getSymbol(Config->IsMips64EL) == 0 to catch such
errors. The symbol index can be 0 (e.g. R_*_NONE R_ARM_V4BX) and we shouldn't error on them.

Reviewed By: ruiu

Differential Revision: https://reviews.llvm.org/D61563

llvm-svn: 361144
2019-05-20 11:25:55 +00:00
Fangrui Song 63514556c4 [MIPS] Update mips-abs-got.s to not use .reloc
As Simon Atanasyan suggested in D61563

llvm-svn: 361142
2019-05-20 11:17:02 +00:00
Yvan Roux bc07278e02 [ELF] Fix tests from r361013 on ARM/AARch64 bots.
llvm-svn: 361128
2019-05-20 08:51:39 +00:00
Fangrui Song 9f1a6de631 [ELF] -z combreloc: sort dynamic relocations by (symbol_index,r_offset)
Fixes PR41692.

We currently sort dynamic relocations by (!is_relative,symbol_index).
Change it to (symbol_index,r_offset). We still place relative
relocations first because R_*_RELATIVE are the only dynamic relocations
with 0 symbol index (except on MIPS, which doesn't use DT_REL[A]COUNT
anyway).

This makes `readelf -r` debugging easier (relocations to the same symbol
are ordered by r_offset).

Refactor the test combreloc.s (renamed from combrelocs.s) to check
R_X86_64_RELATIVE, and delete --expand-relocs.

Reviewed By: ruiu

Differential Revision: https://reviews.llvm.org/D61477

llvm-svn: 361125
2019-05-20 07:22:55 +00:00
Rui Ueyama faf541e1e1 Make replaceSymbol a member function of Symbol.
This is a mechanical rewrite of replaceSymbol(A, B) to A->replace(B).
I also added a comment to Symbol::replace().

Technically this change is not necessary, but this change makes code a
bit more concise.

Differential Revision: https://reviews.llvm.org/D62117

llvm-svn: 361123
2019-05-20 03:36:33 +00:00
Fangrui Song a6720e7407 [ELF] Copy IsPreemptible in replaceSymbol()
Otherwise, we may set IsPreemptible (e.g. --dynamic-list) then clear it
(in replaceCommonSymbols()).

Reviewed By: ruiu

Differential Revision: https://reviews.llvm.org/D62107

llvm-svn: 361122
2019-05-20 02:07:03 +00:00
Michael Liao 63621832da Suppress false-positive GCC -Wreturn-type warning.
llvm-svn: 361094
2019-05-18 06:35:47 +00:00
Martin Storsjo 5fab538e2a [MinGW] Set the right updated option help for the updated pdb option. NFC
I forgot to amend this change before committing it in SVN r361014, this
is what was agreed upon in the review.

llvm-svn: 361093
2019-05-18 04:20:31 +00:00
Fangrui Song ed2ad77ccb [ARM][AArch64] Revert Android Bionic PT_TLS overaligning hack
This reverts D53906.

D53906 increased p_align of PT_TLS on ARM/AArch64 to 32/64 to make the
static TLS layout compatible with Android Bionic's ELF TLS. However,
this may cause glibc ARM/AArch64 programs to crash (see PR41527).

The faulty PT_TLS in the executable satisfies p_vaddr%p_align != 0. The
remainder is normally 0 but may be non-zero with the hack in place. The
problem is that we increase PT_TLS's p_align after OutputSections'
addresses are fixed (assignAddress()). It is possible that
p_vaddr%old_p_align = 0 while p_vaddr%new_p_align != 0.

For a thread local variable defined in the executable, lld computed TLS
offset (local exec) is different from glibc computed TLS offset from
another module (initial exec/generic dynamic). Note: PR41527 said the
bug affects initial exec but actually generic dynamic is affected as
well.

(glibc is correct in that it compute offsets that satisfy
`offset%p_align == p_vaddr%p_align`, which is a basic ELF requirement.
This hack appears to work on FreeBSD rtld, musl<=1.1.22, and Bionic, but
that is just because they (and lld) incorrectly compute offsets that
satisfy `offset%p_align = 0` instead.)

Android developers are fine to revert this patch, carry this patch in
their tree before figuring out a long-term solution (e.g. a dummy .tdata
with sh_addralign=64 sh_size={0,1} in crtbegin*.o files. The overhead is
now insignificant after D62059).

Reviewed By: rprichard, srhines

Differential Revision: https://reviews.llvm.org/D62055

llvm-svn: 361090
2019-05-18 03:16:00 +00:00
Fangrui Song 898896836d [ELF][X86] Fix R_RELAX_TLS_GD_TO_LE_NEG and R_NEG_TLS after D62059
After D62059, we don't align p_memsz of PT_TLS to p_align. The
getRelocTargetVA formula should align it instead.

It becomes clear that R_NEG_TLS and R_TLS are opposite from each other.

In i386-tls-le-align.s, I put ret after call ___tls_get_addr@plt as
otherwise ld.bfd would reject the relaxation:
TLS transition from R_386_TLS_GD to R_386_TLS_LE_32 against `a' at 0x3 in section `.text' failed

llvm-svn: 361088
2019-05-18 01:58:40 +00:00
Fangrui Song db5cb0fce7 [ELF] Add {i386,x86-64}-tls-le-align.s to test TP offsets for TLS Variant 2
I forgot to add them in rLLD361084. I made another mistake, rLLD361084 fixed Variant 2, not Variant 1.

llvm-svn: 361085
2019-05-18 00:57:30 +00:00
Fangrui Song 348731aeed [ELF] Fix TP offset of TLS Variant I after D62059
As Ryan Prichard pointed out, after D62059, the TP offset is incorrect.

Add x86-64-tls-le-align.s to check this.  Better formulae for both
variants should take p_vaddr%p_align into account (offset%p_align =
p_vaddr%p_align is a basic ELF requirement), but I can't find a way to
test the behavior.

llvm-svn: 361084
2019-05-18 00:43:10 +00:00
Russell Gallop 3a02b12439 Fix tests from r361013 on X86 bots.
llvm-svn: 361041
2019-05-17 15:38:01 +00:00
Fangrui Song f3a3b93f54 [ELF] -r: fix R_*_NONE to section symbols on Elf*_Rel targets
On Elf*_Rel targets, for a relocation to a section symbol, an R_ABS is
added which will be used by relocateOne() to compute the implicit
addend.

Addends of R_*_NONE should be ignored, so don't emit an R_ABS.

This fixes crashes on X86 and ARM because their relocateOne() do not
handle R_*_NONE.

Reviewed By: peter.smith

Differential Revision: https://reviews.llvm.org/D62052

llvm-svn: 361036
2019-05-17 14:11:03 +00:00
Fangrui Song f3dccc64af [ELF] Don't align PT_TLS's p_memsz
The code was added in r252352, probably to address some layout issues.
Actually PT_TLS's p_memsz doesn't need to be aligned on either variant.
ld.bfd doesn't do that.

In case of larger alignment (e.g. 64 for Android Bionic on AArch64, see
D62055), this may make the overhead smaller.

Reviewed By: ruiu

Differential Revision: https://reviews.llvm.org/D62059

llvm-svn: 361029
2019-05-17 12:48:53 +00:00
Martin Storsjo 6ff6a8f656 [MinGW] Include --enable-auto-import in the help listing
Libtool concludes that the linker doesn't support shared libraries,
unless this flag is listed in the output of --help.

Differential Revision: https://reviews.llvm.org/D62053

llvm-svn: 361017
2019-05-17 11:07:46 +00:00
Martin Storsjo 6863dfaa21 [MinGW] Implement the -v and --version flags for the MinGW driver
Differential Revision: https://reviews.llvm.org/D62030

llvm-svn: 361016
2019-05-17 11:07:42 +00:00
Martin Storsjo 9ae0d222dc [MinGW] Implement --help for the MinGW driver
Differential Revision: https://reviews.llvm.org/D62029

llvm-svn: 361015
2019-05-17 11:07:38 +00:00
Martin Storsjo 2c52ddf31f [MinGW] Allow requesting PDB output without giving a file name
When integrating PDB output in mingw targeting build systems, it
might be a lot of extra work to specify unique file names for
the pdb output. Therefore allow omitting the actual file name
and let it implicitly be the same name as the linker output, with
a pdb extension.

As the current form of the pdb option takes a separate parameter value,
e.g. "-pdb out.pdb", it is impractical to leave out the parameter value.

Therefore, introduce a second syntax for the option, with an equals
sign, like -pdb=out.pdb, where the value easily can be omitted.

The form -pdb= for requesting pdb files with an implicit name should
work fine, even though it looks a bit unconventional in that form.

Differential Revision: https://reviews.llvm.org/D62004

llvm-svn: 361014
2019-05-17 11:07:33 +00:00
Fangrui Song ef9b8e03fd [ELF][test] Reorganize some R_*_NONE tests
Change R_{386,AARCH64}_NONE yaml2obj tests/icf10.test to use assembly

Add relocation-none-{arm,x86_64}.s.
  Check the referenced section survives under --gc-sections.
  Check -r copies R_X86_64_NONE R_AARCH64_NONE. (Elf*_Rel arches currently have a bug)
  Delete the dtrace tests as they are covered by the R_X86_64_NONE test.

Reviewed By: ruiu

Differential Revision: https://reviews.llvm.org/D62051

llvm-svn: 361013
2019-05-17 10:44:05 +00:00
Ben Dunbobbin 1d16515fb4 [ELF] Implement Dependent Libraries Feature
This patch implements a limited form of autolinking primarily designed to allow
either the --dependent-library compiler option, or "comment lib" pragmas (
https://docs.microsoft.com/en-us/cpp/preprocessor/comment-c-cpp?view=vs-2017) in
C/C++ e.g. #pragma comment(lib, "foo"), to cause an ELF linker to automatically
add the specified library to the link when processing the input file generated
by the compiler.

Currently this extension is unique to LLVM and LLD. However, care has been taken
to design this feature so that it could be supported by other ELF linkers.

The design goals were to provide:

- A simple linking model for developers to reason about.
- The ability to to override autolinking from the linker command line.
- Source code compatibility, where possible, with "comment lib" pragmas in other
  environments (MSVC in particular).

Dependent library support is implemented differently for ELF platforms than on
the other platforms. Primarily this difference is that on ELF we pass the
dependent library specifiers directly to the linker without manipulating them.
This is in contrast to other platforms where they are mapped to a specific
linker option by the compiler. This difference is a result of the greater
variety of ELF linkers and the fact that ELF linkers tend to handle libraries in
a more complicated fashion than on other platforms. This forces us to defer
handling the specifiers to the linker.

In order to achieve a level of source code compatibility with other platforms
we have restricted this feature to work with libraries that meet the following
"reasonable" requirements:

1. There are no competing defined symbols in a given set of libraries, or
   if they exist, the program owner doesn't care which is linked to their
   program.
2. There may be circular dependencies between libraries.

The binary representation is a mergeable string section (SHF_MERGE,
SHF_STRINGS), called .deplibs, with custom type SHT_LLVM_DEPENDENT_LIBRARIES
(0x6fff4c04). The compiler forms this section by concatenating the arguments of
the "comment lib" pragmas and --dependent-library options in the order they are
encountered. Partial (-r, -Ur) links are handled by concatenating .deplibs
sections with the normal mergeable string section rules. As an example, #pragma
comment(lib, "foo") would result in:

.section ".deplibs","MS",@llvm_dependent_libraries,1
         .asciz "foo"

For LTO, equivalent information to the contents of a the .deplibs section can be
retrieved by the LLD for bitcode input files.

LLD processes the dependent library specifiers in the following way:

1. Dependent libraries which are found from the specifiers in .deplibs sections
   of relocatable object files are added when the linker decides to include that
   file (which could itself be in a library) in the link. Dependent libraries
   behave as if they were appended to the command line after all other options. As
   a consequence the set of dependent libraries are searched last to resolve
   symbols.
2. It is an error if a file cannot be found for a given specifier.
3. Any command line options in effect at the end of the command line parsing apply
   to the dependent libraries, e.g. --whole-archive.
4. The linker tries to add a library or relocatable object file from each of the
   strings in a .deplibs section by; first, handling the string as if it was
   specified on the command line; second, by looking for the string in each of the
   library search paths in turn; third, by looking for a lib<string>.a or
   lib<string>.so (depending on the current mode of the linker) in each of the
   library search paths.
5. A new command line option --no-dependent-libraries tells LLD to ignore the
   dependent libraries.

Rationale for the above points:

1. Adding the dependent libraries last makes the process simple to understand
   from a developers perspective. All linkers are able to implement this scheme.
2. Error-ing for libraries that are not found seems like better behavior than
   failing the link during symbol resolution.
3. It seems useful for the user to be able to apply command line options which
   will affect all of the dependent libraries. There is a potential problem of
   surprise for developers, who might not realize that these options would apply
   to these "invisible" input files; however, despite the potential for surprise,
   this is easy for developers to reason about and gives developers the control
   that they may require.
4. This algorithm takes into account all of the different ways that ELF linkers
   find input files. The different search methods are tried by the linker in most
   obvious to least obvious order.
5. I considered adding finer grained control over which dependent libraries were
   ignored (e.g. MSVC has /nodefaultlib:<library>); however, I concluded that this
   is not necessary: if finer control is required developers can fall back to using
   the command line directly.

RFC thread: http://lists.llvm.org/pipermail/llvm-dev/2019-March/131004.html.

Differential Revision: https://reviews.llvm.org/D60274

llvm-svn: 360984
2019-05-17 03:44:15 +00:00
Rui Ueyama bbf154cf9c Move symbol resolution code out of SymbolTable class.
This is the last patch of the series of patches to make it possible to
resolve symbols without asking SymbolTable to do so.

The main point of this patch is the introduction of
`elf::resolveSymbol(Symbol *Old, Symbol *New)`. That function resolves
or merges given symbols by examining symbol types and call
replaceSymbol (which memcpy's New to Old) if necessary.

With the new function, we have now separated symbol resolution from
symbol lookup. If you already have a Symbol pointer, you can directly
resolve the symbol without asking SymbolTable to do that.

Now that the nice abstraction become available, I can start working on
performance improvement of the linker. As a starter, I'm thinking of
making --{start,end}-lib faster.

--{start,end}-lib is currently unnecessarily slow because it looks up
the symbol table twice for each symbol.

 - The first hash table lookup/insertion occurs when we instantiate a
   LazyObject file to insert LazyObject symbols.

 - The second hash table lookup/insertion occurs when we create an
   ObjFile from LazyObject file. That overwrites LazyObject symbols
   with Defined symbols.

I think it is not too hard to see how we can now eliminate the second
hash table lookup. We can keep LazyObject symbols in Step 1, and then
call elf::resolveSymbol() to do Step 2.

Differential Revision: https://reviews.llvm.org/D61898

llvm-svn: 360975
2019-05-17 01:55:20 +00:00
Bob Haarman 5ff1eb6418 Revert r358069 "Discard debuginfo for object files empty after GC"
The change broke some scenarios where debug information is still
needed, although MarkLive cannot see it, including the
Chromium/Android build. Reverting to unbreak that build.

llvm-svn: 360955
2019-05-16 23:33:06 +00:00
Sam Clegg d029bf0f8c [WebAssembly] Move code and data section generation to finalizeContent. NFC.
Previously these sections were being generated during their
constructors.  This moves the work to finalizeContent, and also does
the same for the relocation sections because their contents depends
on the final layout too.

This change is part of a larger refactor to how we deal with synthetic
sections: https://reviews.llvm.org/D61811

Differential Revision: https://reviews.llvm.org/D61971

llvm-svn: 360941
2019-05-16 21:36:06 +00:00
Sam Clegg 1a53ff2a13 [WebAssembly] Don't generate empty type sections.
Differential Revision: https://reviews.llvm.org/D61991

llvm-svn: 360940
2019-05-16 21:22:43 +00:00
Yvan Roux 671fc5f3f4 [lld-link] Add missing "REQUIRES: x86" to COFF/lib-module-asm.ll test.
This should fix ARM bots.

llvm-svn: 360875
2019-05-16 11:29:30 +00:00
Igor Kudrin 261a1bc129 Add missing "REQUIRES: x86" to the lto/irmover-warning.ll test.
llvm-svn: 360866
2019-05-16 09:04:52 +00:00
Igor Kudrin 4669cf2750 [LTO] Improve readability of module IDs
Module IDs can appear in diagnostic messages.
This patch adds some auxiliary symbols to improve their readability.

Differential Revision: https://reviews.llvm.org/D61857

llvm-svn: 360858
2019-05-16 05:23:25 +00:00
Rui Ueyama 54ee6df247 Pemove SymbolTable::addBitcode as it is redundant.
Differential Revision: https://reviews.llvm.org/D61897

llvm-svn: 360846
2019-05-16 03:54:50 +00:00
Rui Ueyama d668873bfe Consistently return `Symbol *` from SymbolTable's add-family functions.
llvm-svn: 360845
2019-05-16 03:54:41 +00:00
Rui Ueyama 943cd00580 De-template parseFile() and SymbolTable's add-family functions.
Differential Revision: https://reviews.llvm.org/D61896

llvm-svn: 360844
2019-05-16 03:45:13 +00:00
Rui Ueyama 5c073a94f9 Introduce CommonSymbol.
Previously, we handled common symbols as a kind of Defined symbol,
but what we were doing for common symbols is pretty different from
regular defined symbols.

Common symbol and defined symbol are probably as different as shared
symbol and defined symbols are different.

This patch introduces CommonSymbol to represent common symbols.
After symbols are resolved, they are converted to Defined symbols
residing in a .bss section.

Differential Revision: https://reviews.llvm.org/D61895

llvm-svn: 360841
2019-05-16 03:29:03 +00:00
Rui Ueyama 7d4761928e Simplify SymbolTable::add{Defined,Undefined,...} functions.
SymbolTable's add-family functions have lots of parameters because
when they have to create a new symbol, they forward given arguments
to Symbol's constructors. Therefore, the functions take at least as
many arguments as their corresponding constructors.

This patch simplifies the add-family functions. Now, the functions
take a symbol instead of arguments to construct a symbol. If there's
no existing symbol, a given symbol is memcpy'ed to the symbol table.
Otherwise, the functions attempt to merge the existing and a given
new symbol.

I also eliminated `CanOmitFromDynSym` parameter, so that the functions
take really one argument.

Symbol classes are trivially constructible, so looks like constructing
them to pass to add-family functions is as cheap as passing a lot of
arguments to the functions. A quick benchmark showed that this patch
seems performance-neutral.

This is a preparation for
http://lists.llvm.org/pipermail/llvm-dev/2019-April/131902.html

Differential Revision: https://reviews.llvm.org/D61855

llvm-svn: 360838
2019-05-16 02:14:00 +00:00
Sam Clegg e7ab59eda9 [ELF] Fix typo in header guard. NFC.
llvm-svn: 360832
2019-05-16 00:45:50 +00:00
Sam Clegg 5e6ea24497 [lld] Remove 2>&1 from --trace-symbol tests
The tracing goes to stdout so this is not needed.

Also remove the "not" from the final check in ELF/trace-symbols.s.
According the comment the check is that we don't crash, so we should
be checking for success here. Previously this step is error'ing with
undefined symbols because it didn't include all the needed objects.

Differential Revision: https://reviews.llvm.org/D61928

llvm-svn: 360794
2019-05-15 19:01:51 +00:00
Sam Clegg 697f2149f1 [WebAssembly] LTO: Honor comdat groups when loading bitcode files
But don't apply comdat groups when loading the LTO object files.
This is basically the same logic used by the ELF linker.

Differential Revision: https://reviews.llvm.org/D61924

llvm-svn: 360782
2019-05-15 16:03:28 +00:00
Fangrui Song e041d15f5e [LLD][ELF] Add the -z ifunc-noplt option
Patch by Mark Johnston!

Summary:
When the option is configured, ifunc calls do not go through the PLT;
rather, they appear as regular function calls with relocations
referencing the ifunc symbol, and the resolver is invoked when
applying the relocation.  This is intended for use in freestanding
environments where text relocations are permissible and is incompatible
with the -z text option.  The option is motivated by ifunc usage in the
FreeBSD kernel, where ifuncs are used to elide CPU feature flag bit
checks in hot paths.  Instead of replacing the cost of a branch with that
of an indirect function call, the -z ifunc-noplt option is used to ensure
that ifunc calls carry no hidden overhead relative to normal function
calls.

Test Plan:
I added a couple of regression tests and tested the FreeBSD kernel
build using the latest lld sources.

To demonstrate the effects of the change, I used a micro-benchmark
which results in frequent invocations of a FreeBSD kernel ifunc.  The
benchmark was run with and without IBRS enabled, and with and without
-zifunc-noplt configured.  The observed speedup is small and consistent,
and is significantly larger with IBRS enabled:

https://people.freebsd.org/~markj/ifunc-noplt/noibrs.txt
https://people.freebsd.org/~markj/ifunc-noplt/ibrs.txt

Reviewed By: ruiu, MaskRay

Differential Revision: https://reviews.llvm.org/D61613

llvm-svn: 360685
2019-05-14 15:25:21 +00:00
Fangrui Song ed4dbe6326 [ELF] --gdb-index: fix SIGSEGV when a DWARFAddressRange has invalid SectionIndex
See D61891: llvm had a bug that might create invalid (DW_AT_low_pc,DW_AT_high_pc) pairs or range list entries due to missing DW_AT_addr_base.

Reviewed By: ruiu

Differential Revision: https://reviews.llvm.org/D61889

llvm-svn: 360679
2019-05-14 14:41:20 +00:00
Rui Ueyama 2dd5283d2a Move SymbolTable::addFile to InputFiles.cpp.
The symbol table used to be a container of vectors of input files,
but that's no longer the case because the vectors are moved out of
SymbolTable and are now global variables.

Therefore, addFile doesn't have to belong to any class. This patch
moves the function out of the class.

This patch is a preparation for my RFC [1].

[1] http://lists.llvm.org/pipermail/llvm-dev/2019-April/131902.html

Differential Revision: https://reviews.llvm.org/D61854

llvm-svn: 360666
2019-05-14 12:03:13 +00:00
Fangrui Song e1cb2c0f40 [Object] Change ObjectFile::getSectionContents to return Expected<ArrayRef<uint8_t>>
Change
std::error_code getSectionContents(DataRefImpl, StringRef &) const;
to
Expected<ArrayRef<uint8_t>> getSectionContents(DataRefImpl) const;

Many object formats use ArrayRef<uint8_t> as the underlying type, which
is generally better than StringRef to represent binary data, so change
the type to decrease the number of type conversions.

Reviewed By: ruiu, sbc100

Differential Revision: https://reviews.llvm.org/D61781

llvm-svn: 360648
2019-05-14 04:22:51 +00:00
Sam Clegg 0b13ca2f5e [WebAssembly] Refactor relocation processing. NFC.
This is the remaining NFC part of https://reviews.llvm.org/D61539 which
was reverted.

Differential Revision: https://reviews.llvm.org/D61800

llvm-svn: 360598
2019-05-13 16:42:52 +00:00
Peter Smith 4e21c770ec [ELF] Full support for -n (--nmagic) and -N (--omagic) via common page
The -n (--nmagic) disables page alignment, and acts as a -Bstatic
The -N (--omagic) does what -n does but also marks the executable segment as
writeable. As page alignment is disabled headers are not allocated unless
explicit in the linker script.

To disable page alignment in LLD we choose to set the page sizes to 1 so
that any alignment based on the page size does nothing. To set the
Target->PageSize to 1 we implement -z common-page-size, which has the side
effect of allowing the user to set the value as well.

Setting the page alignments to 1 does mean that any use of
CONSTANT(MAXPAGESIZE) or CONSTANT(COMMONPAGESIZE) in a linker script will
return 1, unlike in ld.bfd. However given that -n and -N disable paging
these probably shouldn't be used in a linker script where -n or -N is in
use.

Differential Revision: https://reviews.llvm.org/D61688

llvm-svn: 360593
2019-05-13 16:01:26 +00:00
Reid Kleckner c10f80eb7b [COFF] Update LLD yaml test cases to include .bss size
These yaml test cases appear to have been affected by PR41836

Right now what happens is that these empty .bss sections are merged into
.data, then the .data output section ends up having a zero virtual size,
and it is discarded from the output after addresses are assigned.
However, we've already assigned OutputSections to Chunks, so we don't
correctly report the zero-sized chunks that were in there as having been
discarded. Soon, we will report them as discarded, so these test cases
need to be updated to have a non-zero size so they aren't discarded.

llvm-svn: 360476
2019-05-10 22:12:51 +00:00
Fangrui Song 6150407951 [llvm-objdump] Print st_other
Add support for ".hidden" ".internal" ".protected" and " 0x%02x" for
other st_other bits used by some architectures.

Reviewed By: sfertile

Differential Revision: https://reviews.llvm.org/D61718

llvm-svn: 360439
2019-05-10 16:24:57 +00:00
Fangrui Song 6cdd68e386 [PPC64] Define getThunkSectionSpacing() based on the range of R_PPC64_REL24
Suggested by Sean Fertile and Peter Smith.

Thunk section spacing decrease the total number of thunks. I measured a
decrease of 1% or less in some large programs, with no perceivable
slowdown in link time. Override getThunkSectionSpacing() to enable it.
0x2000000 is the farthest point R_PPC64_REL24 can reach. I tried several
numbers and found 0x2000000 works the best. Numbers near 0x2000000 work
as well but let's just use the simpler number.

As demonstrated by the updated tests, this essentially changes placement
of most thunks to the end of the output section. We leverage this
property to fix PR40740 reported by Alfredo Dal'Ava Júnior:

The output section .init consists of input sections from several object
files (crti.o crtbegin.o crtend.o crtn.o). Sections other than the last
one do not have a terminator. With this patch, we create the thunk after
the last .init input section and thus fix the issue. This is not
foolproof but works quite well for such sections (with no terminator) in
practice.

Reviewed By: ruiu, sfertile

Differential Revision: https://reviews.llvm.org/D61720

llvm-svn: 360405
2019-05-10 05:51:00 +00:00
Sam Clegg ea38ac5ba3 [WebAssembly] Don't assume that strongly defined symbols are DSO-local
The current PIC model for WebAssembly is more like ELF in that it
allows symbol interposition.

This means that more functions end up being addressed via the GOT
and fewer directly added to the wasm table.

One effect is a reduction in the number of wasm table entries similar
to the previous attempt in https://reviews.llvm.org/D61539 which was
reverted.

Differential Revision: https://reviews.llvm.org/D61772

llvm-svn: 360402
2019-05-10 01:52:08 +00:00
Reid Kleckner 4c64256b51 [COFF] Simplify Chunk::writeTo and remove OutputSectionOff, NFC
Summary:
Prior to this change, every implementation of writeTo would add
OutputSectionOff to the output section buffer start before writing data.
Instead, do this math in the caller, so that it can be written once
instead of many times.

The output section offset is always equivalent to the difference between
the chunk RVA and the output section RVA, so we can replace the one
remaining usage of OutputSectionOff with that subtraction.

This doesn't change the size of SectionChunk because of alignment
requirements, but I will rearrange the fields in a follow-up change to
accomplish that.

Reviewers: ruiu, aganea

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D61696

llvm-svn: 360376
2019-05-09 21:21:22 +00:00
Sam Clegg 08fa01a9b7 Revert "[WebAssembly] Don't generate unused table entries."
This reverts commit b33fdb7768.

This change apparently broke am emscripten test.

llvm-svn: 360367
2019-05-09 19:34:32 +00:00
Ben Dunbobbin 3edca1ac1a [LLD][NFC] Refactor: BuildID hash size now computed in one place.
Differential Revision: https://reviews.llvm.org/D61078

llvm-svn: 360316
2019-05-09 08:08:09 +00:00
Fangrui Song bd086817f6 [ELF] Initialize Target before it may be dereferenced by findAux when reporting "duplicate symbol" error
for (InputFile *F : Files)
      Symtab->addFile<ELFT>(F); // if there is a duplicate symbol error

    ...

    Target = getTarget();

When parsing .debug_info in the object file (for better diagnostics),
DWARF.cpp findAux may dereference the null pointer Target

    auto *DR = dyn_cast<Defined>(&File->getRelocTargetSym(Rel));
    if (!DR) {
      // Broken debug info may point to a non-defined symbol,
      // some asan object files may also contain R_X86_64_NONE
      RelType Type = Rel.getType(Config->IsMips64EL);
      if (Type != Target->NoneRel) /// Target is null

Move the assignment of Target to an earlier place to fix this.

Reviewed By: ruiu

Differential Revision: https://reviews.llvm.org/D61712

llvm-svn: 360305
2019-05-09 01:45:53 +00:00
Bob Haarman f3fb7fac32 [lld-link] initialize targets and asmparsers before invoking lib
Summary:
When using lld-link to build static libraries containing object files
with module assembly, the program would crash with "Assertion `T &&
T->hasMCAsmParser()' failed". This change causes the code in lld-link
that initialized Targets, TargetInfos, and AsmParsers (which already
existed) to be run before entering the lib building path (which needs
it). This avoids the error (and is what llvm-lib and llvm-ar do, too).

Fixes PR41803.

Reviewers: ruiu, rnk, hans

Reviewed By: ruiu

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D61699

llvm-svn: 360295
2019-05-08 22:11:02 +00:00
Sam Clegg a1282a39ba [WebAssembly] Handle command line options consistently with the ELF backend.
Differential Revision: https://reviews.llvm.org/D61645

llvm-svn: 360266
2019-05-08 16:20:05 +00:00
Reid Kleckner 34e9c41164 [COFF] Store Chunk RVAs and section offsets as uint32_t
Saves 8 bytes on SectionChunk, one of the most commonly allocated data
structures.

llvm-svn: 360188
2019-05-07 20:30:41 +00:00
Simon Atanasyan 3bdb81c26d [mips] Fix ld instruction in PLT entries on MIPS64
Use `ld` and `daddiu` instructions in MIPS64 PLT records. That fixes a
segmentation fault.

Patch by Qiao Pengcheng.

Differential Revision: https://reviews.llvm.org/D61586

llvm-svn: 360187
2019-05-07 20:26:23 +00:00
Simon Atanasyan 494b763cfc [mips] Rename test case. NFC
This test case checks MIPS PLT records for N64 ABI. For the N32 ABI case
there is a separate test case `mips-plt-n32.s`.

llvm-svn: 360186
2019-05-07 20:26:12 +00:00
Sam Clegg b33fdb7768 [WebAssembly] Don't generate unused table entries.
When generating PIC output only relocations of type
R_WASM_TABLE_INDEX_REL_SLEB should generate table entries.

R_WASM_TABLE_INDEX_I32 get resolved at runtime via the auto-generated
__wasm_apply_relocs functions.

R_WASM_TABLE_INDEX_SLEB are not allowed in PIC code.

Differential Revision: https://reviews.llvm.org/D61539

llvm-svn: 360165
2019-05-07 15:46:30 +00:00
Nico Weber 4b81e9f8d1 lld-link: Allow /? as option prefix, like -? is allowed
link.exe seems to allow `/?foo` and `-?foo` in addition to `/foo` and `-foo`.

Since lld-link already supports the `-?foo` spelling, support `/?foo` as well.

Differential Revision: https://reviews.llvm.org/D61375

llvm-svn: 360150
2019-05-07 14:15:35 +00:00
Nico Weber 54743d5767 Add typo correction for command-line flags to ELF and COFF lld drivers
For lld-link, unknown '/'-style flags are treated as filenames on POSIX
systems, so only '-'-style flags get typo correction for now. This
matches clang-cl.

PR37006.

Differential Revision: https://reviews.llvm.org/D61443

llvm-svn: 360145
2019-05-07 13:48:30 +00:00
George Rimar 72f7a98876 [LLD][ELF] - Remove symbol-name-offset.elf binary from test cases.
It was possible to convert the test case to YAML test.
After that, we have only one binary test left in LLD/ELF.

llvm-svn: 360139
2019-05-07 12:59:44 +00:00
Fangrui Song f3994e4dfa [ELF] Reorder BitcodeFiles.empty() to call thinLTOCreateEmptyIndexFiles() in only one place
It makes the --plugin-opt=obj-path= and --plugin-opt=thinlto-index-only=
behavior more consistent - the files will be created in the
BitcodeFiles.empty() case, but I assume whether it behaves this way is
not required by anyone.

LTOObj->run() cannot run with empty BitcodeFiles. There would be an error:

    ld.lld: error: No available targets are compatible with triple ""

Differential Revision: https://reviews.llvm.org/D61635

llvm-svn: 360129
2019-05-07 10:40:26 +00:00
Fangrui Song 912251e82f [PPC64] toc-indirect to toc-relative relaxation
This is based on D54720 by Sean Fertile.

When accessing a global symbol which is not defined in the translation unit,
compilers will generate instructions that load the address from the toc entry.

If the symbol is defined, non-preemptable, and addressable with a 32-bit
signed offset from the toc pointer, the address can be computed
directly. e.g.

    addis 3, 2, .LC0@toc@ha  # R_PPC64_TOC16_HA
    ld    3, .LC0@toc@l(3)   # R_PPC64_TOC16_LO_DS, load the address from a .toc entry
    ld/lwa 3, 0(3)           # load the value from the address

    .section .toc,"aw",@progbits
    .LC0: .tc var[TC],var

can be relaxed to

    addis 3,2,var@toc@ha     # this may be relaxed to a nop,
    addi  3,3,var@toc@l      # then this becomes addi 3,2,var@toc
    ld/lwa 3, 0(3)           # load the value from the address

We can delete the test ppc64-got-indirect.s as its purpose is covered by
newly added ppc64-toc-relax.s and ppc64-toc-relax-constants.s

Reviewed By: ruiu, sfertile

Differential Revision: https://reviews.llvm.org/D60958

llvm-svn: 360112
2019-05-07 04:26:05 +00:00
Sam Clegg 5f8c2edef3 [WebAssembly] Add more test coverage for reloctions against section symbols
The only known user of this relocation type and symbol type is
the debug info sections, but we were not testing the `--relocatable`
output path.

This change adds a minimal test case to cover relocations against
section symbols includes `--relocatable` output.

Differential Revision: https://reviews.llvm.org/D61623

llvm-svn: 360110
2019-05-07 03:53:16 +00:00
Fangrui Song 12fb52007b [AMDGPU][test] Define local symbols used in amdgpu-relocs.s
Differential Revision: https://reviews.llvm.org/D61594

llvm-svn: 360046
2019-05-06 14:17:59 +00:00
Alexander Kornienko 8b92ec521d [lld] A better version of the fix in r359942.
Thanks to George Rimar for the suggestion.

llvm-svn: 360040
2019-05-06 12:11:30 +00:00
Alexander Kornienko 3f796f974d [lld] Specify output file explicitly
The test shouldn't try to create `a.out` in the current directory, which can be
read-only (and it is in our test setup).

llvm-svn: 359942
2019-05-03 23:11:32 +00:00
Reid Kleckner 0a1b1d6e62 Shrink SectionChunk by combining Relocs and SectionName sizes
SectionChunk is one of the most frequently allocated data structures in
LLD, since there are about four per function when optimizations and
debug info are enabled (.text, .pdata, .xdata, .debug$S).

A PE COFF file cannot be larger than 2GB, so there is an inherent limit
on the length of the section name and the number of relocations.
Decompose the ArrayRef and StringRef into pointer and size, and put them
back together in the accessors for section name and relocation list.

I plan to gather complete performance numbers later by padding
SectionChunk with dead data and measuring performance after all the size
optimizations are done.

llvm-svn: 359923
2019-05-03 20:17:14 +00:00
Fangrui Song d45df09435 [ELF] Place SHT_NOTE sections with the same alignment into one PT_NOTE
Summary:
While the generic ABI requires notes to be 8-byte aligned in ELF64, many
vendor-specific notes (from Linux, NetBSD, Solaris, etc) use 4-byte
alignment.

In a PT_NOTE segment, if 4-byte aligned notes are followed by an 8-byte
aligned note, the possible 4-byte padding may make consumers fail to
parse the 8-byte aligned note. See PR41000 for a recent report about
.note.gnu.property (NT_GNU_PROPERTY_TYPE_0).
(Note, for NT_GNU_PROPERTY_TYPE_0, the consumers should probably migrate
to PT_GNU_PROPERTY, but the alignment issue affects other notes as well.)

To fix the issue, don't mix notes with different alignments in one
PT_NOTE. If compilers emit 4-byte aligned notes before 8-byte aligned
notes, we'll create at most 2 segments.

sh_size%sh_addralign=0 is actually implied by the rule for linking
unrecognized sections (in generic ABI), so we don't have to check that.
Notes that match in name, type and attribute flags are concatenated into
a single output section. The compilers have to ensure
sh_size%sh_addralign=0 to make concatenated notes parsable.

An alternative approach is to create a PT_NOTE for each SHT_NOTE, but
we'll have to incur the sizeof(Elf64_Phdr)=56 overhead every time a new
note section is introduced.

Reviewers: ruiu, jakehehrlich, phosek, jhenderson, pcc, espindola

Subscribers: emaste, arichardson, krytarowski, fedor.sergeev, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D61296

llvm-svn: 359853
2019-05-03 00:35:49 +00:00
Nico Weber 81862f82ee lld-link: Add /force:multipleres extension to make dupe resource diag non-fatal
As a side benefit, lld-link now reports more than one duplicate resource
entry before exiting with an error even if the new flag is not passed.

llvm-svn: 359829
2019-05-02 21:21:55 +00:00
Fangrui Song 0178cff279 [ELF] --plugin-opt=thinlto-index-only: create empty index files even if all bitcode files are lazy
Summary:
The gold plugin behavior (creating empty index files for lazy bitcode
files) was added in D46034, but it missed the case when there is no
non-lazy bitcode files, e.g.

    ld.lld -shared crti.o crtbeginS.o --start-lib bitcode.o --end-lib ...

crti.o crtbeginS.o are not bitcode, but our distributed build system
wants bitcode.o.thinlto.bc to confirm all expected outputs are created
based on all of the modules provided to the linker.

Differential Revision: https://reviews.llvm.org/D61420

llvm-svn: 359788
2019-05-02 14:05:20 +00:00
Fangrui Song 8be28cdc52 [Object] Change getSectionName() to return Expected<StringRef>
Summary:
It currently receives an output parameter and returns
std::error_code. Expected<StringRef> fits for this purpose perfectly.

Differential Revision: https://reviews.llvm.org/D61421

llvm-svn: 359774
2019-05-02 10:32:03 +00:00
Fangrui Song d8c2fa99c1 [ELF] Delete a cant-write test from test/lto/thinlto-index-only.ll
The test is performed by thinlto-cant-write-index.ll

llvm-svn: 359769
2019-05-02 09:29:24 +00:00
Nico Weber 413517ecfe lld-link: Make "duplicate resource" error message a bit more concise
Reduces the error message from:
    lld-link: error: failed to parse .res file: duplicate resource: type STRINGTABLE (ID 6)/name ID 3/language 1033, in test1.res and in test2.res

To:
    lld-link: error: duplicate resource: type STRINGTABLE (ID 6)/name ID 3/language 1033, in test1.res and in test2.res

Make sure every error message emitted by cvtres contains the name of at
least one ".res" file, so that removing the "failed to parse .res file"
string doesn't lose information.

Differential Revision: https://reviews.llvm.org/D61388

llvm-svn: 359749
2019-05-02 01:52:24 +00:00
Fangrui Song c669ef1721 Delete trailing \r. NFC
llvm-svn: 359745
2019-05-02 00:39:03 +00:00
Ben Dunbobbin 6e32dd6cfd [LLD] Emit dynamic relocations for references to script symbols in -pie links
https://reviews.llvm.org/D55423 caused LLD to stop emitting dynamic relocations for references to script symbols in -pie links.

This patch fixes that regression.

https://reviews.llvm.org/D61298

llvm-svn: 359683
2019-05-01 14:07:31 +00:00
Fangrui Song 5387c2cd17 [llvm-objdump] Print newlines before and after "Disassembly of section ...:"
This improves readability and the behavior is consistent with GNU objdump.

The new test test/tools/llvm-objdump/X86/disassemble-section-name.s
checks we print newlines before and after "Disassembly of section ...:"

Differential Revision: https://reviews.llvm.org/D61127

llvm-svn: 359668
2019-05-01 10:40:48 +00:00
Fangrui Song 4672e52e22 [llvm-readobj] llvm-readobj --elf-output-style=GNU => llvm-readelf
While updating the test, change -l -S to -S -l as the output of -S goes
before -l.

llvm-svn: 359653
2019-05-01 06:02:16 +00:00
Fangrui Song b159906a9a [test] Change llvm-readobj -long-option to --long-option or well-known short options. NFC
Also change some options that have different semantics (cause confusion) in llvm-readelf mode:

-s => -S
-t => --symbols
-sd => --section-data

llvm-svn: 359651
2019-05-01 05:49:01 +00:00
Andrew Ng 24896d304d [LLD][ELF] /DISCARD/ output sections should not be orphans
/DISCARD/ output sections were being treated as orphans. As a result, if
a /DISCARD/ output section has been assigned a PHDR, it could cause
incorrect assignment of sections to segments.

Differential Revision: https://reviews.llvm.org/D61186

llvm-svn: 359565
2019-04-30 14:31:22 +00:00
Andrew Ng 0f4c58f6f4 [LLD][ELF] Fix getRankProximity to "ignore" not live sections
This is a follow up to r358979 which made findOrphanPos only consider
live sections. Unfortunately, this required change to getRankProximity,
used by findOrphanPos, was missed.

Differential Revision: https://reviews.llvm.org/D61197

llvm-svn: 359554
2019-04-30 12:27:06 +00:00
Nico Weber 99bad37013 Add more lld release notes
llvm-svn: 359518
2019-04-29 23:26:21 +00:00
Nico Weber aec5dcc457 Add some lld-link 9.0 release notes
llvm-svn: 359412
2019-04-29 00:42:05 +00:00
George Rimar dee900ae59 [LLD][ELF] - Do not remove empty sections referenced in LOADADDR/ADDR commands.
This is https://bugs.llvm.org//show_bug.cgi?id=38750.

If script references empty sections in LOADADDR/ADDR commands

.empty  : { *(.empty ) }
.text   : AT(LOADADDR (.empty) + SIZEOF (.empty)) { *(.text) }
then an empty section will be removed and LOADADDR/ADDR will evaluate to null.
It is not that user may expect from using of the generic script, what is a common case.

Differential revision: https://reviews.llvm.org/D54621

llvm-svn: 359279
2019-04-26 06:59:30 +00:00
Fangrui Song 98b70f6705 [ELF] Change std::max<uint64_t> to uint32_t for section alignment
Summary:
We use `uint32_t SectionBase::Alignment` and `uint32_t
PhdrEntry::p_align` despite alignments being 64 bits in ELF64.
Fix the std::max template arguments accordingly.

The currently 160-byte InputSection will become 168 bytes if we make SectionBase::Alignment uint64_t.

Differential Revision: https://reviews.llvm.org/D61171

llvm-svn: 359268
2019-04-26 04:07:58 +00:00
Sam Clegg b685ddf288 [WebAssembly] Always take into account added when applying runtime relocations
The code we generate for applying data relocations at runtime omitted
the symbols with GOT entries.

Also refactor the code to reduce duplication.

Differential Revision: https://reviews.llvm.org/D61111

llvm-svn: 359207
2019-04-25 17:11:54 +00:00
George Rimar 44f2d74aa5 [LLD][ELF] - Convert symbol-index.s testcase to a YAML test case. NFCI.
This removes one more binary object from the inputs and fixes the
test case description.

Previously it said that:
"symbol-index.elf has incorrect type of .symtab section.
There is no symbol bodies because of that and any symbol index becomes incorrect."

But the real reason of the failture was not the incorrect type of a symbol table,
but invalid index of the symbol used in a relocation, what happened because
previous test tried to read .symtab as a SHT_RELA section.

llvm-svn: 359197
2019-04-25 15:08:52 +00:00
George Rimar e043417268 [LLD][ELF] - Move the test to a correct folder, remove excessive input. NFCI.
This test should live in `invalid` folder.

Also it was possible to avoid adding input
with use of `-docnum=x` yaml2obj argument.

llvm-svn: 359194
2019-04-25 14:53:23 +00:00
Nico Weber c0838af754 lld-link: Implement /swaprun: flag
r191276 added this to old LLD, but it never made it to new LLD -- except
that the flag was in Options.td, so it was silently ignored. I figured
it should be easy to implement, so I did that instead of removing the
flags from Options.td.

I then discovered that link.exe also supports comma-separated lists of
'cd' and 'net', which made the parsing code a bit annoying.

The Alias technique in Options.td is to get nice help output.

Differential Revision: https://reviews.llvm.org/D61067

llvm-svn: 359192
2019-04-25 14:02:26 +00:00
Nico Weber 23cb79ff93 llvm-cvtres: Make new dupe resource error a bit friendlier
For well-known type IDs, include the name of the type.

To not duplicate the ID->name map, make llvm-readobj call this new
function as well.  It has slightly different output, so this also
requires updating a few tests.

Differential Revision: https://reviews.llvm.org/D61086

llvm-svn: 359153
2019-04-24 23:26:30 +00:00
Reid Kleckner 54c8182a3f [COFF] Don't emit .gfids sections when CFG is off
Put them on the list of GuardFidChunks instead of the main Chunks list,
even with CFG is off. It will be ignored if CFG is disabled.

llvm-svn: 359137
2019-04-24 20:38:37 +00:00