Commit Graph

149 Commits

Author SHA1 Message Date
Martin Storsjo c9f4d25f26 [COFF] Create range extension thunks for ARM64
On ARM64, this is normally necessary only after a module exceeds
128 MB in size (while the limit for thumb is 16 MB). For conditional
branches, the range limit is only 1 MB though (the same as for thumb),
and for the tbz instruction, the range is only 32 KB, which allows for
a test much smaller than the full 128 MB.

This fixes PR40467.

Differential Revision: https://reviews.llvm.org/D57575

llvm-svn: 352929
2019-02-01 22:08:09 +00:00
Martin Storsjo acaa78b171 [COFF] Add support for the new relocation IMAGE_REL_ARM{,64}_REL32
Differential Revision: https://reviews.llvm.org/D57292

llvm-svn: 352325
2019-01-27 19:57:50 +00:00
Chandler Carruth 2946cd7010 Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

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

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

llvm-svn: 351636
2019-01-19 08:50:56 +00:00
Rui Ueyama c310742dc3 Do not assume .idata is zero-initialized.
We initialize .text section with 0xcc (INT3 instruction), so we need to
explicitly write data even if it is zero if it can be in a .text section.
If you specify /merge:.rdata=.text, .rdata (which contains .idata) is put
to .text, so we need to do this.

Fixes https://bugs.llvm.org/show_bug.cgi?id=39826

Differential Revision: https://reviews.llvm.org/D55098

llvm-svn: 348000
2018-11-30 16:34:56 +00:00
Reid Kleckner 551acf03dc [COFF] Simplify relocation to discarded section diagnostic code, NFC
Move it out of the loop that applies relocations for readability.

llvm-svn: 346777
2018-11-13 18:30:31 +00:00
Reid Kleckner 7a44fe956a [COFF] Improve relocation against discarded section error
Summary:
Reuse the "referenced by" note diagnostic code that we already use for
undefined symbols. In my case, it turned this:
  lld-link: error: relocation against symbol in discarded section: .text
  lld-link: error: relocation against symbol in discarded section: .text
  ...

Into this:
  lld-link: error: relocation against symbol in discarded section: .text
  >>> referenced by libANGLE.lib(CompilerGL.obj):(.SCOVP$M)
  >>> referenced by libANGLE.lib(CompilerGL.obj):(.SCOVP$M)
  ...

  lld-link: error: relocation against symbol in discarded section: .text
  >>> referenced by obj/third_party/angle/libGLESv2/entry_points_egl_ext.obj:(.SCOVP$M)
  >>> referenced by obj/third_party/angle/libGLESv2/entry_points_egl_ext.obj:(.SCOVP$M)
  ...

I think the new output is more useful.

Reviewers: ruiu, pcc

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D54240

llvm-svn: 346427
2018-11-08 18:38:17 +00:00
Martin Storsjo 8cc0f71261 [COFF] Add and use a Wordsize field in Config. NFCI.
Differential Revision: https://reviews.llvm.org/D53143

llvm-svn: 344265
2018-10-11 17:45:58 +00:00
Alexandre Ganea 149de8de19 [LLD][COFF] Fix ordering of CRT global initializers in COMDAT sections
(patch by Benoit Rousseau)

This patch fixes a bug where the global variable initializers were sometimes not invoked in the correct order when it involved a C++ template instantiation.

Differential Revision: https://reviews.llvm.org/D52749

llvm-svn: 343847
2018-10-05 12:56:46 +00:00
Martin Storsjo 0f8f0d6d1d [COFF] In MinGW mode, ignore relocations against a discarded section
When GCC produces a jump table as part of a comdat function, the
jump table itself is produced as plain non-comdat rdata section. When
linked with ld.bfd, all of those rdata sections are kept, with
relocations unchanged in the sections that refer to discarded comdat
sections.

This has been observed with at least GCC 5.x and 7.x.

Differential Revision: https://reviews.llvm.org/D52600

llvm-svn: 343422
2018-09-30 18:31:03 +00:00
Martin Storsjo 2bfa125fd6 [COFF] Allow automatic dllimport from gnu import libraries
Don't assume that the IAT chunk will be a DefinedImportData, it can
just as well be a DefinedRegular for gnu import libraries.

Differential Revision: https://reviews.llvm.org/D52381

llvm-svn: 343069
2018-09-26 06:13:39 +00:00
Martin Storsjo 57ddec0dd1 [COFF] Add support for creating range extension thunks for ARM
This is a feature that MS link.exe lacks; it currently errors out on
such relocations, just like lld did before.

This allows linking clang.exe for ARM - practically, any image over
16 MB will likely run into the issue.

Differential Revision: https://reviews.llvm.org/D52156

llvm-svn: 342962
2018-09-25 10:59:29 +00:00
Martin Storsjo 32d21d6a2d [COFF] Add support for delay loading DLLs for ARM64
Differential Revision: https://reviews.llvm.org/D52190

llvm-svn: 342447
2018-09-18 07:22:01 +00:00
Martin Storsjo 7a41693898 [COFF] Provide __CTOR_LIST__ and __DTOR_LIST__ symbols for MinGW
MinGW uses these kind of list terminator symbols for traversing
the constructor/destructor lists. These list terminators are
actual pointers entries in the lists, with the values 0 and
(uintptr_t)-1 (instead of just symbols pointing to the start/end
of the list).

(This mechanism exists in both the mingw-w64 crt startup code and
in libgcc; normally the mingw-w64 one is used, but a DLL build of
libgcc uses the libgcc one. Therefore it's not trivial to change
the mechanism without lots of cross-project synchronization and
potentially invalidating some combinations of old/new versions
of them.)

When mingw-w64 has been used with lld so far, the CRT startup object
files have so far provided these symbols, ending up with different,
incompatible builds of the CRT startup object files depending on
whether binutils or lld are going to be used.

In order to avoid the need of different configuration of the CRT startup
object files depending on what linker to be used, provide these symbols
in lld instead. (Mingw-w64 checks at build time whether the linker
provides these symbols or not.) This unifies this particular detail
between the two linkers.

This does disallow the use of the very latest lld with older versions
of mingw-w64 (the configure check for the list was added recently;
earlier it simply checked whether the CRT was built with gcc or clang),
and requires rebuilding the mingw-w64 CRT. But the number of users of
lld+mingw still is low enough that such a change should be tolerable,
and unifies this aspect of the toolchains, easing interoperability
between the toolchains for the future.

The actual test for this feature is added in ctors_dtors_priority.s,
but a number of other tests that checked absolute output addresses
are updated.

Differential Revision: https://reviews.llvm.org/D52053

llvm-svn: 342294
2018-09-14 22:26:59 +00:00
Martin Storsjo 802fcb4167 [COFF] When doing automatic dll imports, replace whole .refptr.<var> chunks with __imp_<var>
After fixing up the runtime pseudo relocation, the .refptr.<var>
will be a plain pointer with the same value as the IAT entry itself.
To save a little binary size and reduce the number of runtime pseudo
relocations, redirect references to the IAT entry (via the __imp_<var>
symbol) itself and discard the .refptr.<var> chunk (as long as the
same section chunk doesn't contain anything else than the single
pointer).

As there are now cases for both setting the Live variable to true
and false externally, remove the accessors and setters and just make
the variable public instead.

Differential Revision: https://reviews.llvm.org/D51456

llvm-svn: 341175
2018-08-31 07:45:20 +00:00
Martin Storsjo eac1b05f1d [COFF] Support MinGW automatic dllimport of data
Normally, in order to reference exported data symbols from a different
DLL, the declarations need to have the dllimport attribute, in order to
use the __imp_<var> symbol (which contains an address to the actual
variable) instead of the variable itself directly. This isn't an issue
in the same way for functions, since any reference to the function without
the dllimport attribute will end up as a reference to a thunk which loads
the actual target function from the import address table (IAT).

GNU ld, in MinGW environments, supports automatically importing data
symbols from DLLs, even if the references didn't have the appropriate
dllimport attribute. Since the PE/COFF format doesn't support the kind
of relocations that this would require, the MinGW's CRT startup code
has an custom framework of their own for manually fixing the missing
relocations once module is loaded and the target addresses in the IAT
are known.

For this to work, the linker (originall in GNU ld) creates a list of
remaining references needing fixup, which the runtime processes on
startup before handing over control to user code.

While this feature is rather controversial, it's one of the main features
allowing unix style libraries to be used on windows without any extra
porting effort.

Some sort of automatic fixing of data imports is also necessary for the
itanium C++ ABI on windows (as clang implements it right now) for importing
vtable pointers in certain cases, see D43184 for some discussion on that.

The runtime pseudo relocation handler supports 8/16/32/64 bit addresses,
either PC relative references (like IMAGE_REL_*_REL32*) or absolute
references (IMAGE_REL_AMD64_ADDR32, IMAGE_REL_AMD64_ADDR32,
IMAGE_REL_I386_DIR32). On linking, the relocation is handled as a
relocation against the corresponding IAT slot. For the absolute references,
a normal base relocation is created, to update the embedded address
in case the image is loaded at a different address.

The list of runtime pseudo relocations contains the RVA of the
imported symbol (the IAT slot), the RVA of the location the relocation
should be applied to, and a size of the memory location. When the
relocations are fixed at runtime, the difference between the actual
IAT slot value and the IAT slot address is added to the reference,
doing the right thing for both absolute and relative references.

With this patch alone, things work fine for i386 binaries, and mostly
for x86_64 binaries, with feature parity with GNU ld. Despite this,
there are a few gotchas:
- References to data from within code works fine on both x86 architectures,
  since their relocations consist of plain 32 or 64 bit absolute/relative
  references. On ARM and AArch64, references to data doesn't consist of
  a plain 32 or 64 bit embedded address or offset in the code. On ARMNT,
  it's usually a MOVW+MOVT instruction pair represented by a
  IMAGE_REL_ARM_MOV32T relocation, each instruction containing 16 bit of
  the target address), on AArch64, it's usually an ADRP+ADD/LDR/STR
  instruction pair with an even more complex encoding, storing a PC
  relative address (with a range of +/- 4 GB). This could theoretically
  be remedied by extending the runtime pseudo relocation handler with new
  relocation types, to support these instruction encodings. This isn't an
  issue for GCC/GNU ld since they don't support windows on ARMNT/AArch64.
- For x86_64, if references in code are encoded as 32 bit PC relative
  offsets, the runtime relocation will fail if the target turns out to be
  out of range for a 32 bit offset.
- Fixing up the relocations at runtime requires making sections writable
  if necessary, with the VirtualProtect function. In Windows Store/UWP apps,
  this function is forbidden.

These limitations are addressed by a few later patches in lld and
llvm.

Differential Revision: https://reviews.llvm.org/D50917

llvm-svn: 340726
2018-08-27 08:43:31 +00:00
Martin Storsjo c4b0061c05 [COFF] Check the instructions in ARM MOV32T relocations
For this relocation, which applies to two consecutive instructions,
it's plausible that the second instruction might not actually be
the right one.

Differential Revision: https://reviews.llvm.org/D50998

llvm-svn: 340715
2018-08-27 06:04:36 +00:00
Martin Storsjo c0ee24033c [COFF] Move a comment close to the code it refers to. NFC.
llvm-svn: 340400
2018-08-22 11:35:02 +00:00
Martin Storsjo 6c67e04345 [COFF] Change fatal() into error() when writing chunks to the output
In most of these cases, it's easy to go on despite the error,
printing as many valuable error messages as possible from one run
as possible.

Differential Revision: https://reviews.llvm.org/D51087

llvm-svn: 340399
2018-08-22 11:34:58 +00:00
Bob Haarman 30913ac39d [COFF] report file containing unsupported relocation
Summary:
When reporting an unsupported relocation type, let's also report the
file we encountered it in to aid diagnosis.

Reviewers: ruiu, rnk

Reviewed By: rnk

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D45911

llvm-svn: 334154
2018-06-07 00:50:03 +00:00
Peter Collingbourne 62f7af712c COFF: Allow ICFing sections with different alignments.
The combined section gets the maximum alignment of all sections.

Differential Revision: https://reviews.llvm.org/D46786

llvm-svn: 332273
2018-05-14 18:36:51 +00:00
Martin Storsjo cc80776eff [COFF] Implement the remaining ARM64 relocations
Now only IMAGE_REL_ARM64_ABSOLUTE and IMAGE_REL_ARM64_TOKEN
are unhandled.

Also add range checks for the existing BRANCH26 relocation.

Differential Revision: https://reviews.llvm.org/D46354

llvm-svn: 331505
2018-05-04 06:06:27 +00:00
Bob Haarman 8679a7ecea Fix nullptr passed to memcpy in lld/COFF/Chunks.cpp
Summary:
ubsan found that we sometimes pass nullptr to memcpy in
SectionChunk::writeTo(). This change adds a check that avoids that.

Reviewers: ruiu

Reviewed By: ruiu

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D45789

llvm-svn: 330490
2018-04-20 22:16:09 +00:00
Peter Collingbourne 71c7de5b77 COFF: Preserve section type when processing /section flag.
It turns out that we were dropping this before.

Differential Revision: https://reviews.llvm.org/D45802

llvm-svn: 330481
2018-04-20 21:23:16 +00:00
Peter Collingbourne be084eca5b COFF: Remove OutputSection::getPermissions() and getCharacteristics().
All callers can just access the header directly.

Differential Revision: https://reviews.llvm.org/D45800

llvm-svn: 330367
2018-04-19 21:48:37 +00:00
Peter Collingbourne fa322abee9 COFF: Rename Chunk::getPermissions to getOutputCharacteristics.
In an upcoming change I will need to make a distinction between section
type (code, data, bss) and permissions. The term that I use for both
of these things is "output characteristics".

Differential Revision: https://reviews.llvm.org/D45799

llvm-svn: 330361
2018-04-19 20:03:24 +00:00
Peter Collingbourne 2f6d00612d COFF: Make SectionChunk::Relocs field an ArrayRef. NFCI.
Differential Revision: https://reviews.llvm.org/D45714

llvm-svn: 330172
2018-04-17 01:54:34 +00:00
Peter Collingbourne f1a11f87a0 COFF: Implement string tail merging.
In COFF, duplicate string literals are merged by placing them in a
comdat whose leader symbol name contains a specific prefix followed
by the hash and partial contents of the string literal. This gives
us an easy way to identify sections containing string literals in
the linker: check for leader symbol names with the given prefix.

Any sections that are identified in this way as containing string
literals may be tail merged. We do so using the StringTableBuilder
class, which is also used to tail merge string literals in the ELF
linker. Tail merging is enabled only if ICF is enabled, as this
provides a signal as to whether the user cares about binary size.

Differential Revision: https://reviews.llvm.org/D44504

llvm-svn: 327668
2018-03-15 21:14:02 +00:00
Rui Ueyama c6c66225a3 Simplify.
llvm-svn: 325453
2018-02-17 23:37:26 +00:00
Rui Ueyama b3107476a4 Remove an unused accessor and simplify the logic a bit. NFC.
llvm-svn: 325445
2018-02-17 20:41:38 +00:00
Rui Ueyama 03c7f3a2d0 Factor out common code from applySecRel functions.
Differential Revision: https://reviews.llvm.org/D43412

llvm-svn: 325444
2018-02-17 20:28:15 +00:00
Martin Storsjo ef4f78bbf2 [COFF] Add support for ARM64 secrel relocations for add/load instructions
Differential Revision: https://reviews.llvm.org/D43287

llvm-svn: 325396
2018-02-16 22:02:38 +00:00
Reid Kleckner af2f7da74c [COFF] Add minimal support for /guard:cf
Summary:
This patch adds some initial support for Windows control flow guard. At
the end of the day, the linker needs to synthesize a table of RVAs very
similar to the structured exception handler table (/safeseh).

Both /safeseh and /guard:cf take sections of symbol table indices
(.sxdata and .gfids$y) and turn them into RVA tables referenced by the
load config struct in the CRT through special symbols.

Reviewers: ruiu, amccarth

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D42592

llvm-svn: 324306
2018-02-06 01:58:26 +00:00
Martin Storsjo 94d72b89d6 [COFF] Error out if 20 bit thumb branches are out of range
This is similar to what was added in SVN r277838 for 24 bit
branch instructions.

Differential Revision: https://reviews.llvm.org/D41163

llvm-svn: 320677
2017-12-14 08:56:36 +00:00
Peter Collingbourne 1621c20ffc Reland r319090, "COFF: Do not create SectionChunks for discarded comdat sections." with a fix for debug sections.
If /debug was not specified, readSection will return a null
pointer for debug sections. If the debug section is associative with
another section, we need to make sure that the section returned from
readSection is not a null pointer before adding it as an associative
section.

Differential Revision: https://reviews.llvm.org/D40533

llvm-svn: 319133
2017-11-28 01:30:07 +00:00
Peter Collingbourne c8477b8234 Revert r319090, "COFF: Do not create SectionChunks for discarded comdat sections."
Caused test failures in check-cfi on Windows.
http://lab.llvm.org:8011/builders/sanitizer-windows/builds/20284

llvm-svn: 319100
2017-11-27 21:37:51 +00:00
Peter Collingbourne 3f2921f5ec COFF: Do not create SectionChunks for discarded comdat sections.
With this change, instead of creating a SectionChunk for each section
in the object file, we only create them when we encounter a prevailing
comdat section.

Also change how symbol resolution occurs between comdat symbols. Now
only the comdat leader participates in comdat resolution, and not any
other external associated symbols. This is more in line with how COFF
semantics are defined, and should allow for a more straightforward
implementation of non-ANY comdat types.

On my machine, this change reduces our runtime linking a release
build of chrome_child.dll with /nopdb from 5.65s to 4.54s (median of
50 runs).

Differential Revision: https://reviews.llvm.org/D40238

llvm-svn: 319090
2017-11-27 20:42:34 +00:00
Peter Collingbourne 31275d4472 COFF: Correctly handle relocations against early discarded sections.
Don't crash if we encounter a reference to an early discarded section
(such as .drectve). Instead, handle them the same way as sections
discarded by comdat merging, i.e. either print an error message or
(for debug sections) silently ignore the relocation.

Differential Revision: https://reviews.llvm.org/D40235

llvm-svn: 318689
2017-11-20 19:37:07 +00:00
Martin Storsjo bfe2fed2c4 [COFF] Add support for IMAGE_REL_ARM64_SECREL
I never ran into this until lld-link started enabling debug output
by default for the mingw mode. I haven't been able to verify that
this actually behaves correctly, but this relocation is handled
identically on all other architectures so far.

Differential Revision: https://reviews.llvm.org/D39754

llvm-svn: 317669
2017-11-08 07:31:50 +00:00
Martin Storsjo ee8c973884 [COFF] Handle ARM64 in getDefaultType
Differential Revision: https://reviews.llvm.org/D39634

llvm-svn: 317455
2017-11-06 07:02:33 +00:00
Rui Ueyama 7782abe5e6 [COFF] Avoid "Body" as a local variable name.
Since SymbolBody is gone, "Body" is not a good variable name.
This patch renames or eliminates them.

llvm-svn: 317384
2017-11-03 22:49:02 +00:00
Rui Ueyama f52496e1e0 Rename SymbolBody -> Symbol
Now that we have only SymbolBody as the symbol class. So, "SymbolBody"
is a bit strange name now. This is a mechanical change generated by

  perl -i -pe s/SymbolBody/Symbol/g $(git grep -l SymbolBody lld/ELF lld/COFF)

nd clang-format-diff.

Differential Revision: https://reviews.llvm.org/D39459

llvm-svn: 317370
2017-11-03 21:21:47 +00:00
Bob Haarman b8a59c8aa5 [lld] unified COFF and ELF error handling on new Common/ErrorHandler
Summary:
The COFF linker and the ELF linker have long had similar but separate
Error.h and Error.cpp files to implement error handling. This change
introduces new error handling code in Common/ErrorHandler.h, changes the
COFF and ELF linkers to use it, and removes the old, separate
implementations.

Reviewers: ruiu

Reviewed By: ruiu

Subscribers: smeenai, jyknight, emaste, sdardis, nemanjai, nhaehnle, mgorny, javed.absar, kbarton, fedor.sergeev, llvm-commits

Differential Revision: https://reviews.llvm.org/D39259

llvm-svn: 316624
2017-10-25 22:28:38 +00:00
Martin Storsjo ea460a2d0c [COFF] Implement support for IMAGE_REL_ARM64_ADDR32NB
This is implemented in the same way as the other ADDR32NB relocations
for ARM and X64.

Differential Revision: https://reviews.llvm.org/D38815

llvm-svn: 315561
2017-10-12 05:37:06 +00:00
Shoaib Meenai e61ca35463 [COFF] Adjust secrel limit check
According to Microsoft's PE/COFF documentation, a SECREL relocation is
"The 32-bit offset of the target from the beginning of its section". By
my reading, the "from the beginning of its section" implies that the
offset is unsigned.

Change from an assertion to an error, since it's possible to trigger
this condition normally for input files with very large sections, and we
should fail gracefully for those instead of asserting.

Differential Revision: https://reviews.llvm.org/D38020

llvm-svn: 313703
2017-09-20 00:21:58 +00:00
Rui Ueyama cfc2f80df6 Remove {get,set}Align accessor functions and use Alignment member variable instead.
llvm-svn: 313204
2017-09-13 21:54:55 +00:00
Martin Storsjo d2752aa9ec [COFF] Add support for aligncomm directives
These are emitted for comm symbols in object files, when targeting
a GNU environment.

Alternatively, just ignore them since we already align CommonChunk
to the natural size of the content (up to 32 bytes). That would only
trade away the possibility to overalign small symbols, which doesn't
sound like something that might not need to be handled?

Differential Revision: https://reviews.llvm.org/D36304

llvm-svn: 310871
2017-08-14 19:07:27 +00:00
Rui Ueyama e1b48e099c Rename ObjectFile ObjFile for COFF as well.
llvm-svn: 309228
2017-07-26 23:05:24 +00:00
Martin Storsjo 38608c0975 [COFF, ARM64] Handle ADRP immediate offsets in relocations
Also handle overflow correctly in LDR/STR relocations. Even if the
offset range of a 8 byte LDR instruction is 15 bit (even if the immediate
itself is 12 bit) due to a 3 bit shift, only include up to 12 bits of offset
after doing the relocation, by limiting the range of the immediate by the
number of shifted bits.

Differential Revision: https://reviews.llvm.org/D35792

llvm-svn: 309175
2017-07-26 20:51:47 +00:00
Martin Storsjo 82eaf6cb50 [COFF] Add support for delay loading DLLs on ARM
Differential Revision: https://reviews.llvm.org/D35768

llvm-svn: 309017
2017-07-25 20:00:37 +00:00
Martin Storsjo 5ae7649a4e [COFF] Support 128 bit SIMD/FP ldr/str in IMAGE_REL_ARM64_PAGEOFFSET_12L
Also extend the tests for IMAGE_REL_ARM64_PAGEOFFSET_12L to test
all 8/16/32/64 bit GPR and 8/16/32/64/128 SIMD/FP bit ldr/str variants,
and a ldr with an existing offset.

Differential revision: https://reviews.llvm.org/D35647

llvm-svn: 308631
2017-07-20 16:48:33 +00:00