Commit Graph

12957 Commits

Author SHA1 Message Date
Sam Clegg 0a6c4d8d2e [WebAssmebly] Add support for defined wasm globals in MC and lld
This change add support for defined wasm globals in the .s format,
the MC layer, and wasm-ld

Currently there is no support custom initialization and all wasm
globals are initialized to zero.

Fixes: PR45742

Differential Revision: https://reviews.llvm.org/D79137
2020-04-30 12:43:15 -07:00
Thomas Preud'homme 9ecddde321 [test] Fix ELF/linkerscript/input-archive.s w/ @ in path
Lld test ELF/linkerscript/input-archive.s fails when path contain a @
because is not accepted in unquoted token in linker scripts which leads
to the path being broken in 2 around the @. This commit quotes the path
used in the linker script created by this and similar testcases allowing
the test to pass even in the presence of an @ sign in the path.

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D79103
2020-04-30 20:14:22 +01:00
Fangrui Song b257d3c8a8 [ELF][PPC64] Suppress toc-indirect to toc-relative relaxation if R_PPC64_TOC16_LO is seen
The current implementation assumes that R_PPC64_TOC16_HA is always followed
by R_PPC64_TOC16_LO_DS. This can break with R_PPC64_TOC16_LO:

  // Load the address of the TOC entry, instead of the value stored at that address
  addis 3, 2, .LC0@tloc@ha  # R_PPC64_TOC16_HA
  addi  3, 3, .LC0@tloc@l   # R_PPC64_TOC16_LO
  blr

which is used by boringssl's util/fipstools/delocate/delocate.go
https://github.com/google/boringssl/blob/master/crypto/fipsmodule/FIPS.md has some documentation.
In short, this tool converts an assembly file to avoid any potential relocations.
The distance to an input .toc is not a constant after linking, so it cannot use an `addis;ld` pair.
Instead, it jumps to a stub which loads the TOC entry address with `addis;addi`.

This patch checks the presence of R_PPC64_TOC16_LO and suppresses
toc-indirect to toc-relative relaxation if R_PPC64_TOC16_LO is seen.
This approach is conservative and loses some relaxation opportunities but is easy to implement.

  addis 3, 2, .LC0@toc@ha  # no relaxation
  addi  3, 3, .LC0@toc@l   # no relaxation
  li    9, 0
  addis 4, 2, .LC0@toc@ha  # can relax but suppressed
  ld    4, .LC0@toc@l(4)   # can relax but suppressed

Also note that interleaved R_PPC64_TOC16_HA and R_PPC64_TOC16_LO_DS is
possible and this patch accounts for that.

  addis 3, 2, .LC1@toc@ha  # can relax
  addis 4, 2, .LC2@toc@ha  # can relax
  ld    3, .LC1@toc@l(3)   # can relax
  ld    4, .LC2@toc@l(4)   # can relax

Reviewed By: #powerpc, sfertile

Differential Revision: https://reviews.llvm.org/D78431
2020-04-30 09:16:51 -07:00
Fangrui Song b912b887d8 [ELF] Add --print-archive-stats=
gold has an option --print-symbol-counts= which prints:

  // For each archive
  archive $archive $members $fetched_members
  // For each object file
  symbols $object $defined_symbols $used_defined_symbols

In most cases, `$defined_symbols = $used_defined_symbols` unless weak
symbols are present. Strangely `$used_defined_symbols` includes symbols defined relative to --gc-sections discarded sections.
The `symbols` lines do not appear to be useful.

`archive` lines are useful: `$fetched_members=0` lines correspond to
unused archives. The information can be used to trim dependencies.

This patch implements --print-archive-stats= which prints the number of
members and the number of fetched members for each archive.

Reviewed By: grimar

Differential Revision: https://reviews.llvm.org/D78983
2020-04-29 18:04:37 -07:00
Fangrui Song e96d7b5e9e [ELF] Add --rosegment to complement --no-rosegment
This option can cancel --no-rosegment and it just seems right to have
a corresponding positive option for a --no-* negative option.

Anecdotally, gold had --rosegment but did not have --no-rosegment.
I added --no-rosegment (https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=9a6c68caa9543e09b064b7ac7c2b658f277bc19c) for binutils>=2.35
2020-04-29 18:00:00 -07:00
Jez Ng e82c5e17b5 [lld-macho] Support X86_64_RELOC_BRANCH
Relatively straightforward diff, to set the stage for calling functions
in dylibs.

Differential Revision: https://reviews.llvm.org/D78269
2020-04-29 15:45:01 -07:00
Jez Ng df92377823 [lld-macho] Have Symbol::getVA() return a non-relative virtual address
Currently, getVA() returns a virtual address with the assumption that
the ImageBase is zero. As I understand, this is what lld-ELF is doing.
However, under our current design, it seems like an awkward setup --
I'm finding that I have to add and subtract ImageBase in several places
to make things work out.

As such, I think it's simpler to have getVA() return a non-relative VA,
but I'm not sure if I'm missing something. Would love to hear more from
folks familiar with lld-ELF.

Differential Revision: https://reviews.llvm.org/D78168
2020-04-29 15:44:50 -07:00
Jez Ng 918948db4d [lld-macho] Support reading of universal binaries
Differential Revision: https://reviews.llvm.org/D77006
2020-04-29 15:44:44 -07:00
Jez Ng 89285a1a97 [lld-macho] Disable colors in errors when not printing to a pty
This makes for better tests (and is just the right thing to do)

Differential Revision: https://reviews.llvm.org/D79069
2020-04-29 15:44:35 -07:00
Jez Ng 9854edd817 [lld-macho] Implement basic export trie
Build the trie by performing a three-way radix quicksort: We start by
sorting the strings by their first characters, then sort the strings
with the same first characters by their second characters, and so on
recursively. Each time the prefixes diverge, we add a node to the trie.
Thanks to @ruiu for the idea.

I used llvm-mc's radix quicksort implementation as a starting point. The
trie offset fixpoint code was taken from
MachONormalizedFileBinaryWriter.cpp.

Differential Revision: https://reviews.llvm.org/D76977
2020-04-29 15:44:27 -07:00
Fangrui Song 1ccde53342 [ELF] --gdb-index: support .debug_loclists
--gdb-index currently crashes when reading a translation unit with
DWARF v5 .debug_loclists . Call stack:

```
SyntheticSections.cpp GdbIndexSection::create
SyntheticSections.cpp readAddressAreas
DWARFUnit.cpp DWARFUnit::tryExtractDIEsIfNeeded
DWARFListTable.cpp DWARFListTableHeader::extract
...
DWARFDataExtractor.cpp DWARFDataExtractor::getRelocatedValue
lld/ELF/DWARF.cpp LLDDwarfObj<ELFT>::find (sec.sec is nullptr)
...

```

This patch adds support for .debug_loclists to make `DWARFUnit::tryExtractDIEsIfNeeded` happy.
Building --gdb-index does not need .debug_loclists

Reviewed By: dblaikie, grimar

Differential Revision: https://reviews.llvm.org/D79061
2020-04-29 15:04:13 -07:00
Fangrui Song 53ff95254d Reland D78837 [lld] Remove special cases from default ld driver mode.
Drops the behavior from rL217112.

Use the Gnu driver mode by default for all platforms when ld is
invoked. Other names for the program (such as link or ld64) continue
working as before.

Reviewed By: MaskRay, srhines, smeenai, ruiu

Differential Revision: https://reviews.llvm.org/D78837
2020-04-29 14:45:44 -07:00
Dan Albert 0a78e42b1f Revert "[lld] Remove special cases from default ld driver mode."
This reverts commit da093c388f.

Broke a test on Darwin. Will fix the test and resubmit.
2020-04-29 14:14:51 -07:00
Dan Albert da093c388f [lld] Remove special cases from default ld driver mode.
Summary:
Use the Gnu driver mode by default for all platforms when ld is
invoked. Other names for the program (such as link or ld64) continue
working as before.

Reviewers: MaskRay, int3, srhines, smeenai, ruiu

Reviewed By: MaskRay, srhines, smeenai, ruiu

Subscribers: smeenai, srhines, nickdesaulniers, llvm-commits

Tags: #lld, #llvm

Differential Revision: https://reviews.llvm.org/D78837
2020-04-29 12:28:29 -07:00
Sean Fertile f9106e85c4 Revert "[ELF][PPC64] Don't perform toc-indirect to toc-relative relax... "
This reverts commit 03ffe58605.

Full tile of reverted commit is:
[ELF][PPC64] Don't perform toc-indirect to toc-relative relaxation for
R_PPC64_TOC16_HA not followed by R_PPC64_TOC16_LO_DS

Breaks the multistage lld PowerPC buildbot.
2020-04-29 10:30:35 -04:00
Saleem Abdulrasool 216833b32b Revert "Temporarily revert "build: use `find_package(Python3)` if available""
This reverts commit 35edd704e0.

Revert the revert and extend the patch further to account for the use of
the `PYTHONINTERP_FOUND`.
2020-04-29 01:38:08 +00:00
Jez Ng 62b8f32f76 [lld-macho][reland] Add support for emitting dylibs with a single symbol
This got reverted due to UBSAN errors in a diff lower in the stack,
which is being fixed in https://reviews.llvm.org/D79050. This diff is
otherwise identical to the original https://reviews.llvm.org/D76908
(which was committed in 9598778bd1 and reverted in b52bc2653b).

Differential Revision: https://reviews.llvm.org/D79051
2020-04-28 17:08:32 -07:00
Jez Ng 4f0cccdd7a [lld-macho][reland] Add basic symbol table output
This diff implements basic support for writing a symbol table.

Attributes are loosely supported for extern symbols and not at all for
other types.

Initial version by Kellie Medlin <kelliem@fb.com>

Originally committed in a3d95a50ee and reverted in fbae153ca5 due to
UBSAN erroring over unaligned writes. That has been fixed in the
current diff with the following changes:

```
diff --git a/lld/MachO/SyntheticSections.cpp b/lld/MachO/SyntheticSections.cpp
--- a/lld/MachO/SyntheticSections.cpp
+++ b/lld/MachO/SyntheticSections.cpp
@@ -133,6 +133,9 @@ SymtabSection::SymtabSection(StringTableSection &stringTableSection)
     : stringTableSection(stringTableSection) {
   segname = segment_names::linkEdit;
   name = section_names::symbolTable;
+  // TODO: When we introduce the SyntheticSections superclass, we should make
+  // all synthetic sections aligned to WordSize by default.
+  align = WordSize;
 }

 size_t SymtabSection::getSize() const {
diff --git a/lld/MachO/Writer.cpp b/lld/MachO/Writer.cpp
--- a/lld/MachO/Writer.cpp
+++ b/lld/MachO/Writer.cpp
@@ -371,6 +371,7 @@ void Writer::assignAddresses(OutputSegment *seg) {
     ArrayRef<InputSection *> sections = p.second;
     for (InputSection *isec : sections) {
       addr = alignTo(addr, isec->align);
+      // We must align the file offsets too to avoid misaligned writes of
+      // structs.
+      fileOff = alignTo(fileOff, isec->align);
       isec->addr = addr;
       addr += isec->getSize();
       fileOff += isec->getFileSize();
@@ -396,6 +397,7 @@ void Writer::writeSections() {
     uint64_t fileOff = seg->fileOff;
     for (auto &sect : seg->getSections()) {
       for (InputSection *isec : sect.second) {
+        fileOff = alignTo(fileOff, isec->align);
         isec->writeTo(buf + fileOff);
         fileOff += isec->getFileSize();
       }
```

I don't think it's easy to write a test for alignment (that doesn't
involve brittly hard-coding file offsets), so there isn't one... but
UBSAN builds pass now.

Differential Revision: https://reviews.llvm.org/D79050
2020-04-28 17:07:06 -07:00
Eric Christopher 35edd704e0 Temporarily revert "build: use `find_package(Python3)` if available"
as it seems to be causing multiple people problems with running tests
and building.

This reverts commit c4c3883b00.
2020-04-28 16:41:22 -07:00
Fangrui Song 03ffe58605 [ELF][PPC64] Don't perform toc-indirect to toc-relative relaxation for R_PPC64_TOC16_HA not followed by R_PPC64_TOC16_LO_DS
The current implementation assumes that R_PPC64_TOC16_HA is always followed
by R_PPC64_TOC16_LO_DS. This can break with:

// Load the address of the TOC entry, instead of the value stored at that address
  addis 3, 2, .LC0@tloc@ha  # R_PPC64_TOC16_HA
  addi  3, 3, .LC0@tloc@l   # R_PPC64_TOC16_LO
  blr

which is used by boringssl's util/fipstools/delocate/delocate.go
https://github.com/google/boringssl/blob/master/crypto/fipsmodule/FIPS.md has some documentation.
In short, this tool converts an assembly file to avoid any potential relocations.
The distance to an input .toc is not a constant after linking, so the assembly cannot use an `addis;ld` pair.
Instead, delocate changes the code to jump to a stub (`addis;addi`) which loads the TOC entry address.

Reviewed By: sfertile

Differential Revision: https://reviews.llvm.org/D78431
2020-04-28 12:13:27 -07:00
Shoaib Meenai fbae153ca5 Revert "[lld-macho] Add basic symbol table output"
This reverts commit a3d95a50ee.

Reverting due to UBSan failures:
http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-fast/builds/40817/steps/check-lld%20ubsan/logs/stdio
2020-04-28 11:34:03 -07:00
Shoaib Meenai b52bc2653b Revert "[lld-macho] Add support for emitting dylibs with a single symbol"
This reverts commit 9598778bd1.

Reverting due to UBSan failures:
http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-fast/builds/40817/steps/check-lld%20ubsan/logs/stdio
2020-04-28 11:34:03 -07:00
Shoaib Meenai af40bff32d [MachO] Fix UB in memcpy
UBSan complains about a memcpy with a null pointer, so just skip the
memcpy call if the data is empty.
2020-04-28 11:33:54 -07:00
Reid Kleckner 01b5f52140 [COFF] Add a fastpath for /INCLUDE: in .drective sections
This speeds up linking chrome.dll with PGO instrumentation by 13%
(154271ms -> 134033ms).

LLVM's Option library is very slow. In particular, it allocates at least
one large-ish heap object (Arg) for every argument. When PGO
instrumentation is enabled, all the __profd_* symbols are added to the
@llvm.used list, which compiles down to these /INCLUDE: directives. This
means we have O(#symbols) directives to parse in the section, so we end
up allocating an Arg for every function symbol in the object file. This
is unnecessary.

To address the issue and speed up the link, extend the fast path that we
already have for /EXPORT:, which has similar scaling issues.

I promise that I took a hard look at optimizing the Option library, but
its data structures are very general and would need a lot of cleanup. We
have accumulated lots of optional features (option groups, aliases,
multiple values) over the years, and these are now properties of every
parsed argument, when the vast majority of arguments do not use these
features.

Reviewed By: thakis

Differential Revision: https://reviews.llvm.org/D78845
2020-04-28 10:35:57 -07:00
Fangrui Song d9786b566b [ELF] Clear lazyObjFiles in lld:🧝:link after D46034 2020-04-28 09:54:20 -07:00
Saleem Abdulrasool c4c3883b00 build: use `find_package(Python3)` if available
This is primarily motivated by the desire to move from Python2 to
Python3.  `PYTHON_EXECUTABLE` is ambiguous.  This explicitly identifies
the python interpreter in use.  Since the LLVM build seems to be able to
completed successfully with python3, use that across the build.  The old
path aliases `PYTHON_EXECUTABLE` to be treated as Python3.
2020-04-28 09:24:27 -07:00
Igor Kudrin 9f65f5acca [LLD][ELF] Eliminate symbols of merged .ARM.exidx sections.
GNU tools generate mapping symbols "$d" for .ARM.exidx sections. The
symbols are added to the symbol table much earlier than the merging
takes place, and after that, they become dangling. Before the patch,
LLD output those symbols as SHN_ABS with the value of 0. The patch
removes such symbols from the symbol table.

Differential Revision: https://reviews.llvm.org/D78820
2020-04-28 18:58:40 +07:00
Jez Ng 9598778bd1 [lld-macho] Add support for emitting dylibs with a single symbol
Summary:
Add logic for emitting the correct set of load commands and segments
when `-dylib` is passed.

I haven't gotten to implementing a real export trie yet, so we can only
emit a single symbol, but it's enough to replace the YAML test files
introduced in D76252.

Differential Revision: https://reviews.llvm.org/D76908
2020-04-27 13:33:46 -07:00
Jez Ng a3d95a50ee [lld-macho] Add basic symbol table output
This diff implements basic support for writing a symbol table.

- Attributes are loosely supported for extern symbols and not at all for
  other types

Immediate future work will involve implementing section merging.

Initial version by Kellie Medlin <kelliem@fb.com>

Differential Revision: https://reviews.llvm.org/D76742
2020-04-27 13:33:15 -07:00
Jez Ng 6f63216c3d [lld-macho] Extend SyntheticSections to cover all segment load commands
Previously, the special segments `__PAGEZERO` and `__LINKEDIT` were
implemented as special LoadCommands. This diff implements them using
special sections instead which have an `isHidden()` attribute. We do not
emit section headers for hidden sections, but we use their addresses and
file offsets to determine that of their containing segments. In addition
to allowing us to share more segment-related code, this refactor is also
important for the next step of emitting dylibs:

1) dylibs don't have segments like __PAGEZERO, so we need an easy way of
   omitting them w/o messing up segment indices
2) Unlike the kernel, which is happy to run an executable with
   out-of-order segments, dyld requires dylibs to have their segment
   load commands arranged in increasing address order. The refactor
   makes it easier to implement sorting of sections and segments.

Differential Revision: https://reviews.llvm.org/D76839
2020-04-27 12:58:12 -07:00
Nico Weber 76f74d15fe remove temporary logging again now that things are figured out 2020-04-27 14:01:37 -04:00
Hongtao Yu 964ef8eecc [lld] Support --lto-emit-asm and --plugin-opt=emit-asm
Summary: The switch --plugin-opt=emit-asm can be used with the gold linker to dump the final assembly code generated by LTO in a user-friendly way. Unfortunately it doesn't work with lld. I'm hooking it up with lld. With that switch, lld emits assembly code into the output file (specified by -o) and if there are multiple input files, each of their assembly code will be emitted into a separate file named by suffixing the output file name with a unique number, respectively. The linking then stops after generating those assembly files.

Reviewers: espindola, wenlei, tejohnson, MaskRay, grimar

Reviewed By: tejohnson, MaskRay, grimar

Subscribers: pcc, emaste, inglorion, arichardson, hiraditya, MaskRay, steven_wu, dexonsmith, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D77231
2020-04-27 11:00:46 -07:00
Simon Pilgrim 0847cfa334 [lld][macho] Fix implicit dependency on DenseMap.h include
It was depending on CachedHashString.h providing the include.
2020-04-27 14:05:29 +01:00
Sam Clegg 4b8e2d8e81 [lld][WebAssembly] Fix crash on function signature mismatch with --relocatable
These stub new function were not being added to the symbol table
which in turn meant that we were crashing when trying to output
relocations against them.

Differential Revision: https://reviews.llvm.org/D78779
2020-04-25 10:26:11 -07:00
Igor Kudrin 66e4eb9c1b [LLD][ELF] Implement --discard-* for cases when -r or --emit-relocs are used.
When discarding local symbols with --discard-all or --discard-locals,
the ones which are used in relocations should be preserved. LLD used
the simplest approach and just ignored those switches when -r or
--emit-relocs was specified.

The patch implements handling the --discard-* switches for the cases
when relocations are kept by identifying used local symbols and allowing
removing only unused ones. This makes the behavior of LLD compatible
with GNU linkers.

Differential Revision: https://reviews.llvm.org/D77807
2020-04-25 18:59:41 +07:00
Peter Smith 3b1622d63a [LLD][ELF][ARM] recommit Fix ARM Exidx order for non monotonic section order
Fixed error detected by msan. The size field of the .ARM.exidx synthetic
section needs to be initialized to at least estimation level before
calling assignAddresses as that will use the size field.

This was previously reverted in 1ca16fc4f5.

Differential Revision: https://reviews.llvm.org/D78422
2020-04-24 13:47:28 +01:00
Peter Smith 1ca16fc4f5 Revert "[LLD][ELF][ARM] Fix ARM Exidx order for non monotonic section order"
This reverts commit f969c2aa65.

There are some msan buildbot failures sanitzer-x86_64-linux-fast that
I need to investigate.

Differential Revision: https://reviews.llvm.org/D78422
2020-04-23 16:58:50 +01:00
Peter Smith f969c2aa65 [LLD][ELF][ARM] Fix ARM Exidx order for non monotonic section order
The contents of the .ARM.exidx section must be ordered by SHF_LINK_ORDER
rules. We don't need to know the precise address for this order, but we
do need to know the relative order of sections. We have been using the
sectionIndex for this purpose, this works when the OutputSection order
has a monotonically increasing virtual address, but it is possible to
write a linker script with non-monotonically increasing virtual address.
For these cases we need to evaluate the base address of the OutputSection
so that we can order the .ARM.exidx sections properly.

This change moves the finalisation of .ARM.exidx till after the first
call to AssignAddresses. This permits us to sort on virtual address which
is linker script safe. It also permits a fix for part of pr44824 where
we generate .ARM.exidx section for the vector table when that table is so
far away it is out of range of the .ARM.exidx section. This fix will come
in a follow up patch.

Differential Revision: https://reviews.llvm.org/D78422
2020-04-23 15:46:44 +01:00
Sergej Jaskiewicz 2899103108 [TimeProfiler] Emit clock synchronization point
Time profiler emits relative timestamps for events (the number of
microseconds passed since the start of the current process).

This patch allows combining events from different processes while
preserving their relative timing by emitting a new attribute
"beginningOfTime". This attribute contains the system time that
corresponds to the zero timestamp of the time profiler.

This has at least two use cases:

- Build systems can use this to merge time traces from multiple compiler
  invocations and generate statistics for the whole build. Tools like
  ClangBuildAnalyzer could also leverage this feature.

- Compilers that use LLVM as their backend by invoking llc/opt in
  a child process. If such a compiler supports generating time traces
  of its own events, it could merge those events with LLVM-specific
  events received from llc/opt, and produce a more complete time trace.

A proof-of-concept script that merges multiple logs that
contain a synchronization point into one log:
https://github.com/broadwaylamb/merge_trace_events

Differential Revision: https://reviews.llvm.org/D78030
2020-04-23 01:09:31 +03:00
Sergej Jaskiewicz a5bf02815d [TimeProfiler] Emit real process ID and thread names
Differential Revision: https://reviews.llvm.org/D78027
2020-04-23 00:12:51 +03:00
Fangrui Song c384ca3c6a [ELF] For relative paths in INPUT() and GROUP(), search the directory of the current linker script before searching other paths
For a relative path in INPUT() or GROUP(), this patch changes the search order by adding the directory of the current linker script.
The new search order (consistent with GNU ld >= 2.35 regarding the new test `test/ELF/input-relative.s`):

1. the directory of the current linker script (GNU ld from Binutils 2.35 onwards; https://sourceware.org/bugzilla/show_bug.cgi?id=25806)
2. the current working directory
3. library paths (-L)

This behavior makes it convenient to replace a .so or .a with a linker script with additional input. For example, glibc

```
% cat /usr/lib/x86_64-linux-gnu/libm.a
/* GNU ld script
*/
OUTPUT_FORMAT(elf64-x86-64)
GROUP ( /usr/lib/x86_64-linux-gnu/libm-2.29.a /usr/lib/x86_64-linux-gnu/libmvec.a )
```

could be simplified as `GROUP(libm-2.29.a libmvec.a)`.

Another example is to make libc++.a a linker script:
```
INPUT(libc++.a.1 libc++abi.a)
```

Note, -l is not affected.

Reviewed By: psmith

Differential Revision: https://reviews.llvm.org/D77779
2020-04-22 12:34:20 -07:00
Peter Smith 673612a035 [LLD][ELF][ARM] Replace adr, ldr with .inst .reloc in test [NFC]
After D78301 MC no longer emits a relocation for this case. Change to use
.inst and .reloc to synthesize the same instruction and relocation. One
more test case I missed.
2020-04-22 12:55:26 +01:00
Fangrui Song 01d2a01e79 [ELF] Fix a null pointer dereference when relocating a Local-Exec TLS relocation for a lazy symbol
If there is no SHF_TLS section, there will be no PT_TLS and Out::tlsPhdr may be a nullptr.
If the symbol referenced by an R_TLS is lazy, we should treat the symbol as undefined.

Also reorganize tls-in-archive.s and tls-weak-undef.s . They do not test what they intended to test.
2020-04-21 15:39:31 -07:00
Jez Ng 060efd24c7 [lld-macho] Add basic support for linking against dylibs
This diff implements:

* dylib loading (much of which is being restored from @pcc and @ruiu's
  original work)
* The GOT_LOAD relocation, which allows us to load non-lazy dylib
  symbols
* Basic bind opcode emission, which tells `dyld` how to populate the GOT

Differential Revision: https://reviews.llvm.org/D76252
2020-04-21 13:43:19 -07:00
Fangrui Song 497c76e96d [ELF] Keep local symbols when both --emit-relocs and --discard-all are specified
This fixes a bug as exposed by D77807.

Add tests for {--emit-relocs,-r} x {--discard-locals,--discard-all}. They add coverage for previously undertested cases:

* STT_SECTION associated to GCed sections (`gc`)
* STT_SECTION associated to retained sections (`text`)
* STT_SECTION associated to non-SHF_ALLOC sections (`.comment`)
* STB_LOCAL in GCed sections (`unused_gc`)

Reviewed By: grimar, ikudrin

Differential Revision: https://reviews.llvm.org/D78389
2020-04-21 08:28:12 -07:00
Fangrui Song 58207d6fe1 [ELF] Fix "TLS attribute mismatch" false positives for STT_NOTYPE undefined symbols
D13550 added the diagnostic to address/work around a crash.
The rule was refined by D19836 (test/ELF/tls-archive.s) to exclude Lazy symbols.

https://bugs.llvm.org/show_bug.cgi?id=45598 reported another case where the current logic has a false positive:

Bitcode does not record undefined module-level inline assembly symbols
(`IRSymtab.cpp:Builder::addSymbol`). Such an undefined symbol does not
have the FB_tls bit and lld will not consider it STT_TLS. When the symbol is
later replaced by a STT_TLS Defined, lld will error "TLS attribute mismatch".

This patch fixes this false positive by allowing a STT_NOTYPE undefined
symbol to be replaced by a STT_TLS.

Considered alternative:

Moving the diagnostics to scanRelocs() can improve the diagnostics (PR36049)
but that requires a fair amount of refactoring. We will need more
RelExpr members. It requires more thoughts whether it is worthwhile.

See `test/ELF/tls-mismatch.s` for behavior differences. We will fail to
diagnose a likely runtime bug (STT_NOTYPE non-TLS relocation referencing
a TLS definition). This is probably acceptable because compiler
generated code sets symbol types properly.

Reviewed By: grimar, psmith

Differential Revision: https://reviews.llvm.org/D78438
2020-04-21 07:56:35 -07:00
Fangrui Song 6e1fe78569 [ELF][test] Reorganize "TLS attribute mismatch" tests 2020-04-21 07:56:35 -07:00
Eli Friedman 875e26d343 Fix lld testcases I missed in D78413 (9b9454a) 2020-04-20 12:48:57 -07:00
Fangrui Song 232578804a [ELF] Add --warn-backrefs-exclude=<glob>
D77522 changed --warn-backrefs to not warn for linking sandwich
problems (-ldef1 -lref -ldef2). This removed lots of false positives.

However, glibc still has some problems. libc.a defines some symbols
which are normally in libm.a and libpthread.a, e.g. __isnanl/raise.

For a linking order `-lm -lpthread -lc`, I have seen:

```
// different resolutions: GNU ld/gold select libc.a(s_isnan.o) as the definition
backward reference detected: __isnanl in libc.a(printf_fp.o) refers to libm.a(m_isnanl.o)

// different resolutions: GNU ld/gold select libc.a(raise.o) as the definition
backward reference detected: raise in libc.a(abort.o) refers to libpthread.a(pt-raise.o)
```

To facilitate deployment of --warn-backrefs, add --warn-backrefs-exclude= so that
certain known issues (which may be impractical to fix) can be whitelisted.

Deliberate choices:

* Not a comma-separated list (`--warn-backrefs-exclude=liba.a,libb.a`).
  -Wl, splits the argument at commas, so we cannot use commas.
  --export-dynamic-symbol is similar.
* Not in the style of `--warn-backrefs='*' --warn-backrefs=-liba.a`.
  We just need exclusion, not inclusion. For easier build system
  integration, we should avoid order dependency. With the current
  scheme, we enable --warn-backrefs, and indivial libraries can add
  --warn-backrefs-exclude=<glob> to their LDFLAGS.

Reviewed By: psmith

Differential Revision: https://reviews.llvm.org/D77512
2020-04-20 07:52:15 -07:00
Peter Smith 61bccda9d9 [LLD][ELF][ARM] Convert ADR/LDR to .inst .reloc
After D78301 MC no longer emits a relocation for this case. Change to use
.inst and .reloc to synthesize the same instruction and relocation.
2020-04-20 13:59:05 +01:00