Commit Graph

6308 Commits

Author SHA1 Message Date
Fangrui Song 2fc704a0a5 [ELF] --emit-relocs: fix st_value of STT_SECTION in the presence of a gap before the first input section
In the presence of a gap, the st_value field of a STT_SECTION symbol is the
address of the first input section (incorrect if there is a gap). Set it to the
output section address instead.

In -r mode, this bug can cause an incorrect non-zero st_value of a STT_SECTION
symbol (while output sections have zero addresses, input sections may have
non-zero outSecOff).  The non-zero st_value can cause the final link to have
incorrect relocation computation (both GNU ld and LLD add st_value of the
STT_SECTION symbol to the output section address).

Reviewed By: grimar

Differential Revision: https://reviews.llvm.org/D90520
2020-11-02 08:37:15 -08:00
Sam Clegg 1800b44651 [lld][WebAssembly] Remove bad-reloc test
This test was checking behaviour that only exists in the debug
configuration so will fail in release builds.

Perhaps there is way to keep this test around and only run
it in debug builds but for now I'm removing so fix the
release builders.

Differential Revision: https://reviews.llvm.org/D90542
2020-10-31 16:42:55 -07:00
Reid Kleckner 09662eeb46 Fix lld/wasm test portability issue, and XFAIL the test
I don't see any warnings from lld.wasm locally. Needs more
investigation.
2020-10-31 11:19:28 -07:00
Ali Tamur ca55c99d56 [lld][WebAssembly] Do not specify temporary file name in tests.
bad-reloc.yaml test introduced at 9d1409df87 uses a name (out.wasm) to specify a
temporary output file name, which causes breakage in our system.
2020-10-30 18:27:28 -07:00
Sam Clegg 9d1409df87 [lld][WebAssembly] Give better warnings on bad relocation sites
Differential Revision: https://reviews.llvm.org/D90443
2020-10-30 10:11:04 -07:00
Wouter van Oortmerssen b8c2d60df5 [WebAssembly] Improved LLD error messages in case of mixed wasm32/wasm64 object files
Differential Revision: https://reviews.llvm.org/D90428
2020-10-29 17:15:59 -07:00
Fangrui Song ae73091f30 [ELF] -r: don't crash when a non-SHF_LINK_ORDER orphan is added before a SHF_LINK_ORDER orphan
Fixes https://github.com/ClangBuiltLinux/linux/issues/1186

If a non-SHF_LINK_ORDER orphan is added first, `firstIsec->flags & SHF_LINK_ORDER`
will be zero and we currently assert when calling `getLinkOrderDep`.

Reviewed By: grimar

Differential Revision: https://reviews.llvm.org/D90200
2020-10-28 08:56:42 -07:00
Sam Clegg 84129150ce [lld][WebAssembly] Fix memory size in dylink section for -pie exectuables
This field to represents the amount of static data needed by
an dynamic library or executable it should not include things
like heap or stack areas, which in the case of `-pie` are
not determined until runtime (e.g. __stack_pointer is imported).

Differential Revision: https://reviews.llvm.org/D90261
2020-10-27 16:05:52 -07:00
Benjamin Kramer 85e2af7ffe [lld][ELF] Don't write output to the test directory. NFC. 2020-10-26 18:10:31 +01:00
Fangrui Song 398b81067c [ELF] Don't crash on R_X86_64_GOTPCRELX for test/binop instructions
While MC did not produce R_X86_64_GOTPCRELX for test/binop instructions
(movl/adcl/addl/andl/...) before the previous commit, this code path has been
exercised by -fno-integrated-as for GNU as since 2016: -no-pie relaxing
may incorrectly access loc[-3] and produce a corrupted instruction.

Simply handle test/binop R_X86_64_GOTPCRELX like R_X86_64_GOTPCREL.
2020-10-24 15:14:17 -07:00
Fangrui Song 9267caebfa [ELF] Don't error on R_PPC64_REL24/R_PPC64_REL24_NOTOC referencing __tls_get_addr for missing R_PPC64_TLSGD/R_PPC64_TLSLD
This partially reverts D85994.

In glibc, elf/dl-sym.c calls the raw `__tls_get_addr` by specifying the
tls_index parameter. Such a call does not have a pairing R_PPC64_TLSGD/R_PPC64_TLSLD.
This is legitimate. Since we cannot distinguish the benign case from cases due
to toolchain issues, we have to be permissive.

Acked by Stefan Pintilie
2020-10-23 10:38:07 -07:00
Stefan Pintilie c6561ccfd9 [PowerPC][LLD] Support for PC Relative TLS for Local Dynamic
Add support to LLD for PC Relative Thread Local Storage for Local Dynamic.
This patch adds support for two relocations: R_PPC64_GOT_TLSLD_PCREL34 and
R_PPC64_DTPREL34.

The Local Dynamic code is:
```
pla r3, x@got@tlsld@pcrel        R_PPC64_GOT_TLSLD_PCREL34
bl __tls_get_addr@notoc(x@tlsld) R_PPC64_TLSLD
                                 R_PPC64_REL24_NOTOC
...
paddi r9, r3, x@dtprel           R_PPC64_DTPREL34
```

After relaxation to Local Exec:
```
paddi r3, r13, 0x1000
nop
...
paddi r9, r3, x@dtprel          R_PPC64_DTPREL34
```

Reviewed By: NeHuang, sfertile

Differential Revision: https://reviews.llvm.org/D87504
2020-10-23 08:23:56 -05:00
James Henderson 342040bf00 [lld][ELF][test] Add additional test coverage for LTO
These are all inspired by existing test coverage we have in an internal
testsuite.

Reviewed by: grimar, MaskRay

Differential Revision: https://reviews.llvm.org/D89775
2020-10-23 09:51:30 +01:00
Fangrui Song ce3c5dae06 [ELF] --warn-backrefs: save the referenced InputFile *
For a diagnostic `A refers to B` where B refers to a bitcode file, if the
symbol gets optimized out, the user may see `A refers to <internal>`; if the
symbol is retained, the user may see `A refers to lto.tmp`.

Save the reference InputFile * in the DenseMap so that the original filename is
available in reportBackrefs().
2020-10-22 15:27:19 -07:00
Fangrui Song a8f9f08018 [ELF] Set SHF_INFO_LINK for .rel[a].plt and .rel[a].dyn
The ELF spec says

> If the sh_flags field for this section header includes the attribute SHF_INFO_LINK, then this member represents a section header table index.

Set SHF_INFO_LINK so that binary manipulation tools know that sh_info is
a section header table index instead of (the number of local symbols in the case of SHT_SYMTAB/SHT_DYNSYM).
We have already added SHF_INFO_LINK for --emit-relocs retained SHT_REL[A].

For example, we can teach llvm-objcopy to preserve the section index of the sh_info referenced section if
SHF_INFO_LINK is set. (GNU objcopy recognizes .rel[a].plt and updates
sh_info even if SHF_INFO_LINK is not set).

Reviewed By: grimar, psmith

Differential Revision: https://reviews.llvm.org/D89828
2020-10-22 09:48:19 -07:00
Fangrui Song b6e4aae2cc [ELF] --gc-sections: retain dependent sections of non-SHF_ALLOC sections
Fix http://lists.llvm.org/pipermail/llvm-dev/2020-October/145908.html

Currently non-SHF_ALLOC SHT_REL[A] (due to --emit-relocs) and SHF_LINK_ORDER are not
marked live.

Reviewed By: grimar, psmith

Differential Revision: https://reviews.llvm.org/D89841
2020-10-21 10:11:26 -07:00
Fangrui Song 38b632c16e [ELF] --gdb-index: support --icf={safe,all}
The combination has not been tested before. In the case of ICF,
`e.section->getVA(0)` equals the start address of the output section.

This can cause incorrect overlapping with the actual function at the
start of the output section and potentially trigger a GDB internal error
in `dw2_find_pc_sect_compunit_symtab` (presumably because:
if a short address range incorrectly starts at the start address of the
output section, GDB may pick it instead of the correct longer address
range. When mapping an address within the long address range but
out of the scope of the short address range, the routine may find
nothing - while the code asserts that it can find something).

Note that in the case of ICF there may be duplicate address range entries,
but GDB appears to be fine with them.

Reviewed By: grimar

Differential Revision: https://reviews.llvm.org/D89751
2020-10-20 09:35:32 -07:00
Martin Storsjö 3785a413fe Reapply [LLD] [COFF] Implement a GNU/ELF like -wrap option
Add a simple forwarding option in the MinGW frontend, and implement
the private -wrap option in the COFF linker.

The feature in lld-link isn't gated by the -lldmingw option, but
the option is left as a private, undocumented option primarily
used by the MinGW driver.

The implementation is significantly based on the support for --wrap
in the ELF linker, but many small nuance details are different
between the ELF and COFF linkers, ending up with more than a few
implementation differences.

This fixes https://bugs.llvm.org/show_bug.cgi?id=47384.

Differential Revision: https://reviews.llvm.org/D89004

Reapplied with the bitfield member canInline fixed so it doesn't break
builds targeting windows.
2020-10-15 22:14:02 +03:00
Arthur Eubanks 3d338f6813 Revert "[LLD] [COFF] Implement a GNU/ELF like -wrap option"
This reverts commit a012c704b5.

Breaks Windows builds.

C:\src\llvm-mint\lld\COFF\Symbols.cpp(26,1): error: static_assert failed due to requirement 'sizeof(lld::coff::SymbolUnion) <= 48' "symbols should be optimized for memory usage"
static_assert(sizeof(SymbolUnion) <= 48,
2020-10-15 10:27:25 -07:00
Martin Storsjö a012c704b5 [LLD] [COFF] Implement a GNU/ELF like -wrap option
Add a simple forwarding option in the MinGW frontend, and implement
the private -wrap option in the COFF linker.

The feature in lld-link isn't gated by the -lldmingw option, but
the option is left as a private, undocumented option primarily
used by the MinGW driver.

The implementation is significantly based on the support for --wrap
in the ELF linker, but many small nuance details are different
between the ELF and COFF linkers, ending up with more than a few
implementation differences.

This fixes https://bugs.llvm.org/show_bug.cgi?id=47384.

Differential Revision: https://reviews.llvm.org/D89004
2020-10-15 18:34:02 +03:00
Andrew Ng 88ce27c39c [LLD][ELF] Improve ICF for relocations to ineligible sections via "aliases"
ICF was not able to merge equivalent sections because of relocations to
sections ineligible for ICF that use alternative symbols, e.g. symbol
aliases or section relative relocations.

Merging in this scenario has been enabled by giving the sections that
are ineligible for ICF a unique ID, i.e. an equivalence class of their
own. This approach also provides another benefit as it improves the
hashing that is used to perform the initial equivalance grouping for
ICF. This is because the ICF ineligible sections can now contribute a
unique value towards the hashes instead of the same value of zero. This
has been seen to reduce link time with ICF by ~68% for objects compiled
with -fprofile-instr-generate.

In order to facilitate this use of a unique ID, the existing
inconsistent approach to the setting of the InputSection eqClass in ICF
has been changed so that there is a clear distinction between the
eqClass values of ICF eligible sections and those of the ineligible
sections that have a unique ID. This inconsistency could have caused
incorrect equivalence class equality in the past, although it appears
that no issues were encountered in actual use.

Differential Revision: https://reviews.llvm.org/D88830
2020-10-15 12:43:14 +01:00
Luqman Aden 6a73d6564a [LLD] Set alignment as part of Characteristics in TLS table.
Fixes https://bugs.llvm.org/show_bug.cgi?id=46473

LLD wasn't previously specifying any specific alignment in the TLS table's Characteristics field so the loader would just assume the default value (16 bytes). This works most of the time except if you have thread locals that want specific higher alignments (e.g. 32 as in the bug) *even* if they specify an alignment on the thread local. This change updates LLD to take the max alignment from tls section.

Reviewed By: rnk

Differential Revision: https://reviews.llvm.org/D88637
2020-10-15 00:22:40 -07:00
Luqman Aden f87c98def8 Revert "[LLD] Set alignment as part of Characteristics in TLS table."
Revert individual wip commits and will instead follow up with a
single commit with all the changes. Makes cherry-picking easier
and will contain all the right tags.

This reverts commit 32a4ad3b6c.
This reverts commit 7fe13af676.
This reverts commit 51fbc1bef6.
This reverts commit f80950a8bb.
This reverts commit 0778cad9f3.
This reverts commit 8b70d527d7.
2020-10-15 00:21:36 -07:00
Luqman Aden f80950a8bb Update tests. 2020-10-14 19:34:32 -07:00
Konstantin Zhuravlyov 3fdf3b1539 AMDGPU: Update AMDHSA code object version handling
Differential Revision: https://reviews.llvm.org/D89076
2020-10-14 13:04:27 -04:00
Luqman Aden dc128e5968 [test][lld] Mark TLS tests as REQUIRES: x86.
Fixes http://lab.llvm.org:8011/#/builders/119/builds/92
2020-10-14 00:29:06 -07:00
Luqman Aden 6b7738e204 [LLD] Add baseline test for TLS alignment. NFC.
Reviewed By: rnk

Differential Revision: https://reviews.llvm.org/D88646
2020-10-13 20:53:32 -07:00
Alexandre Ganea 617d64f6c5 Re-land [ThinLTO] Re-order modules for optimal multi-threaded processing
This reverts 9b5b305023 and fixes the unwanted re-ordering when generating ThinLTO indexes.

The goal of this patch is to better balance thread utilization during ThinLTO in-process linking (in llvm-lto2 or in LLD). Before this patch, large modules would often be scheduled late during execution, taking a long time to complete, thus starving the thread pool.

We now sort modules in descending order, based on each module's bitcode size, so that larger modules are processed first. By doing so, smaller modules have a better chance to keep the thread pool active, and thus avoid starvation when the bitcode compilation is almost complete.

In our case (on dual Intel Xeon Gold 6140, Windows 10 version 2004, two-stage build), this saves 15 sec when linking `clang.exe` with LLD & -flto=thin, /opt:lldltojobs=all, no ThinLTO cache, -DLLVM_INTEGRATED_CRT_ALLOC=d:\git\rpmalloc.

Before patch: 100 sec
After patch: 85 sec

Inspired by the work done by David Callahan in D60495.

Differential Revision: https://reviews.llvm.org/D87966
2020-10-13 21:54:15 -04:00
Andrew Paverd cfd8481da1 Reland [CFGuard] Add address-taken IAT tables and delay-load support
This patch adds support for creating Guard Address-Taken IAT Entry Tables (.giats$y sections) in object files, matching the behavior of MSVC. These contain lists of address-taken imported functions, which are used by the linker to create the final GIATS table.
Additionally, if any DLLs are delay-loaded, the linker must look through the .giats tables and add the respective load thunks of address-taken imports to the GFIDS table, as these are also valid call targets.

Reviewed By: rnk

Differential Revision: https://reviews.llvm.org/D87544
2020-10-13 13:20:52 -07:00
Konstantin Zhuravlyov f218652a36 LLD/AMDGPU: Infer os abi based on input llvm bitcode
Differential Revision: https://reviews.llvm.org/D89042
2020-10-13 12:20:28 -04:00
Paulo Matos 388fb67b0d [WebAssembly] Added .tabletype to asm and multiple table support in obj files
Adds more testing in basic-assembly.s and a new test tables.s.
Adds support to yaml reading and writing of tables as well.

Differential Revision: https://reviews.llvm.org/D88815
2020-10-13 07:52:23 -07:00
Sam Clegg b3b4cda104 [lld][WebAssembly] Don't GC library objects under `--whole-archive`
Followup on https://reviews.llvm.org/D85062 which ignores
entire library objects when no symbols are used within them.
This is shouldn't apply with `--whole-archive` since this
is specified to treat them like direct object inputs.

Differential Revision: https://reviews.llvm.org/D89290
2020-10-12 21:19:19 -07:00
Dan Gohman 950ae43091 [WebAssembly] GC constructor functions in otherwise unused archive objects
This allows `__wasilibc_populate_libpreopen` to be GC'd in more cases
where it isn't needed, including when linked from Rust's libstd.

Differential Revision: https://reviews.llvm.org/D85062
2020-10-12 18:54:57 -07:00
Sam Clegg 2513407d39 [lld][WebAssembly] Add support for -Bsymbolic flag
This flag works in a similar way to the ELF linker in that it
will resolve any defined symbols to their local definition with
a shared library or -pie executable.

This flag has no effect on static linking.

Differential Revision: https://reviews.llvm.org/D89152
2020-10-12 17:25:04 -07:00
Fangrui Song db1988f038 [ELF] Don't change binding to STB_WEAK for an undefined specified by -u
Similar to D66992.
In GNU ld, a -u specified symbol is a STB_DEFAULT undefined.
It cannot be changed to STB_WEAK by a later STB_WEAK undefined in a regular object file.

The behavior is consistent with our model because -u means "we need to fetch a lazy definition".
It should not be altered just because there is also a STB_WEAK undefined.

Note, our -u semantics are still different from GNU ld (https://github.com/ClangBuiltLinux/linux/issues/515):
we don't force the specified symbol to appear in .symtab This is a deliberate decision.

Reviewed By: grimar

Differential Revision: https://reviews.llvm.org/D88945
2020-10-08 08:31:34 -07:00
Mateusz Mikuła 9b58b0c06e [LLD] Ignore ELF tests when ld.lld defaults to MinGW
Follow-up to D87418.

Differential Revision: https://reviews.llvm.org/D88991
2020-10-08 09:34:46 +03:00
Martin Storsjö 61e2f9fa2e [LLD] [MinGW] Support setting the subsystem version via the subsystem argument
If a version is specified both with --{major,minor}-subsystem-version and
with --subsystem <name>:<version>, the one specified last (that actually
sets a version) takes precedance in GNU ld; thus doing the same here.

Differential Revision: https://reviews.llvm.org/D88804
2020-10-05 23:08:08 +03:00
Martin Storsjö bc8f3b424c [LLD] [MinGW] Simplify handling of os/subsystem version
As they can be set independently after D88802, we can get rid of a bit
of extra code - simplifying the logic here before adding more
complication to it later.

Differential Revision: https://reviews.llvm.org/D88803
2020-10-05 23:08:02 +03:00
Martin Storsjö 45c4c54003 [LLD] [COFF] Add a private option for setting the os version separately from subsystem version
The MinGW driver has separate options for OS and subsystem version.
Having this available in lld-link allows the MinGW driver to both match
GNU ld better and simplifies the code for merging two (potentially
mismatching) arguments into one.

Differential Revision: https://reviews.llvm.org/D88802
2020-10-05 23:08:01 +03:00
Martin Storsjö 19e86336ef [LLD] [COFF] Fix parsing version numbers with leading zeros
Parse the components as decimal, instead of decuding the base from
the string. This avoids ambiguity if the second number contains leading
zeros, which previously were parsed as indicating an octal number.

MS link.exe doesn't support hexadecimal numbers in the version numbers,
neither in /version nor in /subsystem.

Differential Revision: https://reviews.llvm.org/D88801
2020-10-05 23:08:00 +03:00
Alexandre Ganea 55b97a6d2a [LLD][COFF] Add more type record information to /summary
This adds the following two new lines to /summary:

      21351 Input OBJ files (expanded from all cmd-line inputs)
         61 PDB type server dependencies
         38 Precomp OBJ dependencies
 1420669231 Input type records         <<<<
78665073382 Input type records bytes   <<<<
    8801393 Merged TPI records
    3177158 Merged IPI records
      59194 Output PDB strings
   71576766 Global symbol records
   25416935 Module symbol records
    2103431 Public symbol records

Differential Revision: https://reviews.llvm.org/D88703
2020-10-02 09:36:11 -04:00
Alexandre Ganea 4140f0744f [LLD][COFF] Fix crash with /summary and PCH input files
Before this patch /summary was crashing with some .PCH.OBJ files, because tpiMap[srcIdx++] was reading at the wrong location. When the TpiSource depends on a .PCH.OBJ file, the types should be offset by the previously merged PCH.OBJ set of indices.

Differential Revision: https://reviews.llvm.org/D88678
2020-10-01 17:08:35 -04:00
Fangrui Song 88f2fe5cad Raland D87318 [LLD][PowerPC] Add support for R_PPC64_GOT_TLSGD_PCREL34 used in TLS General Dynamic
Add Thread Local Storage support for the 34 bit relocation R_PPC64_GOT_TLSGD_PCREL34 used in General Dynamic.

The compiler will produce code that looks like:
```
pla r3, x@got@tlsgd@pcrel            R_PPC64_GOT_TLSGD_PCREL34
bl __tls_get_addr@notoc(x@tlsgd)     R_PPC64_TLSGD
                                     R_PPC64_REL24_NOTOC
```
LLD should be able to correctly compute the relocation for  R_PPC64_GOT_TLSGD_PCREL34 as well as do the following two relaxations where possible:
General Dynamic to Local Exec:
```
paddi r3, r13, x@tprel
nop
```
and General Dynamic to Initial Exec:
```
pld r3, x@got@tprel@pcrel
add r3, r3, r13
```
Note:
This patch adds support for the PC Relative (no TOC) version of General Dynamic on top of the existing support for the TOC version of General Dynamic.
The ABI does not provide any way to tell by looking only at the relocation `R_PPC64_TLSGD` when it is being used in a TOC instruction sequence or and when it is being used in a no TOC sequence. The TOC sequence should always be 4 byte aligned. This patch adds one to the offset of the relocation when it is being used in a no TOC sequence. In this way LLD can tell by looking at the alignment of the offset of `R_PPC64_TLSGD` whether or not it is being used as part of a TOC or no TOC sequence.

Reviewed By: NeHuang, sfertile, MaskRay

Differential Revision: https://reviews.llvm.org/D87318
2020-10-01 12:36:33 -07:00
Arthur Eubanks 499260c03b Revert "[CFGuard] Add address-taken IAT tables and delay-load support"
This reverts commit ef4e971e5e.
2020-10-01 11:29:54 -07:00
Stefan Pintilie 5f3e565f59 Revert "[LLD][PowerPC] Add support for R_PPC64_GOT_TLSGD_PCREL34 used in TLS General Dynamic"
This reverts commit 79122868f9.
2020-10-01 13:28:35 -05:00
Stefan Pintilie 79122868f9 [LLD][PowerPC] Add support for R_PPC64_GOT_TLSGD_PCREL34 used in TLS General Dynamic
Add Thread Local Storage support for the 34 bit relocation R_PPC64_GOT_TLSGD_PCREL34 used in General Dynamic.

The compiler will produce code that looks like:
```
pla r3, x@got@tlsgd@pcrel            R_PPC64_GOT_TLSGD_PCREL34
bl __tls_get_addr@notoc(x@tlsgd)     R_PPC64_TLSGD
                                     R_PPC64_REL24_NOTOC
```
LLD should be able to correctly compute the relocation for  R_PPC64_GOT_TLSGD_PCREL34 as well as do the following two relaxations where possible:
General Dynamic to Local Exec:
```
paddi r3, r13, x@tprel
nop
```
and General Dynamic to Initial Exec:
```
pld r3, x@got@tprel@pcrel
add r3, r3, r13
```
Note:
This patch adds support for the PC Relative (no TOC) version of General Dynamic on top of the existing support for the TOC version of General Dynamic.
The ABI does not provide any way to tell by looking only at the relocation `R_PPC64_TLSGD` when it is being used in a TOC instruction sequence or and when it is being used in a no TOC sequence. The TOC sequence should always be 4 byte aligned. This patch adds one to the offset of the relocation when it is being used in a no TOC sequence. In this way LLD can tell by looking at the alignment of the offset of `R_PPC64_TLSGD` whether or not it is being used as part of a TOC or no TOC sequence.

Reviewed By: NeHuang, sfertile, MaskRay

Differential Revision: https://reviews.llvm.org/D87318
2020-10-01 13:00:37 -05:00
James Henderson a20168d030 [Archive] Don't throw away errors for malformed archive members
When adding an archive member with a problem, e.g. a new bitcode with an
old archiver, containing an unsupported attribute, or an ELF file with a
malformed symbol table, the archiver would throw away the error and
simply add the member to the archive without any symbol entries. This
meant that the resultant archive could be silently unusable when not
using --whole-archive, and result in unexpected undefined symbols.

This change fixes this issue by addressing two FIXMEs and only throwing
away not-an-object errors. However, this meant that some LLD tests which
didn't need symbol tables and were using invalid members deliberately to
test the linker's malformed input handling no longer worked, so this
patch also stops the archiver from looking for symbols in an object if
it doesn't require a symbol table, and updates the tests accordingly.

Differential Revision: https://reviews.llvm.org/D88288

Reviewed by: grimar, rupprecht, MaskRay
2020-10-01 14:03:34 +01:00
Andrew Paverd ef4e971e5e [CFGuard] Add address-taken IAT tables and delay-load support
This patch adds support for creating Guard Address-Taken IAT Entry Tables (.giats$y sections) in object files, matching the behavior of MSVC. These contain lists of address-taken imported functions, which are used by the linker to create the final GIATS table.
Additionally, if any DLLs are delay-loaded, the linker must look through the .giats tables and add the respective load thunks of address-taken imports to the GFIDS table, as these are also valid call targets.

Reviewed By: rnk

Differential Revision: https://reviews.llvm.org/D87544
2020-10-01 12:45:07 +01:00
Fangrui Song 4e9277eda1 [ELF] --wrap: don't unnecessarily expose __real_
The routing rules are:

sym -> __wrap_sym
__real_sym -> sym

__wrap_sym and sym are routing targets, so they need to be exposed to the symbol
table. __real_sym is not and can be eliminated if not used by regular object.
2020-09-30 20:09:25 -07:00
Dan Gohman 6cd8511e59 [WebAssembly] New-style command support
This adds support for new-style command support. In this mode, all exports
are considered command entrypoints, and the linker inserts calls to
`__wasm_call_ctors` and `__wasm_call_dtors` for all such entrypoints.

This enables support for:

 - Command entrypoints taking arguments other than strings and return values
   other than `int`.
 - Multicall executables without requiring on the use of string-based
   command-line arguments.

This new behavior is disabled when the input has an explicit call to
`__wasm_call_ctors`, indicating code not expecting new-style command
support.

This change does mean that wasm-ld no longer supports DCE-ing the
`__wasm_call_ctors` function when there are no calls to it. If there are no
calls to it, and there are ctors present, we assume it's wasm-ld's job to
insert the calls. This seems ok though, because if there are ctors present,
the program is expecting them to be called. This change affects the
init-fini-gc.ll test.
2020-09-30 19:02:40 -07:00