Currently we have to set 'Machine' to something in our
YAML descriptions. Usually we use 'EM_X86_64' for 64-bit targets
and 'EM_386' for 32-bit targets. At the same time, in fact, in most
cases our tests do not need a machine type and we can use
'EM_NONE'.
This is cleaner, because avoids the need of using a particular machine.
In this patch I've made the 'Machine' key optional (the default value,
when it is not specified is `EM_NONE`) and removed it (where possible)
from yaml2obj, obj2yaml and llvm-readobj tests.
There are few tests left where I decided not to remove it, because
I didn't want to touch CHECK lines or doing anything more complex
than a removing a "Machine: *" line and formatting lines around.
Differential revision: https://reviews.llvm.org/D86202
We currently call the `llvm_unreachable` for the following YAML:
```
--- !ELF
FileHeader:
Class: ELFCLASS32
Data: ELFDATA2LSB
Type: ET_REL
Machine: EM_NONE
Flags: [ ]
```
it happens because the `Flags` key is present, though `EM_NONE` is a
machine type that has no known `EF_*` values and we call `llvm_unreachable` by mistake.
Differential revision: https://reviews.llvm.org/D86138
This adds the `ShType` key similar to others `Sh*` keys we have.
My use case is the following. Imagine we have a `SHT_SYMTAB_SHNDX`
section and want to hide it from a dumper. The natural way would be to
do something like:
```
- Name: .symtab_shndx
Type: [[TYPE=SHT_SYMTAB_SHNDX]]
Entries: [ 0, 1 ]
```
and then change the TYPE from `SHT_SYMTAB_SHNDX` to something else,
for example to `SHT_PROGBITS`.
But we have a problem: regular sections does not have `Entries` key,
so yaml2obj will be unable to produce a section.
The solution is to introduce a `ShType` key to override the final type.
This is not the first time I am facing the need to change the type. I
was able to invent workarounds or solved issues differently in the past,
but finally came to conclusion that we just should support the `ShType`.
Differential revision: https://reviews.llvm.org/D84738
This rewrites the mips-abiflags.test to stop using recompiled objects,
adds testing for all missed bits and also adds two missing enum values
to lib/ObjectYAML, which are used in the new test.
Differential revision: https://reviews.llvm.org/D83954
In D83482 we agreed to name e_* fields that are used for overriding
values (like e_phoff) as EPh* (e.g. EPhOff).
Currently we have a set of e_sh* fields that are named inconsistently
with this rule. This patch renames all of them.
Differential revision: https://reviews.llvm.org/D83766
Imagine we have an YAML description for some object and we want to
produce 2 outputs: with and without the section header.
A natural way to do it would look like:
```
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_REL
Machine: EM_X86_64
Sections:
...
SectionHeaderTable:
NoHeaders: [[NOHEADERS]]
```
But currently, we do not distinguish between no `NoHeaders` key case
and `NoHeaders == false`. Because of this we can't simply specify
`NOHEADERS = false`, as tool starts to complain.
With this patch the behavior changed. When we have:
```
SectionHeaderTable:
NoHeaders: false
```
it is the same as we have no `SectionHeaderTable` at all.
(`NoHeaders` key still can't be used with `Sections/Excluded` keys)
Differential revision: https://reviews.llvm.org/D83672
This adds `EPhOff`, `EPhEntSize` and `EPhNum` keys.
Will be useful for creating broken objects for testing llvm-readelf.
Differential revision: https://reviews.llvm.org/D83482
We have an issue currently. The following YAML piece just ignores the `Excluded` key.
```
SectionHeaderTable:
Sections: []
Excluded:
- Name: .foo
```
Currently the meaning is: exclude the whole table.
The code checks that the `Sections` key is empty and doesn't catch/check
invalid/duplicated/missed `Excluded` entries.
Also there is no way to exclude all sections except the first null section,
because `Sections: []` currently just excludes the whole the sections header table.
To fix it, I suggest a change of the behavior.
1) A new `NoHeaders` key is added. It provides an explicit syntax to drop the whole table.
2) The meaning of the following is changed:
```
SectionHeaderTable:
Sections: []
Excluded:
- Name: .foo
```
Assuming there are 2 sections in the object (a null section and `.foo`), with this patch it
means: exclude the `.foo` section, keep the null section. The null section is an implicit
section and I think it is reasonable to make "Sections: []" to mean it is implicitly added.
It will be consistent with the global "Sections" tag that is used to describe sections.
3) `SectionHeaderTable->Sections` is now optional. No `Sections` is the same as
`Sections: []` (I think it avoids a confusion).
4) Using of `NoHeaders` together with `Sections`/`Excluded` is not allowed.
5) It is possible to use the `Excluded` key without the `Sections` key now (in this case
`Excluded` must contain all sections).
6) `SectionHeaderTable:` or `SectionHeaderTable: []` is not allowed.
7) When the `SectionHeaderTable` key is present, we still require all sections to be
present in `Sections` and `Excluded` lists. No changes here, we are still strict.
Differential revision: https://reviews.llvm.org/D81655
This patch adds a new field `bool Is64bit` in `DWARFYAML::Data` to indicate the address size of target. It's helpful for inferring the `AddrSize` in some DWARF sections.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D81709
This implements a new "Excluded" key that can be used
to exclude entries from section header:
```
SectionHeaderTable:
Sections:
...
Excluded:
- Name: .foo
```
Differential revision: https://reviews.llvm.org/D81005
This patch helps infer the endianness of DWARF sections from `FileHeader`.
Reviewed By: jhenderson, grimar
Differential Revision: https://reviews.llvm.org/D81051
With the "SectionHeaderTable" it is now possible to reorder
entries in the section header table.
It also allows to stop emitting the table.
Differential revision: https://reviews.llvm.org/D80002
Summary:
Define ELF binary code for VE and modify code where should use this new code.
Depends on D79544.
Reviewed By: jhenderson
Differential Revision: https://reviews.llvm.org/D79545
Currently there is no good way to set a physical offset for a section:
* We have the `ShOffset` that allows to override the `sh_offset`, but
it does not affect the real data written.
* We can use a `Filler` to create an artificial gap, but it is more like a hack
rather than a proper solution for this problem.
This patch adds the `Offset` property which allows setting physical
offsets for sections.
It also generalizes the code, so that we set sh_offset field in one place
Differential revision: https://reviews.llvm.org/D78927
Leverage ARM ELF build attribute section to create ELF attribute section
for RISC-V. Extract the common part of parsing logic for this section
into ELFAttributeParser.[cpp|h] and ELFAttributes.[cpp|h].
Differential Revision: https://reviews.llvm.org/D74023
This patch makes `Relocation::Addend` to be `ELFYAML::YAMLIntUInt` and not `int64_t`.
`ELFYAML::YAMLIntUInt` it is a new type and it has the following benefits/features:
1) For an 64-bit object any hex/decimal addends
in the range [INT64_MIN, UINT64_MAX] is accepted.
2) For an 32-bit object any hex/decimal addends
in range [INT32_MIN, UINT32_MAX] is accepted.
3) Negative hex numbers like -0xffffffff are not accepted.
4) It is printed as decimal. I.e. obj2yaml will print
something like "Addend: 125", this matches the current behavior.
This fixes all FIXMEs in `relocation-addend.yaml`.
Differential revision: https://reviews.llvm.org/D75527
`PAddr` corresponds to `p_paddr` of a program header, which is the segment's physical
address for systems in which physical addressing is relevant. `p_paddr` is often equal
to `p_vaddr`, which is the virtual address of a segment.
This patch changes the default for `PAddr` from 0 to a value of `VAddr`.
Differential revision: https://reviews.llvm.org/D76131
Currently `yaml2obj` require `Offset` field in a relocation description.
There are many cases when `Offset` is insignificant in a context of a test case.
Making `Offset` optional allows to simplify our test cases.
This is what this patch does.
Also, with this patch `obj2yaml` does not dump a zero offset of a relocation.
Differential revision: https://reviews.llvm.org/D75608
I've noticed that it is not convenient to create YAMLs from
binaries (using obj2yaml) that have to be test cases for obj2yaml
later (after applying yaml2obj).
The problem, for example is that obj2yaml emits "DynamicSymbols:"
key instead of .dynsym. It also does not create .dynstr.
And when a YAML document without explicitly defined .dynsym/.dynstr
is given to yaml2obj, we have issues:
1) These sections are placed after non-allocatable sections (I've fixed it in D74756).
2) They have VA == 0. User needs create descriptions for such sections explicitly manually
to set a VA.
This patch addresses (2). I suggest to let yaml2obj assign virtual addresses by itself.
It makes an output binary to be much closer to "normal" ELF.
(It is still possible to use "Address: 0x0" for a section to get the original behavior
if it is needed)
Differential revision: https://reviews.llvm.org/D74764
Previously the description allowed to describe symbols with use of
`Name` and `Index` keys. This patch removes them and now it is still
possible to use either names or symbol indexes, but the code is simpler
and the format is slightly different.
Such a change will be useful for another patches, e.g:
https://reviews.llvm.org/D73788#inline-671077
Differential revision: https://reviews.llvm.org/D73888
Note: this is a reland with a trivial 2 lines fix in ELFState<ELFT>::writeSectionContent.
It adds a check similar to ones we already have for other sections to fix the case revealed
by bots, like http://lab.llvm.org:8011/builders/llvm-clang-lld-x86_64-scei-ps4-ubuntu-fast/builds/60744.
The encoded sequence of Elf*_Relr entries in a SHT_RELR section looks
like [ AAAAAAAA BBBBBBB1 BBBBBBB1 ... AAAAAAAA BBBBBB1 ... ]
i.e. start with an address, followed by any number of bitmaps. The address
entry encodes 1 relocation. The subsequent bitmap entries encode up to 63(31)
relocations each, at subsequent offsets following the last address entry.
More information is here:
https://github.com/llvm-mirror/llvm/blob/master/lib/Object/ELF.cpp#L272
This patch adds a support for these sections.
Differential revision: https://reviews.llvm.org/D71872
The encoded sequence of Elf*_Relr entries in a SHT_RELR section looks
like [ AAAAAAAA BBBBBBB1 BBBBBBB1 ... AAAAAAAA BBBBBB1 ... ]
i.e. start with an address, followed by any number of bitmaps. The address
entry encodes 1 relocation. The subsequent bitmap entries encode up to 63(31)
relocations each, at subsequent offsets following the last address entry.
More information is here:
https://github.com/llvm-mirror/llvm/blob/master/lib/Object/ELF.cpp#L272
This patch adds a support for these sections.
Differential revision: https://reviews.llvm.org/D71872
There was no way to set an unsupported or unknown OS ABI.
With this patch it is possible to use any numeric value.
Differential revision: https://reviews.llvm.org/D71765
Currently we have the `Flags` property that allows to
set flags for a section. The problem is that it does not
allow us to set an arbitrary value, because of bit fields
validation under the hood. An arbitrary values can be used
to test specific broken cases.
We probably do not want to relax the validation, so this
patch adds a `ShSize` property that allows to
override the `sh_size`. It is inline with others `Sh*` properties
we have already.
Differential revision: https://reviews.llvm.org/D71411
The PT_GNU_PROPERTY is generated by a linker to describe the
.note.gnu.property section. The Linux kernel uses this program header to
locate the .note.gnu.property section.
It is described in "The Linux gABI extension"
Include support for llvm-readelf, llvm-readobj and the yaml reader and
writers.
Differential Revision: https://reviews.llvm.org/D70959
This section contains strings specifying libraries to be added to the link by the linker.
The strings are encoded as standard null-terminated UTF-8 strings.
This patch adds a way to describe and dump SHT_LLVM_DEPENDENT_LIBRARIES sections.
I introduced a new YAMLFlowString type here. That used to teach obj2yaml to dump
them like:
```
Libraries: [ foo, bar ]
```
instead of the following (if StringRef would be used):
```
Libraries:
- foo
- bar
```
Differential revision: https://reviews.llvm.org/D70598
SHT_LLVM_LINKER_OPTIONS section contains pairs of null-terminated strings.
This patch adds support for them.
Differential revision: https://reviews.llvm.org/D69895
Currently there is no way to describe the data that is not a part of an output section.
It can be a data used to align sections or to fill the gaps with something,
or another kind of custom data. In this patch I suggest a way to describe it. It looks like that:
```
Sections:
- Type: CustomFiller
Pattern: "CCDD"
Size: 4
- Name: .bar
Type: SHT_PROGBITS
Content: "FF"
```
I.e. I've added a kind of synthetic section with a synthetic type "CustomFiller".
In the code it is called a "SyntheticFiller", which is "a synthetic section which
might be used to write the custom data around regular output sections. It does
not present in the sections header table, but it might affect the output file size and
program headers produced. Think about it as about piece of data."
`SyntheticFiller` currently has a `Pattern` field and a `Size` field + an optional `Name`.
When written, `Size` of bytes in the output will be filled with a `Pattern`.
It is possible to reference a named filler it by name from the program headers description,
just like any other normal section.
Differential revision: https://reviews.llvm.org/D69709
Currently, when we do not specify "Info" field in a YAML description
for SHT_GROUP section, yaml2obj reports an error:
"error: unknown symbol referenced: '' by YAML section '.group1'"
Also, we do not link it with a symbol table by default,
though it is what we do for AddrsigSection, HashSection, RelocationSection.
(http://www.sco.com/developers/gabi/latest/ch4.sheader.html#sh_link)
The patch fixes missings mentioned.
Differential revision: https://reviews.llvm.org/D69299
SHT_NOTE is the section that consists of
namesz, descsz, type, name + padding, desc + padding data.
This patch teaches yaml2obj, obj2yaml to dump and parse them.
This patch implements the section how it is described here:
https://docs.oracle.com/cd/E23824_01/html/819-0690/chapter6-18048.html
Which says: "For 64–bit objects and 32–bit objects, each entry is an array of 4-byte words in
the format of the target processor"
The official specification is different
http://www.sco.com/developers/gabi/latest/ch5.pheader.html#note_section
And says: "n 64-bit objects (files with e_ident[EI_CLASS] equal to ELFCLASS64), each entry is an array
of 8-byte words in the format of the target processor. In 32-bit objects (files with e_ident[EI_CLASS]
equal to ELFCLASS32), each entry is an array of 4-byte words in the format of the target processor"
Since LLVM uses the first, 32-bit way, this patch follows it.
Differential revision: https://reviews.llvm.org/D68983
It allows using "Size" with or without "Content" in YAML descriptions of
SHT_LLVM_ADDRSIG sections.
Differential revision: https://reviews.llvm.org/D68334
llvm-svn: 373610
This is a follow-up for D68085 which allows using "Size"
tag together with "Content" tag or alone.
Differential revision: https://reviews.llvm.org/D68216
llvm-svn: 373473
Currently we can't use unique suffixes in section names to describe
stack sizes sections. E.g. '.stack_sizes [1]' will be treated as a regular section.
This happens because we recognize stack sizes section by name and
do not yet drop the suffix before the check.
The patch fixes it.
Differential revision: https://reviews.llvm.org/D68018
llvm-svn: 372853
It is a follow-up requested in the review comment
for D67757. Allows to use Content + Size or just Size
when describing .stack_sizes sections in YAML document
Differential revision: https://reviews.llvm.org/D67958
llvm-svn: 372845
.stack_sizes is a SHT_PROGBITS section that contains pairs of
<address (4/8 bytes), stack size (uleb128)>.
This patch teach tools to parse and dump it.
Differential revision: https://reviews.llvm.org/D67757
llvm-svn: 372762
Currently when e_machine is set to something that is not supported by YAML lib,
then tools fail with llvm_unreachable.
In this patch I allow them to handle relocations in this case.
It can be used to dump and create objects for broken or unsupported targets.
Differential revision: https://reviews.llvm.org/D67657
llvm-svn: 372377
We do not support them and fail with llvm_unreachable currently.
This is not the only target we do not support and also seems we are missing
the tests for those we have already. But I needed this one for another patch,
so posted it separatelly.
Relocation names are taken from llvm\include\llvm\BinaryFormat\ELFRelocs\PowerPC64.def
Differential revision: https://reviews.llvm.org/D67615
llvm-svn: 372109
Currently we only allow using a known named constants
for `Machine` field in YAML documents.
This patch allows using any numbers (valid or "unknown")
and adds test cases for current and new functionality.
With this it is possible to write a test cases for really unknown
EM_* targets.
Differential revision: https://reviews.llvm.org/D67652
llvm-svn: 372108
`struct Elf*_Shdr` has a field `sh_offset`, named `ShOffset` in
llvm::ELFYAML::Section. Rename SHOffset (e_shoff) to SHOff to prevent confusion.
Reviewed By: grimar
Differential Revision: https://reviews.llvm.org/D67254
llvm-svn: 371185
See http://lists.llvm.org/pipermail/llvm-dev/2019-February/130583.html
and D60242 for the lld partition feature.
This patch:
* Teaches yaml2obj to parse the 3 section types.
* Teaches llvm-readobj/llvm-readelf to dump the 3 section types.
There is no test for SHT_LLVM_DEPENDENT_LIBRARIES in llvm-readobj. Add
it as well.
Reviewed By: thakis
Differential Revision: https://reviews.llvm.org/D67228
llvm-svn: 371157
Fix: added missing return "return 0;"
Original commit message:
This eliminates one of the error(1) call in this lib.
It is different from the others because happens on a fields mapping stage
and can be easily fixed.
Differential revision: https://reviews.llvm.org/D67150
llvm-svn: 371030
This eliminates one of the error(1) call in this lib.
It is different from the others because happens on a fields mapping stage
and can be easily fixed.
Differential revision: https://reviews.llvm.org/D67150
llvm-svn: 371023
PT_GNU_STACK is used in an llvm-objcopy test.
I plan to use PT_GNU_RELRO in a patch to improve nested segment
processing in llvm-objcopy (PR42963).
Reviewed By: grimar
Differential Revision: https://reviews.llvm.org/D67146
llvm-svn: 370857
This is in line with the previous changes which allowed to
override the sh_offset/sh_size and useful for writing test cases.
Differential revision: https://reviews.llvm.org/D66998
llvm-svn: 370633
Currenly we can encode the 'st_other' field of symbol using 3 fields.
'Visibility' is used to encode STV_* values.
'Other' is used to encode everything except the visibility, but it can't handle arbitrary values.
'StOther' is used to encode arbitrary values when 'Visibility'/'Other' are not helpfull enough.
'st_other' field is used to encode symbol visibility and platform-dependent
flags and values. Problem to encode it is that it consists of Visibility part (STV_* values)
which are enumeration values and the Other part, which is different and inconsistent.
For MIPS the Other part contains flags for all STO_MIPS_* values except STO_MIPS_MIPS16.
(Like comment in ELFDumper says: "Someones in their infinite wisdom decided to make
STO_MIPS_MIPS16 flag overlapped with other ST_MIPS_xxx flags."...)
And for PPC64 the Other part might actually encode any value.
This patch implements custom logic for handling the st_other and removes
'Visibility' and 'StOther' fields.
Here is an example of a new YAML style this patch allows:
- Name: foo
Other: [ 0x4 ]
- Name: bar
Other: [ STV_PROTECTED, 4 ]
- Name: zed
Other: [ STV_PROTECTED, STO_MIPS_OPTIONAL, 0xf8 ]
Differential revision: https://reviews.llvm.org/D66886
llvm-svn: 370472
This relands this commit, I mistakenly reverted the original change
thinking it was the cause of the observed MSan failures but it was not.
llvm-svn: 370206
This is a follow up discussed in the comments of D66583.
Currently, if for example, we have both StOther and Other set in YAML document for a symbol,
then yaml2obj reports an "unknown key 'Other'" error.
It happens because 'mapOptional()' is never called for 'Other/Visibility' in this case,
leaving those unhandled.
This message does not describe the reason of the error well. This patch fixes it.
Differential revision: https://reviews.llvm.org/D66642
llvm-svn: 370032
st_other field of a symbol usually contains its visibility.
Other bits are usually 0, though some targets, like
MIPS can set them using the named bit field values.
Problem is that there is no way to set an arbitrary value now,
though that might be useful for our test cases.
In this patch I introduced a way to set st_other to any numeric
value using the new StOther field.
I added a test and simplified the existent one to show the effect/benefit
Differential revision: https://reviews.llvm.org/D66583
llvm-svn: 369742
In some cases a symbol might have section index == SHN_XINDEX.
This is an escape value indicating that the actual section header index
is too large to fit in the containing field.
Then the SHT_SYMTAB_SHNDX section is used. It contains the 32bit values
that stores section indexes.
ELF gABI says that there can be multiple SHT_SYMTAB_SHNDX sections,
i.e. for example one for .symtab and one for .dynsym
(1) https://groups.google.com/forum/#!topic/generic-abi/-XJAV5d8PRg
(2) DT_SYMTAB_SHNDX: http://www.sco.com/developers/gabi/latest/ch5.dynamic.html
In this patch I am only supporting a single SHT_SYMTAB_SHNDX associated
with a .symtab. This is a more or less common case which is used a few tests I saw in LLVM.
I decided not to create the SHT_SYMTAB_SHNDX section as "implicit",
but implement is like a kind of regular section for now.
i.e. tools do not recreate this section or its content, like they do for
symbol table sections, for example. That should allow to write all kind of
possible broken test cases for our needs and keep the output closer to requested.
Differential revision: https://reviews.llvm.org/D65446
llvm-svn: 368272
There is no way to set broken sh_size field currently
for sections. It can be usefull for writing the
test cases.
Differential revision: https://reviews.llvm.org/D64401
llvm-svn: 365766
Some of our test cases are using objects which
has sections with a broken sh_offset field.
There was no way to set it from YAML until this patch.
Differential revision: https://reviews.llvm.org/D63879
llvm-svn: 364898
This allows setting different values for e_shentsize, e_shoff, e_shnum
and e_shstrndx fields and is useful for producing broken inputs for various
test cases.
Differential revision: https://reviews.llvm.org/D63771
llvm-svn: 364517
Summary:
The directive defines a symbol as an group/local memory (LDS) symbol.
LDS symbols behave similar to common symbols for the purposes of ELF,
using the processor-specific SHN_AMDGPU_LDS as section index.
It is the linker and/or runtime loader's job to "instantiate" LDS symbols
and resolve relocations that reference them.
It is not possible to initialize LDS memory (not even zero-initialize
as for .bss).
We want to be able to link together objects -- starting with relocatable
objects, but possible expanding to shared objects in the future -- that
access LDS memory in a flexible way.
LDS memory is in an address space that is entirely separate from the
address space that contains the program image (code and normal data),
so having program segments for it doesn't really make sense.
Furthermore, we want to be able to compile multiple kernels in a
compilation unit which have disjoint use of LDS memory. In that case,
we may want to place LDS symbols differently for different kernels
to save memory (LDS memory is very limited and physically private to
each kernel invocation), so we can't simply place LDS symbols in a
.lds section.
Hence this solution where LDS symbols always stay undefined.
Change-Id: I08cbc37a7c0c32f53f7b6123aa0afc91dbc1748f
Reviewers: arsenm, rampitec, t-tye, b-sumner, jsjodin
Subscribers: kzhuravl, jvesely, wdng, yaxunl, dstuttard, tpr, rupprecht, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D61493
llvm-svn: 364296
With this patch we get ability to set any flags we want
for implicit sections defined in YAML.
Differential revision: https://reviews.llvm.org/D63136
llvm-svn: 363367
This is a follow-up for D62809.
Content and Size fields should be optional as was discussed in comments
of the D62809's thread. With that, we can describe a specific string table and
symbol table sections in a more correct way and also show appropriate errors.
The patch adds lots of test cases where the behavior is described in details.
Differential revision: https://reviews.llvm.org/D62957
llvm-svn: 362931
In glibc, DT_PPC_GOT indicates that PowerPC32 Secure PLT ABI is used.
I plan to use it in D62464.
DT_PPC_OPT currently indicates if a TLSDESC inspired TLS optimization is
enabled.
Reviewed By: grimar, jhenderson, rupprecht
Differential Revision: https://reviews.llvm.org/D62851
llvm-svn: 362569
ELF for the 64-bit Arm Architecture defines two processor-specific dynamic
tags:
DT_AARCH64_BTI_PLT 0x70000001, d_val
DT_AARCH64_PAC_PLT 0x70000003, d_val
These presence of these tags indicate that PLT sequences have been
protected using Branch Target Identification and Pointer Authentication
respectively. The presence of both indicates that the PLT sequences have
been protected with both Branch Target Identification and Pointer
Authentication.
This patch adds the tags and tests for llvm-readobj and yaml2obj.
As some of the processor specific dynamic tags overlap, this patch splits
them up, keeping their original default value if they were not previously
mentioned explicitly in a switch case.
Differential Revision: https://reviews.llvm.org/D62596
llvm-svn: 362493
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
In some cases it is useful to explicitly set symbol's st_name value.
For example, I am using it in a patch for LLD to remove the broken
binary from a test case and replace it with a YAML test.
Differential revision: https://reviews.llvm.org/D61180
llvm-svn: 360137
Currently, YAML has the following syntax for describing the symbols:
Symbols:
Local:
LocalSymbol1:
...
LocalSymbol2:
...
...
Global:
GlobalSymbol1:
...
Weak:
...
GNUUnique:
I.e. symbols are grouped by their bindings. That is not very convenient,
because:
It does not allow to set a custom binding, what can be useful for producing
broken/special outputs for test cases. Adding a new binding would require to
change a syntax (what we observed when added GNUUnique recently).
It does not allow to change the order of the symbols in .symtab/.dynsym,
i.e. currently all Local symbols are placed first, then Global, Weak and GNUUnique
are following, but we are not able to change the order.
It is not consistent. Binding is just one of the properties of the symbol,
we do not group them by other properties.
It makes the code more complex that it can be. This patch shows it can be simplified
with the change performed.
The patch changes the syntax to just:
Symbols:
Symbol1:
...
Symbol2:
...
...
With that, we are able to work with the binding field just like with any other symbol property.
Differential revision: https://reviews.llvm.org/D60122
llvm-svn: 357595
yaml2obj currently derives the p_filesz, p_memsz, and p_offset values of
program headers from their sections. This makes writing tests for
certain formats more complex, and sometimes impossible. This patch
allows setting these fields explicitly, overriding the default value,
when relevant.
Reviewed by: jakehehrlich, Higuoxing
Differential Revision: https://reviews.llvm.org/D59372
llvm-svn: 356247
I need this to remove a binary from LLD test suite.
The patch also simplifies the code a bit.
Differential revision: https://reviews.llvm.org/D59082
llvm-svn: 355591
This is for tweaking SHT_SYMTAB sections.
Their sh_info contains the (number of symbols + 1) usually.
But for creating invalid inputs for test cases it would be convenient
to allow explicitly override this field from YAML.
Differential revision: https://reviews.llvm.org/D58779
llvm-svn: 355193
This allows tools to parse/dump the architecture specific tags
like DT_MIPS_*, DT_PPC64_* and DT_HEXAGON_*
Also fixes a bug in DynamicTags.def which was revealed in this patch.
Differential revision: https://reviews.llvm.org/D58667
llvm-svn: 354876
Recently, support was added to yaml2obj to allow dynamic sections to
have a list of entries, to make it easier to write tests with dynamic
sections. However, this change also removed the ability to provide
custom contents to the dynamic section, making it hard to test
malformed contents (e.g. because the section is not a valid size to
contain an array of entries). This change reinstates this. An error is
emitted if raw content and dynamic entries are both specified.
Reviewed by: grimar, ruiu
Differential Review: https://reviews.llvm.org/D58543
llvm-svn: 354770
In order to test tool handling of invalid section indexes, I need to
create an object containing such an invalid section index. I could
create a hex-edited binary, but having the ability to use yaml2obj is
preferable. Prior to this change, yaml2obj would reject any explicit
section indexes less than SHN_LORESERVE. This patch changes it to allow
any value.
I had to change the test to use llvm-readelf instead of llvm-readobj,
because llvm-readobj does not like invalid section indexes. I've also
expanded the test to show that the most common SHN_* values are accepted
(SHN_UNDEF, SHN_ABS, SHN_COMMON).
Reviewed by: grimar, jakehehrlich
Differential Revision: https://reviews.llvm.org/D58445
llvm-svn: 354566
yaml2obj/obj2yaml previously supported SHT_LOOS, SHT_HIOS, and
SHT_LOPROC for section types. These are simply values that delineate a
range and don't really make sense as valid values. For example if a
section has type value 0x70000000, obj2yaml shouldn't print this value
as SHT_LOPROC. Additionally, this was missing the three other range
markers (SHT_HIPROC, SHT_LOUSER and SHT_HIUSER).
This change removes these three range markers. It also adds support for
specifying the type as an integer, to allow section types that LLVM
doesn't know about.
Reviewed by: grimar
Differential Revision: https://reviews.llvm.org/D58383
llvm-svn: 354344
Fix:
Replace
assert(!IO.getContext() && "The IO context is initialized already");
with
assert(IO.getContext() && "The IO context is not initialized");
(this was introduced in r354329, where I tried to quickfix the darwin BB
and seems copypasted the assert from the wrong place).
Original commit message:
The section is described here:
https://refspecs.linuxfoundation.org/LSB_1.3.0/gLSB/gLSB/symverrqmts.html
Patch just teaches obj2yaml/yaml2obj to dump and parse such sections.
We did the finalization of string tables very late,
and I had to move the logic to make it a bit earlier.
That was needed in this patch since .gnu.version_r adds strings to .dynstr.
This might also be useful for implementing other special sections.
Everything else changed in this patch seems to be straightforward.
Differential revision: https://reviews.llvm.org/D58119
llvm-svn: 354335
Georgii Rymar