Adds Wrapper classes for MCSymbol and MCSection into the XCOFF target
object writer. Also adds a class to represent the top-level sections, which we
materialize in the ObjectWriter.
executePostLayoutBinding will map all csects into the appropriate
container depending on its storage mapping class, and map all symbols
into their containing csect. Once all symbols have been processed we
- Assign addresses and symbol table indices.
- Calaculte section sizes.
- Build the section header table.
- Assign the sections raw-pointer value for non-virtual sections.
Since the .bss section is virtual, writing the header table is enough to
add support. Writing of a sections raw data, or of any relocations is
not included in this patch.
Testing is done by dumping the section header table, but it needs to be
extended to include dumping the symbol table once readobj support for
dumping auxiallary entries lands.
Differential Revision: https://reviews.llvm.org/D65159
llvm-svn: 369454
Debug sections are special in that they can contain relocations against
symbols that are not present in the final output (i.e. not live).
However it is also possible to have R_WASM_TABLE_INDEX relocations
against symbols that don't have a table index assigned (since they are
not address taken by actual code.
Fixes: https://github.com/emscripten-core/emscripten/issues/9023
Differential Revision: https://reviews.llvm.org/D66435
llvm-svn: 369423
The hack dated back to 2010 (r121076) and was documented by r122144:
// FIXME: The use if InSet = Addrs is a hack. Setting InSet causes us
// absolutize differences across sections and that is what the MachO writer
// uses Addrs for.
llvm-svn: 369337
WebAssembly doesn't support PC relative relocation or relocation
expressions that can't be reduced to single symbol.
The only support for we have for fixups involving two symbols are when
both symbols are defined and withing the same section. In this case
evaluateFixup will already have evaluated to the expression before
calling recordRelocation.
llvm-svn: 369317
Replace
- error: No relocation available to represent this relative expression
with
+ error: symbol 'undef' can not be undefined in a subtraction expression
or
+ error: Cannot represent a difference across sections
Keep !IsPcRel as an assertion after the two diagnostic checks are done.
llvm-svn: 369239
GNU as keeps the original symbol in the symbol table for defined @ and
@@, but suppresses it in other cases (@@@ or undefined). The original
symbol is usually undesired:
In a shared object, the original symbol can be localized with a version
script, but it is hard to remove/localize in an archive:
1) a post-processing step removes the undesired original symbol
2) consumers (executable) of the archive are built with the
version script
Moreover, it can cause linker issues like binutils PR/18703 if the
original symbol name and the base name of the versioned symbol is the
same (both ld.bfd and gold have some code to work around defined @ and
@@). In lld, if it sees f and f@v1:
--version-script =(printf 'v1 {};') => f and f@v1
--version-script =(printf 'v1 { f; };') => f@v1 and f@@v1
It can be argued that @@@ added on 2000-11-13 corrected the @ and @@ mistake.
This patch catches some more multiple version errors (defined @ and @@),
and consistently suppress the original symbol. This addresses all the
problems listed above.
If the user wants other aliases to the versioned symbol, they can copy
the original symbol to other symbol names with .set directive, e.g.
.symver f, f@v1 # emit f@v1 but not f into .symtab
.set f_impl, f # emit f_impl into .symtab
llvm-svn: 369233
Now that we've moved to C++14, we no longer need the llvm::make_unique
implementation from STLExtras.h. This patch is a mechanical replacement
of (hopefully) all the llvm::make_unique instances across the monorepo.
llvm-svn: 369013
Addresses post-commit comments on https://reviews.llvm.org/D64825. Use
assert instead of llvm_unreachable to check if invalid csect types are being
generated. Use report_fatal_error on unimplemented XCOFF features.
Differential Revision: https://reviews.llvm.org/D64825
llvm-svn: 368720
Summary:
This patch keeps track of MCSymbols created for blocks that were
referenced in inline asm. It prevents creating a new symbol which
doesn't refer to the block.
Inline asm may have a reference to a label. The asm parser however
doesn't recognize it as a label and tries to create a new symbol. The
result being that instead of the original symbol (e.g. ".Ltmp0") the
parser replaces it in the inline asm with the new one (e.g. ".Ltmp00")
without updating it in the symbol table. So the machine basic block
retains the "old" symbol (".Ltmp0"), but the inline asm uses the new one
(".Ltmp00").
Reviewers: nickdesaulniers, craig.topper
Subscribers: nathanchance, javed.absar, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65304
llvm-svn: 368477
Summary:
This patch enable assembly output of local commons for AIX using .lcomm
directives. Adds a EmitXCOFFLocalCommonSymbol to MCStreamer so we can emit the
AIX version of .lcomm assembly directives which include a csect name. Handle the
case of BSS locals in PPCAIXAsmPrinter by using EmitXCOFFLocalCommonSymbol. Adds
a test for generating .lcomm on AIX Targets.
Reviewers: cebowleratibm, hubert.reinterpretcast, Xiangling_L, jasonliu, sfertile
Reviewed By: sfertile
Subscribers: wuzish, nemanjai, hiraditya, kbarton, MaskRay, jsji, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D64825
llvm-svn: 368306
This patch replaces a TODO comment with a call to `report_fatal_error`.
The path that reaches the added call to `report_fatal_error` manifestly
dereferences a null pointer.
llvm-svn: 368048
Summary:
As part of this, define DenseMapInfo for MCRegister (and Register while I'm at it)
Depends on D65599
Reviewers: arsenm
Subscribers: MatzeB, qcolombet, jvesely, wdng, nhaehnle, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65605
llvm-svn: 367719
Addresses number of comment made on D64652 after commiting:
- Reorders function decls in the TargetLoweringObjectFileXCOFF class.
- Fix comment in MCSectionXCOFF to include description of external reference
csects.
- Convert several llvm_unreachables to report_fatal_error
- Convert several dyn_casts to casts as they are expected not to fail.
- Avoid copying DataLayout object.
llvm-svn: 367324
Summary:
Add a new method which tries to compute the target address referenced by an operand.
This patch supports x86_64 RIP-relative addressing for now.
It is necessary to print referenced symbol names in llvm-objdump.
Reviewers: andreadb, MaskRay, grosbach, jgalenson, craig.topper
Reviewed By: MaskRay, craig.topper
Subscribers: bcain, rupprecht, jhenderson, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63847
llvm-svn: 366987
Stubs out a TargetLoweringObjectFileXCOFF class, implementing only
SelectSectionForGlobal for common symbols. Also adds an override of
EmitGlobalVariable in PPCAIXAsmPrinter which adds a number of defensive errors
and adds support for emitting common globals.
llvm-svn: 366727
This reverts commit r366686 as it appears to be causing buildbot
failures on sanitizer-x86_64-linux-android and sanitizer-x86_64-linux.
llvm-svn: 366708
This patch was not the reason of the buildbot failure.
Deleted code was introduced as a work around for a bug in the gold linker
(http://sourceware.org/PR16794). Test case that was given as a reason for
this part of code, the one on previous link, now works for the gold.
This condition is too strict and when a code is compiled with debug info
it forces generation of numerous relocations with symbol for architectures
that do not have relocation addend.
Reviewers: arsenm, espindola
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D64327
llvm-svn: 366686
In debug frame information, some fields, e.g., Length in CIE/FDE and
Offset in FDE are attributes to describe the structure of CIE/FDE. They
are not related to the relaxed code. However, these attributes are
symbol differences. So, in current design, these attributes will be
filled as zero and LLVM generates relocations for them.
We only need to generate relocations for symbols in executable sections.
So, if the symbols are not located in executable sections, we still
evaluate their values under relaxation.
Differential Revision: https://reviews.llvm.org/D61584
llvm-svn: 366531
It is necessary to generate fixups in .debug_frame or .eh_frame as
relaxation is enabled due to the address delta may be changed after
relaxation.
There is an opcode with 6-bits data in debug frame encoding. So, we
also need 6-bits fixup types.
Differential Revision: https://reviews.llvm.org/D58335
llvm-svn: 366524
It is necessary to generate fixups in .debug_frame or .eh_frame as
relaxation is enabled due to the address delta may be changed after
relaxation.
There is an opcode with 6-bits data in debug frame encoding. So, we
also need 6-bits fixup types.
Differential Revision: https://reviews.llvm.org/D58335
llvm-svn: 366442
assembly command
'macCatalyst' is more readable than 'maccatalyst'. I renamed the objdump output,
but the assembly should match it as well.
llvm-svn: 365964
Rework the TTI cache and software prefetching APIs to prepare for the
introduction of a general system model. Changes include:
- Marking existing interfaces const and/or override as appropriate
- Adding comments
- Adding BasicTTIImpl interfaces that delegate to a subtarget
implementation
- Adding a default "no information" subtarget implementation
Only a handful of targets use these interfaces currently: AArch64,
Hexagon, PPC and SystemZ. AArch64 already has a custom subtarget
implementation, so its custom TTI implementation is migrated to use
the new facilities in BasicTTIImpl to invoke its custom subtarget
implementation. The custom TTI implementations continue to exist for
the other targets with this change. They are not moved over to
subtarget-based implementations.
The end goal is to have the default subtarget implementation defer to
the system model defined by the target. With this change, the default
subtarget implementation essentially returns "no information" for
these interfaces. None of the existing users of TTI will hit that
implementation because they define their own custom TTI
implementations and won't use the BasicTTIImpl implementations.
Once system models are in place for the targets that use these
interfaces, their custom TTI implementations can be removed.
Differential Revision: https://reviews.llvm.org/D63614
llvm-svn: 365676
Deleted code was introduced as a work around for a bug in the gold linker
(http://sourceware.org/PR16794). Test case that was given as a reason for
this part of code, the one on previous link, now works for the gold.
This condition is too strict and when a code is compiled with debug info
it forces generation of numerous relocations with symbol for architectures
that do not have relocation addend.
Reviewers: arsenm, espindola
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D64327
llvm-svn: 365618
Stubs out a number of the classes needed to produce a new object file format
(XCOFF) for the powerpc-aix target. For testing input is an empty module which
produces an object file with just a file header.
Differential Revision: https://reviews.llvm.org/D61694
llvm-svn: 365541
Summary:
This makes it so that IR files using triples without an environment work
out of the box, without normalizing them.
Typically, the MSVC behavior is more desirable. For example, it tends to
enable things like constant merging, use of associative comdats, etc.
Addresses PR42491
Reviewers: compnerd
Subscribers: hiraditya, dexonsmith, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D64109
llvm-svn: 365387
Mac Catalyst is a new MachO platform in macOS Catalina.
It always uses the build_version MachO load command.
Differential Revision: https://reviews.llvm.org/D64107
llvm-svn: 364981
Summary:
These are output by clang -S, so can now be roundtripped thru clang.
(partially) fixes: https://bugs.llvm.org/show_bug.cgi?id=34544
Reviewers: dschuff
Subscribers: sbc100, jgravelle-google, aheejin, sunfish, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63901
llvm-svn: 364658
The weak alias should have the characteristics set to
`IMAGE_EXTERN_WEAK_SEARCH_ALIAS` to indicate that the weak external here
is a symbol alias and that the symbol is aliased to a locally defined
symbol. We were previously setting the characteristics to
`IMAGE_EXTERN_WEAK_SEARCH_LIBRARY` which indicates that the symbol
should be looked for in the libraries.
llvm-svn: 364370
Summary:
The list of relocations with addend in lld was missing `R_WASM_MEMORY_ADDR_REL_SLEB`,
causing `wasm-ld` to generate corrupted output. This fixes that problem and while
we're at it pulls the list of such relocations into the Wasm.h header, to avoid
duplicating it in multiple places.
Reviewers: sbc100
Differential Revision: https://reviews.llvm.org/D63696
llvm-svn: 364367
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
llvm-mc or clang with -g normally produces debug info describing the
assembler source itself; however, if that source already contains some
.file/.loc directives, we should instead emit the debug info described
by those directives. For certain assembler sources seen in the wild
(particularly in the Chrome build) this was causing a crash due to
incorrect assumptions about legal sequences of assembler source text.
Fixes PR38994.
Differential Revision: https://reviews.llvm.org/D63573
llvm-svn: 364039
This patch allows clang users to print out a list of supported CPU models using
clang [--target=<target triple>] --print-supported-cpus
Then, users can select the CPU model to compile to using
clang --target=<triple> -mcpu=<model> a.c
It is a handy feature to help cross compilation.
llvm-svn: 363464
We should keep the symbol type (STT_GNU_IFUNC) for a local ifunc because
it may result in an IRELATIVE reloc that the dynamic loader will use to
resolve the address at startup time.
There is another problem that is not fixed by this patch: a PC relative
relocation should also create a relocation with the ifunc symbol.
llvm-svn: 362767
Summary:
(1) Function descriptor on AIX
On AIX, a called routine may have 2 distinct symbols associated with it:
* A function descriptor (Name)
* A function entry point (.Name)
The descriptor structure on AIX is the same as those in the ELF V1 ABI:
* The address of the entry point of the function.
* The TOC base address for the function.
* The environment pointer.
The descriptor symbol uses the same name as the source level function in C.
The function entry point is analogous to the symbol we would generate for a
function in a non-descriptor-based ABI, except that it is renamed by
prepending a ".".
Which symbol gets referenced depends on the context:
* Taking the address of the function references the descriptor symbol.
* Calling the function references the entry point symbol.
(2) Speaking of implementation on AIX, for direct function call target, we
create proper MCSymbol SDNode(e.g . ".foo") while constructing SDAG to
replace original TargetGlobalAddress SDNode. Then down the path, we can
take advantage of this MCSymbol.
Patch by: Xiangling_L
Reviewed by: sfertile, hubert.reinterpretcast, jasonliu, syzaara
Differential Revision: https://reviews.llvm.org/D62532
llvm-svn: 362735
Testing with debuggers shows that our previous behavior was correct.
The reason I thought MSVC did things differently is that MSVC prefers to
use the 0xB combined code offset and code length update opcode when
inline sites are discontiguous.
Keep the test changes, and update the llvm-pdbutil inline line table
dumper to account for this new interpretation of the opcodes.
llvm-svn: 362277
After improving the inline line table dumper in llvm-pdbutil and looking
at MSVC's inline line tables, it is clear that setting the length of the
inlined code region does not update the code offset. This means that the
delta to the beginning of a new discontiguous inlined code region should
be calculated relative to the last code offset, excluding the length.
Implementing this is a one line fix for MC: simply don't update
LastLabel.
While I'm updating these test cases, switch them to use llvm-objdump -d
and llvm-pdbutil. This allows us to show offsets of each instruction and
correlate the line table offsets to the actual code.
llvm-svn: 362264
D18885 emitted 5 bytes for call *foo@tlsdesc(%rax). It should use the
2-byte form instead and let R_X86_64_TLSDESC_CALL apply to the beginning
of the call instruction.
The 2-byte form was deliberately chosen to make ->LE and ->IE relaxation work:
0: 48 8d 05 00 00 00 00 lea 0x0(%rip),%rax # 7 <.text+0x7>
3: R_X86_64_GOTPC32_TLSDESC a-0x4
7: ff 10 callq *(%rax)
7: R_X86_64_TLSDESC_CALL a
=>
0: 48 c7 c0 fc ff ff ff mov $0xfffffffffffffffc,%rax
7: 66 90 xchg %ax,%ax
Also change the symbol type to STT_TLS when VK_TLSCALL or VK_TLSDESC is
seen.
Reviewed By: compnerd
Differential Revision: https://reviews.llvm.org/D62512
llvm-svn: 361910
Those two subtarget features were awkward because their semantics are
reversed: each one indicates the _lack_ of support for something in
the architecture, rather than the presence. As a consequence, you
don't get the behavior you want if you combine two sets of feature
bits.
Each SubtargetFeature for an FP architecture version now comes in four
versions, one for each combination of those options. So you can still
say (for example) '+vfp2' in a feature string and it will mean what
it's always meant, but there's a new string '+vfp2d16sp' meaning the
version without those extra options.
A lot of this change is just mechanically replacing positive checks
for the old features with negative checks for the new ones. But one
more interesting change is that I've rearranged getFPUFeatures() so
that the main FPU feature is appended to the output list *before*
rather than after the features derived from the Restriction field, so
that -fp64 and -d32 can override defaults added by the main feature.
Reviewers: dmgreen, samparker, SjoerdMeijer
Subscribers: srhines, javed.absar, eraman, kristof.beyls, hiraditya, zzheng, Petar.Avramovic, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D60691
llvm-svn: 361845
This provides the correct file path for the original source, rather
than the preprocessed source.
Part of the fix for PR41839.
Differential Revision: https://reviews.llvm.org/D62074
llvm-svn: 361248
This option provides only the base filename, not a full relative path.
Part of the fix for PR41839.
Differential Revision: https://reviews.llvm.org/D62071
llvm-svn: 361245
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
R_ARM_NONE can be used to create references among sections. When
--gc-sections is used, the referenced section will be retained if the
origin section is retained.
Add a generic MCFixupKind FK_NONE as this kind of no-op relocation is
ubiquitous on ELF and COFF, and probably available on many other binary
formats. See D62014.
Reviewed By: peter.smith
Differential Revision: https://reviews.llvm.org/D61992
llvm-svn: 360980
On PowerPC64 ELFv2 ABI, the top 3 bits of st_other encode the local
entry offset. A versioned symbol alias created by .symver should copy
the bits from the source symbol.
This partly fixes PR41048. A full fix needs tracking of .set assignments
and updating st_other fields when finish() is called, see D56586.
Patch by Alfredo Dal'Ava Júnior
Differential Revision: https://reviews.llvm.org/D59436
llvm-svn: 360442
The primary fix here is to WinException.cpp: we need to exclude jump
tables when computing the length of a function, or else we fail to
correctly compute the length. (We can only compute the number of bytes
consumed by certain assembler directives after the entire file is
parsed. ".p2align" is one of those directives, and is used by jump table
generation.)
The secondary fix, to MCWin64EH, is to make sure we don't silently
miscompile if we hit a similar situation in the future.
It's possible we could extend ARM64EmitUnwindInfo so it allows function
bodies that contain assembler directives, but that's a lot more
complicated; see the FIXME in MCWin64EH.cpp.
Fixes https://bugs.llvm.org/show_bug.cgi?id=41581 .
Differential Revision: https://reviews.llvm.org/D61095
llvm-svn: 359849
About the compressed sections spec says:
(https://docs.oracle.com/cd/E37838_01/html/E36783/section_compression.html)
sh_addralign fields of the section header for a compressed section
reflect the requirements of the compressed section.
Currently, llvm-mc always puts uncompressed section alignment to sh_addralign.
It is not correct. zlib styled section contains an Elfxx_Chdr header,
so we should either use 4 or 8 values depending on the target
(Uncompressed section alignment is stored in ch_addralign field of the compression header).
GNU assembler version 2.31.1 also has this issue,
but in 2.32.51 it was already fixed. This is how it was found
during debugging of the https://bugs.llvm.org/show_bug.cgi?id=40482
actually.
Differential revision: https://reviews.llvm.org/D60965
llvm-svn: 358960
Another attempt to land the changes in debug line header to prevent duplicate
files in Dwarf 5. I rolled back my previous commit because of a mistake in
generating the object file in a test. Meanwhile, I addressed some offline
comments and changed the implementation; the largest difference is that
MCDwarfLineTableHeader does not keep DwarfVersion but gets it as a parameter. I
also merged the patch to fix two lld tests that will strt to fail into this
patch.
Original Commit:
https://reviews.llvm.org/D59515
Original Message:
Motivation: In previous dwarf versions, file name indexes started from 1, and
the primary source file was not explicit. Dwarf 5 standard (6.2.4) prescribes
the primary source file to be explicitly given an entry with an index number 0.
The current implementation honors the specification by just duplicating the
main source file, once with index number 0, and later maybe with another
index number. While this is compliant with the letter of the standard, the
duplication causes problems for consumers of this information such as lldb.
(Some files are duplicated, where only some of them have a line table although
all refer to the same file)
With this change, dwarf 5 debug line section files always start from 0, and
the zeroth entry is not duplicated whenever possible. This requires different
handling of dwarf 4 and dwarf 5 during generation (e.g. when a function returns
an index zero for a file name, it signals an error in dwarf 4, but not in dwarf
5) However, I think the minor complication is worth it, because it enables all
consumers (lldb, gdb, dwarfdump, objdump, and so on) to treat all files in the
file name list homogenously.
llvm-svn: 358732
Summary:
This ensures that object files will continue to validate as
WebAssembly modules in the presence of bulk memory operations. Engines
that don't support bulk memory operations will not recognize the
DataCount section and will report validation errors, but that's ok
because object files aren't supposed to be run directly anyway.
Reviewers: aheejin, dschuff, sbc100
Subscribers: jgravelle-google, hiraditya, sunfish, rupprecht, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D60623
llvm-svn: 358315
the MCDwarf.h include.
This removes 50 transitive dependencies for a modification of
MCDwarf.h in a build of llc for a pair of out of line functions
and reduces the build overhead of 'touch MCDwarf.h" by 15% without
impacting test time of check-llvm.
llvm-svn: 358264
This removes 50 transitive dependencies for a modification of
MCDwarf.h in a build of llc for a single out of line function
and reduces the build overhead by 20% without impacting test
time of check-llvm.
llvm-svn: 358258
This special section is named .symtab_shndx, according to gABI Chapter 4
Sections, and the name is used by some other tools. Though the section
type SHT_SYMTAB_SHNDX is what really matters, let's fix the typo
introduced in rL204769 :)
llvm-svn: 358247
This patch has three related fixes to improve float literal lexing:
1. Make AsmLexer::LexDigit handle floats without a decimal point more
consistently.
2. Make AsmLexer::LexFloatLiteral print an error for floats which are
apparently missing an "e".
3. Make APFloat::convertFromString use binutils-compatible exponent
parsing.
Together, this fixes some cases where a float would be incorrectly
rejected, fixes some cases where the compiler would crash, and improves
diagnostics in some cases.
Patch by Brandon Jones.
Differential Revision: https://reviews.llvm.org/D57321
llvm-svn: 357214
These fixup kinds are not explicitly related to the code section. They
are there to signal how to apply the fixup.
Also, a couple of other minor wasm cleanups.
Differential Revision: https://reviews.llvm.org/D59908
llvm-svn: 357145
A section containing metadata on remark diagnostics will be emitted if
the flag (-mllvm) -remarks-section is present.
For now, the metadata is:
* a magic number for remarks: "REMARKS\0"
* the version number: a little-endian uint64_t
* the absolute file path to the serialized remark diagnostics: a
null-terminated string.
Differential Revision: https://reviews.llvm.org/D59571
llvm-svn: 357043
This reverts commit rL357020.
The commit broke the test llvm/test/tools/llvm-objdump/embedded-source.test
on some builds including clang-ppc64be-linux-multistage,
clang-s390x-linux, clang-with-lto-ubuntu, clang-x64-windows-msvc,
llvm-clang-lld-x86_64-scei-ps4-windows10pro-fast (and others).
llvm-svn: 357026
This change implements lowering of references global symbols in PIC
mode.
This change implements lowering of global references in PIC mode using a
new @GOT reference type. @GOT references can be used with function or
data symbol names combined with the get_global instruction. In this case
the linker will insert the wasm global that stores the address of the
symbol (either in memory for data symbols or in the wasm table for
function symbols).
For now I'm continuing to use the R_WASM_GLOBAL_INDEX_LEB relocation
type for this type of reference which means that this relocation type
can refer to either a global or a function or data symbol. We could
choose to introduce specific relocation types for GOT entries in the
future. See the current dynamic linking proposal:
https://github.com/WebAssembly/tool-conventions/blob/master/DynamicLinking.md
Differential Revision: https://reviews.llvm.org/D54647
llvm-svn: 357022
Reapply rL356941 after regenerating the object file in the failing test
llvm/test/tools/llvm-objdump/embedded-source.test from source.
Original commit message:
[llvm] Prevent duplicate files in debug line header in dwarf 5.
Motivation: In previous dwarf versions, file name indexes started from 1, and
the primary source file was not explicit. Dwarf 5 standard (6.2.4) prescribes
the primary source file to be explicitly given an entry with an index number 0.
The current implementation honors the specification by just duplicating the
main source file, once with index number 0, and later maybe with another
index number. While this is compliant with the letter of the standard, the
duplication causes problems for consumers of this information such as lldb.
(Some files are duplicated, where only some of them have a line table although
all refer to the same file)
With this change, dwarf 5 debug line section files always start from 0, and
the zeroth entry is not duplicated whenever possible. This requires different
handling of dwarf 4 and dwarf 5 during generation (e.g. when a function returns
an index zero for a file name, it signals an error in dwarf 4, but not in dwarf 5)
However, I think the minor complication is worth it, because it enables all
consumers (lldb, gdb, dwarfdump, objdump, and so on) to treat all files in the
file name list homogenously.
Tags: #llvm, #debug-info
Differential Revision: https://reviews.llvm.org/D59515
llvm-svn: 357018
Summary:
Motivation: In previous dwarf versions, file name indexes started from 1, and
the primary source file was not explicit. Dwarf 5 standard (6.2.4) prescribes
the primary source file to be explicitly given an entry with an index number 0.
The current implementation honors the specification by just duplicating the
main source file, once with index number 0, and later maybe with another
index number. While this is compliant with the letter of the standard, the
duplication causes problems for consumers of this information such as lldb.
(Some files are duplicated, where only some of them have a line table although
all refer to the same file)
With this change, dwarf 5 debug line section files always start from 0, and
the zeroth entry is not duplicated whenever possible. This requires different
handling of dwarf 4 and dwarf 5 during generation (e.g. when a function returns
an index zero for a file name, it signals an error in dwarf 4, but not in dwarf 5)
However, I think the minor complication is worth it, because it enables all
consumers (lldb, gdb, dwarfdump, objdump, and so on) to treat all files in the
file name list homogenously.
Reviewers: dblaikie, probinson, aprantl, espindola
Reviewed By: probinson
Subscribers: emaste, jvesely, nhaehnle, aprantl, javed.absar, arichardson, hiraditya, MaskRay, rupprecht, jdoerfert, llvm-commits
Tags: #llvm, #debug-info
Differential Revision: https://reviews.llvm.org/D59515
llvm-svn: 356941
Spec says about the first symbol table entry that index 0 both designates the first entry in the table
and serves as the undefined symbol index. It should have zero value.
Hence the first symbol table entry has no name. And so has to have a st_name == 0.
(http://refspecs.linuxbase.org/elf/gabi4+/ch4.symtab.html)
Currently, we do not emit zero value for the first symbol table entry.
That happens because we add empty strings to the string builder, which
for each such case adds a zero byte:
(https://github.com/llvm-mirror/llvm/blob/master/lib/MC/StringTableBuilder.cpp#L185)
After the string optimization performed it might return non zero indexes for the
empty string requested.
The patch fixes this issue for the case above and other sections with no names.
Differential revision: https://reviews.llvm.org/D59496
llvm-svn: 356739
Summary:
Implements a new target features section in assembly and object files
that records what features are used, required, and disallowed in
WebAssembly objects. The linker uses this information to ensure that
all objects participating in a link are feature-compatible and records
the set of used features in the output binary for use by optimizers
and other tools later in the toolchain.
The "atomics" feature is always required or disallowed to prevent
linking code with stripped atomics into multithreaded binaries. Other
features are marked used if they are enabled globally or on any
function in a module.
Future CLs will add linker flags for ignoring feature compatibility
checks and for specifying the set of allowed features, implement using
the presence of the "atomics" feature to control the type of memory
and segments in the linked binary, and add front-end flags for
relaxing the linkage policy for atomics.
Reviewers: aheejin, sbc100, dschuff
Subscribers: jgravelle-google, hiraditya, sunfish, mgrang, jfb, jdoerfert, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D59173
llvm-svn: 356610
Introduce a DW_OP_LLVM_convert Dwarf expression pseudo op that allows
for a convenient way to perform type conversions on the Dwarf expression
stack. As an additional bonus it paves the way for using other Dwarf
v5 ops that need to reference a base_type.
The new DW_OP_LLVM_convert is used from lib/Transforms/Utils/Local.cpp
to perform sext/zext on debug values but mainly the patch is about
preparing terrain for adding other Dwarf v5 ops that need to reference a
base_type.
For Dwarf v5 the op maps to DW_OP_convert and for earlier versions a
complex shift & mask pattern is generated to emulate sext/zext.
This is a recommit of r356442 with trivial fixes for the failing tests.
Differential Revision: https://reviews.llvm.org/D56587
llvm-svn: 356451
Introduce a DW_OP_LLVM_convert Dwarf expression pseudo op that allows
for a convenient way to perform type conversions on the Dwarf expression
stack. As an additional bonus it paves the way for using other Dwarf
v5 ops that need to reference a base_type.
The new DW_OP_LLVM_convert is used from lib/Transforms/Utils/Local.cpp
to perform sext/zext on debug values but mainly the patch is about
preparing terrain for adding other Dwarf v5 ops that need to reference a
base_type.
For Dwarf v5 the op maps to DW_OP_convert and for earlier versions a
complex shift & mask pattern is generated to emulate sext/zext.
Differential Revision: https://reviews.llvm.org/D56587
llvm-svn: 356442
This isn't necessary according to the DWARF standard, but it matches the
.eh_frame sections emitted by other tools in practice, and the Android
libunwindstack rejects .eh_frame sections where an FDE refers to a CIE
other than the closest previous CIE. So match the other tools and also
sort accordingly.
I consider this a bug in libunwindstack, but it's easy enough to emit
a compatible .eh_frame section for compatibility with installed
operating systems.
Differential Revision: https://reviews.llvm.org/D58266
llvm-svn: 356216
This patch adds an XCOFF triple object format type into LLVM.
This XCOFF triple object file type will be used later by object file and assembly generation for the AIX platform.
Differential Revision: https://reviews.llvm.org/D58930
llvm-svn: 355989
Emit an error for an unsupported relocation. mach-o relocations can't
encode the form -SYM + cst.
Differential Revision: https://reviews.llvm.org/D58944
llvm-svn: 355527
These arrays are both keyed by CPU name and go into the same tablegenerated file. Merge them so we only need to store keys once.
This also removes a weird space saving quirk where we used the ProcDesc.size() to create to build an ArrayRef for ProcSched.
Differential Revision: https://reviews.llvm.org/D58939
llvm-svn: 355431
The description for CPUs was just the CPU name wrapped with "Select the " and " processor". We can just do that directly in the help printer instead of making a separate version in the binary for each CPU.
Also remove the Value field that isn't needed and was always 0.
Differential Revision: https://reviews.llvm.org/D58938
llvm-svn: 355429
The SubtargetFeature class managed a list of features as strings. And it also had functions for setting bits in a FeatureBitset.
The methods that operated on the Feature list as strings are used in other parts of the backend. But the parts that operate on FeatureBitset are very tightly coupled to MCSubtargetInfo and requires passing in the arrays that MCSubtargetInfo owns. And the same struct type is used for ProcFeatures and ProcDesc.
This has led to MCSubtargetInfo having 2 arrays keyed by CPU name. One containing a mapping from a CPU name to its features. And one containing a mapping from CPU name to its scheduler model.
I would like to make a single CPU array containing all CPU information and remove some unneeded fields the ProcDesc array currently has. But I don't want to make SubtargetFeatures.h have to know about the scheduler model type and have to forward declare or pull in the header file.
Differential Revision: https://reviews.llvm.org/D58937
llvm-svn: 355428
Summary:
This is quite minimal so far, introduce them with .section,
fill them with .int8 or .asciz, end with .size
Reviewers: dschuff, sbc100, aheejin
Subscribers: jgravelle-google, sunfish, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D58660
llvm-svn: 355321
This was sometimes causing clang or llvm-mc to crash, and in other
cases could emit a bogus DWARF line-table header. I did an interim
patch in r352541; this patch should be a cleaner and more complete
fix, and retains the test.
Addresses PR40538.
Differential Revision: https://reviews.llvm.org/D58750
llvm-svn: 355226
Subtarget features are stored in a std::bitset that has been subclassed. There is a special constructor to allow the tablegen files to provide a list of bits to initialize the std::bitset to. This constructor isn't constexpr and std::bitset doesn't support many constexpr operations either. This results in a static global constructor being used to initialize the feature bitsets in these files at startup.
To fix this I've introduced a new FeatureBitArray class that holds three 64-bit values representing the initial bit values and taught tablegen to emit hex constants for them based on the feature enum values. This makes the tablegen files less readable than they were before. I can add the list of features back as a comment if we think that's important.
I've added a method to convert from this class into the std::bitset subclass we had before. I considered making the new FeatureBitArray class just implement the std::bitset interface we need instead, but thought I'd see how others felts about that first.
I've simplified the interfaces to SetImpliedBits and ClearImpliedBits a little minimize the number of times we need to convert to the bitset.
This removes about 27K from my local release+asserts build of llc.
Differential Revision: https://reviews.llvm.org/D58520
llvm-svn: 355167
We record the type of the symbol (event/function/data/global) in the
MCWasmSymbol and so it should always be clear how to handle a relocation
based on the symbol itself.
The exception is a function which still needs the special @TYPEINDEX
then the relocation contains the signature rather than the address
of the functions.
Differential Revision: https://reviews.llvm.org/D58472
llvm-svn: 354697
`__linear_memory` and `__indirect_function_table` are both generated
as imports in wasm object files but are actually symbols and don't
appear in any symbols table or relocation entry. Indeed we
don't have any symbol type to meaningfully represent either of them.
Differential Revision: https://reviews.llvm.org/D58487
llvm-svn: 354599
Summary:
Rename MemoryIndex to InitFlags and implement logic for determining
data segment layout in ObjectYAML and MC. Also adds a "passive" flag
for the .section assembler directive although this cannot be assembled
yet because the assembler does not support data sections.
Reviewers: sbc100, aardappel, aheejin, dschuff
Subscribers: jgravelle-google, hiraditya, sunfish, rupprecht, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D57938
llvm-svn: 354397
This class is used for two difference tablegen generated tables. For one of the tables the Value FeatureBitset only has one bit set. For the other usage the Implies field was unused.
This patch changes the Value field to just be an unsigned. For the usage that put a real vector in bitset, we now use the previously unused Implies field and leave the Value field unused instead.
This is good for a 16K reduction in the size of llc on my local build with all targets enabled.
llvm-svn: 354243
We stil don't have a source location, which is pretty lame, but at least
we won't tell the user to file a clang bug report anymore.
Fixes PR40712
llvm-svn: 353907
Summary:
Take care of some missing clean-ups that belong with r249548 and some
other copy/paste that had happened. In particular, the destructors are
no longer vtable anchors after r249548; and `setSectionName` in
`MCSectionWasm` is private and unused since r313058 culled its only
caller. The destructors are now implicitly defined, and the unused
function is removed.
Reviewers: nemanjai, jasonliu, grosbach
Reviewed By: nemanjai
Subscribers: sbc100, aheejin, sunfish, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D57182
llvm-svn: 353597
When a landing pad is calculated in a program that is compiled for micromips
with -fPIC flag, it will point to an even address.
Such an error will cause a segmentation fault, as the instructions in
micromips are aligned on odd addresses. This patch sets the last bit of the
offset where a landing pad is, to 1, which will effectively be an odd
address and point to the instruction exactly.
r344591 fixed this issue for -static compilation.
Patch by Aleksandar Beserminji.
Differential Revision: https://reviews.llvm.org/D57677
llvm-svn: 353480
Add a flag to allow symbols to have a wasm import name which differs from the
linker symbol name, allowing the linker to link code using the import_module
attribute.
This is the MC/Object portion of the patch.
Differential Revision: https://reviews.llvm.org/D57632
llvm-svn: 353474
Summary:
Before r349976, MC ignored such directives when producing an object file
and asserted when re-producing textual assembly output. I turned this
assertion into a hard error in both cases in r349976, but this makes it
unnecessarily difficult to write a single assembly file that supports
both MachO and other object formats that support .file. A user reported
this as PR40578, and we decided to go back to ignoring the directive.
Fixes PR40578
Reviewers: mstorsjo
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D57772
llvm-svn: 353218
Summary:
This patch fixes clang-tidy warnings on wasm-only files.
The list of checks used is:
`-*,clang-diagnostic-*,llvm-*,misc-*,-misc-unused-parameters,readability-identifier-naming,modernize-*`
(LLVM's default .clang-tidy list is the same except it does not have
`modernize-*`. But I've seen in multiple CLs in LLVM the modernize style
was recommended and code was fixed based on the style, so I added it as
well.)
The common fixes are:
- Variable names start with an uppercase letter
- Function names start with a lowercase letter
- Use `auto` when you use casts so the type is evident
- Use inline initialization for class member variables
- Use `= default` for empty constructors / destructors
- Use `using` in place of `typedef`
Reviewers: sbc100, tlively, aardappel
Subscribers: dschuff, sunfish, jgravelle-google, yurydelendik, kripken, MatzeB, mgorny, rupprecht, llvm-commits
Differential Revision: https://reviews.llvm.org/D57500
llvm-svn: 353075
Summary:
These were "boilerplate" that repeated information already present
in .functype and end_function, that needed to be repeated to Please
the particular way our object writing works, and missing them would
generate errors.
Instead, we generate the information for these automatically so the
user can concern itself with writing more canonical wasm functions
that always work as expected.
Reviewers: dschuff, sbc100
Subscribers: jgravelle-google, aheejin, sunfish, llvm-commits
Differential Revision: https://reviews.llvm.org/D57546
llvm-svn: 353067
See https://github.com/WebAssembly/tool-conventions/pull/95.
This is less typing and IMHO more readable, and it also fits with
our naming around the binary format which tends to use the short name.
e.g.
include/llvm/BinaryFormat/Wasm.h
tools/llvm-objdump/WasmDump.cpp
etc..
Differential Revision: https://reviews.llvm.org/D57611
llvm-svn: 353062
This patch removes hidden codegen flag -print-schedule effectively reverting the
logic originally committed as r300311
(https://llvm.org/viewvc/llvm-project?view=revision&revision=300311).
Flag -print-schedule was originally introduced by r300311 to address PR32216
(https://bugs.llvm.org/show_bug.cgi?id=32216). That bug was about adding "Better
testing of schedule model instruction latencies/throughputs".
These days, we can use llvm-mca to test scheduling models. So there is no longer
a need for flag -print-schedule in LLVM. The main use case for PR32216 is
now addressed by llvm-mca.
Flag -print-schedule is mainly used for debugging purposes, and it is only
actually used by x86 specific tests. We already have extensive (latency and
throughput) tests under "test/tools/llvm-mca" for X86 processor models. That
means, most (if not all) existing -print-schedule tests for X86 are redundant.
When flag -print-schedule was first added to LLVM, several files had to be
modified; a few APIs gained new arguments (see for example method
MCAsmStreamer::EmitInstruction), and MCSubtargetInfo/TargetSubtargetInfo gained
a couple of getSchedInfoStr() methods.
Method getSchedInfoStr() had to originally work for both MCInst and
MachineInstr. The original implmentation of getSchedInfoStr() introduced a
subtle layering violation (reported as PR37160 and then fixed/worked-around by
r330615).
In retrospect, that new API could have been designed more optimally. We can
always query MCSchedModel to get the latency and throughput. More importantly,
the "sched-info" string should not have been generated by the subtarget.
Note, r317782 fixed an issue where "print-schedule" didn't work very well in the
presence of inline assembly. That commit is also reverted by this change.
Differential Revision: https://reviews.llvm.org/D57244
llvm-svn: 353043
Linker relaxation may change code size. We need to fix up the alignment
of alignment directive in text section by inserting Nops and R_RISCV_ALIGN
relocation type. So then linker could satisfy the alignment by removing Nops.
To do this:
1. Add shouldInsertExtraNopBytesForCodeAlign target hook to calculate
the Nops we need to insert.
2. Add shouldInsertFixupForCodeAlign target hook to insert
R_RISCV_ALIGN fixup type.
Differential Revision: https://reviews.llvm.org/D47755
llvm-svn: 352616
N_FUNC_COLD is a new MachO symbol attribute. It's a hint to the linker
to order a symbol towards the end of its section, to improve locality.
Example:
```
void a1() {}
__attribute__((cold)) void a2() {}
void a3() {}
int main() {
a1();
a2();
a3();
return 0;
}
```
A linker that supports N_FUNC_COLD will order _a2 to the end of the text
section. From `nm -njU` output, we see:
```
_a1
_a3
_main
_a2
```
Differential Revision: https://reviews.llvm.org/D57190
llvm-svn: 352227
This patch adds a new ReadAdvance definition named ReadInt2Fpu.
ReadInt2Fpu allows x86 scheduling models to accurately describe delays caused by
data transfers from the integer unit to the floating point unit.
ReadInt2Fpu currently defaults to a delay of zero cycles (i.e. no delay) for all
x86 models excluding BtVer2. That means, this patch is only a functional change
for the Jaguar cpu model only.
Tablegen definitions for instructions (V)PINSR* have been updated to account for
the new ReadInt2Fpu. That read is mapped to the the GPR input operand.
On Jaguar, int-to-fpu transfers are modeled as a +6cy delay. Before this patch,
that extra delay was added to the opcode latency. In practice, the insert opcode
only executes for 1cy. Most of the actual latency is actually contributed by the
so-called operand-latency. According to the AMD SOG for family 16h, (V)PINSR*
latency is defined by expression f+1, where f is defined as a forwarding delay
from the integer unit to the fpu.
When printing instruction latency from MCA (see InstructionInfoView.cpp) and LLC
(only when flag -print-schedule is speified), we now need to account for any
extra forwarding delays. We do this by checking if scheduling classes declare
any negative ReadAdvance entries. Quoting a code comment in TargetSchedule.td:
"A negative advance effectively increases latency, which may be used for
cross-domain stalls". When computing the instruction latency for the purpose of
our scheduling tests, we now add any extra delay to the formula. This avoids
regressing existing codegen and mca schedule tests. It comes with the cost of an
extra (but very simple) hook in MCSchedModel.
Differential Revision: https://reviews.llvm.org/D57056
llvm-svn: 351965
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
Summary:
objdump was interpreting the function header containing the locals
declaration as instructions. To parse these without injecting target
specific code in objdump, MCDisassembler::onSymbolStart was added to
be implemented by the WebAssembly implemention.
WasmObjectFile now returns a code offset for the "address" of a symbol,
rather than the index. This is also more in-line with what other
targets do.
Also ensured that the AsmParser correctly puts each function
in its own segment to enable this test case.
Reviewers: sbc100, dschuff
Subscribers: jgravelle-google, aheejin, sunfish, rupprecht, llvm-commits
Differential Revision: https://reviews.llvm.org/D56684
llvm-svn: 351460
There are cases where we have multiple epilogues that have the exact same unwind
code sequence. In that case, the epilogues can share the same unwind codes in
the .xdata section. This should get us past the assert "SEH unwind data
splitting not yet implemented" in many cases.
We still need to add support for generating multiple .pdata/.xdata sections for
those functions that need to be split into fragments.
Differential Revision: https://reviews.llvm.org/D56813
llvm-svn: 351421
Summary:
Everything before the word "version" is the tool, and everything after
the word "version" is the version.
Reviewers: aheejin, dschuff
Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits
Differential Revision: https://reviews.llvm.org/D56742
llvm-svn: 351399
Use report_fatal_error in MCStreamer::EmitRawTextImpl instead of
using errs() and explain the rationale behind it not being
llvm_unreachable() to save confusion for any future maintainers.
Differential Revision: https://reviews.llvm.org/D56245
llvm-svn: 350342
Summary:
It does so using a simple nesting stack, and gives clear errors upon
violation. This is unique to wasm, since most CPUs do not have
any nested constructs.
Had to add an end of file check to the general assembler for this.
Note: if/else/end instructions are not currently supported in our
tablegen defs, so these tests will be enabled in a follow-up.
They already pass the nesting check.
Reviewers: dschuff, aheejin
Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits
Differential Revision: https://reviews.llvm.org/D55797
llvm-svn: 350078
Summary:
The "single parameter" .file directive appears to be an ELF-only feature
that is intended to insert the main source filename into the string
table table.
I noticed that if you assemble an ELF .s file for COFF, typically it
will assert right away on a .file directive near the top of the file. My
first change was to make this emit a proper error in the asm parser so
that we don't assert so easily.
However, COFF actually does have some support for this directive, and if
you emit an object file, llvm-mc does not assert. When emitting a COFF
object, MC will take those file names and create "debug" symbol table
entries for them. I'm not familiar with these kinds of symbol table
entries, and I'm not aware of any users of them, but @compnerd added
them a while ago. They don't introduce absolute paths, and most main
source file paths are short enough that this extra entry shouldn't cause
any problems, so I enabled the flag in MCAsmInfoCOFF that indicates that
it's supported.
This has the side effect of adding an extra debug symbol to every object
produced by clang, which is a pretty big functional change. My question
is, should we keep the functionality or remove it in the name of symbol
table minimalism?
Reviewers: mstorsjo, compnerd
Subscribers: hiraditya, compnerd, llvm-commits
Differential Revision: https://reviews.llvm.org/D55900
llvm-svn: 349976
- When signing return addresses with -msign-return-address=<scope>{+<key>},
either the A key instructions or the B key instructions can be used. To
correctly authenticate the return address, the unwinder/debugger must know
which key was used to sign the return address.
- When and exception is thrown or a break point reached, it may be necessary to
unwind the stack. To accomplish this, the unwinder/debugger must be able to
first authenticate an the return address if it has been signed.
- To enable this, the augmentation string of CIEs has been extended to allow
inclusion of a 'B' character. Functions that are signed using the B key
variant of the instructions should have and FDE whose associated CIE has a 'B'
in the augmentation string.
- One must also be able to preserve these semantics when first stepping from a
high level language into assembly and then, as a second step, into an object
file. To achieve this, I have introduced a new assembly directive
'.cfi_b_key_frame ', that tells the assembler the current frame uses return
address signing with the B key.
- This ensures that the FDE is associated with a CIE that has 'B' in the
augmentation string.
Differential Revision: https://reviews.llvm.org/D51798
llvm-svn: 349895
Summary:
Add PLATFORM constants for iOS, tvOS, and watchOS simulators, as well
as human readable names for these constants, to the Mach-O file format
header files.
rdar://46854119
Reviewers: ab, davide
Reviewed By: ab, davide
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D55905
llvm-svn: 349779
- Reapply changes intially introduced in r343089
- The archtecture info is no longer loaded whenever a DWARFContext is created
- The runtimes libraries (santiziers) make use of the dwarf context classes but
do not intialise the target info
- The architecture of the object can be obtained without loading the target info
- Adding a method to the dwarf context to get this information and multiplex the
string printing later on
Differential Revision: https://reviews.llvm.org/D55774
llvm-svn: 349472
The default still is dwarf, but SEH exceptions can now be enabled
optionally for the MinGW target.
Differential Revision: https://reviews.llvm.org/D55748
llvm-svn: 349451
This was a pre-existing bug that could be triggered with assembly like
this:
.p2align 2
.LtmpN:
.cv_def_range "..."
I noticed this when attempting to change clang to emit aligned symbol
records.
llvm-svn: 349403
build version load commands in the object file
This commit introduces a new metadata node called "SDK Version". It will be set
by the frontend to mark the platform SDK (macOS/iOS/etc) version which was used
during that particular compilation.
This node is used when machine code is emitted, by either saving the SDK version
into the appropriate macho load command (version min/build version), or by
emitting the assembly for these load commands with the SDK version specified as
well.
The assembly for both load commands is extended by allowing it to contain the
sdk_version X, Y [, Z] trailing directive to represent the SDK version
respectively.
rdar://45774000
Differential Revision: https://reviews.llvm.org/D55612
llvm-svn: 349119
Making the section writable doesn't affect how windows does
base relocs in case a DLL can't be loaded at the intended base
address.
This comment dates back to SVN r79346.
Differential Revision:
llvm-svn: 348178
This improves compatibility with GCC produced object files, where
the .eh_frame sections are read only. With mixed flags for the
involved .eh_frame sections, LLD creates two separate .eh_frame
sections in the output binary, one for each flag combination,
while ld.bfd probably merges them.
The previous setup of flags can be traced back to SVN r79346.
Differential Revision: https://reviews.llvm.org/D55209
llvm-svn: 348177
Currently, variadic operands on an MCInst are assumed to be uses,
because they come after the defs. However, this is not always the case,
for example the Arm/Thumb LDM instructions write to a variable number of
registers.
This adds a property of instruction definitions which can be used to
mark variadic operands as defs. This only affects MCInst, because
MachineInstruction already tracks use/def per operand in each instance
of the instruction, so can already represent this.
This property can then be checked in MCInstrDesc, allowing us to remove
some special cases in ARMAsmParser::isITBlockTerminator.
Differential revision: https://reviews.llvm.org/D54853
llvm-svn: 348114
In the Arm assembly parser, we first match an instruction, then call
processInstruction to possibly change it to a different encoding, to
match rules in the architecture manual which can't be expressed by the
table-generated matcher.
This adds debug printing so that this process is visible when using the
-debug option.
To support this, I've added a new overload of MCInst::dump_pretty which
takes the opcode name as a StringRef, since we don't have an InstPrinter
instance in the assembly parser. Instead, we can get the same
information directly from the MCInstrInfo.
Differential revision: https://reviews.llvm.org/D54852
llvm-svn: 348113
This patch adds BPF Debug Format (BTF) as a standalone
LLVM debuginfo. The BTF related sections are directly
generated from IR. The BTF debuginfo is generated
only when the compilation target is BPF.
What is BTF?
============
First, the BPF is a linux kernel virtual machine
and widely used for tracing, networking and security.
https://www.kernel.org/doc/Documentation/networking/filter.txthttps://cilium.readthedocs.io/en/v1.2/bpf/
BTF is the debug info format for BPF, introduced in the below
linux patch
69b693f0ae (diff-06fb1c8825f653d7e539058b72c83332)
in the patch set mentioned in the below lwn article.
https://lwn.net/Articles/752047/
The BTF format is specified in the above github commit.
In summary, its layout looks like
struct btf_header
type subsection (a list of types)
string subsection (a list of strings)
With such information, the kernel and the user space is able to
pretty print a particular bpf map key/value. One possible example below:
Withtout BTF:
key: [ 0x01, 0x01, 0x00, 0x00 ]
With BTF:
key: struct t { a : 1; b : 1; c : 0}
where struct is defined as
struct t { char a; char b; short c; };
How BTF is generated?
=====================
Currently, the BTF is generated through pahole.
https://git.kernel.org/pub/scm/devel/pahole/pahole.git/commit/?id=68645f7facc2eb69d0aeb2dd7d2f0cac0feb4d69
and available in pahole v1.12
https://git.kernel.org/pub/scm/devel/pahole/pahole.git/commit/?id=4a21c5c8db0fcd2a279d067ecfb731596de822d4
Basically, the bpf program needs to be compiled with -g with
dwarf sections generated. The pahole is enhanced such that
a .BTF section can be generated based on dwarf. This format
of the .BTF section matches the format expected by
the kernel, so a bpf loader can just take the .BTF section
and load it into the kernel.
8a138aed4a
The .BTF section layout is also specified in this patch:
with file include/llvm/BinaryFormat/BTF.h.
What use cases this patch tries to address?
===========================================
Currently, only the bpf instruction stream is required to
pass to the kernel. The kernel verifies it, jits it if configured
to do so, attaches it to a particular kernel attachment point,
and later executes when a particular event happens.
This patch tries to expand BTF to support two more use cases below:
(1). BPF supports subroutine calls.
During performance analysis, it would be good to
differentiate which call is hot instead of just
providing a virtual address. This would require to
pass a unique identifier for each subroutine to
the kernel, the subroutine name is a natual choice.
(2). If a particular jitted instruction is hot, we want
user to know which source line this jitted instruction
belongs to. This would require the source information
is available to various profiling tools.
Note that in a single ELF file,
. there may be multiple loadable bpf programs,
. for a particular to-be-loaded bpf instruction stream,
its instructions may come from multiple PROGBITS sections,
the bpf loader needs to merge them together to a single
consecutive insn stream before loading to the kernel.
For example:
section .text: subroutines funcFoo
section _progA: calling funcFoo
section _progB: calling funcFoo
The bpf loader could construct two loadable bpf instruction
streams and load them into the kernel:
. _progA funcFoo
. _progB funcFoo
So per ELF section function offset and instruction offset
will need to be adjusted before passing to the kernel, and
the kernel essentially expect only one code section regardless
of how many in the ELF file.
What do we propose and Why?
===========================
To support the above two use cases, we propose to
add an additional section, .BTF.ext, to the ELF file
which is the input of the bpf loader. A different section
is preferred since loader may need to manipulate it before
loading part of its data to the kernel.
The .BTF.ext section has a similar header to the .BTF section
and it contains two subsections for func_info and line_info.
. the func_info maps the func insn byte offset to a func
type in the .BTF type subsection.
. the line_info maps the insn byte offset to a line info.
. both func_info and line_info subsections are organized
by ELF PROGBITS AX sections.
pahole is not a good place to implement .BTF.ext as
pahole is mostly for structure hole information and more
importantly, we want to pass the actual code to the kernel.
. bpf program typically is small so storage overhead
should be small.
. in bpf land, it is totally possible that
an application loads the bpf program into the
kernel and then that application quits, so
holding debug info by the user space application
is not practical as you may not even know who
loads this bpf program.
. having source codes directly kept by kernel
would ease deployment since the original source
code does not need ship on every hosts and
kernel-devel package does not need to be
deployed even if kernel headers are used.
LLVM is a good place to implement.
. The only reliable time to get the source code is
during compilation time. This will result in both more
accurate information and easier deployment as
stated in the above.
. Another consideration is for JIT. The project like bcc
(https://github.com/iovisor/bcc)
use MCJIT to compile a C program into bpf insns and
load them to the kernel. The llvm generated BTF sections
will be readily available for such cases as well.
Design and implementation of emiting .BTF/.BTF.ext sections
===========================================================
The BTF debuginfo format is defined. Both .BTF and .BTF.ext
sections are generated directly from IR when both
"-target bpf" and "-g" are specified. Note that
dwarf sections are still generated as dwarf is used
by user space tools like llvm-objdump etc. for BPF target.
This patch also contains tests to verify generated
.BTF and .BTF.ext sections for all supported types, func_info
and line_info subsections. The patch is also tested
against linux kernel bpf sample tests and selftests.
Signed-off-by: Yonghong Song <yhs@fb.com>
Differential Revision: https://reviews.llvm.org/D53736
llvm-svn: 347999
Currently, expressions like
.reloc 1f, R_MIPS_JALR, foo
1: nop
are not allowed, ie. an offset in .reloc can only be absolute value.
This patch adds support for labels as offsets.
If offset is a forward declared label, MCObjectStreamer keeps the fixup locally
and adds it to the fixups vector after the label (and its offset) is defined.
label+number is not supported yet.
Differential revision: https://reviews.llvm.org/D53990
llvm-svn: 347397
Summary:
This makes it easier/cleaner to generate a single signature from
this directive. Also:
- Adds the symbol name, such that we don't depend on the location
of this directive anymore.
- Actually constructs the signature in the assembler, and make the
assembler own it.
- Refactor the use of MVT vs ValType in the streamer and assembler
to require less conversions overall.
- Changed 700 or so tests to use it.
Reviewers: sbc100, dschuff
Subscribers: jgravelle-google, eraman, aheejin, sunfish, jfb, llvm-commits
Differential Revision: https://reviews.llvm.org/D54652
llvm-svn: 347228
Summary:
This adds support for the 'event section' specified in the exception
handling proposal. (This was named 'exception section' first, but later
renamed to 'event section' to take possibilities of other kinds of
events into consideration. But currently we only store exception info in
this section.)
The event section is added between the global section and the export
section. This is for ease of validation per request of the V8 team.
This patch:
- Creates the event symbol type, which is a weak symbol
- Makes 'throw' instruction take the event symbol '__cpp_exception'
- Adds relocation support for events
- Adds WasmObjectWriter / WasmObjectFile (Reader) support
- Adds obj2yaml / yaml2obj support
- Adds '.eventtype' printing support
Reviewers: dschuff, sbc100, aardappel
Subscribers: jgravelle-google, sunfish, llvm-commits
Differential Revision: https://reviews.llvm.org/D54096
llvm-svn: 346825
Summary:
DW_CFA_restore can only encode register numbers up to 64 (6 bits unsigned
int). For regsiter numbers > 64 we have to use DW_CFA_restore_extended
instead which uses a ULEB128 value.
I discovered this problem in the out-of-tree CHERI target since we use
DWARF register number 89 for our return capability register.
Reviewers: probinson, dblaikie, aprantl, espindola
Reviewed By: dblaikie
Subscribers: JohnReagan, emaste, JDevlieghere, llvm-commits
Differential Revision: https://reviews.llvm.org/D54420
llvm-svn: 346751
Summary:
This is to replace the ELFAsmParser that WebAssembly was using, which
so far was a stub that didn't do anything, and couldn't work correctly
with wasm.
This new class is there to implement generic directives related to
wasm as a binary format. Wasm target specific directives are still
parsed in WebAssemblyAsmParser as before. The two classes now
cooperate more correctly too.
Also implemented .result which was missing. Any unknown directives
will now result in errors.
Reviewers: dschuff, sbc100
Subscribers: mgorny, jgravelle-google, eraman, aheejin, sunfish, llvm-commits
Differential Revision: https://reviews.llvm.org/D54360
llvm-svn: 346700
Use report_fatal_error instead of crashing or miscompiling. (It's
currently easier than it should be to hit this case because we don't
reuse codes across epilogs.)
llvm-svn: 346440
Summary:
The assembler was able to assemble and then dump back to .s, but
was failing to parse certain directives necessary for valid .o
output:
- .type directives are now recognized to distinguish function symbols
and others.
- .size is now parsed to provide function size.
- .globaltype (introduced in https://reviews.llvm.org/D54012) is now
recognized to ensure symbols like __stack_pointer have a proper type
set for both .s and .o output.
Also added tests for the above.
Reviewers: sbc100, dschuff
Subscribers: jgravelle-google, aheejin, dexonsmith, kristina, llvm-commits, sunfish
Differential Revision: https://reviews.llvm.org/D53842
llvm-svn: 346047
Summary:
This changes int types to unsigned int in a few places: function indices
and `wasm::Valtype` (which is unsigend int enum). Currently these
values cannot have negative values anyway, so this should not be a
functional change for now.
Reviewers: sbc100
Subscribers: dschuff, jgravelle-google, sunfish, llvm-commits
Differential Revision: https://reviews.llvm.org/D54044
llvm-svn: 346031
Summary:
This adds dummy implementation of `EmitRawText` in `MCNullStreamer`.
This fixes the behavior of `AsmPrinter` with `MCNullStreamer` on targets
on which no integrated assembler is used. An attempt to emit inline asm
on such a target would previously lead to a crash, since `AsmPrinter` does not
check for `hasRawTextSupport` in `EmitInlineAsm` and calls `EmitRawText`
anyway if integrated assembler is disabled (the behavior has changed
in D2686).
Error message printed by MCStreamer:
> EmitRawText called on an MCStreamer that doesn't support it, something
> must not be fully mc'ized
Patch by Eugene Sharygin
Reviewers: dsanders, echristo
Reviewed By: dsanders
Subscribers: eraman, llvm-commits
Differential Revision: https://reviews.llvm.org/D53938
llvm-svn: 345841
Add ARM64 unwind codes to MCLayer, as well SEH directives that will be emitted
by the frame lowering patch to follow. We only emit unwind codes into object
object files for now.
Differential Revision: https://reviews.llvm.org/D50166
llvm-svn: 345450
.debug_loclists is the DWARF 5 version of the .debug_loc.
With that patch, it will be emitted when DWARF 5 is used.
Differential revision: https://reviews.llvm.org/D53365
llvm-svn: 345377
Summary:
This adds support for LSDA (exception table) generation for wasm EH.
Wasm EH mostly follows the structure of Itanium-style exception tables,
with one exception: a call site table entry in wasm EH corresponds to
not a call site but a landing pad.
In wasm EH, the VM is responsible for stack unwinding. After an
exception occurs and the stack is unwound, the control flow is
transferred to wasm 'catch' instruction by the VM, after which the
personality function is called from the compiler-generated code. (Refer
to WasmEHPrepare pass for more information on this part.)
This patch:
- Changes wasm.landingpad.index intrinsic to take a token argument, to
make this 1:1 match with a catchpad instruction
- Stores landingpad index info and catch type info MachineFunction in
before instruction selection
- Lowers wasm.lsda intrinsic to an MCSymbol pointing to the start of an
exception table
- Adds WasmException class with overridden methods for table generation
- Adds support for LSDA section in Wasm object writer
Reviewers: dschuff, sbc100, rnk
Subscribers: mgorny, jgravelle-google, sunfish, llvm-commits
Differential Revision: https://reviews.llvm.org/D52748
llvm-svn: 345345
Summary:
This renames the IsParsingMSInlineAsm member variable of AsmLexer to
LexMasmIntegers and moves it up to MCAsmLexer. This is the only behavior
controlled by that variable. I added a public setter, so that it can be
set from outside or from the llvm-mc command line. We may need to
arrange things so that users can get this behavior from clang, but
that's future work.
I also put additional hex literal lexing functionality under this flag
to fix PR32973. It appears that this hex literal parsing wasn't intended
to be enabled in non-masm-style blocks.
Now, masm integers (0b1101 and 0ABCh) work in __asm blocks from clang,
but 0b label references work when using .intel_syntax in standalone .s
files.
However, 0b label references will *not* work from __asm blocks in clang.
They will work from GCC inline asm blocks, which it sounds like is
important for Crypto++ as mentioned in PR36144.
Essentially, we only lex masm literals for inline asm blobs that use
intel syntax. If the .intel_syntax directive is used inside a gnu-style
inline asm statement, masm literals will not be lexed, which is
compatible with gas and llvm-mc standalone .s assembly.
This fixes PR36144 and PR32973.
Reviewers: Gerolf, avt77
Subscribers: eraman, hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D53535
llvm-svn: 345189
Summary:
If the target does not support `.asciz` and `.ascii` directives, the
strings are represented as bytes and each byte is placed on the new line
as a separate byte directive `.b8 <data>`. NVPTX target allows to
represent the vector of the data of the same type as a vector, where
values are separated using `,` symbol: `.b8 <data1>,<data2>,...`. This
allows to reduce the size of the final PTX file. Ptxas tool includes ptx
files into the resulting binary object, so reducing the size of the PTX
file is important.
Reviewers: tra, jlebar, echristo
Subscribers: jholewinski, llvm-commits
Differential Revision: https://reviews.llvm.org/D45822
llvm-svn: 345142
I was considering adding another boolean here. I standardized on bools
since they allow default member initializers in the class definition.
This makes ShowParsedOperands protected instead of private, but that's
probably fine.
Reduce the SmallVector size while we're at it, since the common case is
that there is never a pending error.
llvm-svn: 344967
This avoids a crash (with asserts) or bad codegen (without asserts)
in Dwarf streamer later on. This patch fixes this condition in
MCStreamer and propogates SMLoc down when it's available with an
added bonus of source locations for those specific types of errors.
Further patches could use similar improvements as currently most
non-Windows CFI directives lack an SMLoc parameter.
Modified an existing test to verify source location propogation and
added an object-file version of it to verify that it does not crash in
addition to a standalone test to only ensure it does not crash.
Differential Revision: https://reviews.llvm.org/D51695
llvm-svn: 344781
When a landing pad is calculated in a program that is compiled
for micromips, it will point to an even address. Such an error will
cause a segmentation fault, as the instructions in micromips are
aligned on odd addresses. This patch sets the last bit of the offset
where a landing pad is, to 1, which will effectively be
an odd address and point to the instruction exactly.
Differential Revision: https://reviews.llvm.org/D52985
llvm-svn: 344591
Summary:
This adds support for LSDA (exception table) generation for wasm EH.
Wasm EH mostly follows the structure of Itanium-style exception tables,
with one exception: a call site table entry in wasm EH corresponds to
not a call site but a landing pad.
In wasm EH, the VM is responsible for stack unwinding. After an
exception occurs and the stack is unwound, the control flow is
transferred to wasm 'catch' instruction by the VM, after which the
personality function is called from the compiler-generated code. (Refer
to WasmEHPrepare pass for more information on this part.)
This patch:
- Changes wasm.landingpad.index intrinsic to take a token argument, to
make this 1:1 match with a catchpad instruction
- Stores landingpad index info and catch type info MachineFunction in
before instruction selection
- Lowers wasm.lsda intrinsic to an MCSymbol pointing to the start of an
exception table
- Adds WasmException class with overridden methods for table generation
- Adds support for LSDA section in Wasm object writer
Reviewers: dschuff, sbc100, rnk
Subscribers: mgorny, jgravelle-google, sunfish, llvm-commits
Differential Revision: https://reviews.llvm.org/D52748
llvm-svn: 344575
The initial patch was not reviewed, and does not have any tests;
it should not have been merged.
This reverts 344395, 344390, 344387, 344385, 344381, 344376,
and 344366.
llvm-svn: 344405
* Move #include outside of namespaces
* Add missing #include
* Add out-of-line virtual destructor to BTFTypeEntry
designated initializers should also be fixed
llvm-svn: 344376
BTF is the debug format for BPF, a kernel virtual machine
and widely used for tracing, networking and security, etc ([1]).
Currently only instruction streams are passed to kernel,
the kernel verifier verifies them before execution. In order to
provide better visibility of bpf programs to user space
tools, some debug information, e.g., function names and
debug line information are desirable for kernel so tools
can get such information with better annotation
for jited instructions for performance or other reasons.
The dwarf is too complicated in kernel and for BPF.
Hence, BTF is designed to be the debug format for BPF ([2]).
Right now, pahole supports BTF for types, which
are generated based on dwarf sections in the ELF file.
In order to annotate performance metrics for jited bpf insns,
it is necessary to pass debug line info to the kernel.
Furthermore, we want to pass the actual code to the
kernel because of the following reasons:
. bpf program typically is small so storage overhead
should be small.
. in bpf land, it is totally possible that
an application loads the bpf program into the
kernel and then that application quits, so
holding debug info by the user space application
is not practical.
. having source codes directly kept by kernel
would ease deployment since the original source
code does not need ship on every hosts and
kernel-devel package does not need to be
deployed even if kernel headers are used.
The only reliable time to get the source code is
during compilation time. This will result in both more
accurate information and easier deployment as
stated in the above.
Another consideration is for JIT. The project like bcc
use MCJIT to compile a C program into bpf insns and
load them to the kernel ([3]). The generated BTF sections
will be readily available for such cases as well.
This patch implemented generation of BTF info in llvm
compiler. The BTF related sections will be generated
when both -target bpf and -g are specified. Two sections
are generated:
.BTF contains all the type and string information, and
.BTF.ext contains the func_info and line_info.
The separation is related to how two sections are used
differently in bpf loader, e.g., linux libbpf ([4]).
The .BTF section can be loaded into the kernel directly
while .BTF.ext needs loader manipulation before loading
to the kernel. The format of the each section is roughly
defined in llvm:include/llvm/MC/MCBTFContext.h and
from the implementation in llvm:lib/MC/MCBTFContext.cpp.
A later example also shows the contents in each section.
The type and func_info are gathered during CodeGen/AsmPrinter
by traversing dwarf debug_info. The line_info is
gathered in MCObjectStreamer before writing to
the object file. After all the information is gathered,
the two sections are emitted in MCObjectStreamer::finishImpl.
With cmake CMAKE_BUILD_TYPE=Debug, the compiler can
dump out all the tables except insn offset, which
will be resolved later as relocation records.
The debug type "btf" is used for BTFContext dump.
Dwarf tests the debug info generation with
llvm-dwarfdump to decode the binary sections and
check whether the result is expected. Currently
we do not have such a tool yet. We will implement
btf dump functionality in bpftool ([5]) as the bpftool is
considered the recommended tool for bpf introspection.
The implementation for type and func_info is tested
with linux kernel test cases. The line_info is visually
checked with dump from linux kernel libbpf ([4]) and
checked with readelf dumping section raw data.
Note that the .BTF and .BTF.ext information will not
be emitted to assembly code and there is no assembler
support for BTF either.
In the below, with a clang/llvm built with CMAKE_BUILD_TYPE=Debug,
Each table contents are shown for a simple C program.
-bash-4.2$ cat -n test.c
1 struct A {
2 int a;
3 char b;
4 };
5
6 int test(struct A *t) {
7 return t->a;
8 }
-bash-4.2$ clang -O2 -target bpf -g -mllvm -debug-only=btf -c test.c
Type Table:
[1] FUNC name_off=1 info=0x0c000001 size/type=2
param_type=3
[2] INT name_off=12 info=0x01000000 size/type=4
desc=0x01000020
[3] PTR name_off=0 info=0x02000000 size/type=4
[4] STRUCT name_off=16 info=0x04000002 size/type=8
name_off=18 type=2 bit_offset=0
name_off=20 type=5 bit_offset=32
[5] INT name_off=22 info=0x01000000 size/type=1
desc=0x02000008
String Table:
0 :
1 : test
6 : .text
12 : int
16 : A
18 : a
20 : b
22 : char
27 : test.c
34 : int test(struct A *t) {
58 : return t->a;
FuncInfo Table:
sec_name_off=6
insn_offset=<Omitted> type_id=1
LineInfo Table:
sec_name_off=6
insn_offset=<Omitted> file_name_off=27 line_off=34 line_num=6 column_num=0
insn_offset=<Omitted> file_name_off=27 line_off=58 line_num=7 column_num=3
-bash-4.2$ readelf -S test.o
......
[12] .BTF PROGBITS 0000000000000000 0000028d
00000000000000c1 0000000000000000 0 0 1
[13] .BTF.ext PROGBITS 0000000000000000 0000034e
0000000000000050 0000000000000000 0 0 1
[14] .rel.BTF.ext REL 0000000000000000 00000648
0000000000000030 0000000000000010 16 13 8
......
-bash-4.2$
The latest linux kernel ([6]) can already support .BTF with type information.
The [7] has the reference implementation in linux kernel side
to support .BTF.ext func_info. The .BTF.ext line_info support is not
implemented yet. If you have difficulty accessing [6], you can
manually do the following to access the code:
git clone https://github.com/yonghong-song/bpf-next-linux.git
cd bpf-next-linux
git checkout btf
The change will push to linux kernel soon once this patch is landed.
References:
[1]. https://www.kernel.org/doc/Documentation/networking/filter.txt
[2]. https://lwn.net/Articles/750695/
[3]. https://github.com/iovisor/bcc
[4]. https://github.com/torvalds/linux/tree/master/tools/lib/bpf
[5]. https://github.com/torvalds/linux/tree/master/tools/bpf/bpftool
[6]. https://github.com/torvalds/linux
[7]. https://github.com/yonghong-song/bpf-next-linux/tree/btf
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Differential Revision: https://reviews.llvm.org/D52950
llvm-svn: 344366
Sean Fertile