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
Sam Clegg