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
For O32 and N32 ABI FDE/CFI encoding should be `DW_EH_PE_sdata4` and only
N64 ABI uses `DW_EH_PE_sdata8`. To cover all cases this patch check code
pointer size and setup a correct FDE/CFI encoding type.
Differential revision: https://reviews.llvm.org/D52876
llvm-svn: 344040
The following instruction:
> str q28, [x0, #1*6*4*@]
contains a @ which is parsed as an empty symbol. The parser returns true
but has no error, so the assembler continues by ignoring the
instruction.
Differential Revision: https://reviews.llvm.org/D52645
llvm-svn: 343961
Summary:
These are emitted by the wasm backend for e.g.
__stack_pointer@GLOBAL which previously wasn't accepted by the
assembler.
Reviewers: aheejin, dschuff
Subscribers: sbc100, jgravelle-google, llvm-commits, sunfish
Differential Revision: https://reviews.llvm.org/D52911
llvm-svn: 343830
MCContext does not destroy MCSymbols on shutdown. So, rather than putting
SmallVectors (which may heap-allocate) inside MCSymbolWasm, use unowned pointer
to a WasmSignature instead. The signatures are now owned by the AsmPrinter.
Also uses WasmSignature instead of param and result vectors in TargetStreamer,
and leaves some TODOs for further simplification.
Differential Revision: https://reviews.llvm.org/D52580
llvm-svn: 343733
- Add fix so that all code paths that create DWARFContext
with an ObjectFile initialise the target architecture in the context
- Add an assert that the Arch is known in the Dwarf CallFrameString method
llvm-svn: 343317
This caused the DebugInfo/Sparc/gnu-window-save.ll test to fail.
> Functions that have signed return addresses need additional dwarf support:
> - After signing the LR, and before authenticating it, the LR register is in a
> state the is unusable by a debugger or unwinder
> - To account for this a new directive, .cfi_negate_ra_state, is added
> - This directive says the signed state of the LR register has now changed,
> i.e. unsigned -> signed or signed -> unsigned
> - This directive has the same CFA code as the SPARC directive GNU_window_save
> (0x2d), adding a macro to account for multiply defined codes
> - This patch matches the gcc implementation of this support:
> https://patchwork.ozlabs.org/patch/800271/
>
> Differential Revision: https://reviews.llvm.org/D50136
llvm-svn: 343103
Functions that have signed return addresses need additional dwarf support:
- After signing the LR, and before authenticating it, the LR register is in a
state the is unusable by a debugger or unwinder
- To account for this a new directive, .cfi_negate_ra_state, is added
- This directive says the signed state of the LR register has now changed,
i.e. unsigned -> signed or signed -> unsigned
- This directive has the same CFA code as the SPARC directive GNU_window_save
(0x2d), adding a macro to account for multiply defined codes
- This patch matches the gcc implementation of this support:
https://patchwork.ozlabs.org/patch/800271/
Differential Revision: https://reviews.llvm.org/D50136
llvm-svn: 343089
The Lexer doesn't use this state itself. It is only set and used by AsmParser so it seems like it should just be part of AsmParser.
Differential Revision: https://reviews.llvm.org/D52515
llvm-svn: 343027
DWARF5 spec says about single file split case:
"The sections that do not require relocation, however, can be written
to the relocatable object (.o) file but ignored by the
the linker or they can be written to a separate DWARF object (.dwo) file
that need not be accessed by the linker."
Nice way to make linker to ignore them is to set SHF_EXCLUDE flag.
It seems to be not harmful to always set it for .dwo sections.
That is what this patch does.
Differential revision: https://reviews.llvm.org/D52303
llvm-svn: 342800
This patch adds the ability for processor models to describe dependency breaking
instructions.
Different processors may specify a different set of dependency-breaking
instructions.
That means, we cannot assume that all processors of the same target would use
the same rules to classify dependency breaking instructions.
The main goal of this patch is to provide the means to describe dependency
breaking instructions directly via tablegen, and have the following
TargetSubtargetInfo hooks redefined in overrides by tabegen'd
XXXGenSubtargetInfo classes (here, XXX is a Target name).
```
virtual bool isZeroIdiom(const MachineInstr *MI, APInt &Mask) const {
return false;
}
virtual bool isDependencyBreaking(const MachineInstr *MI, APInt &Mask) const {
return isZeroIdiom(MI);
}
```
An instruction MI is a dependency-breaking instruction if a call to method
isDependencyBreaking(MI) on the STI (TargetSubtargetInfo object) evaluates to
true. Similarly, an instruction MI is a special case of zero-idiom dependency
breaking instruction if a call to STI.isZeroIdiom(MI) returns true.
The extra APInt is used for those targets that may want to select which machine
operands have their dependency broken (see comments in code).
Note that by default, subtargets don't know about the existence of
dependency-breaking. In the absence of external information, those method calls
would always return false.
A new tablegen class named STIPredicate has been added by this patch to let
processor models classify instructions that have properties in common. The idea
is that, a MCInstrPredicate definition can be used to "generate" an instruction
equivalence class, with the idea that instructions of a same class all have a
property in common.
STIPredicate definitions are essentially a collection of instruction equivalence
classes.
Also, different processor models can specify a different variant of the same
STIPredicate with different rules (i.e. predicates) to classify instructions.
Tablegen backends (in this particular case, the SubtargetEmitter) will be able
to process STIPredicate definitions, and automatically generate functions in
XXXGenSubtargetInfo.
This patch introduces two special kind of STIPredicate classes named
IsZeroIdiomFunction and IsDepBreakingFunction in tablegen. It also adds a
definition for those in the BtVer2 scheduling model only.
This patch supersedes the one committed at r338372 (phabricator review: D49310).
The main advantages are:
- We can describe subtarget predicates via tablegen using STIPredicates.
- We can describe zero-idioms / dep-breaking instructions directly via
tablegen in the scheduling models.
In future, the STIPredicates framework can be used for solving other problems.
Examples of future developments are:
- Teach how to identify optimizable register-register moves
- Teach how to identify slow LEA instructions (each subtarget defining its own
concept of "slow" LEA).
- Teach how to identify instructions that have undocumented false dependencies
on the output registers on some processors only.
It is also (in my opinion) an elegant way to expose knowledge to both external
tools like llvm-mca, and codegen passes.
For example, machine schedulers in LLVM could reuse that information when
internally constructing the data dependency graph for a code region.
This new design feature is also an "opt-in" feature. Processor models don't have
to use the new STIPredicates. It has all been designed to be as unintrusive as
possible.
Differential Revision: https://reviews.llvm.org/D52174
llvm-svn: 342555
In r319995, we fixed the line table format to version 2 on Darwin
because dsymutil didn't yet understand the new format which caused test
failures for the LLDB bots. This has been resolved in the meantime so
there's no reason to keep this limitation.
rdar://problem/35968332
llvm-svn: 342136
The main use case for this directive is to allow assembly writers to
write their own FPO data strings without going through the .cv_fpo*
directive family.
I'm experimenting with different RPN programs to fix PR38857, and I
figured I should go ahead and make this directive permanent.
llvm-svn: 341712
SHF_ARM_PURECODE flag when being built with the -mexecute-only flag.
All code sections of an ELF must have the flag set for the final .text
section to be execute-only, otherwise the flag gets removed.
A HasData flag is added to MCSection to aid in the determination that
the section is empty. A virtual setTargetSectionFlags is added to
MCELFObjectTargetWriter to allow subclasses to set target specific
section flags to be added to sections which we then use in the ARM
backend to set SHF_ARM_PURECODE.
Patch by Ivan Lozano!
Reviewed By: echristo
Differential Revision: https://reviews.llvm.org/D48792
llvm-svn: 341593
Remove braces around two, single statement "if" blocks in line with rest
of the file and the general LLVM code style. NFC, testing commit access.
llvm-svn: 341294
Summary:
Per clang-tidy:
function 'llvm::MCStreamer::checkCVLocSection' has a definition with different parameter names
.../llvm/lib/MC/MCStreamer.cpp:275:18: the definition seen here
.../llvm/include/llvm/MC/MCStreamer.h:235:8: differing parameters are named here: ('FuncId'), in definition: ('FunctionId')
Reviewers: bkramer
Reviewed By: bkramer
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D51406
llvm-svn: 340912
I am experimenting with a single split dwarf (.dwo sections in .o files).
I want to make linker to ignore .dwo sections in .o, for that I am trying to add
SHF_EXCLUDE flag ("E") for them in my asm sample.
I found that currently, it is impossible to add any flag for debug sections using llvm-mc.
That happens because we have a set of predefined unique sections created early with default flags:
https://github.com/llvm-mirror/llvm/blob/master/lib/MC/MCObjectFileInfo.cpp#L391
This patch allows a user to add any flags he wants.
I had to edit TargetLoweringObjectFileImpl.cpp to set MetaData type for debug sections.
Their kind was Data by default (so they were allocatable) and so after changes introduced by
this patch the SHF_ALLOC flag was applied for them, what does not make sense for debug sections.
One of OrcJITTests tests failed because of that.
Differential revision: https://reviews.llvm.org/D51361
llvm-svn: 340904
Now that we create the label at the point of the directive, we don't
need to set the "current CV location", and then later when we emit the
next instruction, create a label for it and emit it.
DWARF still defers the labels used in .debug_loc until the next
instruction or value, for reasons unknown.
llvm-svn: 340883
Previously we followed the DWARF implementation, which waits until the
next instruction or data to emit the label to use in the .debug_loc
section. We might want to consider re-evaluating that design choice as
well, since it means the .loc skips alignment padding, for better or
worse.
This was the most minimal fix I could come up with, but we should be
able to do a lot of cleanups now that we don't need to save a pending CV
location on the CodeViewContext. I plan to do those next, but this
immediately fixes an assertion for some of our users.
llvm-svn: 340878
Summary:
For assembly input files, generate debug info even when the .file
directive is present, provided it does not include a file-number
argument. Fixes PR38695.
Reviewers: probinson, sidneym
Subscribers: aprantl, hiraditya, JDevlieghere, llvm-commits
Differential Revision: https://reviews.llvm.org/D51315
llvm-svn: 340839
Summary:
Handle the case IDVal is an empty string.
This bug was uncovered by a LLVM MC Assembler Protocol Buffer
Fuzzer for the RISC-V assembly language.
Reviewers: rnk
Reviewed By: rnk
Subscribers: rnk, niravd, pcc, peter.smith, asb, grosbach, llvm-commits, bcain, kito-cheng, shiva0217, rogfer01, PkmX
Differential Revision: https://reviews.llvm.org/D50808
llvm-svn: 340678
Aligning section contents is not required, but only
recommended, by the specification. Microsoft's documentation says
(https://docs.microsoft.com/en-us/windows/desktop/debug/pe-format#section-table-section-headers):
"For object files, the value should be aligned on a 4-byte boundary
for best performance."
However, according to my measurements, aligning section contents has
a neutral to negative effect on performance.
I measured the median run time of 100 links of Chromium's
base_unittests on Linux with lld-link and on Windows with link.exe with
both aligned and unaligned sections. On Linux I didn't see a measurable
performance difference, and on Windows the link was slightly faster
with unaligned sections (presumably because on Windows the bottleneck
is I/O).
Also, the sections created by cl.exe are unaligned, so we should expect
tools to broadly accept unaligned sections.
Differential Revision: https://reviews.llvm.org/D51149
llvm-svn: 340514
The format is the same as in ELF: a sequence of ULEB128-encoded
symbol indexes.
Differential Revision: https://reviews.llvm.org/D51047
llvm-svn: 340499
wasm-lld expects relocation entries to be sorted by offset. In most
cases llvm produces them in order, but the CODE section (which combines
many MCSections) is an exception because we order the functions in
Symbol order, not in section order. What is more, its not clear weather
`recordRelocation` is guaranteed to be called in offset order so this
sort of most likely needed in the general case too.
Differential Revision: https://reviews.llvm.org/D51065
llvm-svn: 340423
Remove code for writing auxiliary symbols of type function definition
and begin function. These types of symbols are associated with
pre-CodeView debug info and we never emit them.
llvm-svn: 340113
Handle the case when the symbol is private. Private symbols are not in
the COFF object file symbol table, so they aren't inserted into
SymbolMap. We can't look up the section of the symbol that way. Instead,
get the MCSection from the MCSymbol and map that to the object file
section.
Print a better error message when the symbol has no section, like when
the symbol is undefined.
Fixes PR38607
llvm-svn: 339942
Kristina Brooks