Inlining and zero-cost abstractions tend to produce volumes of debug
info with identical ranges. When built with full debugging information
(the equivalent of -g2) librustc_driver.so has 2.1 million entries in
.debug_ranges. But only 1.1 million of those entries are unique. While
in principle all duplicates could be eliminated with a hashtable,
checking to see if the new range is exactly identical to the previous
range and skipping a new addition if it is is sufficient to eliminate
99.99% of the duplicates. This reduces the size of librustc_driver.so's
.debug_ranges section by 35%, or the overall binary size a little more
than 1%.
Enable Type Units with DWARF5 accelerator tables for monolithic DWARF.
Implementation relies on linker to tombstone offset in LocalTU list to
-1 when
it deduplciates type units using COMDAT.
This reverts commit d80fdc6fc1a6e717af1bcd7a7313e65de433ba85.
split-dwarf-local-impor3.ll fails because of an issue with
Dwo sections emission on Windows platform.
RFC https://discourse.llvm.org/t/rfc-dwarfdebug-fix-and-improve-handling-imported-entities-types-and-static-local-in-subprogram-and-lexical-block-scopes/68544
Fixed PR51501 (tests from D112337).
1. Reuse of DISubprogram's 'retainedNodes' to track other function-local
entities together with local variables and labels (this patch cares about
function-local import while D144006 and D144008 use the same approach for
local types and static variables). So, effectively this patch moves ownership
of tracking local import from DICompileUnit's 'imports' field to DISubprogram's
'retainedNodes' and adjusts DWARF emitter for the new layout. The old layout
is considered unsupported (DwarfDebug would assert on such debug metadata).
DICompileUnit's 'imports' field is supposed to track global imported
declarations as it does before.
This addresses various FIXMEs and simplifies the next part of the patch.
2. Postpone emission of function-local imported entities from
`DwarfDebug::endFunctionImpl()` to `DwarfDebug::endModule()`.
While in `DwarfDebug::endFunctionImpl()` we do not have all the
information about a parent subprogram or a referring subprogram
(whether a subprogram inlined or not), so we can't guarantee we emit
an imported entity correctly and place it in a proper subprogram tree.
So now, we just gather needed details about the import itself and its
parent entity (either a Subprogram or a LexicalBlock) during
processing in `DwarfDebug::endFunctionImpl()`, but all the real work is
done in `DwarfDebug::endModule()` when we have all the required
information to make proper emission.
Authored-by: Kristina Bessonova <kbessonova@accesssoftek.com>
Differential Revision: https://reviews.llvm.org/D144004
This reverts commit ed578f02cf44a52adde16647150e7421f3ef70f3.
Tests llvm/test/DebugInfo/Generic/split-dwarf-local-import*.ll fail
when x86_64 target is not registered.
RFC https://discourse.llvm.org/t/rfc-dwarfdebug-fix-and-improve-handling-imported-entities-types-and-static-local-in-subprogram-and-lexical-block-scopes/68544
Fixed PR51501 (tests from D112337).
1. Reuse of DISubprogram's 'retainedNodes' to track other function-local
entities together with local variables and labels (this patch cares about
function-local import while D144006 and D144008 use the same approach for
local types and static variables). So, effectively this patch moves ownership
of tracking local import from DICompileUnit's 'imports' field to DISubprogram's
'retainedNodes' and adjusts DWARF emitter for the new layout. The old layout
is considered unsupported (DwarfDebug would assert on such debug metadata).
DICompileUnit's 'imports' field is supposed to track global imported
declarations as it does before.
This addresses various FIXMEs and simplifies the next part of the patch.
2. Postpone emission of function-local imported entities from
`DwarfDebug::endFunctionImpl()` to `DwarfDebug::endModule()`.
While in `DwarfDebug::endFunctionImpl()` we do not have all the
information about a parent subprogram or a referring subprogram
(whether a subprogram inlined or not), so we can't guarantee we emit
an imported entity correctly and place it in a proper subprogram tree.
So now, we just gather needed details about the import itself and its
parent entity (either a Subprogram or a LexicalBlock) during
processing in `DwarfDebug::endFunctionImpl()`, but all the real work is
done in `DwarfDebug::endModule()` when we have all the required
information to make proper emission.
Authored-by: Kristina Bessonova <kbessonova@accesssoftek.com>
Differential Revision: https://reviews.llvm.org/D144004
RFC https://discourse.llvm.org/t/rfc-dwarfdebug-fix-and-improve-handling-imported-entities-types-and-static-local-in-subprogram-and-lexical-block-scopes/68544
Fixed PR51501 (tests from D112337).
1. Reuse of DISubprogram's 'retainedNodes' to track other function-local
entities together with local variables and labels (this patch cares about
function-local import while D144006 and D144008 use the same approach for
local types and static variables). So, effectively this patch moves ownership
of tracking local import from DICompileUnit's 'imports' field to DISubprogram's
'retainedNodes' and adjusts DWARF emitter for the new layout. The old layout
is considered unsupported (DwarfDebug would assert on such debug metadata).
DICompileUnit's 'imports' field is supposed to track global imported
declarations as it does before.
This addresses various FIXMEs and simplifies the next part of the patch.
2. Postpone emission of function-local imported entities from
`DwarfDebug::endFunctionImpl()` to `DwarfDebug::endModule()`.
While in `DwarfDebug::endFunctionImpl()` we do not have all the
information about a parent subprogram or a referring subprogram
(whether a subprogram inlined or not), so we can't guarantee we emit
an imported entity correctly and place it in a proper subprogram tree.
So now, we just gather needed details about the import itself and its
parent entity (either a Subprogram or a LexicalBlock) during
processing in `DwarfDebug::endFunctionImpl()`, but all the real work is
done in `DwarfDebug::endModule()` when we have all the required
information to make proper emission.
Authored-by: Kristina Bessonova <kbessonova@accesssoftek.com>
Differential Revision: https://reviews.llvm.org/D144004
Try to revert D113741 once again.
This also reverts 0ac75e82fff93a80ca401d3db3541e8d1d9098f9 (D114705)
as it causes LLDB's lldb-api.lang/cpp/nsimport.TestCppNsImport.py test
failure w/o D113741.
This reverts commit f9607d45f399e2afc39ec16222ea68b4e0831564.
Differential Revision: https://reviews.llvm.org/D116225
This patch causes invalid DWARF to be generated in some cases of LTO +
Split DWARF - follow-up on the original review thread (D113741) contains
further detail and test cases.
This reverts commit 75b622a7959479ccdb758ebe0973061b7b4fcacd.
This reverts commit b6ccca217c35a95b8c2a337a7801b37cb23dbae2.
This reverts commit 514d37441918dd04a2cd4f35c08959d7c3ff096d.
This reverts commits
* ee691970a9a85470948ada623c31f0ab8773617c (D113741),
* 79d3132998b2828be8f7d2ec411f91fb11b3e01f (D114705)
due to lldb and dexter test failures.
Move these data structures closer together so their emission code can
eventually share more of its implementation.
Was an egregious bug (completely untested, evidently) where I hadn't
inverted a DWARFv5 test as needed, so it was doing the exact opposite of
what was required & thus tried to emit a DWARFv5 range list header in
DWARFv4.
Reapply 8e04896288d22ed8bef7ac367923374f96b753d6 which was
reverted in a8154e5e0c83d2f0f65f3b4fb1a0bc68785bd975.
There's no need to have more than one of these (there can be two
DwarfFiles - one for the .o, one for the .dwo - but only one loc/loclist
section (either in the .o or the .dwo) & certainly one per
DebugLocStream, which is currently singular in DwarfDebug)
llvm-svn: 375183
This is an effort to make RangeSpan and DebugLocStream::Entry more
similar to share code for their emission (to reuse the more complicated
code for using (& choosing when to use) base address selection entries,
etc).
It didn't seem like this struct was worth the complexity of
encapsulation - when the members could be initialized by the ctor to any
value (no validation) and the type is assignable (so there's no
mutability or other constraint being implemented by its interface).
llvm-svn: 373533
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
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
Turns out knowing more than just the base address might be useful -
specifically a future change to respect a DICompileUnit flag for the use
of base address specifiers in DWARF < 5.
llvm-svn: 346380
.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
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
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
There are two forms for label debug information in DWARF format.
1. Labels in a non-inlined function:
DW_TAG_label
DW_AT_name
DW_AT_decl_file
DW_AT_decl_line
DW_AT_low_pc
2. Labels in an inlined function:
DW_TAG_label
DW_AT_abstract_origin
DW_AT_low_pc
We will collect label information from DBG_LABEL. Before every DBG_LABEL,
we will generate a temporary symbol to denote the location of the label.
The symbol could be used to get DW_AT_low_pc afterwards. So, we create a
mapping between 'inlined label' and DBG_LABEL MachineInstr in DebugHandlerBase.
The DBG_LABEL in the mapping is used to query the symbol before it.
The AbstractLabels in DwarfCompileUnit is used to process labels in inlined
functions.
We also keep a mapping between scope and labels in DwarfFile to help to
generate correct tree structure of DIEs.
It also generates label debug information under global isel.
Differential Revision: https://reviews.llvm.org/D45556
llvm-svn: 340039
There are two forms for label debug information in DWARF format.
1. Labels in a non-inlined function:
DW_TAG_label
DW_AT_name
DW_AT_decl_file
DW_AT_decl_line
DW_AT_low_pc
2. Labels in an inlined function:
DW_TAG_label
DW_AT_abstract_origin
DW_AT_low_pc
We will collect label information from DBG_LABEL. Before every DBG_LABEL,
we will generate a temporary symbol to denote the location of the label.
The symbol could be used to get DW_AT_low_pc afterwards. So, we create a
mapping between 'inlined label' and DBG_LABEL MachineInstr in DebugHandlerBase.
The DBG_LABEL in the mapping is used to query the symbol before it.
The AbstractLabels in DwarfCompileUnit is used to process labels in inlined
functions.
We also keep a mapping between scope and labels in DwarfFile to help to
generate correct tree structure of DIEs.
It also generates label debug information under global isel.
Differential Revision: https://reviews.llvm.org/D45556
llvm-svn: 339676
There are two forms for label debug information in DWARF format.
1. Labels in a non-inlined function:
DW_TAG_label
DW_AT_name
DW_AT_decl_file
DW_AT_decl_line
DW_AT_low_pc
2. Labels in an inlined function:
DW_TAG_label
DW_AT_abstract_origin
DW_AT_low_pc
We will collect label information from DBG_LABEL. Before every DBG_LABEL,
we will generate a temporary symbol to denote the location of the label.
The symbol could be used to get DW_AT_low_pc afterwards. So, we create a
mapping between 'inlined label' and DBG_LABEL MachineInstr in DebugHandlerBase.
The DBG_LABEL in the mapping is used to query the symbol before it.
The AbstractLabels in DwarfCompileUnit is used to process labels in inlined
functions.
We also keep a mapping between scope and labels in DwarfFile to help to
generate correct tree structure of DIEs.
It also generates label debug information under global isel.
Differential Revision: https://reviews.llvm.org/D45556
llvm-svn: 338390
Previous version of this patch failed on darwin targets because of
different handling of cross-debug-section relocations. This fixes the
tests to emit the DW_AT_str_offsets_base attribute correctly in both
cases. Since doing this is a non-trivial amount of code, and I'm going
to need it in more than one test, I've added a helper function to the
dwarfgen DIE class to do it.
Original commit message follows:
The motivation for this is D49493, where we'd like to test details of
debug_str_offsets behavior which is difficult to trigger from a
traditional test.
This adds the plubming necessary for dwarfgen to generate this section.
The more interesting changes are:
- I've moved emitStringOffsetsTableHeader function from DwarfFile to
DwarfStringPool, so I can generate the section header more easily from
the unit test.
- added a new addAttribute overload taking an MCExpr*. This is used to
generate the DW_AT_str_offsets_base, which links a compile unit to the
offset table.
I've also added a basic test for reading and writing DW_form_strx forms.
Reviewers: dblaikie, JDevlieghere, probinson
Subscribers: llvm-commits, aprantl
Differential Revision: https://reviews.llvm.org/D49670
llvm-svn: 338031
This recommits r337910 after fixing an "ambiguous call to addAttribute"
error with some compilers (gcc circa 4.9 and MSVC). It seems that these
compilers will consider a "false -> pointer" conversion during overload
resolution. This creates ambiguity because one I added an overload which
takes a MCExpr * as an argument.
I fix this by making the new overload take MCExpr&, which avoids the
conversion. It also documents the fact that we expect a valid MCExpr
object.
Original commit message follows:
The motivation for this is D49493, where we'd like to test details of
debug_str_offsets behavior which is difficult to trigger from a
traditional test.
This adds the plubming necessary for dwarfgen to generate this section.
The more interesting changes are:
- I've moved emitStringOffsetsTableHeader function from DwarfFile to
DwarfStringPool, so I can generate the section header more easily from
the unit test.
- added a new addAttribute overload taking an MCExpr*. This is used to
generate the DW_AT_str_offsets_base, which links a compile unit to the
offset table.
I've also added a basic test for reading and writing DW_form_strx forms.
Reviewers: dblaikie, JDevlieghere, probinson
Subscribers: llvm-commits, aprantl
Differential Revision: https://reviews.llvm.org/D49670
llvm-svn: 337933
This reverts commit r337910 as it's generating "ambiguous call to
addAttribute" errors on some bots.
Will resubmit once I get a chance to look into the problem.
llvm-svn: 337924
Summary:
The motivation for this is D49493, where we'd like to test details of
debug_str_offsets behavior which is difficult to trigger from a
traditional test.
This adds the plubming necessary for dwarfgen to generate this section.
The more interesting changes are:
- I've moved emitStringOffsetsTableHeader function from DwarfFile to
DwarfStringPool, so I can generate the section header more easily from
the unit test.
- added a new addAttribute overload taking an MCExpr*. This is used to
generate the DW_AT_str_offsets_base, which links a compile unit to the
offset table.
I've also added a basic test for reading and writing DW_form_strx forms.
Reviewers: dblaikie, JDevlieghere, probinson
Subscribers: llvm-commits, aprantl
Differential Revision: https://reviews.llvm.org/D49670
llvm-svn: 337910
There are two forms for label debug information in DWARF format.
1. Labels in a non-inlined function:
DW_TAG_label
DW_AT_name
DW_AT_decl_file
DW_AT_decl_line
DW_AT_low_pc
2. Labels in an inlined function:
DW_TAG_label
DW_AT_abstract_origin
DW_AT_low_pc
We will collect label information from DBG_LABEL. Before every DBG_LABEL,
we will generate a temporary symbol to denote the location of the label.
The symbol could be used to get DW_AT_low_pc afterwards. So, we create a
mapping between 'inlined label' and DBG_LABEL MachineInstr in DebugHandlerBase.
The DBG_LABEL in the mapping is used to query the symbol before it.
The AbstractLabels in DwarfCompileUnit is used to process labels in inlined
functions.
We also keep a mapping between scope and labels in DwarfFile to help to
generate correct tree structure of DIEs.
Differential Revision: https://reviews.llvm.org/D45556
Patch by Hsiangkai Wang.
llvm-svn: 337799
