[llvm] f8656ed - [llvm][dwarfdump] Add --child-tags option to filter by DWARF tags (#165720)
via llvm-commits
llvm-commits at lists.llvm.org
Tue Nov 4 03:38:00 PST 2025
Author: Michael Buch
Date: 2025-11-04T11:37:56Z
New Revision: f8656ed4557500345ba29128d9ec85ef1a637240
URL: https://github.com/llvm/llvm-project/commit/f8656ed4557500345ba29128d9ec85ef1a637240
DIFF: https://github.com/llvm/llvm-project/commit/f8656ed4557500345ba29128d9ec85ef1a637240.diff
LOG: [llvm][dwarfdump] Add --child-tags option to filter by DWARF tags (#165720)
This patch adds a new option `--child-tags` (`-t` for short), which
makes dwarfdump only dump children whose DWARF tag is in the list of
tags specified by the user.
Motivating examples are:
* dumping all global variables in a CU
* dumping all non-static data members of a structure
* dumping all module import declarations of a CU
* etc.
For tags not known to dwarfdump, we pretend that the tag wasn't
specified.
Note, this flag only takes effect when `--show-children` is set (either
explicitly or implicitly). We error out when trying to use the flag
without dumping children.
Example:
```
$ builds/release/bin/llvm-dwarfdump -t DW_TAG_structure_type a.out.dSYM
...
0x0000000c: DW_TAG_compile_unit
DW_AT_producer ("clang version 22.0.0git (git at github.com:Michael137/llvm-project.git 737da3347c2fb01dd403420cf83e9b8fbea32618)")
DW_AT_language (DW_LANG_C11)
...
0x0000002a: DW_TAG_structure_type
DW_AT_APPLE_block (true)
DW_AT_byte_size (0x20)
0x00000067: DW_TAG_structure_type
DW_AT_APPLE_block (true)
DW_AT_name ("__block_descriptor")
DW_AT_byte_size (0x10)
...
```
```
$ builds/release/bin/llvm-dwarfdump -t DW_TAG_structure_type -t DW_TAG_member a.out.dSYM
...
0x0000000c: DW_TAG_compile_unit
DW_AT_producer ("clang version 22.0.0git (git at github.com:Michael137/llvm-project.git 737da3347c2fb01dd403420cf83e9b8fbea32618)")
DW_AT_language (DW_LANG_C11)
DW_AT_name ("macro.c")
...
0x0000002a: DW_TAG_structure_type
DW_AT_APPLE_block (true)
DW_AT_byte_size (0x20)
0x0000002c: DW_TAG_member
DW_AT_name ("__isa")
DW_AT_type (0x00000051 "void *")
DW_AT_data_member_location (0x00)
0x00000033: DW_TAG_member
DW_AT_name ("__flags")
DW_AT_type (0x00000052 "int")
DW_AT_data_member_location (0x08)
0x0000003a: DW_TAG_member
DW_AT_name ("__reserved")
DW_AT_type (0x00000052 "int")
DW_AT_data_member_location (0x0c)
0x00000041: DW_TAG_member
DW_AT_name ("__FuncPtr")
DW_AT_type (0x00000056 "void (*)(int)")
DW_AT_data_member_location (0x10)
0x00000048: DW_TAG_member
DW_AT_name ("__descriptor")
DW_AT_type (0x00000062 "__block_descriptor *")
DW_AT_alignment (8)
DW_AT_data_member_location (0x18)
0x00000067: DW_TAG_structure_type
DW_AT_APPLE_block (true)
DW_AT_name ("__block_descriptor")
DW_AT_byte_size (0x10)
0x0000006a: DW_TAG_member
DW_AT_name ("reserved")
DW_AT_type (0x00000079 "unsigned long")
DW_AT_data_member_location (0x00)
0x00000071: DW_TAG_member
DW_AT_name ("Size")
DW_AT_type (0x00000079 "unsigned long")
DW_AT_data_member_location (0x08)
...
```
Added:
llvm/test/tools/llvm-dwarfdump/X86/filter-child-tag.yaml
Modified:
llvm/docs/CommandGuide/llvm-dwarfdump.rst
llvm/include/llvm/DebugInfo/DIContext.h
llvm/lib/DebugInfo/DWARF/DWARFDie.cpp
llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp
Removed:
################################################################################
diff --git a/llvm/docs/CommandGuide/llvm-dwarfdump.rst b/llvm/docs/CommandGuide/llvm-dwarfdump.rst
index 137830259eb64..dfc0431f07826 100644
--- a/llvm/docs/CommandGuide/llvm-dwarfdump.rst
+++ b/llvm/docs/CommandGuide/llvm-dwarfdump.rst
@@ -134,6 +134,15 @@ OPTIONS
Abbreviate the description of type unit entries.
+.. option:: -t, --filter-child-tag
+
+ Only dump children whose DWARF tag is one of the specified tags.
+ Example usage:
+
+ .. code-block:: c
+
+ llvm-dwarfdump -t DW_TAG_structure_type -t DW_TAG_member -c
+
.. option:: -x, --regex
Treat any <name> strings as regular expressions when searching
diff --git a/llvm/include/llvm/DebugInfo/DIContext.h b/llvm/include/llvm/DebugInfo/DIContext.h
index e7e87bbfebf38..b404c92e71836 100644
--- a/llvm/include/llvm/DebugInfo/DIContext.h
+++ b/llvm/include/llvm/DebugInfo/DIContext.h
@@ -211,6 +211,8 @@ struct DIDumpOptions {
bool ShowAggregateErrors = false;
bool PrintRegisterOnly = false;
std::string JsonErrSummaryFile;
+ /// List of DWARF tags to filter children by.
+ llvm::SmallVector<unsigned, 0> FilterChildTag;
std::function<llvm::StringRef(uint64_t DwarfRegNum, bool IsEH)>
GetNameForDWARFReg;
diff --git a/llvm/lib/DebugInfo/DWARF/DWARFDie.cpp b/llvm/lib/DebugInfo/DWARF/DWARFDie.cpp
index 6c78ef05e1b61..7496c5a084da4 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFDie.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFDie.cpp
@@ -704,7 +704,9 @@ void DWARFDie::dump(raw_ostream &OS, unsigned Indent,
DIDumpOptions ChildDumpOpts = DumpOpts;
ChildDumpOpts.ShowParents = false;
while (Child) {
- Child.dump(OS, Indent + 2, ChildDumpOpts);
+ if (DumpOpts.FilterChildTag.empty() ||
+ llvm::is_contained(DumpOpts.FilterChildTag, Child.getTag()))
+ Child.dump(OS, Indent + 2, ChildDumpOpts);
Child = Child.getSibling();
}
}
diff --git a/llvm/test/tools/llvm-dwarfdump/X86/filter-child-tag.yaml b/llvm/test/tools/llvm-dwarfdump/X86/filter-child-tag.yaml
new file mode 100644
index 0000000000000..2a8c37da80e64
--- /dev/null
+++ b/llvm/test/tools/llvm-dwarfdump/X86/filter-child-tag.yaml
@@ -0,0 +1,136 @@
+## Tests the --filter-child-tag (-t) option.
+
+# RUN: yaml2obj %s -o %t.o
+
+# RUN: llvm-dwarfdump %t.o --filter-child-tag=DW_TAG_structure_type | FileCheck %s --check-prefix=ONLY_STRUCT
+
+# ONLY_STRUCT: DW_TAG_compile_unit
+# ONLY_STRUCT-NOT: DW_TAG_namespace
+# ONLY_STRUCT-NOT: DW_TAG_structure_type
+
+# RUN: llvm-dwarfdump %t.o -t DW_TAG_structure_type -t DW_TAG_namespace | \
+# RUN: FileCheck %s --check-prefix=STRUCT_AND_NS --implicit-check-not=DW_TAG_subprogram --implicit-check-not=DW_TAG_member
+
+# STRUCT_AND_NS: DW_TAG_compile_unit
+# STRUCT_AND_NS: DW_TAG_namespace
+# STRUCT_AND_NS: DW_TAG_structure_type
+# STRUCT_AND_NS: DW_TAG_structure_type
+
+# RUN: llvm-dwarfdump %t.o -c --name=Foo -t DW_TAG_member | \
+# RUN: FileCheck %s --check-prefix=FOO_MEM --implicit-check-not=DW_TAG_compile_unit --implicit-check-not=DW_TAG_subprogram --implicit-check-not=DW_TAG_namespace
+
+# FOO_MEM: DW_TAG_structure_type
+# FOO_MEM: DW_TAG_member
+# FOO_MEM: DW_TAG_member
+# FOO_MEM: DW_TAG_member
+# FOO_MEM-NOT: DW_TAG_structure_type
+# FOO_MEM-NOT: DW_TAG_member
+
+# RUN: llvm-dwarfdump %t.o -c --name=Foo -t not_a_tag -t DW_TAG_member | \
+# RUN: FileCheck %s --check-prefix=SINGLE_INVALID_TAG --implicit-check-not=DW_TAG_compile_unit --implicit-check-not=DW_TAG_subprogram --implicit-check-not=DW_TAG_namespace
+
+# SINGLE_INVALID_TAG: DW_TAG_structure_type
+# SINGLE_INVALID_TAG: DW_TAG_member
+# SINGLE_INVALID_TAG: DW_TAG_member
+# SINGLE_INVALID_TAG: DW_TAG_member
+# SINGLE_INVALID_TAG-NOT: DW_TAG_structure_type
+# SINGLE_INVALID_TAG-NOT: DW_TAG_member
+
+# RUN: llvm-dwarfdump %t.o -c --name=Foo -t not_a_tag | \
+# RUN: FileCheck %s --check-prefix=ONLY_INVALID_TAGS --implicit-check-not=DW_TAG_compile_unit --implicit-check-not=DW_TAG_subprogram --implicit-check-not=DW_TAG_namespace --implicit-check-not=DW_TAG_member
+
+# ONLY_INVALID_TAGS: DW_TAG_structure_type
+# ONLY_INVALID_TAGS-NOT: DW_TAG_structure_type
+
+# RUN: llvm-dwarfdump %t.o -c -p --name=Foo -t DW_TAG_member | \
+# RUN: FileCheck %s --check-prefix=FOO_MEM_WITH_PARENT --implicit-check-not=DW_TAG_subprogram
+
+# FOO_MEM_WITH_PARENT: DW_TAG_compile_unit
+# FOO_MEM_WITH_PARENT: DW_TAG_namespace
+# FOO_MEM_WITH_PARENT: DW_TAG_structure_type
+# FOO_MEM_WITH_PARENT: DW_TAG_member
+# FOO_MEM_WITH_PARENT: DW_TAG_member
+# FOO_MEM_WITH_PARENT: DW_TAG_member
+# FOO_MEM_WITH_PARENT-NOT: DW_TAG_structure_type
+# FOO_MEM_WITH_PARENT-NOT: DW_TAG_member
+
+## Not specifying --show-children ignores the --filter-child-tag option.
+# RUN: llvm-dwarfdump %t.o --name=Foo -t DW_TAG_member 2>&1 | FileCheck %s --check-prefix=NO_SHOW_CHILDREN
+
+# NO_SHOW_CHILDREN: DW_TAG_structure_type
+
+--- !ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_EXEC
+ Machine: EM_X86_64
+DWARF:
+ debug_abbrev:
+ - Table:
+ - Tag: DW_TAG_compile_unit
+ Children: DW_CHILDREN_yes
+ Attributes:
+ - Attribute: DW_AT_producer
+ Form: DW_FORM_string
+ - Tag: DW_TAG_namespace
+ Children: DW_CHILDREN_yes
+ Attributes:
+ - Attribute: DW_AT_name
+ Form: DW_FORM_string
+ - Tag: DW_TAG_structure_type
+ Children: DW_CHILDREN_yes
+ Attributes:
+ - Attribute: DW_AT_name
+ Form: DW_FORM_string
+ - Tag: DW_TAG_member
+ Children: DW_CHILDREN_no
+ Attributes:
+ - Attribute: DW_AT_name
+ Form: DW_FORM_string
+ - Tag: DW_TAG_subprogram
+ Children: DW_CHILDREN_no
+ Attributes:
+ - Attribute: DW_AT_name
+ Form: DW_FORM_string
+ debug_info:
+ - Version: 5
+ UnitType: DW_UT_compile
+ Entries:
+ - AbbrCode: 1
+ Values:
+ - CStr: handwritten
+ - AbbrCode: 2
+ Values:
+ - CStr: ns
+ - AbbrCode: 3
+ Values:
+ - CStr: Foo
+ - AbbrCode: 4
+ Values:
+ - CStr: mem1
+ - AbbrCode: 4
+ Values:
+ - CStr: mem2
+ - AbbrCode: 4
+ Values:
+ - CStr: mem3
+ - AbbrCode: 3
+ Values:
+ - CStr: NestedInFoo
+ - AbbrCode: 4
+ Values:
+ - CStr: NestedMem1
+ - AbbrCode: 4
+ Values:
+ - CStr: NestedMem2
+ - AbbrCode: 5
+ Values:
+ - CStr: NestedFunc
+ - AbbrCode: 0x0
+ - AbbrCode: 5
+ Values:
+ - CStr: FooFunc
+ - AbbrCode: 0x0
+ - AbbrCode: 0x0
+ - AbbrCode: 0x0
diff --git a/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp b/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp
index 11eb58ea911df..6f120f93700f6 100644
--- a/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp
+++ b/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp
@@ -14,6 +14,7 @@
#include "llvm/ADT/MapVector.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallSet.h"
+#include "llvm/ADT/SmallVectorExtras.h"
#include "llvm/ADT/StringSet.h"
#include "llvm/DebugInfo/DIContext.h"
#include "llvm/DebugInfo/DWARF/DWARFAcceleratorTable.h"
@@ -242,6 +243,15 @@ static opt<bool>
cat(DwarfDumpCategory));
static alias ShowParentsAlias("p", desc("Alias for --show-parents."),
aliasopt(ShowParents), cl::NotHidden);
+
+static list<std::string> FilterChildTag(
+ "filter-child-tag",
+ desc("When --show-children is specified, show only DIEs with the "
+ "specified DWARF tags."),
+ value_desc("list of DWARF tags"), cat(DwarfDumpCategory));
+static alias FilterChildTagAlias("t", desc("Alias for --filter-child-tag."),
+ aliasopt(FilterChildTag), cl::NotHidden);
+
static opt<bool>
ShowForm("show-form",
desc("Show DWARF form types after the DWARF attribute types."),
@@ -330,6 +340,13 @@ static cl::extrahelp
/// @}
//===----------------------------------------------------------------------===//
+static llvm::SmallVector<unsigned>
+makeTagVector(const list<std::string> &TagStrings) {
+ return llvm::map_to_vector(TagStrings, [](const std::string &Tag) {
+ return llvm::dwarf::getTag(Tag);
+ });
+}
+
static void error(Error Err) {
if (!Err)
return;
@@ -356,6 +373,7 @@ static DIDumpOptions getDumpOpts(DWARFContext &C) {
DumpOpts.ShowAddresses = !Diff;
DumpOpts.ShowChildren = ShowChildren;
DumpOpts.ShowParents = ShowParents;
+ DumpOpts.FilterChildTag = makeTagVector(FilterChildTag);
DumpOpts.ShowForm = ShowForm;
DumpOpts.SummarizeTypes = SummarizeTypes;
DumpOpts.Verbose = Verbose;
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