Merge pull request #11745 from swiftlang/llvm/dwarfdump-tag-filter-to-21.x

Michael137 · web-flow · commit 81c6606be4b5 · 2025-11-05T23:27:09.000Z
🍒[llvm][dwarfdump] Add --child-tags option to filter by DWARF tags 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)") 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)") 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) ... ``` (cherry picked from commit f8656ed)
diff --git 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
@@ -210,6 +210,8 @@ struct DIDumpOptions {
   bool DumpNonSkeleton = false;
   bool ShowAggregateErrors = 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
@@ -636,7 +636,9 @@ 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
@@ -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/CMakeLists.txt b/llvm/tools/llvm-dwarfdump/CMakeLists.txt
@@ -1,4 +1,5 @@
 set(LLVM_LINK_COMPONENTS
+  BinaryFormat
   DebugInfoDWARF
   DebugInfoDWARFLowLevel
   AllTargetsDescs
diff --git 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"
@@ -241,6 +242,15 @@ 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."),
@@ -329,6 +339,13 @@ 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;
@@ -355,6 +372,7 @@ 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;

Original file line number	Diff line number	Diff line change
`@@ -636,7 +636,9 @@ void DWARFDie::dump(raw_ostream &OS, unsigned Indent,`
`636`	`636`	`DIDumpOptions ChildDumpOpts = DumpOpts;`
`637`	`637`	`ChildDumpOpts.ShowParents = false;`
`638`	`638`	`while (Child) {`
`639`		`- Child.dump(OS, Indent + 2, ChildDumpOpts);`
	`639`	`+ if (DumpOpts.FilterChildTag.empty() \|\|`
	`640`	`+ llvm::is_contained(DumpOpts.FilterChildTag, Child.getTag()))`
	`641`	`+ Child.dump(OS, Indent + 2, ChildDumpOpts);`
`640`	`642`	`Child = Child.getSibling();`
`641`	`643`	`}`
`642`	`644`	`}`
Original file line number	Diff line number	Diff line change
`@@ -1,4 +1,5 @@`
`1`	`1`	`set(LLVM_LINK_COMPONENTS`
	`2`	`+ BinaryFormat`
`2`	`3`	`DebugInfoDWARF`
`3`	`4`	`DebugInfoDWARFLowLevel`
`4`	`5`	`AllTargetsDescs`