[llvm][dwarfdump] Add --child-tags option to filter by DWARF tags

llvm/docs/CommandGuide/llvm-dwarfdump.rst

@@ -134,6 +134,12 @@ 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:
+            `llvm-dwarfdump -t DW_TAG_structure_type -t DW_TAG_member -c`
+
 .. option:: -x, --regex
 
             Treat any <name> strings as regular expressions when searching

llvm/include/llvm/DebugInfo/DIContext.h

@@ -202,6 +202,8 @@ struct DIDumpOptions {
   bool ShowAddresses = true;
   bool ShowChildren = false;
   bool ShowParents = false;
+  /// List of DWARF tags to filter children by.
+  llvm::SmallVector<unsigned, 0> FilterChildTag;
   bool ShowForm = false;
   bool SummarizeTypes = false;
   bool Verbose = false;

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();
           }
         }

llvm/test/tools/llvm-dwarfdump/X86/filter-child-tag.yaml

@@ -0,0 +1,127 @@
+# 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
+# RUN: llvm-dwarfdump %t.o -t DW_TAG_structure_type -t DW_TAG_namespace | FileCheck %s --check-prefix=STRUCT_AND_NS --implicit-check-not=DW_TAG_subprogram --implicit-check-not=DW_TAG_member
+# RUN: llvm-dwarfdump %t.o -c --name=Foo -t DW_TAG_member | 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
+# RUN: llvm-dwarfdump %t.o -c --name=Foo -t not_a_tag -t DW_TAG_member | 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
+# RUN: llvm-dwarfdump %t.o -c --name=Foo -t not_a_tag | 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
+# RUN: llvm-dwarfdump %t.o -c -p --name=Foo -t DW_TAG_member | FileCheck %s --check-prefix=FOO_MEM_WITH_PARENT --implicit-check-not=DW_TAG_subprogram
+# RUN: not llvm-dwarfdump %t.o --name=Foo -t DW_TAG_member 2>&1 | FileCheck %s --check-prefix=ERROR_NO_SHOW_CHILDREN
+
+# ONLY_STRUCT: DW_TAG_compile_unit
+# ONLY_STRUCT-NOT: DW_TAG_namespace
+# ONLY_STRUCT-NOT: DW_TAG_structure_type
+
+# 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
+
+# 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
+
+# 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
+
+# ONLY_INVALID_TAGS: DW_TAG_structure_type
+# ONLY_INVALID_TAGS-NOT: DW_TAG_structure_type
+
+# 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
+
+# ERROR_NO_SHOW_CHILDREN: incompatible arguments: --filter-child-tag requires --show-children
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_EXEC
+  Machine: EM_X86_64
+DWARF:
+  debug_abbrev:
+    - Table:
+      # 1
+      - Tag:      DW_TAG_compile_unit
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_producer
+            Form:      DW_FORM_string
+      # 2
+      - Tag:      DW_TAG_namespace
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      # 3
+      - Tag:      DW_TAG_structure_type
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      # 4
+      - Tag:      DW_TAG_member
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+      # 5
+      - 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

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;
@@ -899,6 +917,12 @@ int main(int argc, char **argv) {
       Find.empty() && !FindAllApple)
     ShowChildren = true;
 
+  if (!ShowChildren && !FilterChildTag.empty()) {
+    WithColor::error() << "incompatible arguments: --filter-child-tag requires "
+                          "--show-children";
+    return 1;
+  }
+
   // Defaults to a.out if no filenames specified.
   if (InputFilenames.empty())
     InputFilenames.push_back("a.out");