[llvm-readobj][ELF] Implement JSON output for --dynamic-table (#95976)

When printing JSON output with --dynamic-table I noticed that the output
is invalid JSON. This patch overrides the printDynamicTable() function
in the JSONELFDumper to return a list of dictionaries for the
DynamicSection value.
Before the output was:
```
 {
    "FileSummary": {
      "File": "bin/llvm-readelf",
      "Format": "elf64-x86-64",
      "Arch": "x86_64",
      "AddressSize": "64bit",
      "LoadName": "<Not found>"
    }DynamicSection [ (35 entries)
  Tag                Type         Name/Value
  0x000000000000001D RUNPATH      Library runpath: [$ORIGIN/../lib:]
  0x0000000000000001 NEEDED       Shared library: [libm.so.6]
  0x0000000000000001 NEEDED       Shared library: [libz.so.1]
  0x0000000000000001 NEEDED       Shared library: [libzstd.so.1]
```
Now the output looks like:
```
 "DynamicSection": [
      {
        "Tag": 29,
        "Type": "RUNPATH",
        "Value": 6322,
        "Path": [
          "$ORIGIN/../lib"
        ]
      },
      {
        "Tag": 1,
        "Type": "NEEDED",
        "Value": 6109,
        "Library": "libm.so.6"
      },
```

2 files changed, 418 insertions, 0 deletions

diff --git a/llvm/test/tools/llvm-readobj/ELF/dynamic-tags.test b/llvm/test/tools/llvm-readobj/ELF/dynamic-tags.test
index 5610ed8..d05eed0 100644
--- a/llvm/test/tools/llvm-readobj/ELF/dynamic-tags.test
+++ b/llvm/test/tools/llvm-readobj/ELF/dynamic-tags.test
@@ -8,6 +8,8 @@
 # RUN: llvm-readelf --dynamic-table %t1 \
 # RUN:   | FileCheck %s --strict-whitespace --match-full-lines --check-prefix=GNU64
 # RUN: llvm-readelf -d %t1 | FileCheck %s --check-prefix=GNU64
+# RUN: llvm-readelf --dynamic-table --pretty-print --elf-output-style=JSON %t1 \
+# RUN:   | FileCheck %s --strict-whitespace --check-prefix=JSON64
 
 #      LLVM64:DynamicSection [ (61 entries)
 # LLVM64-NEXT:  Tag                Type                 Name/Value
@@ -138,6 +140,361 @@
 # GNU64-NEXT:  0x0000000076543210 (<unknown:>0x76543210) 0x5555666677778888
 # GNU64-NEXT:  0x0000000000000000 (NULL)                 0x0
 
+#      JSON64:"DynamicSection": [
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 1,
+# JSON64-NEXT:      "Type": "NEEDED",
+# JSON64-NEXT:      "Value": 1,
+# JSON64-NEXT:      "Library": "D"
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 2,
+# JSON64-NEXT:      "Type": "PLTRELSZ",
+# JSON64-NEXT:      "Value": 16
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 3,
+# JSON64-NEXT:      "Type": "PLTGOT",
+# JSON64-NEXT:      "Value": 4096
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 4,
+# JSON64-NEXT:      "Type": "HASH",
+# JSON64-NEXT:      "Value": 4096
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 5,
+# JSON64-NEXT:      "Type": "STRTAB",
+# JSON64-NEXT:      "Value": 4096
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 6,
+# JSON64-NEXT:      "Type": "SYMTAB",
+# JSON64-NEXT:      "Value": 4096
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 7,
+# JSON64-NEXT:      "Type": "RELA",
+# JSON64-NEXT:      "Value": 4096
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 8,
+# JSON64-NEXT:      "Type": "RELASZ",
+# JSON64-NEXT:      "Value": 16
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 9,
+# JSON64-NEXT:      "Type": "RELAENT",
+# JSON64-NEXT:      "Value": 1929
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 10,
+# JSON64-NEXT:      "Type": "STRSZ",
+# JSON64-NEXT:      "Value": 16
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 11,
+# JSON64-NEXT:      "Type": "SYMENT",
+# JSON64-NEXT:      "Value": 2439
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 12,
+# JSON64-NEXT:      "Type": "INIT",
+# JSON64-NEXT:      "Value": 4096
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 13,
+# JSON64-NEXT:      "Type": "FINI",
+# JSON64-NEXT:      "Value": 4096
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 14,
+# JSON64-NEXT:      "Type": "SONAME",
+# JSON64-NEXT:      "Value": 3,
+# JSON64-NEXT:      "Name": "U"
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 15,
+# JSON64-NEXT:      "Type": "RPATH",
+# JSON64-NEXT:      "Value": 5,
+# JSON64-NEXT:      "Path": [
+# JSON64-NEXT:          "f"
+# JSON64-NEXT:      ]
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 16,
+# JSON64-NEXT:      "Type": "SYMBOLIC",
+# JSON64-NEXT:      "Value": 1311768467294899695
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 17,
+# JSON64-NEXT:      "Type": "REL",
+# JSON64-NEXT:      "Value": 4096
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 18,
+# JSON64-NEXT:      "Type": "RELSZ",
+# JSON64-NEXT:      "Value": 16
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 19,
+# JSON64-NEXT:      "Type": "RELENT",
+# JSON64-NEXT:      "Value": 291
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 20,
+# JSON64-NEXT:      "Type": "PLTREL",
+# JSON64-NEXT:      "Value": 7
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 21,
+# JSON64-NEXT:      "Type": "DEBUG",
+# JSON64-NEXT:      "Value": 18364757930599072545
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 22,
+# JSON64-NEXT:      "Type": "TEXTREL",
+# JSON64-NEXT:      "Value": 1234605616436508552
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 23,
+# JSON64-NEXT:      "Type": "JMPREL",
+# JSON64-NEXT:      "Value": 4096
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 24,
+# JSON64-NEXT:      "Type": "BIND_NOW",
+# JSON64-NEXT:      "Value": 9833440827789222417
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 25,
+# JSON64-NEXT:      "Type": "INIT_ARRAY",
+# JSON64-NEXT:      "Value": 4096
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 26,
+# JSON64-NEXT:      "Type": "FINI_ARRAY",
+# JSON64-NEXT:      "Value": 4096
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 27,
+# JSON64-NEXT:      "Type": "INIT_ARRAYSZ",
+# JSON64-NEXT:      "Value": 16
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 28,
+# JSON64-NEXT:      "Type": "FINI_ARRAYSZ",
+# JSON64-NEXT:      "Value": 16
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 29,
+# JSON64-NEXT:      "Type": "RUNPATH",
+# JSON64-NEXT:      "Value": 7,
+# JSON64-NEXT:      "Path": [
+# JSON64-NEXT:          "w"
+# JSON64-NEXT:      ]
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 30,
+# JSON64-NEXT:      "Type": "FLAGS",
+# JSON64-NEXT:      "Value": 18446744073709551615,
+# JSON64-NEXT:      "Flags": [
+# JSON64-NEXT:          "ORIGIN",
+# JSON64-NEXT:          "SYMBOLIC",
+# JSON64-NEXT:          "TEXTREL",
+# JSON64-NEXT:          "BIND_NOW",
+# JSON64-NEXT:          "STATIC_TLS"
+# JSON64-NEXT:      ]
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 32,
+# JSON64-NEXT:      "Type": "PREINIT_ARRAY",
+# JSON64-NEXT:      "Value": 4096
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 33,
+# JSON64-NEXT:      "Type": "PREINIT_ARRAYSZ",
+# JSON64-NEXT:      "Value": 16
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 34,
+# JSON64-NEXT:      "Type": "SYMTAB_SHNDX",
+# JSON64-NEXT:      "Value": 4096
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 35,
+# JSON64-NEXT:      "Type": "RELRSZ",
+# JSON64-NEXT:      "Value": 16
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 36,
+# JSON64-NEXT:      "Type": "RELR",
+# JSON64-NEXT:      "Value": 4096
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 37,
+# JSON64-NEXT:      "Type": "RELRENT",
+# JSON64-NEXT:      "Value": 17185
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 1610612751,
+# JSON64-NEXT:      "Type": "ANDROID_REL",
+# JSON64-NEXT:      "Value": 4096
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 1610612752,
+# JSON64-NEXT:      "Type": "ANDROID_RELSZ",
+# JSON64-NEXT:      "Value": 16
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 1610612753,
+# JSON64-NEXT:      "Type": "ANDROID_RELA",
+# JSON64-NEXT:      "Value": 4096
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 1610612754,
+# JSON64-NEXT:      "Type": "ANDROID_RELASZ",
+# JSON64-NEXT:      "Value": 16
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 1879040000,
+# JSON64-NEXT:      "Type": "ANDROID_RELR",
+# JSON64-NEXT:      "Value": 4096
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 1879040001,
+# JSON64-NEXT:      "Type": "ANDROID_RELRSZ",
+# JSON64-NEXT:      "Value": 16
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 1879040003,
+# JSON64-NEXT:      "Type": "ANDROID_RELRENT",
+# JSON64-NEXT:      "Value": 4660
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 1879047925,
+# JSON64-NEXT:      "Type": "GNU_HASH",
+# JSON64-NEXT:      "Value": 4096
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 1879047926,
+# JSON64-NEXT:      "Type": "TLSDESC_PLT",
+# JSON64-NEXT:      "Value": 4096
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 1879047927,
+# JSON64-NEXT:      "Type": "TLSDESC_GOT",
+# JSON64-NEXT:      "Value": 4096
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 1879048185,
+# JSON64-NEXT:      "Type": "RELACOUNT",
+# JSON64-NEXT:      "Value": 0
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 1879048186,
+# JSON64-NEXT:      "Type": "RELCOUNT",
+# JSON64-NEXT:      "Value": 0
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 1879048187,
+# JSON64-NEXT:      "Type": "FLAGS_1"
+# JSON64-NEXT:      "Value": 18446744073709551615,
+# JSON64-NEXT:      "Flags": [
+# JSON64-NEXT:          "NOW",
+# JSON64-NEXT:          "GLOBAL",
+# JSON64-NEXT:          "GROUP",
+# JSON64-NEXT:          "NODELETE",
+# JSON64-NEXT:          "LOADFLTR",
+# JSON64-NEXT:          "INITFIRST",
+# JSON64-NEXT:          "NOOPEN",
+# JSON64-NEXT:          "ORIGIN",
+# JSON64-NEXT:          "DIRECT",
+# JSON64-NEXT:          "TRANS",
+# JSON64-NEXT:          "INTERPOSE",
+# JSON64-NEXT:          "NODEFLIB",
+# JSON64-NEXT:          "NODUMP",
+# JSON64-NEXT:          "CONFALT",
+# JSON64-NEXT:          "ENDFILTEE",
+# JSON64-NEXT:          "DISPRELDNE",
+# JSON64-NEXT:          "DISPRELPND",
+# JSON64-NEXT:          "NODIRECT",
+# JSON64-NEXT:          "IGNMULDEF",
+# JSON64-NEXT:          "NOKSYMS",
+# JSON64-NEXT:          "NOHDR",
+# JSON64-NEXT:          "EDITED",
+# JSON64-NEXT:          "NORELOC",
+# JSON64-NEXT:          "SYMINTPOSE",
+# JSON64-NEXT:          "GLOBAUDIT",
+# JSON64-NEXT:          "SINGLETON",
+# JSON64-NEXT:          "PIE"
+# JSON64-NEXT:      ]
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 1879048176,
+# JSON64-NEXT:      "Type": "VERSYM",
+# JSON64-NEXT:      "Value": 4096
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 1879048188,
+# JSON64-NEXT:      "Type": "VERDEF",
+# JSON64-NEXT:      "Value": 4096
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 1879048189,
+# JSON64-NEXT:      "Type": "VERDEFNUM",
+# JSON64-NEXT:      "Value": 0
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 1879048190,
+# JSON64-NEXT:      "Type": "VERNEED",
+# JSON64-NEXT:      "Value": 4096
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 1879048191,
+# JSON64-NEXT:      "Type": "VERNEEDNUM",
+# JSON64-NEXT:      "Value": 0
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 2147483645,
+# JSON64-NEXT:      "Type": "AUXILIARY"
+# JSON64-NEXT:      "Value": 1,
+# JSON64-NEXT:      "Library": "D"
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 2147483646,
+# JSON64-NEXT:      "Type": "USED",
+# JSON64-NEXT:      "Value": 3,
+# JSON64-NEXT:      "Object": "U"
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 2147483647,
+# JSON64-NEXT:      "Type": "FILTER",
+# JSON64-NEXT:      "Value": 3,
+# JSON64-NEXT:      "Library": "U"
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 305419896,
+# JSON64-NEXT:      "Type": "<unknown:>0x12345678",
+# JSON64-NEXT:      "Value": 9756277979052589857
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 1790762736,
+# JSON64-NEXT:      "Type": "<unknown:>0x6abcdef0",
+# JSON64-NEXT:      "Value": 11063223766036525858
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 1985229328,
+# JSON64-NEXT:      "Type": "<unknown:>0x76543210",
+# JSON64-NEXT:      "Value": 6148933456521300104
+# JSON64-NEXT:  },
+# JSON64-NEXT:  {
+# JSON64-NEXT:      "Tag": 0,
+# JSON64-NEXT:      "Type": "NULL",
+# JSON64-NEXT:      "Value": 0
+# JSON64-NEXT:  }
+# JSON64-NEXT:]
+
 --- !ELF
 FileHeader:
   Class:      ELFCLASS[[BITS=64]]
diff --git a/llvm/tools/llvm-readobj/ELFDumper.cpp b/llvm/tools/llvm-readobj/ELFDumper.cpp
index c696934..734b28d 100644
--- a/llvm/tools/llvm-readobj/ELFDumper.cpp
+++ b/llvm/tools/llvm-readobj/ELFDumper.cpp
@@ -793,7 +793,11 @@ public:
 
   void printEmptyGroupMessage() const override;
 
+  void printDynamicTable() override;
+
 private:
+  void printAuxillaryDynamicTableEntryInfo(const Elf_Dyn &Entry);
+
   std::unique_ptr<DictScope> FileScope;
 };
 
@@ -7365,6 +7369,63 @@ template <class ELFT> void LLVMELFDumper<ELFT>::printDynamicTable() {
   W.startLine() << "]\n";
 }
 
+template <class ELFT>
+void JSONELFDumper<ELFT>::printAuxillaryDynamicTableEntryInfo(
+    const Elf_Dyn &Entry) {
+  auto FormatFlags = [this, Value = Entry.getVal()](auto Flags) {
+    ListScope L(this->W, "Flags");
+    for (const auto &Flag : Flags) {
+      if (Flag.Value != 0 && (Value & Flag.Value) == Flag.Value)
+        this->W.printString(Flag.Name);
+    }
+  };
+  switch (Entry.getTag()) {
+  case DT_SONAME:
+    this->W.printString("Name", this->getDynamicString(Entry.getVal()));
+    break;
+  case DT_AUXILIARY:
+  case DT_FILTER:
+  case DT_NEEDED:
+    this->W.printString("Library", this->getDynamicString(Entry.getVal()));
+    break;
+  case DT_USED:
+    this->W.printString("Object", this->getDynamicString(Entry.getVal()));
+    break;
+  case DT_RPATH:
+  case DT_RUNPATH: {
+    StringRef Value = this->getDynamicString(Entry.getVal());
+    ListScope L(this->W, "Path");
+    while (!Value.empty()) {
+      auto [Front, Back] = Value.split(':');
+      this->W.printString(Front);
+      Value = Back;
+    }
+    break;
+  }
+  case DT_FLAGS:
+    FormatFlags(ArrayRef(ElfDynamicDTFlags));
+    break;
+  case DT_FLAGS_1:
+    FormatFlags(ArrayRef(ElfDynamicDTFlags1));
+    break;
+  default:
+    return;
+  }
+}
+
+template <class ELFT> void JSONELFDumper<ELFT>::printDynamicTable() {
+  Elf_Dyn_Range Table = this->dynamic_table();
+  ListScope L(this->W, "DynamicSection");
+  for (const auto &Entry : Table) {
+    DictScope D(this->W);
+    uintX_t Tag = Entry.getTag();
+    this->W.printHex("Tag", Tag);
+    this->W.printString("Type", this->Obj.getDynamicTagAsString(Tag));
+    this->W.printHex("Value", Entry.getVal());
+    this->printAuxillaryDynamicTableEntryInfo(Entry);
+  }
+}
+
 template <class ELFT> void LLVMELFDumper<ELFT>::printDynamicRelocations() {
   W.startLine() << "Dynamic Relocations {\n";
   W.indent();