[llvm] [llvm-objdump] Handle .callgraph section (PR #151009)

[Paul Kirth via llvm-commits]

================
@@ -3131,6 +3225,207 @@ void Dumper::printSymbol(const SymbolRef &Symbol,
   outs() << ' ' << SymName << '\n';
 }
 
+static void printCallGraphInfo(ObjectFile *Obj) {
+  // Get function info through disassembly.
+  disassembleObject(Obj, /*InlineRelocs=*/false, outs());
+
+  // Get the .callgraph section.
+  StringRef CallGraphSectionName(".callgraph");
+  std::optional<object::SectionRef> CallGraphSection;
+  for (auto Sec : ToolSectionFilter(*Obj)) {
+    StringRef Name;
+    if (Expected<StringRef> NameOrErr = Sec.getName())
+      Name = *NameOrErr;
+    else
+      consumeError(NameOrErr.takeError());
+
+    if (Name == CallGraphSectionName) {
+      CallGraphSection = Sec;
+      break;
+    }
+  }
+  if (!CallGraphSection)
+    reportWarning("there is no .callgraph section", Obj->getFileName());
+
+  // Map type id to indirect call sites.
+  MapVector<uint64_t, SmallVector<uint64_t>> TypeIdToIndirCallSites;
----------------
ilovepi wrote:

I'd consider a `using` statement to make this type easier to reason about. 

```
using TypIdCallSiteMap = MapVector<uint64_t, SmallVector<uint64_t>>
```

https://github.com/llvm/llvm-project/pull/151009