[lldb][Format] Add function.suffix frame-format variable (#137763)

This patch adds another frame-format variable (currently only
implemented in the CPlusPlus language plugin) that represents the
"suffix" of a function. The name is derived from the `DotSuffix` node of
LLVM's Itanium demangler.

For a function name such as `int foo() (.cold)`, the suffix would be
`(.cold)`.

1 files changed, 33 insertions, 0 deletions

diff --git a/lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.cpp b/lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.cpp
index 283e867..6491fb7 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.cpp
+++ b/lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.cpp
@@ -381,6 +381,30 @@ GetDemangledScope(const SymbolContext &sc) {
   return demangled_name.slice(info->ScopeRange.first, info->ScopeRange.second);
 }
 
+/// Handles anything printed after the FunctionEncoding ItaniumDemangle
+/// node. Most notably the DotSUffix node.
+static std::optional<llvm::StringRef>
+GetDemangledFunctionSuffix(const SymbolContext &sc) {
+  Mangled mangled = sc.GetPossiblyInlinedFunctionName();
+  if (!mangled)
+    return std::nullopt;
+
+  auto demangled_name = mangled.GetDemangledName().GetStringRef();
+  if (demangled_name.empty())
+    return std::nullopt;
+
+  const std::optional<DemangledNameInfo> &info = mangled.GetDemangledInfo();
+  if (!info)
+    return std::nullopt;
+
+  // Function without a basename is nonsense.
+  if (!info->hasBasename())
+    return std::nullopt;
+
+  return demangled_name.slice(info->QualifiersRange.second,
+                              llvm::StringRef::npos);
+}
+
 bool CPlusPlusLanguage::CxxMethodName::TrySimplifiedParse() {
   // This method tries to parse simple method definitions which are presumably
   // most comman in user programs. Definitions that can be parsed by this
@@ -1966,6 +1990,15 @@ bool CPlusPlusLanguage::HandleFrameFormatVariable(
 
     return true;
   }
+  case FormatEntity::Entry::Type::FunctionSuffix: {
+    std::optional<llvm::StringRef> suffix = GetDemangledFunctionSuffix(sc);
+    if (!suffix)
+      return false;
+
+    s << *suffix;
+
+    return true;
+  }
   default:
     return false;
   }