[LLDB][DWARF] Add an option to silence unsupported DW_FORM warnings (#106609)

My build of LLDB is all the time loading targets with a version of
libc++ that was built with gcc that uses the DW_FORM 0x1e that is not
implemented by LLVM, and I doubt it'll ever implement it. It's used for
some 128 bit encoding of numbers, which is just very weird. Because of
this, LLDB is showing some warnings all the time for my users, so I'm
adding a flag to control the enablement of this warning.

Author: walter-erquinigo

lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp

@@ -87,7 +87,7 @@
 #include <cctype>
 #include <cstring>
 
-//#define ENABLE_DEBUG_PRINTF // COMMENT OUT THIS LINE PRIOR TO CHECKIN
+// #define ENABLE_DEBUG_PRINTF // COMMENT OUT THIS LINE PRIOR TO CHECKIN
 
 #ifdef ENABLE_DEBUG_PRINTF
 #include <cstdio>
@@ -129,6 +129,11 @@ class PluginProperties : public Properties {
   bool IgnoreFileIndexes() const {
     return GetPropertyAtIndexAs<bool>(ePropertyIgnoreIndexes, false);
   }
+
+  bool EmitUnsupportedDWFormValueWarning() const {
+    return GetPropertyAtIndexAs<bool>(
+        ePropertyEmitUnsupportedDWFormValueWarning, true);
+  }
 };
 
 } // namespace
@@ -624,12 +629,14 @@ uint32_t SymbolFileDWARF::CalculateAbilities() {
       llvm::DWARFDebugAbbrev *abbrev = DebugAbbrev();
       std::set<dw_form_t> unsupported_forms = GetUnsupportedForms(abbrev);
       if (!unsupported_forms.empty()) {
-        StreamString error;
-        error.Printf("unsupported DW_FORM value%s:",
-                     unsupported_forms.size() > 1 ? "s" : "");
-        for (auto form : unsupported_forms)
-          error.Printf(" %#x", form);
-        m_objfile_sp->GetModule()->ReportWarning("{0}", error.GetString());
+        if (GetGlobalPluginProperties().EmitUnsupportedDWFormValueWarning()) {
+          StreamString error;
+          error.Printf("unsupported DW_FORM value%s:",
+                       unsupported_forms.size() > 1 ? "s" : "");
+          for (auto form : unsupported_forms)
+            error.Printf(" %#x", form);
+          m_objfile_sp->GetModule()->ReportWarning("{0}", error.GetString());
+        }
         return 0;
       }
 
@@ -1770,16 +1777,17 @@ SymbolFileDWARF *SymbolFileDWARF::GetDIERefSymbolFile(const DIERef &die_ref) {
     return this;
 
   if (file_index) {
-      // We have a SymbolFileDWARFDebugMap, so let it find the right file
+    // We have a SymbolFileDWARFDebugMap, so let it find the right file
     if (SymbolFileDWARFDebugMap *debug_map = GetDebugMapSymfile())
       return debug_map->GetSymbolFileByOSOIndex(*file_index);
-    
+
     // Handle the .dwp file case correctly
     if (*file_index == DIERef::k_file_index_mask)
       return GetDwpSymbolFile().get(); // DWP case
 
     // Handle the .dwo file case correctly
-    return DebugInfo().GetUnitAtIndex(*die_ref.file_index())
+    return DebugInfo()
+        .GetUnitAtIndex(*die_ref.file_index())
         ->GetDwoSymbolFile(); // DWO case
   }
   return this;
@@ -3621,7 +3629,7 @@ VariableSP SymbolFileDWARF::ParseVariableDIE(const SymbolContext &sc,
     lldb::addr_t location_DW_OP_addr = LLDB_INVALID_ADDRESS;
     if (!location_is_const_value_data) {
       bool op_error = false;
-      const DWARFExpression* location = location_list.GetAlwaysValidExpr();
+      const DWARFExpression *location = location_list.GetAlwaysValidExpr();
       if (location)
         location_DW_OP_addr =
             location->GetLocation_DW_OP_addr(location_form.GetUnit(), op_error);

lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFProperties.td

@@ -5,4 +5,8 @@ let Definition = "symbolfiledwarf" in {
     Global,
     DefaultFalse,
     Desc<"Ignore indexes present in the object files and always index DWARF manually.">;
+  def EmitUnsupportedDWFormValueWarning: Property<"emit-unsupported-dwform-value", "Boolean">,
+    Global,
+    DefaultTrue,
+    Desc<"Emit warnings about unsupported DW_Form values.">;
 }