Fallback to the cu cache or walking cu's if aranges lookup fails

src/symbols/symbols_with_libdwarf.cpp

@@ -95,6 +95,7 @@ namespace libdwarf {
         std::unordered_map<Dwarf_Off, std::vector<subprogram_entry>> subprograms_cache;
         // Vector of ranges and their corresponding CU offsets
         std::vector<cu_entry> cu_cache;
+        bool generated_cu_cache = false;
         // Map from CU -> {srcfiles, count}
         std::unordered_map<Dwarf_Off, std::pair<char**, Dwarf_Signed>> srcfiles_cache;
 
@@ -165,21 +166,6 @@ namespace libdwarf {
                 // Check for .debug_aranges for fast lookup
                 wrap(dwarf_get_aranges, dbg, &aranges, &arange_count);
             }
-            if(ok && !aranges && get_cache_mode() != cache_mode::prioritize_memory) {
-                walk_compilation_units([this] (const die_object& cu_die) {
-                    Dwarf_Half offset_size = 0;
-                    Dwarf_Half dwversion = 0;
-                    dwarf_get_version_of_die(cu_die.get(), &dwversion, &offset_size);
-                    auto ranges_vec = cu_die.get_rangelist_entries(dwversion);
-                    for(auto range : ranges_vec) {
-                        cu_cache.push_back({ cu_die.clone(), dwversion, range.first, range.second });
-                    }
-                    return true;
-                });
-                std::sort(cu_cache.begin(), cu_cache.end(), [] (const cu_entry& a, const cu_entry& b) {
-                    return a.low < b.low;
-                });
-            }
         }
 
         CPPTRACE_FORCE_NO_INLINE_FOR_PROFILING
@@ -213,6 +199,7 @@ namespace libdwarf {
             line_contexts(std::move(other.line_contexts)),
             subprograms_cache(std::move(other.subprograms_cache)),
             cu_cache(std::move(other.cu_cache)),
+            generated_cu_cache(other.generated_cu_cache),
             srcfiles_cache(std::move(other.srcfiles_cache))
         {
             other.dbg = nullptr;
@@ -228,6 +215,7 @@ namespace libdwarf {
             line_contexts = std::move(other.line_contexts);
             subprograms_cache = std::move(other.subprograms_cache);
             cu_cache = std::move(other.cu_cache);
+            generated_cu_cache = other.generated_cu_cache;
             srcfiles_cache = std::move(other.srcfiles_cache);
             other.dbg = nullptr;
             other.aranges = nullptr;
@@ -282,6 +270,25 @@ namespace libdwarf {
             }
         }
 
+        void lazy_generate_cu_cache() {
+            if(!generated_cu_cache) {
+                walk_compilation_units([this] (const die_object& cu_die) {
+                    Dwarf_Half offset_size = 0;
+                    Dwarf_Half dwversion = 0;
+                    dwarf_get_version_of_die(cu_die.get(), &dwversion, &offset_size);
+                    auto ranges_vec = cu_die.get_rangelist_entries(dwversion);
+                    for(auto range : ranges_vec) {
+                        cu_cache.push_back({ cu_die.clone(), dwversion, range.first, range.second });
+                    }
+                    return true;
+                });
+                std::sort(cu_cache.begin(), cu_cache.end(), [] (const cu_entry& a, const cu_entry& b) {
+                    return a.low < b.low;
+                });
+                generated_cu_cache = true;
+            }
+        }
+
         std::string subprogram_symbol(
             const die_object& die,
             Dwarf_Half dwversion
@@ -787,8 +794,13 @@ namespace libdwarf {
                     }
                     retrieve_line_info(cu_die, pc, frame); // no offset for line info
                     retrieve_symbol(cu_die, pc, dwversion, frame, inlines);
+                    return;
                 }
-            } else {
+            }
+            // otherwise, or if not in aranges
+            // one reason to fallback here is if the compilation has dwarf generated from different compilers and only
+            // some of them generate aranges (e.g. static linking with cpptrace after specifying clang++ as the c++
+            // compiler while the C compiler defaults to an older gcc)
             if(get_cache_mode() == cache_mode::prioritize_memory) {
                 // walk for the cu and go from there
                 walk_compilation_units([this, pc, &frame, &inlines] (const die_object& cu_die) {
@@ -818,6 +830,7 @@ namespace libdwarf {
                     return true;
                 });
             } else {
+                lazy_generate_cu_cache();
                 // look up the cu
                 auto vec_it = std::lower_bound(
                     cu_cache.begin(),
@@ -844,7 +857,6 @@ namespace libdwarf {
                 }
             }
         }
-        }
 
         CPPTRACE_FORCE_NO_INLINE_FOR_PROFILING
         frame_with_inlines resolve_frame(const object_frame& frame_info) {