DebugInfo: ensure type and namespace names are included in pubnames/pubtypes even when they are only present in type units

While looking to add support for placing singular types (types that will
only be emitted in one place (such as attached to a strong vtable or
explicit template instantiation definition)) not in type units (since
type units have overhead) I stumbled across that change causing an
increase in pubtypes.

Turns out we were missing some types from type units if they were only
referenced from other type units and not from the debug_info section.

This fixes that, following GCC's line of describing the offset of such
entities as the CU die (since there's no compile unit-relative offset
that would describe such an entity - they aren't in the CU). Also like
GCC, this change prefers to describe the type stub within the CU rather
than the "just use the CU offset" fallback where possible. This may give
the DWARF consumer some opportunity to find the extra info in the type
stub - though I'm not sure GDB does anything with this currently.

The size of the pubnames/pubtypes sections now match exactly with or
without type units enabled.

This nearly triples (+189%) the pubtypes section for a clang self-host
and grows pubnames by 0.07% (without compression). For a total of 8%
increase in debug info sections of the objects of a Split DWARF build
when using type units.

llvm-svn: 293971

1 files changed, 25 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index 0db623bbc29..d4c7ff193dc 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -697,7 +697,7 @@ void DwarfCompileUnit::emitHeader(bool UseOffsets) {
 }
 
 /// addGlobalName - Add a new global name to the compile unit.
-void DwarfCompileUnit::addGlobalName(StringRef Name, DIE &Die,
+void DwarfCompileUnit::addGlobalName(StringRef Name, const DIE &Die,
                                      const DIScope *Context) {
   if (includeMinimalInlineScopes())
     return;
@@ -705,6 +705,18 @@ void DwarfCompileUnit::addGlobalName(StringRef Name, DIE &Die,
   GlobalNames[FullName] = &Die;
 }
 
+void DwarfCompileUnit::addGlobalNameForTypeUnit(StringRef Name,
+                                                const DIScope *Context) {
+  if (includeMinimalInlineScopes())
+    return;
+  std::string FullName = getParentContextString(Context) + Name.str();
+  // Insert, allowing the entry to remain as-is if it's already present
+  // This way the CU-level type DIE is preferred over the "can't describe this
+  // type as a unit offset because it's not really in the CU at all, it's only
+  // in a type unit"
+  GlobalNames.insert(std::make_pair(std::move(FullName), &getUnitDie()));
+}
+
 /// Add a new global type to the unit.
 void DwarfCompileUnit::addGlobalType(const DIType *Ty, const DIE &Die,
                                      const DIScope *Context) {
@@ -714,6 +726,18 @@ void DwarfCompileUnit::addGlobalType(const DIType *Ty, const DIE &Die,
   GlobalTypes[FullName] = &Die;
 }
 
+void DwarfCompileUnit::addGlobalTypeUnitType(const DIType *Ty,
+                                             const DIScope *Context) {
+  if (includeMinimalInlineScopes())
+    return;
+  std::string FullName = getParentContextString(Context) + Ty->getName().str();
+  // Insert, allowing the entry to remain as-is if it's already present
+  // This way the CU-level type DIE is preferred over the "can't describe this
+  // type as a unit offset because it's not really in the CU at all, it's only
+  // in a type unit"
+  GlobalTypes.insert(std::make_pair(std::move(FullName), &getUnitDie()));
+}
+
 /// addVariableAddress - Add DW_AT_location attribute for a
 /// DbgVariable based on provided MachineLocation.
 void DwarfCompileUnit::addVariableAddress(const DbgVariable &DV, DIE &Die,