[DWARF] Force a linkage_name on an inlined subprogram's abstract origin.

When we suppress linkage names, for a non-inlined subprogram the name
can still be found in the object-file symbol table, because we have
the code address of the subprogram.  This is not necessarily the case
for an inlined subprogram, so we still want to emit the linkage name
in the DWARF.  Put this on the abstract-origin DIE because it's common
to all inlined instances.

Differential Revision: http://reviews.llvm.org/D18706

llvm-svn: 266692

4 files changed, 30 insertions, 18 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index 0daca72b30d..ff70f6ca044 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -185,7 +185,8 @@ DIE *DwarfCompileUnit::getOrCreateGlobalVariableDIE(
     }
 
     addBlock(*VariableDIE, dwarf::DW_AT_location, Loc);
-    addLinkageName(*VariableDIE, GV->getLinkageName());
+    if (DD->useAllLinkageNames())
+      addLinkageName(*VariableDIE, GV->getLinkageName());
   } else if (const ConstantInt *CI =
                  dyn_cast_or_null<ConstantInt>(GV->getVariable())) {
     addConstantValue(*VariableDIE, CI, GTy);
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 36b87657ae7..373b7e7daa3 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -105,13 +105,21 @@ DwarfPubSections("generate-dwarf-pub-sections", cl::Hidden,
                             clEnumVal(Disable, "Disabled"), clEnumValEnd),
                  cl::init(Default));
 
-static cl::opt<DefaultOnOff>
-DwarfLinkageNames("dwarf-linkage-names", cl::Hidden,
-                  cl::desc("Emit DWARF linkage-name attributes."),
-                  cl::values(clEnumVal(Default, "Default for platform"),
-                             clEnumVal(Enable, "Enabled"),
-                             clEnumVal(Disable, "Disabled"), clEnumValEnd),
-                  cl::init(Default));
+enum LinkageNameOption {
+  DefaultLinkageNames,
+  AllLinkageNames,
+  AbstractLinkageNames
+};
+static cl::opt<LinkageNameOption>
+    DwarfLinkageNames("dwarf-linkage-names", cl::Hidden,
+                      cl::desc("Which DWARF linkage-name attributes to emit."),
+                      cl::values(clEnumValN(DefaultLinkageNames, "Default",
+                                            "Default for platform"),
+                                 clEnumValN(AllLinkageNames, "All", "All"),
+                                 clEnumValN(AbstractLinkageNames, "Abstract",
+                                            "Abstract subprograms"),
+                                 clEnumValEnd),
+                      cl::init(DefaultLinkageNames));
 
 static const char *const DWARFGroupName = "DWARF Emission";
 static const char *const DbgTimerName = "DWARF Debug Writer";
@@ -245,11 +253,11 @@ DwarfDebug::DwarfDebug(AsmPrinter *A, Module *M)
   else
     HasDwarfPubSections = DwarfPubSections == Enable;
 
-  // SCE does not use linkage names.
-  if (DwarfLinkageNames == Default)
-    UseLinkageNames = !tuneForSCE();
+  // SCE defaults to linkage names only for abstract subprograms.
+  if (DwarfLinkageNames == DefaultLinkageNames)
+    UseAllLinkageNames = !tuneForSCE();
   else
-    UseLinkageNames = DwarfLinkageNames == Enable;
+    UseAllLinkageNames = DwarfLinkageNames == AllLinkageNames;
 
   unsigned DwarfVersionNumber = Asm->TM.Options.MCOptions.DwarfVersion;
   DwarfVersion = DwarfVersionNumber ? DwarfVersionNumber
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
index c5861497f64..ad0241cb99b 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -249,8 +249,8 @@ class DwarfDebug : public DebugHandlerBase {
   /// Whether to use the GNU TLS opcode (instead of the standard opcode).
   bool UseGNUTLSOpcode;
 
-  /// Whether to emit DW_AT_[MIPS_]linkage_name.
-  bool UseLinkageNames;
+  /// Whether to emit all linkage names, or just abstract subprograms.
+  bool UseAllLinkageNames;
 
   /// Version of dwarf we're emitting.
   unsigned DwarfVersion;
@@ -478,8 +478,9 @@ public:
     SymSize[Sym] = Size;
   }
 
-  /// Returns whether to emit DW_AT_[MIPS_]linkage_name.
-  bool useLinkageNames() const { return UseLinkageNames; }
+  /// Returns whether we should emit all DW_AT_[MIPS_]linkage_name.
+  /// If not, we still might emit certain cases.
+  bool useAllLinkageNames() const { return UseAllLinkageNames; }
 
   /// Returns whether to use DW_OP_GNU_push_tls_address, instead of the
   /// standard DW_OP_form_tls_address opcode
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
index 387921cb46f..9003af528d0 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
@@ -665,7 +665,7 @@ void DwarfUnit::addConstantValue(DIE &Die, const APInt &Val, bool Unsigned) {
 }
 
 void DwarfUnit::addLinkageName(DIE &Die, StringRef LinkageName) {
-  if (!LinkageName.empty() && DD->useLinkageNames())
+  if (!LinkageName.empty())
     addString(Die,
               DD->getDwarfVersion() >= 4 ? dwarf::DW_AT_linkage_name
                                          : dwarf::DW_AT_MIPS_linkage_name,
@@ -1169,7 +1169,9 @@ bool DwarfUnit::applySubprogramDefinitionAttributes(const DISubprogram *SP,
   assert(((LinkageName.empty() || DeclLinkageName.empty()) ||
           LinkageName == DeclLinkageName) &&
          "decl has a linkage name and it is different");
-  if (DeclLinkageName.empty())
+  if (DeclLinkageName.empty() &&
+      // Always emit it for abstract subprograms.
+      (DD->useAllLinkageNames() || DU->getAbstractSPDies().lookup(SP)))
     addLinkageName(SPDie, LinkageName);
 
   if (!DeclDie)