Merge LLVM r202188:

  Debug info: Support variadic functions.
  Variadic functions have an unspecified parameter tag after the last
  argument. In IR this is represented as an unspecified parameter in the
  subroutine type.

  Paired commit with CFE r202185.

  rdar://problem/13690847

  This re-applies r202184 + a bugfix in DwarfDebug's argument handling.

This merge includes a change to use the LLVM 3.4 API in
lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp:

DwarfUnit -> CompileUnit

Sponsored by:       DARPA, AFRL

Introduced here: http://svnweb.freebsd.org/changeset/base/264826

Index: include/llvm/DIBuilder.h
===================================================================
--- include/llvm/DIBuilder.h	(revision 264825)
+++ include/llvm/DIBuilder.h	(revision 264826)
@@ -439,7 +439,7 @@
     /// through debug info anchors.
     void retainType(DIType T);
 
-    /// createUnspecifiedParameter - Create unspeicified type descriptor
+    /// createUnspecifiedParameter - Create unspecified type descriptor
     /// for a subroutine type.
     DIDescriptor createUnspecifiedParameter();
 
Index: lib/CodeGen/AsmPrinter/DwarfDebug.cpp
===================================================================
--- lib/CodeGen/AsmPrinter/DwarfDebug.cpp	(revision 264825)
+++ lib/CodeGen/AsmPrinter/DwarfDebug.cpp	(revision 264826)
@@ -404,15 +404,21 @@
         DIArray Args = SPTy.getTypeArray();
         uint16_t SPTag = SPTy.getTag();
         if (SPTag == dwarf::DW_TAG_subroutine_type)
+          // FIXME: Use DwarfUnit::constructSubprogramArguments() here.
           for (unsigned i = 1, N = Args.getNumElements(); i < N; ++i) {
-            DIE *Arg =
+            DIType ATy(Args.getElement(i));
+            if (ATy.isUnspecifiedParameter()) {
+              assert(i == N-1 && "ellipsis must be the last argument");
+              SPCU->createAndAddDIE(dwarf::DW_TAG_unspecified_parameters, *SPDie);
+            } else {
+              DIE *Arg =
                 SPCU->createAndAddDIE(dwarf::DW_TAG_formal_parameter, *SPDie);
-            DIType ATy(Args.getElement(i));
-            SPCU->addType(Arg, ATy);
-            if (ATy.isArtificial())
-              SPCU->addFlag(Arg, dwarf::DW_AT_artificial);
-            if (ATy.isObjectPointer())
-              SPCU->addDIEEntry(SPDie, dwarf::DW_AT_object_pointer, Arg);
+              SPCU->addType(Arg, ATy);
+              if (ATy.isArtificial())
+                SPCU->addFlag(Arg, dwarf::DW_AT_artificial);
+              if (ATy.isObjectPointer())
+                SPCU->addDIEEntry(SPDie, dwarf::DW_AT_object_pointer, Arg);
+            }
           }
         DIE *SPDeclDie = SPDie;
         SPDie =
@@ -579,7 +585,7 @@
     DIE *ObjectPointer = NULL;
 
   // Collect arguments for current function.
-  if (LScopes.isCurrentFunctionScope(Scope))
+  if (LScopes.isCurrentFunctionScope(Scope)) {
     for (unsigned i = 0, N = CurrentFnArguments.size(); i < N; ++i)
       if (DbgVariable *ArgDV = CurrentFnArguments[i])
         if (DIE *Arg =
@@ -588,6 +594,16 @@
           if (ArgDV->isObjectPointer()) ObjectPointer = Arg;
         }
 
+    // Create the unspecified parameter that marks a function as variadic.
+    DISubprogram SP(Scope->getScopeNode());
+    assert(SP.Verify());
+    DIArray FnArgs = SP.getType().getTypeArray();
+    if (FnArgs.getElement(FnArgs.getNumElements()-1).isUnspecifiedParameter()) {
+      DIE *Ellipsis = new DIE(dwarf::DW_TAG_unspecified_parameters);
+      Children.push_back(Ellipsis);
+    }
+  }
+
   // Collect lexical scope children first.
   const SmallVectorImpl<DbgVariable *> &Variables =ScopeVariables.lookup(Scope);
   for (unsigned i = 0, N = Variables.size(); i < N; ++i)
Index: lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
===================================================================
--- lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp	(revision 264825)
+++ lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp	(revision 264826)
@@ -1116,6 +1116,22 @@
     addSourceLine(&Buffer, DTy);
 }
 
+/// constructSubprogramArguments - Construct function argument DIEs.
+void CompileUnit::constructSubprogramArguments(DIE &Buffer, DIArray Args) {
+    for (unsigned i = 1, N = Args.getNumElements(); i < N; ++i) {
+      DIDescriptor Ty = Args.getElement(i);
+      if (Ty.isUnspecifiedParameter()) {
+        assert(i == N-1 && "ellipsis must be the last argument");
+        createAndAddDIE(dwarf::DW_TAG_unspecified_parameters, Buffer);
+      } else {
+        DIE *Arg = createAndAddDIE(dwarf::DW_TAG_formal_parameter, Buffer);
+        addType(Arg, DIType(Ty));
+        if (DIType(Ty).isArtificial())
+          addFlag(Arg, dwarf::DW_AT_artificial);
+      }
+    }
+}
+
 /// Return true if the type is appropriately scoped to be contained inside
 /// its own type unit.
 static bool isTypeUnitScoped(DIType Ty, const DwarfDebug *DD) {
@@ -1170,19 +1186,12 @@
       addType(&Buffer, RTy);
 
     bool isPrototyped = true;
-    // Add arguments.
-    for (unsigned i = 1, N = Elements.getNumElements(); i < N; ++i) {
-      DIDescriptor Ty = Elements.getElement(i);
-      if (Ty.isUnspecifiedParameter()) {
-        createAndAddDIE(dwarf::DW_TAG_unspecified_parameters, Buffer);
-        isPrototyped = false;
-      } else {
-        DIE *Arg = createAndAddDIE(dwarf::DW_TAG_formal_parameter, Buffer);
-        addType(Arg, DIType(Ty));
-        if (DIType(Ty).isArtificial())
-          addFlag(Arg, dwarf::DW_AT_artificial);
-      }
-    }
+    if (Elements.getNumElements() == 2 &&
+        Elements.getElement(1).isUnspecifiedParameter())
+      isPrototyped = false;
+
+    constructSubprogramArguments(Buffer, Elements);
+
     // Add prototype flag if we're dealing with a C language and the
     // function has been prototyped.
     uint16_t Language = getLanguage();
@@ -1475,13 +1484,7 @@
 
     // Add arguments. Do not add arguments for subprogram definition. They will
     // be handled while processing variables.
-    for (unsigned i = 1, N = Args.getNumElements(); i < N; ++i) {
-      DIE *Arg = createAndAddDIE(dwarf::DW_TAG_formal_parameter, *SPDie);
-      DIType ATy(Args.getElement(i));
-      addType(Arg, ATy);
-      if (ATy.isArtificial())
-        addFlag(Arg, dwarf::DW_AT_artificial);
-    }
+    constructSubprogramArguments(*SPDie, Args);
   }
 
   if (SP.isArtificial())
Index: lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
===================================================================
--- lib/CodeGen/AsmPrinter/DwarfCompileUnit.h	(revision 264825)
+++ lib/CodeGen/AsmPrinter/DwarfCompileUnit.h	(revision 264826)
@@ -342,6 +342,9 @@
   void emitHeader(const MCSection *ASection, const MCSymbol *ASectionSym);
 
 private:
+  /// constructSubprogramArguments - Construct function argument DIEs.
+  void constructSubprogramArguments(DIE &Buffer, DIArray Args);
+
   /// constructTypeDIE - Construct basic type die from DIBasicType.
   void constructTypeDIE(DIE &Buffer, DIBasicType BTy);