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.

llvm-svn: 202188

5 files changed, 141 insertions, 29 deletions

diff --git a/llvm/include/llvm/DIBuilder.h b/llvm/include/llvm/DIBuilder.h
index c8595a02f1b..7cd5a1bcf0b 100644
--- a/llvm/include/llvm/DIBuilder.h
+++ b/llvm/include/llvm/DIBuilder.h
@@ -442,7 +442,7 @@ namespace llvm {
     /// through debug info anchors.
     void retainType(DIType T);
 
-    /// createUnspecifiedParameter - Create unspeicified type descriptor
+    /// createUnspecifiedParameter - Create unspecified type descriptor
     /// for a subroutine type.
     DIDescriptor createUnspecifiedParameter();
 
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 2425948ae9a..3c5868111d7 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -403,15 +403,21 @@ DIE *DwarfDebug::updateSubprogramScopeDIE(DwarfCompileUnit *SPCU,
         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 =
-                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);
+            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);
+              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 = SPCU->createAndAddDIE(dwarf::DW_TAG_subprogram,
@@ -582,7 +588,7 @@ DIE *DwarfDebug::createScopeChildrenDIE(DwarfCompileUnit *TheCU,
   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 =
@@ -592,6 +598,16 @@ DIE *DwarfDebug::createScopeChildrenDIE(DwarfCompileUnit *TheCU,
             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);
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
index 81dbfc505ac..4626c43f568 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
@@ -1139,6 +1139,22 @@ void DwarfUnit::constructTypeDIE(DIE &Buffer, DIDerivedType DTy) {
     addSourceLine(&Buffer, DTy);
 }
 
+/// constructSubprogramArguments - Construct function argument DIEs.
+void DwarfUnit::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);
+      }
+    }
+}
+
 /// constructTypeDIE - Construct type DIE from DICompositeType.
 void DwarfUnit::constructTypeDIE(DIE &Buffer, DICompositeType CTy) {
   // Add name if not anonymous or intermediate type.
@@ -1162,19 +1178,12 @@ void DwarfUnit::constructTypeDIE(DIE &Buffer, DICompositeType CTy) {
       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();
@@ -1457,13 +1466,7 @@ DIE *DwarfUnit::getOrCreateSubprogramDIE(DISubprogram SP) {
 
     // 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())
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
index 370ecbf831e..bf77272b8a2 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
@@ -476,6 +476,9 @@ protected:
   DIE *getOrCreateStaticMemberDIE(DIDerivedType DT);
 
 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);
 
diff --git a/llvm/test/DebugInfo/X86/varargs.ll b/llvm/test/DebugInfo/X86/varargs.ll
new file mode 100644
index 00000000000..e724d754453
--- /dev/null
+++ b/llvm/test/DebugInfo/X86/varargs.ll
@@ -0,0 +1,90 @@
+; RUN: llc -O0 -filetype=obj -o %t.o %s
+; RUN: llvm-dwarfdump -debug-dump=info %t.o | FileCheck %s
+;
+; Normal variadic function.
+;
+; CHECK: DW_TAG_subprogram
+; CHECK-NOT: DW_TAG
+; CHECK: DW_TAG_formal_parameter
+; CHECK-NOT: DW_TAG
+; CHECK: DW_TAG_unspecified_parameters
+;
+; Variadic C++ member function.
+;
+; CHECK: DW_TAG_subprogram
+; CHECK-NOT: DW_TAG
+; CHECK: DW_TAG_formal_parameter
+; CHECK-NOT: DW_TAG
+; CHECK: DW_TAG_formal_parameter
+; CHECK-NOT: DW_TAG
+; CHECK: DW_TAG_unspecified_parameters
+;
+; Variadic function pointer.
+;
+; CHECK: DW_TAG_subroutine_type
+; CHECK-NOT: DW_TAG
+; CHECK: DW_TAG_formal_parameter
+; CHECK-NOT: DW_TAG
+; CHECK: DW_TAG_unspecified_parameters
+;
+; Test debug info for variadic function arguments.
+; Created from tools/clang/tests/CodeGenCXX/debug-info-varargs.cpp
+;
+; ModuleID = 'llvm/tools/clang/test/CodeGenCXX/debug-info-varargs.cpp'
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.9.0"
+
+%struct.A = type { i8 }
+
+; Function Attrs: nounwind ssp uwtable
+define void @_Z1biz(i32 %c, ...) #0 {
+  %1 = alloca i32, align 4
+  %a = alloca %struct.A, align 1
+  %fptr = alloca void (i32, ...)*, align 8
+  store i32 %c, i32* %1, align 4
+  call void @llvm.dbg.declare(metadata !{i32* %1}, metadata !21), !dbg !22
+  call void @llvm.dbg.declare(metadata !{%struct.A* %a}, metadata !23), !dbg !24
+  call void @llvm.dbg.declare(metadata !{void (i32, ...)** %fptr}, metadata !25), !dbg !27
+  store void (i32, ...)* @_Z1biz, void (i32, ...)** %fptr, align 8, !dbg !27
+  ret void, !dbg !28
+}
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.declare(metadata, metadata) #1
+
+attributes #0 = { nounwind ssp uwtable }
+attributes #1 = { nounwind readnone }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!18, !19}
+!llvm.ident = !{!20}
+
+!0 = metadata !{i32 786449, metadata !1, i32 4, metadata !"clang version 3.5 ", i1 false, metadata !"", i32 0, metadata !2, metadata !3, metadata !13, metadata !2, metadata !2, metadata !""} ; [ DW_TAG_compile_unit ] [llvm/tools/clang/test/CodeGenCXX/debug-info-varargs.cpp] [DW_LANG_C_plus_plus]
+!1 = metadata !{metadata !"llvm/tools/clang/test/CodeGenCXX/debug-info-varargs.cpp", metadata !"radar/13690847"}
+!2 = metadata !{}
+!3 = metadata !{metadata !4}
+!4 = metadata !{i32 786451, metadata !1, null, metadata !"A", i32 3, i64 8, i64 8, i32 0, i32 0, null, metadata !5, i32 0, null, null, metadata !"_ZTS1A"} ; [ DW_TAG_structure_type ] [A] [line 3, size 8, align 8, offset 0] [def] [from ]
+!5 = metadata !{metadata !6}
+!6 = metadata !{i32 786478, metadata !1, metadata !"_ZTS1A", metadata !"a", metadata !"a", metadata !"_ZN1A1aEiz", i32 6, metadata !7, i1 false, i1 false, i32 0, i32 0, null, i32 256, i1 false, null, null, i32 0, metadata !12, i32 6} ; [ DW_TAG_subprogram ] [line 6] [a]
+!7 = metadata !{i32 786453, i32 0, null, metadata !"", i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !8, i32 0, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!8 = metadata !{null, metadata !9, metadata !10, metadata !11}
+!9 = metadata !{i32 786447, null, null, metadata !"", i32 0, i64 64, i64 64, i64 0, i32 1088, metadata !"_ZTS1A"} ; [ DW_TAG_pointer_type ] [line 0, size 64, align 64, offset 0] [artificial] [from _ZTS1A]
+!10 = metadata !{i32 786468, null, null, metadata !"int", i32 0, i64 32, i64 32, i64 0, i32 0, i32 5} ; [ DW_TAG_base_type ] [int] [line 0, size 32, align 32, offset 0, enc DW_ATE_signed]
+!11 = metadata !{i32 786456}
+!12 = metadata !{i32 786468}
+!13 = metadata !{metadata !14}
+!14 = metadata !{i32 786478, metadata !1, metadata !15, metadata !"b", metadata !"b", metadata !"_Z1biz", i32 13, metadata !16, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 false, void (i32, ...)* @_Z1biz, null, null, metadata !2, i32 13} ; [ DW_TAG_subprogram ] [line 13] [def] [b]
+!15 = metadata !{i32 786473, metadata !1}         ; [ DW_TAG_file_type ] [llvm/tools/clang/test/CodeGenCXX/debug-info-varargs.cpp]
+!16 = metadata !{i32 786453, i32 0, null, metadata !"", i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !17, i32 0, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!17 = metadata !{null, metadata !10, metadata !11}
+!18 = metadata !{i32 2, metadata !"Dwarf Version", i32 2}
+!19 = metadata !{i32 1, metadata !"Debug Info Version", i32 1}
+!20 = metadata !{metadata !"clang version 3.5 "}
+!21 = metadata !{i32 786689, metadata !14, metadata !"c", metadata !15, i32 16777229, metadata !10, i32 0, i32 0} ; [ DW_TAG_arg_variable ] [c] [line 13]
+!22 = metadata !{i32 13, i32 0, metadata !14, null}
+!23 = metadata !{i32 786688, metadata !14, metadata !"a", metadata !15, i32 16, metadata !4, i32 0, i32 0} ; [ DW_TAG_auto_variable ] [a] [line 16]
+!24 = metadata !{i32 16, i32 0, metadata !14, null}
+!25 = metadata !{i32 786688, metadata !14, metadata !"fptr", metadata !15, i32 18, metadata !26, i32 0, i32 0} ; [ DW_TAG_auto_variable ] [fptr] [line 18]
+!26 = metadata !{i32 786447, null, null, metadata !"", i32 0, i64 64, i64 64, i64 0, i32 0, metadata !16} ; [ DW_TAG_pointer_type ] [line 0, size 64, align 64, offset 0] [from ]
+!27 = metadata !{i32 18, i32 0, metadata !14, null}
+!28 = metadata !{i32 22, i32 0, metadata !14, null}