[Debug Info] remove DITrivialType and use null to represent unspecified param.

Per feedback on r214111, we are going to use null to represent unspecified
parameter. If the type array is {null}, it means a function that returns void;
If the type array is {null, null}, it means a variadic function that returns
void. In summary if we have more than one element in the type array and the last
element is null, it is a variadic function.

rdar://17628609


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214189 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/IR/DIBuilder.h

@@ -465,7 +465,7 @@ namespace llvm {
 
     /// createUnspecifiedParameter - Create unspecified parameter type
     /// for a subroutine type.
-    DITrivialType createUnspecifiedParameter();
+    DIBasicType createUnspecifiedParameter();
 
     /// getOrCreateArray - Get a DIArray, create one if required.
     DIArray getOrCreateArray(ArrayRef<Value *> Elements);

include/llvm/IR/DebugInfo.h

@@ -129,7 +129,6 @@ public:
   bool isCompositeType() const;
   bool isSubroutineType() const;
   bool isBasicType() const;
-  bool isTrivialType() const;
   bool isVariable() const;
   bool isSubprogram() const;
   bool isGlobalVariable() const;
@@ -142,7 +141,6 @@ public:
   bool isSubrange() const;
   bool isEnumerator() const;
   bool isType() const;
-  bool isUnspecifiedParameter() const;
   bool isTemplateTypeParameter() const;
   bool isTemplateValueParameter() const;
   bool isObjCProperty() const;
@@ -308,36 +306,15 @@ public:
   /// Verify - Verify that a type descriptor is well formed.
   bool Verify() const;
 
-  DIScopeRef getContext() const { 
+  DIScopeRef getContext() const { return getFieldAs<DIScopeRef>(2); }
-    assert(!isTrivialType() && "no context for DITrivialType");
+  StringRef getName() const { return getStringField(3); }
-    return getFieldAs<DIScopeRef>(2);
+  unsigned getLineNumber() const { return getUnsignedField(4); }
-  }
+  uint64_t getSizeInBits() const { return getUInt64Field(5); }
-  StringRef getName() const {
+  uint64_t getAlignInBits() const { return getUInt64Field(6); }
-    assert(!isTrivialType() && "no name for DITrivialType");
-    return getStringField(3);
-  }
-  unsigned getLineNumber() const {
-    assert(!isTrivialType() && "no line number for DITrivialType");
-    return getUnsignedField(4);
-  }
-  uint64_t getSizeInBits() const {
-    assert(!isTrivialType() && "no SizeInBits for DITrivialType");
-    return getUInt64Field(5);
-  }
-  uint64_t getAlignInBits() const {
-    assert(!isTrivialType() && "no AlignInBits for DITrivialType");
-    return getUInt64Field(6);
-  }
   // FIXME: Offset is only used for DW_TAG_member nodes.  Making every type
   // carry this is just plain insane.
-  uint64_t getOffsetInBits() const {
+  uint64_t getOffsetInBits() const { return getUInt64Field(7); }
-    assert(!isTrivialType() && "no OffsetInBits for DITrivialType");
+  unsigned getFlags() const { return getUnsignedField(8); }
-    return getUInt64Field(7);
-  }
-  unsigned getFlags() const {
-    assert(!isTrivialType() && "no flag for DITrivialType");
-    return getUnsignedField(8);
-  }
   bool isPrivate() const { return (getFlags() & FlagPrivate) != 0; }
   bool isProtected() const { return (getFlags() & FlagProtected) != 0; }
   bool isForwardDecl() const { return (getFlags() & FlagFwdDecl) != 0; }
@@ -370,12 +347,6 @@ public:
   void replaceAllUsesWith(MDNode *D);
 };
 
-class DITrivialType : public DIType {
-public:
-  explicit DITrivialType(const MDNode *N = nullptr) : DIType(N) {}
-  bool Verify() const;
-};
-
 /// DIBasicType - A basic type, like 'int' or 'float'.
 class DIBasicType : public DIType {
 public:

lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -469,11 +469,13 @@ DIE *DwarfDebug::createScopeChildrenDIE(
     // If this is a variadic function, add an unspecified parameter.
     DISubprogram SP(Scope->getScopeNode());
     DITypeArray FnArgs = SP.getType().getTypeArray();
-    if (resolve(FnArgs.getElement(FnArgs.getNumElements() - 1))
+    // If we have a single element of null, it is a function that returns void.
-            .isUnspecifiedParameter()) {
+    // If we have more than one elements and the last one is null, it is a
+    // variadic function.
+    if (FnArgs.getNumElements() > 1 &&
+        !resolve(FnArgs.getElement(FnArgs.getNumElements() - 1)))
       Children.push_back(
           make_unique<DIE>(dwarf::DW_TAG_unspecified_parameters));
-    }
   }
 
   // Collect lexical scope children first.

lib/CodeGen/AsmPrinter/DwarfUnit.cpp

@@ -1132,7 +1132,7 @@ void DwarfUnit::constructTypeDIE(DIE &Buffer, DIDerivedType DTy) {
 void DwarfUnit::constructSubprogramArguments(DIE &Buffer, DITypeArray Args) {
   for (unsigned i = 1, N = Args.getNumElements(); i < N; ++i) {
     DIType Ty = resolve(Args.getElement(i));
-    if (Ty.isUnspecifiedParameter()) {
+    if (!Ty) {
       assert(i == N-1 && "Unspecified parameter must be the last argument");
       createAndAddDIE(dwarf::DW_TAG_unspecified_parameters, Buffer);
     } else {
@@ -1168,7 +1168,7 @@ void DwarfUnit::constructTypeDIE(DIE &Buffer, DICompositeType CTy) {
 
     bool isPrototyped = true;
     if (Elements.getNumElements() == 2 &&
-        resolve(Elements.getElement(1)).isUnspecifiedParameter())
+        !resolve(Elements.getElement(1)))
       isPrototyped = false;
 
     constructSubprogramArguments(Buffer, Elements);

lib/IR/DIBuilder.cpp

@@ -875,11 +875,8 @@ void DIBuilder::retainType(DIType T) {
 
 /// createUnspecifiedParameter - Create unspeicified type descriptor
 /// for the subroutine type.
-DITrivialType DIBuilder::createUnspecifiedParameter() {
+DIBasicType DIBuilder::createUnspecifiedParameter() {
-  Value *Elts[] = {
+  return DIBasicType(nullptr);
-    GetTagConstant(VMContext, dwarf::DW_TAG_unspecified_parameters)
-  };
-  return DITrivialType(MDNode::get(VMContext, Elts));
 }
 
 /// createForwardDecl - Create a temporary forward-declared type that

lib/IR/DebugInfo.cpp

@@ -39,7 +39,6 @@ bool DIDescriptor::Verify() const {
   return DbgNode &&
          (DIDerivedType(DbgNode).Verify() ||
           DICompositeType(DbgNode).Verify() || DIBasicType(DbgNode).Verify() ||
-          DITrivialType(DbgNode).Verify() ||
           DIVariable(DbgNode).Verify() || DISubprogram(DbgNode).Verify() ||
           DIGlobalVariable(DbgNode).Verify() || DIFile(DbgNode).Verify() ||
           DICompileUnit(DbgNode).Verify() || DINameSpace(DbgNode).Verify() ||
@@ -155,10 +154,6 @@ MDNode *DIVariable::getInlinedAt() const { return getNodeField(DbgNode, 7); }
 // Predicates
 //===----------------------------------------------------------------------===//
 
-bool DIDescriptor::isTrivialType() const {
-  return DbgNode && getTag() == dwarf::DW_TAG_unspecified_parameters;
-}
-
 bool DIDescriptor::isSubroutineType() const {
   return isCompositeType() && getTag() == dwarf::DW_TAG_subroutine_type;
 }
@@ -233,8 +228,7 @@ bool DIDescriptor::isVariable() const {
 
 /// isType - Return true if the specified tag is legal for DIType.
 bool DIDescriptor::isType() const {
-  return isBasicType() || isCompositeType() || isDerivedType() ||
+  return isBasicType() || isCompositeType() || isDerivedType();
-         isTrivialType();
 }
 
 /// isSubprogram - Return true if the specified tag is legal for
@@ -250,12 +244,6 @@ bool DIDescriptor::isGlobalVariable() const {
                      getTag() == dwarf::DW_TAG_constant);
 }
 
-/// isUnspecifiedParmeter - Return true if the specified tag is
-/// DW_TAG_unspecified_parameters.
-bool DIDescriptor::isUnspecifiedParameter() const {
-  return DbgNode && getTag() == dwarf::DW_TAG_unspecified_parameters;
-}
-
 /// isScope - Return true if the specified tag is one of the scope
 /// related tag.
 bool DIDescriptor::isScope() const {
@@ -459,7 +447,7 @@ bool DIType::Verify() const {
 
   // FIXME: Sink this into the various subclass verifies.
   uint16_t Tag = getTag();
-  if (!isBasicType() && !isTrivialType() && Tag != dwarf::DW_TAG_const_type &&
+  if (!isBasicType() && Tag != dwarf::DW_TAG_const_type &&
       Tag != dwarf::DW_TAG_volatile_type && Tag != dwarf::DW_TAG_pointer_type &&
       Tag != dwarf::DW_TAG_ptr_to_member_type &&
       Tag != dwarf::DW_TAG_reference_type &&
@@ -474,8 +462,6 @@ bool DIType::Verify() const {
   // a CompositeType.
   if (isBasicType())
     return DIBasicType(DbgNode).Verify();
-  else if (isTrivialType())
-    return DITrivialType(DbgNode).Verify();
   else if (isCompositeType())
     return DICompositeType(DbgNode).Verify();
   else if (isDerivedType())
@@ -489,10 +475,6 @@ bool DIBasicType::Verify() const {
   return isBasicType() && DbgNode->getNumOperands() == 10;
 }
 
-bool DITrivialType::Verify() const {
-  return isTrivialType() && DbgNode->getNumOperands() == 1;
-}
-
 /// Verify - Verify that a derived type descriptor is well formed.
 bool DIDerivedType::Verify() const {
   // Make sure DerivedFrom @ field 9 is TypeRef.
@@ -1297,7 +1279,7 @@ void DIEnumerator::printInternal(raw_ostream &OS) const {
 }
 
 void DIType::printInternal(raw_ostream &OS) const {
-  if (!DbgNode || isTrivialType())
+  if (!DbgNode)
     return;
 
   StringRef Res = getName();

test/DebugInfo/varargs.ll

@@ -76,16 +76,15 @@ attributes #1 = { nounwind readnone }
 !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}
+!8 = metadata !{null, metadata !9, metadata !10, null}
 !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}
+!17 = metadata !{null, metadata !10, null}
 !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 "}