3 files changed, 32 insertions, 9 deletions
diff --git a/llvm/lib/DebugInfo/DWARF/DWARFAbbreviationDeclaration.cpp b/llvm/lib/DebugInfo/DWARF/DWARFAbbreviationDeclaration.cpp
index 6126470aa09..08bc74a81e9 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFAbbreviationDeclaration.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFAbbreviationDeclaration.cpp
@@ -56,13 +56,20 @@ DWARFAbbreviationDeclaration::extract(DataExtractor Data,
     auto A = static_cast<Attribute>(Data.getULEB128(OffsetPtr));
     auto F = static_cast<Form>(Data.getULEB128(OffsetPtr));
     if (A && F) {
-      auto FixedFormByteSize = DWARFFormValue::getFixedByteSize(F);
-      AttributeSpecs.push_back(AttributeSpec(A, F, FixedFormByteSize));
+      Optional<int64_t> V;
+      bool IsImplicitConst = (F == DW_FORM_implicit_const);
+      if (IsImplicitConst)
+        V = Data.getSLEB128(OffsetPtr);
+      else if (auto Size = DWARFFormValue::getFixedByteSize(F))
+        V = *Size;
+      AttributeSpecs.push_back(AttributeSpec(A, F, V));
+      if (IsImplicitConst)
+        continue;
       // If this abbrevation still has a fixed byte size, then update the
       // FixedAttributeSize as needed.
       if (FixedAttributeSize) {
-        if (FixedFormByteSize)
-          FixedAttributeSize->NumBytes += *FixedFormByteSize;
+        if (V)
+          FixedAttributeSize->NumBytes += *V;
         else {
           switch (F) {
           case DW_FORM_addr:
@@ -129,6 +136,8 @@ void DWARFAbbreviationDeclaration::dump(raw_ostream &OS) const {
       OS << formString;
     else
       OS << format("DW_FORM_Unknown_%x", Spec.Form);
+    if (Spec.isImplicitConst())
+      OS << '\t' << *Spec.ByteSizeOrValue;
     OS << '\n';
   }
   OS << '\n';
@@ -160,11 +169,15 @@ Optional<DWARFFormValue> DWARFAbbreviationDeclaration::getAttributeValue(
     if (*MatchAttrIndex == AttrIndex) {
       // We have arrived at the attribute to extract, extract if from Offset.
       DWARFFormValue FormValue(Spec.Form);
+      if (Spec.isImplicitConst()) {
+        FormValue.setSValue(*Spec.ByteSizeOrValue);
+        return FormValue;
+      }
       if (FormValue.extractValue(DebugInfoData, &Offset, &U))
         return FormValue;
     }
     // March Offset along until we get to the attribute we want.
-    if (Optional<uint8_t> FixedSize = Spec.getByteSize(U))
+    if (auto FixedSize = Spec.getByteSize(U))
       Offset += *FixedSize;
     else
       DWARFFormValue::skipValue(Spec.Form, DebugInfoData, &Offset, &U);
@@ -185,9 +198,17 @@ size_t DWARFAbbreviationDeclaration::FixedSizeInfo::getByteSize(
   return ByteSize;
 }
 
-Optional<uint8_t> DWARFAbbreviationDeclaration::AttributeSpec::getByteSize(
+Optional<int64_t> DWARFAbbreviationDeclaration::AttributeSpec::getByteSize(
     const DWARFUnit &U) const {
-  return ByteSize ? ByteSize : DWARFFormValue::getFixedByteSize(Form, &U);
+  if (isImplicitConst())
+    return 0;
+  if (ByteSizeOrValue)
+    return ByteSizeOrValue;
+  Optional<int64_t> S;
+  auto FixedByteSize = DWARFFormValue::getFixedByteSize(Form, &U);
+  if (FixedByteSize)
+    S = *FixedByteSize;
+  return S;
 }
 
 Optional<size_t> DWARFAbbreviationDeclaration::getFixedAttributesByteSize(
diff --git a/llvm/lib/DebugInfo/DWARF/DWARFDebugInfoEntry.cpp b/llvm/lib/DebugInfo/DWARF/DWARFDebugInfoEntry.cpp
index 9f623e4954c..c487e1dca7c 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFDebugInfoEntry.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFDebugInfoEntry.cpp
@@ -57,7 +57,7 @@ bool DWARFDebugInfoEntry::extractFast(const DWARFUnit &U, uint32_t *OffsetPtr,
   // Skip all data in the .debug_info for the attributes
   for (const auto &AttrSpec : AbbrevDecl->attributes()) {
     // Check if this attribute has a fixed byte size.
-    if (Optional<uint8_t> FixedSize = AttrSpec.getByteSize(U)) {
+    if (auto FixedSize = AttrSpec.getByteSize(U)) {
       // Attribute byte size if fixed, just add the size to the offset.
       *OffsetPtr += *FixedSize;
     } else if (!DWARFFormValue::skipValue(AttrSpec.Form, DebugInfoData,
diff --git a/llvm/lib/DebugInfo/DWARF/DWARFFormValue.cpp b/llvm/lib/DebugInfo/DWARF/DWARFFormValue.cpp
index e48a6f0981b..dc9310dc4e8 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFFormValue.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFFormValue.cpp
@@ -153,7 +153,7 @@ static Optional<uint8_t> getFixedByteSize(dwarf::Form Form, const T *U) {
       return 16;
 
     case DW_FORM_implicit_const:
-      // The implicit value is stored in the abbreviation as a ULEB128, any
+      // The implicit value is stored in the abbreviation as a SLEB128, and
       // there no data in debug info.
       return 0;
 
@@ -280,6 +280,8 @@ bool DWARFFormValue::isFormClass(DWARFFormValue::FormClass FC) const {
   case DW_FORM_GNU_str_index:
   case DW_FORM_GNU_strp_alt:
     return (FC == FC_String);
+  case DW_FORM_implicit_const:
+    return (FC == FC_Constant);
   default:
     break;
   }