[Debuginfo] Remove redundand variable from getAttributeValue()

Summary: AttrIndex could be removed from DWARFAbbreviationDeclaration::getAttributeValue.

Reviewers: clayborg, dblaikie

Differential Revision: https://reviews.llvm.org/D78672

Author: avl-llvm

llvm/lib/DebugInfo/DWARF/DWARFAbbreviationDeclaration.cpp

@@ -150,6 +150,8 @@ DWARFAbbreviationDeclaration::findAttributeIndex(dwarf::Attribute Attr) const {
 Optional<DWARFFormValue> DWARFAbbreviationDeclaration::getAttributeValue(
     const uint64_t DIEOffset, const dwarf::Attribute Attr,
     const DWARFUnit &U) const {
+  // Check if this abbreviation has this attribute without needing to skip
+  // any data so we can return quickly if it doesn't.
   Optional<uint32_t> MatchAttrIndex = findAttributeIndex(Attr);
   if (!MatchAttrIndex)
     return None;
@@ -159,26 +161,24 @@ Optional<DWARFFormValue> DWARFAbbreviationDeclaration::getAttributeValue(
   // Add the byte size of ULEB that for the abbrev Code so we can start
   // skipping the attribute data.
   uint64_t Offset = DIEOffset + CodeByteSize;
-  uint32_t AttrIndex = 0;
-  for (const auto &Spec : AttributeSpecs) {
-    if (*MatchAttrIndex == AttrIndex) {
-      // We have arrived at the attribute to extract, extract if from Offset.
-      if (Spec.isImplicitConst())
-        return DWARFFormValue::createFromSValue(Spec.Form,
-                                                Spec.getImplicitConstValue());
-
-      DWARFFormValue FormValue(Spec.Form);
-      if (FormValue.extractValue(DebugInfoData, &Offset, U.getFormParams(), &U))
-        return FormValue;
-    }
-    // March Offset along until we get to the attribute we want.
-    if (auto FixedSize = Spec.getByteSize(U))
+  for (uint32_t CurAttrIdx = 0; CurAttrIdx != *MatchAttrIndex; ++CurAttrIdx)
+    // Match Offset along until we get to the attribute we want.
+    if (auto FixedSize = AttributeSpecs[CurAttrIdx].getByteSize(U))
       Offset += *FixedSize;
     else
-      DWARFFormValue::skipValue(Spec.Form, DebugInfoData, &Offset,
-                                U.getFormParams());
-    ++AttrIndex;
-  }
+      DWARFFormValue::skipValue(AttributeSpecs[CurAttrIdx].Form, DebugInfoData,
+                                &Offset, U.getFormParams());
+
+  // We have arrived at the attribute to extract, extract if from Offset.
+  const AttributeSpec &Spec = AttributeSpecs[*MatchAttrIndex];
+  if (Spec.isImplicitConst())
+    return DWARFFormValue::createFromSValue(Spec.Form,
+                                            Spec.getImplicitConstValue());
+
+  DWARFFormValue FormValue(Spec.Form);
+  if (FormValue.extractValue(DebugInfoData, &Offset, U.getFormParams(), &U))
+    return FormValue;
+
   return None;
 }