dwarfdump: support indexed string dumping in dwp based on the STR_OFFSETS component of the index

llvm-svn: 253392
diff --git a/llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp b/llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp
index 51c6c09..53a149b 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp
@@ -37,7 +37,11 @@
                      const DWARFUnitSectionBase &UnitSection,
                      const DWARFUnitIndex::Entry *IndexEntry)
     : Context(DC), InfoSection(Section), Abbrev(DA), RangeSection(RS),
-      LineSection(LS), StringSection(SS), StringOffsetSection(SOS),
+      LineSection(LS), StringSection(SS), StringOffsetSection([&]() {
+        if (const auto *C = IndexEntry->getOffset(DW_SECT_STR_OFFSETS))
+          return SOS.slice(C->Offset, C->Offset + C->Length);
+        return SOS;
+      }()),
       AddrOffsetSection(AOS), isLittleEndian(LE), UnitSection(UnitSection),
       IndexEntry(IndexEntry) {
   clear();
diff --git a/llvm/test/DebugInfo/dwarfdump-dwp.test b/llvm/test/DebugInfo/dwarfdump-dwp.test
index e766cbc..af5de50 100644
--- a/llvm/test/DebugInfo/dwarfdump-dwp.test
+++ b/llvm/test/DebugInfo/dwarfdump-dwp.test
@@ -17,8 +17,7 @@
 ; CHECK-SAME: abbr_offset = 0x0043
 ; CHECK: DW_TAG_compile_unit
 ; CHECK-NOT: DW_TAG
-; FIXME: Implement str_offsets support so we find b.cpp here \/
-; CHECK:   DW_AT_name {{.*}} "a.cpp"
+; CHECK:   DW_AT_name {{.*}} "b.cpp"
 
 ; Verify that abbreviations are decoded using the abbrev offset in the index
 ; CHECK:   DW_TAG_structure_type