[llvm-dwarfutil][DWARFv5] fix reading of DW_FORM_addrx attribute.

[avl]

Summary

llvm::dwarfutil::ObjFileAddressMap::relocateIndexedAddr() does not
read address value. The relocateIndexedAddr() should not relocate
the address as the linked binary has already resolved relocations.
But it should read the value. This patch adds the reading value
of the address.

[avl]

ping.

[probinson]

Test probably doesn't need 8 functions? I'd think two would be enough to show the addresses are handled properly.
Could the test be YAML instead of binary? I know YAML doesn't handle DWARF very well so the answer might be "no."

[avl]

addressed comments(converted test to yaml, reduced number of functions in test)

[clayborg]

Looks good to me. I will let the DWARFLinker owners do the final approval.

[avl]

ping.

[probinson]

LGTM

llvm/test/tools/llvm-dwarfutil/ELF/X86/dwarf5-addrx.test

+## Test that DWARF5 DW_FORM_addrx is correctly recognized
+## and converted into the DW_FORM_addr
+
+# RUN: yaml2obj %s -o %t.o
+
+# RUN: llvm-dwarfutil %t.o %t1
+# RUN: llvm-dwarfdump -verify %t1 | FileCheck %s
+# RUN: llvm-dwarfdump -a --verbose %t1 | FileCheck %s --check-prefix DWARF-CHECK
+
+#CHECK: No errors.
+
+#DWARF-CHECK: DW_TAG_compile_unit
+#DWARF-CHECK:   DW_AT_name [DW_FORM_strp]  {{.*}}     "CU1"
+#DWARF-CHECK:   DW_AT_low_pc [DW_FORM_addr]     (0x0000000000001130)
+#DWARF-CHECK:   DW_AT_high_pc [DW_FORM_data8]   (0x0000000000000030)
+#DWARF-CHECK:   DW_AT_addr_base [DW_FORM_sec_offset]   (0x00000008)
+#DWARF-CHECK:   DW_TAG_subprogram
+#DWARF-CHECK:     DW_AT_name  [DW_FORM_strp] {{.*}}   "foo1"
+#DWARF-CHECK:     DW_AT_low_pc [DW_FORM_addr]     (0x0000000000001130)
+#DWARF-CHECK:     DW_AT_high_pc [DW_FORM_data8]   (0x0000000000000010)
+#DWARF-CHECK:   DW_TAG_subprogram
+#DWARF-CHECK:     DW_AT_name  [DW_FORM_strp] {{.*}}   "foo2"
+#DWARF-CHECK:     DW_AT_low_pc [DW_FORM_addr]     (0x0000000000001140)
+#DWARF-CHECK:     DW_AT_high_pc [DW_FORM_data8]   (0x0000000000000010)
+#DWARF-CHECK:   DW_TAG_subprogram
+#DWARF-CHECK:     DW_AT_name  [DW_FORM_strp] {{.*}}   "foo3"
+#DWARF-CHECK:     DW_AT_low_pc [DW_FORM_addr]     (0x0000000000001150)
+#DWARF-CHECK:     DW_AT_high_pc [DW_FORM_data8]   (0x0000000000000010)
+
+--- !ELF
+FileHeader:
+  Class:    ELFCLASS64
+  Data:     ELFDATA2LSB
+  Type:     ET_REL
+  Machine:  EM_X86_64
+Sections:
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    Address:         0x1130
+    Size:            0x30
+DWARF:
+  debug_abbrev:
+    - Table:
+      - Tag:      DW_TAG_compile_unit
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_producer
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_language
+            Form:      DW_FORM_data2
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addrx
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+          - Attribute: DW_AT_addr_base
+            Form:      DW_FORM_sec_offset
+      - Tag:      DW_TAG_subprogram
+        Children: DW_CHILDREN_yes
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+          - Attribute: DW_AT_low_pc
+            Form:      DW_FORM_addrx
+          - Attribute: DW_AT_high_pc
+            Form:      DW_FORM_data8
+          - Attribute: DW_AT_type
+            Form:      DW_FORM_ref4
+      - Tag:      DW_TAG_base_type
+        Children: DW_CHILDREN_no
+        Attributes:
+          - Attribute: DW_AT_name
+            Form:      DW_FORM_string
+  debug_info:
+    - Version: 5
+      UnitType:   DW_UT_compile
+      Entries:
+        - AbbrCode: 1
+          Values:
+            - CStr: by_hand
+            - Value:  0x04
+            - CStr: CU1
+            - Value:  0x0
+            - Value:  0x30
+            - Value:  0x8
+        - AbbrCode: 2
+          Values:
+            - CStr: foo1
+            - Value: 0x0
+            - Value: 0x10
+            - Value: 0x64
+        - AbbrCode: 0
+        - AbbrCode: 2
+          Values:
+            - CStr: foo2
+            - Value: 0x01
+            - Value: 0x10
+            - Value: 0x64
+        - AbbrCode: 0
+        - AbbrCode: 2
+          Values:
+            - CStr: foo3
+            - Value: 0x02
+            - Value: 0x10
+            - Value: 0x64
+        - AbbrCode: 0
+        - AbbrCode: 3
+          Values:
+            - CStr: int
+        - AbbrCode: 0
+  debug_addr:
+    - Version: 5
+      AddressSize: 0x08
+      Entries:
+        - Address: 0x1130
+        - Address: 0x1140
+        - Address: 0x1150
+...

llvm/tools/llvm-dwarfutil/DebugInfoLinker.cpp

 //=== DebugInfoLinker.cpp -------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "DebugInfoLinker.h"
 #include "Error.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/DWARFLinker/DWARFLinker.h"
 #include "llvm/DWARFLinker/DWARFStreamer.h"
 #include "llvm/DebugInfo/DWARF/DWARFContext.h"
 #include "llvm/DebugInfo/DWARF/DWARFExpression.h"
 #include "llvm/Object/ObjectFile.h"
+#include "llvm/Support/Endian.h"
 #include <memory>
 #include <vector>
 
 namespace llvm {
 namespace dwarfutil {
 
 // ObjFileAddressMap allows to check whether specified DIE referencing
 // dead addresses. It uses tombstone values to determine dead addresses.

 //
 // exec: [LowPC, HighPC] is not inside address ranges of .text sections
 //
 // universal: maxpc and bfd
 class ObjFileAddressMap : public AddressesMap {
 public:
   ObjFileAddressMap(DWARFContext &Context, const Options &Options,
                     object::ObjectFile &ObjFile)
-      : Opts(Options) {
+      : Opts(Options), Context(Context) {
     // Remember addresses of existing text sections.
     for (const object::SectionRef &Sect : ObjFile.sections()) {
       if (!Sect.isText())
         continue;
       const uint64_t Size = Sect.getSize();
       if (Size == 0)
         continue;
       const uint64_t StartAddr = Sect.getAddress();
bool applyValidRelocs(MutableArrayRef<char>, uint64_t, bool) override {
     // no need to apply relocations to the linked binary.
     return false;
   }
 
   RangesTy &getValidAddressRanges() override { return DWARFAddressRanges; };
 
   void clear() override { DWARFAddressRanges.clear(); }
 
-  llvm::Expected<uint64_t> relocateIndexedAddr(uint64_t, uint64_t) override {
-    // should not be called.
-    return object::createError("no relocations in linked binary");
+  llvm::Expected<uint64_t> relocateIndexedAddr(uint64_t StartOffset,
+                                               uint64_t EndOffset) override {
+    // No relocations in linked binary. Return just address value.
+
+    const char *AddrPtr =
+        Context.getDWARFObj().getAddrSection().Data.data() + StartOffset;
+    support::endianness Endianess =
+        Context.getDWARFObj().isLittleEndian() ? support::little : support::big;
+
+    assert(EndOffset > StartOffset);
+    switch (EndOffset - StartOffset) {
+    case 1:
+      return *AddrPtr;
+    case 2:
+      return support::endian::read16(AddrPtr, Endianess);
+    case 4:
+      return support::endian::read32(AddrPtr, Endianess);
+    case 8:
+      return support::endian::read64(AddrPtr, Endianess);
+    }
+
+    llvm_unreachable("relocateIndexedAddr unhandled case!");
   }
 
 protected:
   // returns true if specified address range is inside address ranges
   // of executable sections.
   bool isInsideExecutableSectionsAddressRange(uint64_t LowPC,
                                               Optional<uint64_t> HighPC) {
     Optional<AddressRange> Range =
bool isDeadAddress(uint64_t LowPC, uint16_t Version, TombstoneKind Tombstone,
                      uint8_t AddressByteSize) {
     return isDeadAddressRange(LowPC, None, Version, Tombstone, AddressByteSize);
   }
 
 private:
   RangesTy DWARFAddressRanges;
   AddressRanges TextAddressRanges;
   const Options &Opts;
+  DWARFContext &Context;
 };
 
 static bool knownByDWARFUtil(StringRef SecName) {
   return llvm::StringSwitch<bool>(SecName)
       .Case(".debug_info", true)
       .Case(".debug_types", true)
       .Case(".debug_abbrev", true)
       .Case(".debug_loc", true)