1/3: [llvm] Refactorization for fix#2 of DW_AT_ranges DW_FORM_sec_offset not using DW_AT_rnglists_base (used by GCC)

[jankratochvil]

Summary

It is required for: D106466
Fix D98289 so that it works even for 2nd..nth compilation unit (.debug_rnglists).

[jhenderson]

Looks reasonable to me.

[jankratochvil]

With the new variant of D106466 this refactorization is no longer needed.
Thanks for the review, unfortunately I do not think it makes sense on its own (but I can check it in if you think so).

llvm/include/llvm/DebugInfo/DWARF/DWARFListTable.h

Error extract(DWARFDataExtractor Data, uint64_t HeaderOffset,
                 uint64_t *OffsetPtr, StringRef SectionName,
                 StringRef ListStringName);
 };
 
 /// A class representing the header of a list table such as the range list
 /// table in the .debug_rnglists section.
 class DWARFListTableHeader {
   struct Header {
+    // Perform basic validation of the header fields.
+    Error verify() const;
+
     /// The total length of the entries for this table, not including the length
     /// field itself.
     uint64_t Length = 0;
     /// The DWARF version number.
     uint16_t Version;
     /// The size in bytes of an address on the target architecture. For
     /// segmented addressing, this is the size of the offset portion of the
     /// address.

llvm/lib/DebugInfo/DWARF/DWARFListTable.cpp

 #include "llvm/BinaryFormat/Dwarf.h"
 #include "llvm/Support/Errc.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/Format.h"
 #include "llvm/Support/raw_ostream.h"
 
 using namespace llvm;
 
+Error DWARFListTableHeader::Header::verify() const {
+  if (Version != 5)
+    return createStringError(errc::invalid_argument,
+                             "unrecognised version %" PRIu16, Version);
+  if (AddrSize != 4 && AddrSize != 8)
+    return createStringError(errc::not_supported,
+                             "unsupported address size %" PRIu8, AddrSize);
+  if (SegSize != 0)
+    return createStringError(errc::not_supported,
+                             "unsupported segment selector size %" PRIu8,
+                             SegSize);
+  return Error::success();
+}
+
 Error DWARFListTableHeader::extract(DWARFDataExtractor Data,
                                     uint64_t *OffsetPtr) {
   HeaderOffset = *OffsetPtr;
   Error Err = Error::success();
 
   std::tie(HeaderData.Length, Format) = Data.getInitialLength(OffsetPtr, &Err);
   if (Err)
     return createStringError(
return createStringError(errc::invalid_argument,
                        "of length 0x%" PRIx64 " at offset 0x%" PRIx64,
                        SectionName.data(), FullLength, HeaderOffset);
 
   HeaderData.Version = Data.getU16(OffsetPtr);
   HeaderData.AddrSize = Data.getU8(OffsetPtr);
   HeaderData.SegSize = Data.getU8(OffsetPtr);
   HeaderData.OffsetEntryCount = Data.getU32(OffsetPtr);
 
-  // Perform basic validation of the remaining header fields.
-  if (HeaderData.Version != 5)
-    return createStringError(errc::invalid_argument,
-                       "unrecognised %s table version %" PRIu16
-                       " in table at offset 0x%" PRIx64,
-                       SectionName.data(), HeaderData.Version, HeaderOffset);
-  if (HeaderData.AddrSize != 4 && HeaderData.AddrSize != 8)
-    return createStringError(errc::not_supported,
-                       "%s table at offset 0x%" PRIx64
-                       " has unsupported address size %" PRIu8,
-                       SectionName.data(), HeaderOffset, HeaderData.AddrSize);
-  if (HeaderData.SegSize != 0)
-    return createStringError(errc::not_supported,
-                       "%s table at offset 0x%" PRIx64
-                       " has unsupported segment selector size %" PRIu8,
-                       SectionName.data(), HeaderOffset, HeaderData.SegSize);
+  Err = HeaderData.verify();
+  if (Err)
+    return createStringError(
+        errc::invalid_argument, "parsing %s table at offset 0x%" PRIx64 ": %s",
+        SectionName.data(), HeaderOffset, toString(std::move(Err)).c_str());
+
   if (End < HeaderOffset + getHeaderSize(Format) +
                 HeaderData.OffsetEntryCount * OffsetByteSize)
     return createStringError(errc::invalid_argument,
         "%s table at offset 0x%" PRIx64 " has more offset entries (%" PRIu32
         ") than there is space for",
         SectionName.data(), HeaderOffset, HeaderData.OffsetEntryCount);
   Data.setAddressSize(HeaderData.AddrSize);
   *OffsetPtr += HeaderData.OffsetEntryCount * OffsetByteSize;

llvm/test/tools/llvm-dwarfdump/X86/debug_rnglists_invalid.s

 # GOOD-NEXT: range list header: length = 0x0000001a, format = DWARF32, version = 0x0005, addr_size = 0x08, seg_size = 0x00, offset_entry_count = 0x00000000
 # GOOD-NEXT: ranges:
 # GOOD-NEXT: [0x0000000000000030, 0x0000000000000040)
 # GOOD-NEXT: <End of list>
 # GOOD-NOT:  range list header
 
 # CHECK-NOT: error:
 # CHECK: error: .debug_rnglists table at offset 0x22 has too small length (0xb) to contain a complete header
-# CHECK-NEXT: error: unrecognised .debug_rnglists table version 4 in table at offset 0x2d
-# CHECK-NEXT: error: .debug_rnglists table at offset 0x39 has unsupported address size 2
-# CHECK-NEXT: error: .debug_rnglists table at offset 0x45 has unsupported segment selector size 4
+# CHECK-NEXT: error: parsing .debug_rnglists table at offset 0x2d: unrecognised version 4
+# CHECK-NEXT: error: parsing .debug_rnglists table at offset 0x39: unsupported address size 2
+# CHECK-NEXT: error: parsing .debug_rnglists table at offset 0x45: unsupported segment selector size 4
 # CHECK-NEXT: error: .debug_rnglists table at offset 0x51 has more offset entries (12345678) than there is space for
 # CHECK-NEXT: error: read past end of table when reading DW_RLE_start_end encoding at offset 0x69
 # CHECK-NEXT: error: read past end of table when reading DW_RLE_start_length encoding at offset 0x82
 # CHECK-NEXT: error: unknown rnglists encoding 0x2a at offset 0x98
 # CHECK-NEXT: error: no end of list marker detected at end of .debug_rnglists table starting at offset 0xaa
 # CHECK-NEXT: error: section is not large enough to contain a .debug_rnglists table of length 0x1f at offset 0xe5
 # CHECK-NOT: error: