[DWARFYAML] Let the address size of line tables inferred from the object file.

[Higuoxing]

Summary

Currently, the line table uses the first compilation unit's address size
as its address size. It's not the right behavior. The address size should be
inferred from the target machine.

[Higuoxing]

The address size shouldn't be referenced from the .debug_info section.

[jhenderson]

LGTM.

llvm/lib/ObjectYAML/DWARFEmitter.cpp

474–476

[Higuoxing]

Address comments.

llvm/lib/ObjectYAML/DWARFEmitter.cpp

for (auto IncludeDir : LineTable.IncludeDirs) {
       OS.write('\0');
     }
     OS.write('\0');
 
     for (auto File : LineTable.Files)
       emitFileEntry(OS, File);
     OS.write('\0');
 
+    uint8_t AddrSize = DI.Is64BitAddrSize ? 8 : 4;
+
     for (auto Op : LineTable.Opcodes) {
       writeInteger((uint8_t)Op.Opcode, OS, DI.IsLittleEndian);
       if (Op.Opcode == 0) {
         encodeULEB128(Op.ExtLen, OS);
         writeInteger((uint8_t)Op.SubOpcode, OS, DI.IsLittleEndian);
         switch (Op.SubOpcode) {
         case dwarf::DW_LNE_set_address:
         case dwarf::DW_LNE_set_discriminator:
-          // TODO: Test this error.
-          if (Error Err = writeVariableSizedInteger(
-                  Op.Data, DI.CompileUnits[0].AddrSize, OS, DI.IsLittleEndian))
-            return Err;
+          // FIXME: The operand of set_discriminator is not an address.
+          cantFail(writeVariableSizedInteger(Op.Data, AddrSize, OS,
+                                             DI.IsLittleEndian));
           break;
         case dwarf::DW_LNE_define_file:
           emitFileEntry(OS, Op.FileEntry);
           break;
         case dwarf::DW_LNE_end_sequence:
           break;
         default:
           for (auto OpByte : Op.UnknownOpcodeData)

llvm/test/tools/yaml2obj/ELF/DWARF/debug-line.yaml

- Length:                0x70
       DefaultIsStmt:         1
       LineBase:              1
       LineRange:             14
       OpcodeBase:            13
       StandardOpcodeLengths: []
       IncludeDirs:           []
       Files:                 []
       Opcodes:               []
+
+## h) Test that the address size is inferred from the target machine.
+
+# RUN: yaml2obj --docnum=8 -DBITS=64 -DADDR=0x1234567890abcdef %s -o %t8.64-bit.o
+# RUN: llvm-readelf --hex-dump=.debug_line %t8.64-bit.o | \
+# RUN:   FileCheck %s --check-prefix=ADDRSIZE -DADDR="efcdab90 78563412"
+
+#      ADDRSIZE: Hex dump of section '.debug_line':
+# ADDRSIZE-NEXT: 0x00000000 34120000 02003412 00000101 010e0d00 4.....4.........
+##                          ^-------                            unit_length (4-byte)
+##                                   ^---                       version (2-byte)
+##                                       ^--------              header_length (4-byte)
+##                                                ^-            minimum_instruction_length (1-byte)
+##                                                  ^-          default_is_stmt (1-byte)
+##                                                     ^-       line_base (1-byte)
+##                                                       ^-     line_range (1-byte)
+##                                                         ^-   opcode_base (1-byte)
+##                                                           ^- null byte for terminating include_directories
+# ADDRSIZE-NEXT: 0x00000010 00000902 [[ADDR]]
+##                          ^-                                  null byte for terminating file_names
+##                            ^-                                DW_LNS_extended_op
+##                              ^-                              extended op length (ULEB128) 0x09
+##                                ^-                            DW_LNE_set_address
+##                                   ^-------                   address
+
+# RUN: yaml2obj --docnum=8 -DBITS=32 -DADDR=0x12345678 %s -o %t8.32-bit.o
+# RUN: llvm-readelf --hex-dump=.debug_line %t8.32-bit.o | \
+# RUN:   FileCheck %s --check-prefix=ADDRSIZE -DADDR="78563412"
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS[[BITS]]
+  Data:    ELFDATA2LSB
+  Type:    ET_EXEC
+  Machine: EM_X86_64
+DWARF:
+  debug_line:
+    - Length:                0x1234
+      Version:               2
+      PrologueLength:        0x1234
+      MinInstLength:         1
+      DefaultIsStmt:         1
+      LineBase:              1
+      LineRange:             14
+      OpcodeBase:            13
+      StandardOpcodeLengths: []
+      IncludeDirs:           []
+      Files:                 []
+      Opcodes:
+        - Opcode:    DW_LNS_extended_op
+          ExtLen:    9
+          SubOpcode: DW_LNE_set_address
+          Data:      [[ADDR]]