[llvm-readobj][XCOFF] Print the length of the string table.

[Higuoxing]

LGTM.

[shchenz]

LGTM too. Thanks for adding this improvement.

[jhenderson]

Looks good, except for one request.

llvm/tools/llvm-readobj/XCOFFDumper.cpp

463

I'm not sure I'd bother with the "(in bytes)" bit - we don't specify that in other places where the length is specified: bytes is implied, unless a unit is explicitly specified.

[Esme]

Addressed comments.

[jhenderson]

LGTM.

[fhahn]

Looks like this prints building with Clang-based compilers:

llvm/tools/llvm-readobj/XCOFFDumper.cpp:464:5: error: call to member function 'printNumber' is ambiguous
  W.printNumber("Length", StrTabSize);
  ~~^~~~~~~~~~~

[fhahn]

In D107333#2933931, @fhahn wrote:

Looks like this prints building with Clang-based compilers:

*breaks* :)

[Esme]

In D107333#2933931, @fhahn wrote:

Looks like this prints building with Clang-based compilers:

llvm/tools/llvm-readobj/XCOFFDumper.cpp:464:5: error: call to member function 'printNumber' is ambiguous
  W.printNumber("Length", StrTabSize);
  ~~^~~~~~~~~~~

Sorry. rGaefdce8b397a was committed to fix the error.

llvm/test/tools/llvm-readobj/XCOFF/string-table.yaml

 ## Test that the string table is dumped correctly.
 
 ## The string table contains more than one entry.
 # RUN: yaml2obj --docnum=1 %s -o %t1
 # RUN: llvm-readobj --string-table %t1 | FileCheck %s --check-prefix=BASIC
 
 # BASIC:      StringTable {
+# BASIC-NEXT:   Length: 16
 # BASIC-NEXT:   [     4]   name2
 # BASIC-NEXT:   [     a]   name1
 # BASIC-NEXT: }
 
 --- !XCOFF
 FileHeader:
   MagicNumber: 0x01F7
 Symbols:
   - Name: name1
   - Name: name2
 
 ## The string table just contains a single-byte sized string entry.
 # RUN: yaml2obj --docnum=2 %s -o %t2
 # RUN: llvm-readobj --string-table %t2 | FileCheck %s --check-prefix=SINGLE-BYTE
 
 # SINGLE-BYTE:      StringTable {
+# SINGLE-BYTE-NEXT:   Length: 6
 # SINGLE-BYTE-NEXT:   [     4]   n
 # SINGLE-BYTE-NEXT: }
 
 --- !XCOFF
 FileHeader:
   MagicNumber: 0x01F7
 Symbols:
   - Name: n
 
 ## There is no string table.
 # RUN: yaml2obj --docnum=3 %s -o %t3
 # RUN: llvm-readobj --string-table %t3 | FileCheck %s --check-prefix=NO-STRTBL
 
 # NO-STRTBL:      StringTable {
+# NO-STRTBL-NEXT:   Length: 0
 # NO-STRTBL-NEXT: }
 
 --- !XCOFF
 FileHeader:
   MagicNumber: 0x01F7

llvm/test/tools/yaml2obj/XCOFF/basic-doc64.yaml

 # CHECK64-NEXT:     Value (RelocatableAddress): 0x0
 # CHECK64-NEXT:     Section: .text
 # CHECK64-NEXT:     Type: 0x0
 # CHECK64-NEXT:     StorageClass: C_HIDEXT (0x6B)
 # CHECK64-NEXT:     NumberOfAuxEntries: 0
 # CHECK64-NEXT:   }
 # CHECK64-NEXT: ]
 # CHECK64-NEXT: StringTable {
+# CHECK64-NEXT:   Length: 28
 # CHECK64-NEXT:   [     4]   .text
 # CHECK64-NEXT:   [     a]   .abs
 # CHECK64-NEXT:   [     f]   .undef
 # CHECK64-NEXT:   [    16]   .file
 # CHECK64-NEXT: }

llvm/test/tools/yaml2obj/XCOFF/long-symbol-name.yaml

 # CHECK-NEXT:     Value: 0x0
 # CHECK-NEXT:     Section: N_UNDEF
 # CHECK-NEXT:     Type: 0x0
 # CHECK-NEXT:     StorageClass: C_NULL (0x0)
 # CHECK-NEXT:     NumberOfAuxEntries: 0
 # CHECK-NEXT:   }
 # CHECK-NEXT: ]
 # CHECK-NEXT: StringTable {
+# CHECK-NEXT:   Length: 14
 # CHECK-NEXT:   [     4]   .longname
 # CHECK-NEXT: }
 
 --- !XCOFF
 FileHeader:
   MagicNumber: 0x1DF
 Symbols:
   - Name: .symname
   - Name: .longname

llvm/tools/llvm-readobj/XCOFFDumper.cpp

void XCOFFDumper::printSymbols() {
   ListScope Group(W, "Symbols");
   for (const SymbolRef &S : Obj.symbols())
     printSymbol(S);
 }
 
 void XCOFFDumper::printStringTable() {
   DictScope DS(W, "StringTable");
   StringRef StrTable = Obj.getStringTable();
+  size_t StrTabSize = StrTable.size();
+  W.printNumber("Length", StrTabSize);
   // Print strings from the fifth byte, since the first four bytes contain the
   // length (in bytes) of the string table (including the length field).
-  if (StrTable.size() > 4)
+  if (StrTabSize > 4)
     printAsStringList(StrTable, 4);
 }
 
 void XCOFFDumper::printDynamicSymbols() {
   llvm_unreachable("Unimplemented functionality for XCOFFDumper");
 }
 
 void XCOFFDumper::printUnwindInfo() {