[llvm-readelf]Print filename for multiple inputs and fix formatting regression

This patch addresses two closely related bugs:
https://bugs.llvm.org/show_bug.cgi?id=42930 and
https://bugs.llvm.org/show_bug.cgi?id=42931.

GNU readelf prints the file name for every input unless there is only
one input and that input is not an archive. This patch adds the printing
for multiple inputs. A previous change did it for archives, but
introduced a regression with GNU compatibility for single-output
formatting, resulting in a spurious initial blank line. This is fixed in
this patch too.

Reviewed by: grimar, MaskRay

Differential Revision: https://reviews.llvm.org/D65953

llvm-svn: 368435

llvm/test/tools/llvm-readobj/elf-dynamic-malformed.test

@@ -20,7 +20,6 @@
 
 # WARN-GNU-NOT:  warning
 # WARN-GNU:      warning: invalid section size (4) or entity size (16)
-# WARN-GNU-EMPTY:
 # WARN-GNU-NEXT: ELF Header:
 # WARN-GNU:      Symbol table '.symtab' contains 1 entries:
 # WARN-GNU:        0:

llvm/test/tools/llvm-readobj/file-name.test

@@ -0,0 +1,42 @@
+## This test shows that the name of the file is printed under the right
+## circumstances and with the correct formatting for object inputs.
+
+# RUN: yaml2obj %s -o %t1
+# RUN: cp %t1 %t2
+
+## Show that the file name is not printed for a single input for GNU output.
+# RUN: llvm-readelf --file-headers %t1 \
+# RUN:   | FileCheck %s --implicit-check-not=File: --check-prefix=GNU-SINGLE
+
+## Show that the very first line of the output is the one with "ELF Header" on.
+# GNU-SINGLE:      {{^}}
+# GNU-SINGLE-SAME: ELF Header:
+
+## Show that the file names are printed for all inputs for GNU output.
+# RUN: llvm-readelf --file-headers %t1 %t2 \
+# RUN:   | FileCheck %s --check-prefixes=NAME1,GNU,NAME2 -DFILE1=%t1 -DFILE2=%t2
+
+## Show that the file name is printed for a single input for LLVM output.
+# RUN: llvm-readobj --file-headers %t1 | FileCheck %s --check-prefix=NAME1 -DFILE1=%t1
+
+## Show that the file name is printed with correct spacing for multiple inputs
+## with LLVM output.
+# RUN: llvm-readobj --file-headers %t1 %t2 \
+# RUN:   | FileCheck %s --check-prefixes=NAME1,LLVM,NAME2 -DFILE1=%t1 -DFILE2=%t2
+
+## The very first line should be blank. CHECK-EMPTY isn't allowed on the first line.
+# NAME1:      {{^$}}
+# NAME1-NEXT: {{^}}File: [[FILE1]]{{$}}
+
+# GNU:          Section header string table index:
+# LLVM:         StringTableSectionIndex:
+# LLVM-NEXT:  }
+# NAME2-EMPTY:
+# NAME2-NEXT: {{^}}File: [[FILE2]]{{$}}
+
+--- !ELF
+FileHeader:
+  Class:    ELFCLASS64
+  Data:     ELFDATA2LSB
+  Type:     ET_REL
+  Machine:  EM_X86_64

llvm/test/tools/llvm-readobj/stack-sizes.test

@@ -322,11 +322,13 @@ Sections:
 ## tables.
 
 # RUN: llvm-ar rc %t1.a %t01 %t02
-# RUN: llvm-readelf --stack-sizes %t01 %t02 | FileCheck %s --check-prefix=MULTIPLE
+# RUN: llvm-readelf --stack-sizes %t01 %t02 \
+# RUN:   | FileCheck %s --check-prefixes=MULTIPLE,OBJECT -DFILE1=%t01 -DFILE2=%t02
 # RUN: llvm-readelf --stack-sizes %t1.a \
-# RUN:   | FileCheck %s --check-prefix=MULTIPLE --check-prefix=ARCHIVE --strict-whitespace\
+# RUN:   | FileCheck %s --check-prefixes=MULTIPLE,ARCHIVE --strict-whitespace\
 # RUN:   --match-full-lines -DFILE=%t1.a
 
+#        OBJECT:File: [[FILE1]]
 #       ARCHIVE:File: [[FILE]]({{.*01}})
 #      MULTIPLE:Stack Sizes:
 # MULTIPLE-NEXT:         Size     Function
@@ -334,6 +336,7 @@ Sections:
 # MULTIPLE-NEXT:           32     referenced_via_section_bar
 # MULTIPLE-NEXT:            8     separate_text_section_baz
 # MULTIPLE-EMPTY:
+#        OBJECT:File: [[FILE2]]
 #       ARCHIVE:File: [[FILE]]({{.*02}})
 # MULTIPLE-EMPTY:
 # MULTIPLE-NEXT:Stack Sizes:

llvm/tools/llvm-readobj/llvm-readobj.cpp

@@ -484,17 +484,17 @@ static void dumpObject(const ObjectFile *Obj, ScopedPrinter &Writer,
   if (std::error_code EC = createDumper(Obj, Writer, Dumper))
     reportError(FileStr, EC);
 
+  if (opts::Output == opts::LLVM || opts::InputFilenames.size() > 1 || A) {
     Writer.startLine() << "\n";
-  if (opts::Output == opts::LLVM) {
     Writer.printString("File", FileStr);
+  }
+  if (opts::Output == opts::LLVM) {
     Writer.printString("Format", Obj->getFileFormatName());
     Writer.printString("Arch", Triple::getArchTypeName(
                                    (llvm::Triple::ArchType)Obj->getArch()));
     Writer.printString("AddressSize",
                        formatv("{0}bit", 8 * Obj->getBytesInAddress()));
     Dumper->printLoadName();
-  } else if (opts::Output == opts::GNU && A) {
-    Writer.printString("File", FileStr);
   }
 
   if (opts::FileHeaders)