[llvm-readelf] - Don't print OS/Processor specific prefix for known ELF file types.

This is a change suggested in post commit comments for
D93096 (https://reviews.llvm.org/D93096#2451796).

Imagine we want to add a custom OS specific ELF file type.
For that we can update the `ElfObjectFileType` array:

```
static const EnumEntry<unsigned> ElfObjectFileType[] = {
...
  {"Core",         "CORE (Core file)",         ELF::ET_CORE},
  {"MyType",       "MyType (my description)",     0xfe01},
};
```

The current code then might print:
```
OS Specific: (MyType (my description))
```

Though instead we probably would like to see a nicer output, e.g:
```
Type: MyType (my description)
```

To achieve that we can reorder the code slightly.

It is impossible to add a test I think, because we have no custom values in
the `ElfObjectFileType` array in LLVM.

Differential revision: https://reviews.llvm.org/D93217

diff --git a/llvm/tools/llvm-readobj/ELFDumper.cpp b/llvm/tools/llvm-readobj/ELFDumper.cpp
index 27222c5..c9ca221 100644 (file)
--- a/llvm/tools/llvm-readobj/ELFDumper.cpp
+++ b/llvm/tools/llvm-readobj/ELFDumper.cpp
@@ -3528,16 +3528,17 @@ template <class ELFT> void GNUStyle<ELFT>::printFileHeaders() {
               "ABI Version:", std::to_string(e.e_ident[ELF::EI_ABIVERSION]));
 
   Str = printEnum(e.e_type, makeArrayRef(ElfObjectFileType));
-  if (e.e_type >= ET_LOPROC) {
-    Str = "Processor Specific: (" + Str + ")";
-  } else if (e.e_type >= ET_LOOS) {
-    Str = "OS Specific: (" + Str + ")";
-  } else if (makeArrayRef(ElfObjectFileType).end() ==
-             llvm::find_if(ElfObjectFileType,
-                           [&](const EnumEntry<unsigned> &E) {
-                             return E.Value == e.e_type;
-                           }))
-    Str = "<unknown>: " + Str;
+  if (makeArrayRef(ElfObjectFileType).end() ==
+      llvm::find_if(ElfObjectFileType, [&](const EnumEntry<unsigned> &E) {
+        return E.Value == e.e_type;
+      })) {
+    if (e.e_type >= ET_LOPROC)
+      Str = "Processor Specific: (" + Str + ")";
+    else if (e.e_type >= ET_LOOS)
+      Str = "OS Specific: (" + Str + ")";
+    else
+      Str = "<unknown>: " + Str;
+  }
   printFields(OS, "Type:", Str);
 
   Str = printEnum(e.e_machine, makeArrayRef(ElfMachineType));