[dwarfdump] Make -arch accept alternative spellings

[kastiglione]

Summary

llvm-dwarfdump does not accept -arch values for commonly known arch names like
arm64 or i686. All llvm and clang tools I've used allow for these arch names,
this change makes llvm-dwarfdump consistent with other tools.

[kastiglione]

Remove unintended changes.

[aprantl]

See also https://reviews.llvm.org/D60240 :-)

[aprantl]

If you don't mind, I mildly prefer my patch in https://reviews.llvm.org/D60240 because it also adds a test for the MachO CPU type number case.

[kastiglione]

Sounds good @aprantl

llvm/test/tools/llvm-dwarfdump/X86/archive.test

 RUN: llvm-dwarfdump --debug-info %S/../../dsymutil/Inputs/libfat-test.a \
 RUN:   | FileCheck %s
 CHECK: libfat-test.a(x86_64)(fat-test.o):        file format Mach-O 64-bit x86-64
 CHECK: .debug_info contents:
 CHECK: libfat-test.a(i386)(fat-test.o):  file format Mach-O 32-bit i386
 CHECK: .debug_info contents:
 
 RUN: llvm-dwarfdump --debug-info %S/../../dsymutil/Inputs/libfat-test.a \
 RUN:   --arch=i386 | FileCheck %s --check-prefix=I386
 I386-NOT: 64-bit
 I386: file format Mach-O 32-bit i386
 I386-NOT: 64-bit
 
 RUN: llvm-dwarfdump --debug-info %S/../../dsymutil/Inputs/libfat-test.a \
+RUN:   --arch=i686 | FileCheck %s --check-prefix=I686
+I686-NOT: 64-bit
+I686: file format Mach-O 32-bit i386
+I686-NOT: 64-bit
+
+RUN: llvm-dwarfdump --debug-info %S/../../dsymutil/Inputs/libfat-test.a \
 RUN:   --arch=i386 --arch=x86_64 | FileCheck %s
 
 RUN: llvm-dwarfdump --debug-info %S/../../dsymutil/Inputs/libfat-test.a \
 RUN:   --arch=7 | FileCheck %s --check-prefix=I386

llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp

 }
 
 /// Return true if the object file has not been filtered by an --arch option.
 static bool filterArch(ObjectFile &Obj) {
   if (ArchFilters.empty())
     return true;
 
   if (auto *MachO = dyn_cast<MachOObjectFile>(&Obj)) {
-    std::string ObjArch =
-        Triple::getArchTypeName(MachO->getArchTriple().getArch());
+    auto ObjArch = MachO->getArchTriple().getArch();
 
     for (auto Arch : ArchFilters) {
       // Match name.
-      if (Arch == ObjArch)
+      if (Triple(Arch).getArch() == ObjArch)
         return true;
 
       // Match architecture number.
       unsigned Value;
       if (!StringRef(Arch).getAsInteger(0, Value))
         if (Value == getCPUType(*MachO))
           return true;
     }