[lldb][AIX] Updating XCOFF,PPC entry in LLDB ArchSpec (#105523)

This PR is in reference to porting LLDB on AIX.

Link to discussions on llvm discourse and github:

1. https://discourse.llvm.org/t/port-lldb-to-ibm-aix/80640
2. #101657 

The complete changes for porting are present in this draft PR:
#102601 

The changes in this PR are intended to update the Architecture entry for
LLDB with XCOFF,PPC.

1. Added new ArchitectureType `eArchTypeXCOFF`
2. Added a new `ArchDefinitionEntry g_xcoff_arch_entries[]`
3. Added a new case for `XCOFF in ArchSpec::SetArchitecture(..)`
4. Updated `ArchDefinition *g_arch_definitions[]`

lldb/include/lldb/lldb-private-enumerations.h

@@ -65,6 +65,7 @@ enum ArchitectureType {
   eArchTypeMachO,
   eArchTypeELF,
   eArchTypeCOFF,
+  eArchTypeXCOFF,
   kNumArchTypes
 };
 

lldb/source/Utility/ArchSpec.cpp

@@ -16,6 +16,7 @@
 #include "llvm/BinaryFormat/COFF.h"
 #include "llvm/BinaryFormat/ELF.h"
 #include "llvm/BinaryFormat/MachO.h"
+#include "llvm/BinaryFormat/XCOFF.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/TargetParser/ARMTargetParser.h"
 
@@ -459,10 +460,23 @@ static const ArchDefinition g_coff_arch_def = {
     "pe-coff",
 };
 
+static const ArchDefinitionEntry g_xcoff_arch_entries[] = {
+    {ArchSpec::eCore_ppc_generic, llvm::XCOFF::TCPU_COM, LLDB_INVALID_CPUTYPE,
+     0xFFFFFFFFu, 0xFFFFFFFFu},
+    {ArchSpec::eCore_ppc64_generic, llvm::XCOFF::TCPU_PPC64,
+     LLDB_INVALID_CPUTYPE, 0xFFFFFFFFu, 0xFFFFFFFFu}};
+
+static const ArchDefinition g_xcoff_arch_def = {
+    eArchTypeXCOFF,
+    std::size(g_xcoff_arch_entries),
+    g_xcoff_arch_entries,
+    "xcoff",
+};
+
 //===----------------------------------------------------------------------===//
 // Table of all ArchDefinitions
 static const ArchDefinition *g_arch_definitions[] = {
-    &g_macho_arch_def, &g_elf_arch_def, &g_coff_arch_def};
+    &g_macho_arch_def, &g_elf_arch_def, &g_coff_arch_def, &g_xcoff_arch_def};
 
 //===----------------------------------------------------------------------===//
 // Static helper functions.
@@ -903,6 +917,9 @@ bool ArchSpec::SetArchitecture(ArchitectureType arch_type, uint32_t cpu,
         } else if (arch_type == eArchTypeCOFF && os == llvm::Triple::Win32) {
           m_triple.setVendor(llvm::Triple::PC);
           m_triple.setOS(llvm::Triple::Win32);
+        } else if (arch_type == eArchTypeXCOFF && os == llvm::Triple::AIX) {
+          m_triple.setVendor(llvm::Triple::IBM);
+          m_triple.setOS(llvm::Triple::AIX);
         } else {
           m_triple.setVendor(llvm::Triple::UnknownVendor);
           m_triple.setOS(llvm::Triple::UnknownOS);