[AIX] Disable -gsplit-dwarf as it is unsupported at the moment on AIX (#158199)

**-gsplit-dwarf** flag causes an internal compiler error on AIX.
This PR aims to disable the -gsplit-dwarf flag on the AIX platform, as
it is unsupported at the moment.

Co-authored-by: Aditya Chaudhary <[email protected]>

Author: aditya-chaudhary1

clang/lib/Driver/ToolChains/Clang.cpp

@@ -4393,6 +4393,13 @@ renderDebugOptions(const ToolChain &TC, const Driver &D, const llvm::Triple &T,
   // object file generation and no IR generation, -gN should not be needed. So
   // allow -gsplit-dwarf with either -gN or IR input.
   if (IRInput || Args.hasArg(options::OPT_g_Group)) {
+    // FIXME: -gsplit-dwarf on AIX is currently unimplemented.
+    if (TC.getTriple().isOSAIX() && Args.hasArg(options::OPT_gsplit_dwarf)) {
+      D.Diag(diag::err_drv_unsupported_opt_for_target)
+          << Args.getLastArg(options::OPT_gsplit_dwarf)->getSpelling()
+          << TC.getTriple().str();
+      return;
+    }
     Arg *SplitDWARFArg;
     DwarfFission = getDebugFissionKind(D, Args, SplitDWARFArg);
     if (DwarfFission != DwarfFissionKind::None &&

clang/test/Driver/aix-gsplit-dwarf.c

@@ -0,0 +1,12 @@
+// Verify error message is emitted for `-gsplit-dwarf` on AIX 
+// as it's unsupported at the moment.
+
+// RUN: not %clang -target powerpc-ibm-aix -gdwarf-4 -gsplit-dwarf %s 2>&1 \
+// RUN: | FileCheck %s --check-prefix=UNSUP_OPT_AIX
+// RUN: not %clang -target powerpc64-ibm-aix -gdwarf-4 -gsplit-dwarf %s 2>&1 \
+// RUN: | FileCheck %s --check-prefix=UNSUP_OPT_AIX64
+
+// UNSUP_OPT_AIX: error: unsupported option '-gsplit-dwarf' for target 'powerpc-ibm-aix'
+// UNSUP_OPT_AIX64: error: unsupported option '-gsplit-dwarf' for target 'powerpc64-ibm-aix'
+
+int main(){return 0;}