[debug-info] support new tuning debugger type DBX for XCOFF DWARF

Based on this debugger type, for now, we plan to:
1: use inline string by default for XCOFF DWARF
2: generate no column info for debug line table.

Reviewed By: aprantl

Differential Revision: https://reviews.llvm.org/D99400

clang/docs/UsersManual.rst

@@ -2573,13 +2573,12 @@ While Clang generally emits standard DWARF debug info (http://dwarfstd.org),
 different debuggers may know how to take advantage of different specific DWARF
 features. You can "tune" the debug info for one of several different debuggers.
 
-.. option:: -ggdb, -glldb, -gsce
-
-  Tune the debug info for the ``gdb``, ``lldb``, or Sony PlayStation\ |reg|
-  debugger, respectively. Each of these options implies **-g**. (Therefore, if
-  you want both **-gline-tables-only** and debugger tuning, the tuning option
-  must come first.)
+.. option:: -ggdb, -glldb, -gsce, -gdbx
 
+  Tune the debug info for the ``gdb``, ``lldb``, Sony PlayStation\ |reg|
+  debugger, or ``dbx``, respectively. Each of these options implies **-g**.
+  (Therefore, if you want both **-gline-tables-only** and debugger tuning, the
+  tuning option must come first.)
 
 Controlling LLVM IR Output
 --------------------------

clang/include/clang/Basic/CodeGenOptions.def

@@ -340,7 +340,7 @@ ENUM_CODEGENOPT(DebugInfo, codegenoptions::DebugInfoKind, 4, codegenoptions::NoD
 CODEGENOPT(MacroDebugInfo, 1, 0)
 
 /// Tune the debug info for this debugger.
-ENUM_CODEGENOPT(DebuggerTuning, llvm::DebuggerKind, 2,
+ENUM_CODEGENOPT(DebuggerTuning, llvm::DebuggerKind, 3,
                 llvm::DebuggerKind::Default)
 
 /// Dwarf version. Version zero indicates to LLVM that no DWARF should be

clang/include/clang/Driver/Options.td

@@ -2722,6 +2722,7 @@ def ggdb2 : Flag<["-"], "ggdb2">, Group<ggdbN_Group>;
 def ggdb3 : Flag<["-"], "ggdb3">, Group<ggdbN_Group>;
 def glldb : Flag<["-"], "glldb">, Group<gTune_Group>;
 def gsce : Flag<["-"], "gsce">, Group<gTune_Group>;
+def gdbx : Flag<["-"], "gdbx">, Group<gTune_Group>;
 // Equivalent to our default dwarf version. Forces usual dwarf emission when
 // CodeView is enabled.
 def gdwarf : Flag<["-"], "gdwarf">, Group<g_Group>, Flags<[CoreOption]>,
@@ -4612,8 +4613,8 @@ def default_function_attr : Separate<["-"], "default-function-attr">,
 def dwarf_version_EQ : Joined<["-"], "dwarf-version=">,
   MarshallingInfoInt<CodeGenOpts<"DwarfVersion">>;
 def debugger_tuning_EQ : Joined<["-"], "debugger-tuning=">,
-  Values<"gdb,lldb,sce">,
-  NormalizedValuesScope<"llvm::DebuggerKind">, NormalizedValues<["GDB", "LLDB", "SCE"]>,
+  Values<"gdb,lldb,sce,dbx">,
+  NormalizedValuesScope<"llvm::DebuggerKind">, NormalizedValues<["GDB", "LLDB", "SCE", "DBX"]>,
   MarshallingInfoEnum<CodeGenOpts<"DebuggerTuning">, "Default">;
 def dwarf_debug_flags : Separate<["-"], "dwarf-debug-flags">,
   HelpText<"The string to embed in the Dwarf debug flags record.">,

clang/lib/Driver/ToolChains/AIX.h

@@ -77,6 +77,10 @@ public:
   // Set default DWARF version to 3 for now as latest AIX OS supports version 3.
   unsigned GetDefaultDwarfVersion() const override { return 3; }
 
+  llvm::DebuggerKind getDefaultDebuggerTuning() const override {
+    return llvm::DebuggerKind::DBX;
+  }
+
 protected:
   Tool *buildAssembler() const override;
   Tool *buildLinker() const override;

clang/lib/Driver/ToolChains/Clang.cpp

@@ -1051,6 +1051,9 @@ static void RenderDebugEnablingArgs(const ArgList &Args, ArgStringList &CmdArgs,
   case llvm::DebuggerKind::SCE:
     CmdArgs.push_back("-debugger-tuning=sce");
     break;
+  case llvm::DebuggerKind::DBX:
+    CmdArgs.push_back("-debugger-tuning=dbx");
+    break;
   default:
     break;
   }
@@ -3895,6 +3898,8 @@ static void renderDebugOptions(const ToolChain &TC, const Driver &D,
         DebuggerTuning = llvm::DebuggerKind::LLDB;
       else if (A->getOption().matches(options::OPT_gsce))
         DebuggerTuning = llvm::DebuggerKind::SCE;
+      else if (A->getOption().matches(options::OPT_gdbx))
+        DebuggerTuning = llvm::DebuggerKind::DBX;
       else
         DebuggerTuning = llvm::DebuggerKind::GDB;
     }

clang/lib/Driver/ToolChains/CommonArgs.cpp

@@ -550,6 +550,8 @@ void tools::addLTOOptions(const ToolChain &ToolChain, const ArgList &Args,
       CmdArgs.push_back("-plugin-opt=-debugger-tune=lldb");
     else if (A->getOption().matches(options::OPT_gsce))
       CmdArgs.push_back("-plugin-opt=-debugger-tune=sce");
+    else if (A->getOption().matches(options::OPT_gdbx))
+      CmdArgs.push_back("-plugin-opt=-debugger-tune=dbx");
     else
       CmdArgs.push_back("-plugin-opt=-debugger-tune=gdb");
   }

clang/test/Driver/debug-options.c

@@ -18,6 +18,8 @@
 // RUN:             | FileCheck -check-prefix=G_STANDALONE -check-prefix=G_LLDB %s
 // RUN: %clang -### -c -gsce %s -target x86_64-linux-gnu 2>&1 \
 // RUN:             | FileCheck -check-prefix=G_LIMITED -check-prefix=G_SCE %s
+// RUN: %clang -### -c -gdbx %s -target x86_64-linux-gnu 2>&1 \
+// RUN:             | FileCheck -check-prefix=G_LIMITED -check-prefix=G_DBX %s
 
 // Android.
 // Android should always generate DWARF4.
@@ -102,6 +104,12 @@
 // RUN: %clang -### -c %s -gsce -target x86_64-unknown-linux 2>&1 \
 // RUN:             | FileCheck -check-prefix=NOCI %s
 
+// On the AIX, -g defaults to -gdbx and limited debug info.
+// RUN: %clang -### -c -g %s -target powerpc-ibm-aix-xcoff 2>&1 \
+// RUN:             | FileCheck -check-prefix=G_LIMITED -check-prefix=G_DBX %s
+// RUN: %clang -### -c -g %s -target powerpc64-ibm-aix-xcoff 2>&1 \
+// RUN:             | FileCheck -check-prefix=G_LIMITED -check-prefix=G_DBX %s
+
 // RUN: %clang -### -c -gdwarf-2 %s 2>&1 \
 // RUN:             | FileCheck -check-prefix=G_ONLY_DWARF2 %s
 //
@@ -294,6 +302,7 @@
 // G_GDB:  "-debugger-tuning=gdb"
 // G_LLDB: "-debugger-tuning=lldb"
 // G_SCE:  "-debugger-tuning=sce"
+// G_DBX:  "-debugger-tuning=dbx"
 //
 // G_NOTUNING: "-cc1"
 // G_NOTUNING-NOT: "-debugger-tuning="

llvm/include/llvm/Target/TargetOptions.h

@@ -105,10 +105,11 @@ namespace llvm {
   /// in DwarfDebug; if a given feature has a more specific command-line option,
   /// that option should take precedence over the tuning.
   enum class DebuggerKind {
-    Default,  // No specific tuning requested.
-    GDB,      // Tune debug info for gdb.
-    LLDB,     // Tune debug info for lldb.
-    SCE       // Tune debug info for SCE targets (e.g. PS4).
+    Default, ///< No specific tuning requested.
+    GDB,     ///< Tune debug info for gdb.
+    LLDB,    ///< Tune debug info for lldb.
+    SCE,     ///< Tune debug info for SCE targets (e.g. PS4).
+    DBX      ///< Tune debug info for dbx.
   };
 
   /// Enable abort calls when global instruction selection fails to lower/select