[clang][AIX] Omitting Explicit Debugger Tuning Option

[qiongsiwu1]

Summary

On AIX, the default debugger is dbx so it is not necessary to explicitly set -debugger-tuning=dbx in the presence of -g.

[qiongsiwu1]

Adding one more test case.

[shchenz]

clang/lib/Driver/ToolChains/AIX.h

91 ↗

(On Diff #468626)

This sounds not right. Omitting -debugger-tuning=dbx does not mean we will change the default tuning debugger on AIX, right? i.e. DBX is still the default debugger on AIX no matter in the clang fe or llvm be.

We should just be able to do some customization when we call RenderDebugEnablingArgs for AIX in https://github.com/llvm/llvm-project/blob/main/clang/lib/Driver/ToolChains/Clang.cpp#L4367-L4368

[qiongsiwu1]

Address the review comment.

[shchenz]

LGTM except one minor in the testcase.

Thanks for adding this improvement.

clang/test/Driver/debug-options.c

121

nit: we can check that no -debugger-tuning= is emitted by check G_NOTUNING

[qiongsiwu1]

Adding two test cases to match G_NOTUNING.

[qiongsiwu1]

clang/test/Driver/debug-options.c

121

Ah thanks for catching this! Fixed.

[probinson]

clang/lib/Driver/ToolChains/Clang.cpp

4374

Seems like you should be able to return DebuggerKind::Default from getDefaultDebuggerTuning then you wouldn't need this complication?

[qiongsiwu1]

clang/lib/Driver/ToolChains/Clang.cpp

4374

Ah thanks for the suggestion!

We looked into an approach along this line in an earlier version (see https://reviews.llvm.org/D136187?id=468626), but it seemed that modifying the AIX default was not ideal. There are two drawbacks.

1. It complicates setting gstrict-dwarf and setting gno-column-info. The earlier version had to revise those conditions.
2. It may complicate future development that relies on the AIX tuning defaulting to DBX.

Therefore we ended up with this local change. That said, I am all ears for different ways to avoid the complication.

clang/lib/Driver/ToolChains/Clang.cpp

if (checkDebugInfoOption(A, Args, D, TC) &&
           DebugInfoKind == codegenoptions::DebugDirectivesOnly ||
           (DebugInfoKind == codegenoptions::DebugLineTablesOnly &&
            SplitDWARFInlining))
         DwarfFission = DwarfFissionKind::None;
     }
   }
 
   // If a debugger tuning argument appeared, remember it.
+  bool HasDebuggerTuning = false;
   if (const Arg *A =
           Args.getLastArg(options::OPT_gTune_Group, options::OPT_ggdbN_Group)) {
+    HasDebuggerTuning = true;
     if (checkDebugInfoOption(A, Args, D, TC)) {
       if (A->getOption().matches(options::OPT_glldb))
         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
static void renderDebugOptions(const ToolChain &TC, const Driver &D,
   // When emitting remarks, we need at least debug lines in the output.
   if (willEmitRemarks(Args) &&
       DebugInfoKind <= codegenoptions::DebugDirectivesOnly)
     DebugInfoKind = codegenoptions::DebugLineTablesOnly;
 
   // Adjust the debug info kind for the given toolchain.
   TC.adjustDebugInfoKind(DebugInfoKind, Args);
 
+  // On AIX, the debugger tuning option can be omitted if it is not explicitly
+  // set.
   RenderDebugEnablingArgs(Args, CmdArgs, DebugInfoKind, EffectiveDWARFVersion,
-                          DebuggerTuning);
+                          T.isOSAIX() && !HasDebuggerTuning
+                              ? llvm::DebuggerKind::Default
+                              : DebuggerTuning);
 
   // -fdebug-macro turns on macro debug info generation.
   if (Args.hasFlag(options::OPT_fdebug_macro, options::OPT_fno_debug_macro,
                    false))
     if (checkDebugInfoOption(Args.getLastArg(options::OPT_fdebug_macro), Args,
                              D, TC))
       CmdArgs.push_back("-debug-info-macro");
 

clang/test/Driver/debug-options.c

 // RUN:             | FileCheck -check-prefix=SNLDTLTOGARANGE %s
 // RUN: %clang -### %s -g -flto=full -target x86_64-scei-ps4 2>&1 \
 // RUN:             | FileCheck -check-prefix=SNLDFLTOGARANGE %s
 // RUN: %clang -### %s -g -flto -target x86_64-scei-ps5 2>&1 \
 // RUN:             | FileCheck -check-prefix=LLDGARANGE %s
 // RUN: %clang -### %s -g -target x86_64-scei-ps5 2>&1 \
 // RUN:             | FileCheck -check-prefix=LDGARANGE %s
 
-// On the AIX, -g defaults to -gdbx and limited debug info.
+// On the AIX, -g defaults to 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:             | FileCheck -check-prefix=G_LIMITED %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:             | FileCheck -check-prefix=G_LIMITED %s
+// RUN: %clang -### -c -g %s -target powerpc-ibm-aix-xcoff 2>&1 \
+// RUN:             | FileCheck -check-prefix=G_NOTUNING %s
+// RUN: %clang -### -c -g %s -target powerpc64-ibm-aix-xcoff 2>&1 \
+// RUN:             | FileCheck -check-prefix=G_NOTUNING %s
+// RUN: %clang -### -c -g -gdbx %s -target powerpc-ibm-aix-xcoff 2>&1 \
+// RUN:             | FileCheck -check-prefixes=G_LIMITED,G_DBX %s
+// RUN: %clang -### -c -g -gdbx %s -target powerpc64-ibm-aix-xcoff 2>&1 \
+// RUN:             | FileCheck -check-prefixes=G_LIMITED,G_DBX %s
 
 // For DBX, -g defaults to -gstrict-dwarf.
 // RUN: %clang -### -c -g %s -target powerpc-ibm-aix-xcoff 2>&1 \
 // RUN:             | FileCheck -check-prefix=STRICT %s
 // RUN: %clang -### -c -g %s -target powerpc64-ibm-aix-xcoff 2>&1 \
 // RUN:             | FileCheck -check-prefix=STRICT %s
 // RUN: %clang -### -c -g -gno-strict-dwarf %s -target powerpc-ibm-aix-xcoff \
 // RUN:             2>&1 | FileCheck -check-prefix=NOSTRICT %s