[Debug-Info] implement -gstrict-dwarf

[shchenz]

Summary

This patch implements -gstrict-dwarf option in clang FE.

We had this option in clang code base just not used it.

We plan to verify the DWARF info based on DWARF 3.

[dblaikie]

clang/docs/ClangCommandLineReference.rst

3549–3550

This description is probably backwards/doesn't explicitly clarify which version of the flag does which behavior.

I guess the only nearby example is the -gembed-source, which describes the effect of -gembed-source, not the effect of -gno-embed-source.

clang/lib/Driver/ToolChains/Clang.cpp

3973–3974

@aprantl or anyone else - is this the right use of checkDebugInfoOption? I forget what it's for/how it should be used.

clang/test/Driver/debug-options.c

329–330

"STRICT" v "G_STRICT" seems confusing to me - how do other flags differentiate their positive/negative tests? (looks like GNO_X/GX or GX/NOX, etc - something like that'd be good)

[shchenz]

address @dblaikie comments.

clang/lib/Driver/ToolChains/Clang.cpp

3973–3974

See the nearby example for -gcolumn-info:

if (const Arg *A = Args.getLastArg(options::OPT_gcolumn_info))
  (void)checkDebugInfoOption(A, Args, D, TC)

clang/test/Driver/debug-options.c

329–330

use the similar way like GPUB & NOPUB

[probinson]

Nit on the description, this patch supports -gstrict-dwarf in the frontend.

clang/docs/ClangCommandLineReference.rst

3549–3550

Maybe something like, "Restrict DWARF features to those defined in the specified version, avoiding features from later versions."

clang/lib/Driver/ToolChains/Clang.cpp

3973–3974

It's a wrapper for ToolChain::supportsDebugInfoOption() and the only implementation I see is for Cuda, which has severely limited support for the g options. I think this is correct.

[dblaikie]

Sounds good

[shchenz]

Thanks for your review! @probinson @dblaikie @aprantl

clang/docs/ClangCommandLineReference.rst

3549–3550

Thanks, will update in the commit

clang/docs/ClangCommandLineReference.rst

 .. program:: clang1
 .. option:: -gsplit-dwarf=<arg>
 .. program:: clang
 
 Set DWARF fission mode to either 'split' or 'single'
 
 .. option:: -gstrict-dwarf, -gno-strict-dwarf
 
+Don't use DWARF extensions in later DWARF versions for strict DWARF.
+
 .. option:: -gz=<arg>, -gz (equivalent to -gz=zlib)
 
 DWARF debug sections compression type
 
 Static analyzer flags
 =====================
 
 Flags controlling the behavior of the Clang Static Analyzer.

clang/include/clang/Basic/CodeGenOptions.def

CODEGENOPT(StackRealignment  , 1, 0) ///< Control whether to force stack
                                      ///< realignment.
 CODEGENOPT(UseInitArray      , 1, 0) ///< Control whether to use .init_array or
                                      ///< .ctors.
 VALUE_CODEGENOPT(StackAlignment    , 32, 0) ///< Overrides default stack
                                             ///< alignment, if not 0.
 VALUE_CODEGENOPT(StackProbeSize    , 32, 4096) ///< Overrides default stack
                                                ///< probe size, even if 0.
 CODEGENOPT(NoStackArgProbe, 1, 0) ///< Set when -mno-stack-arg-probe is used
+CODEGENOPT(DebugStrictDwarf, 1, 1) ///< Whether or not to use strict DWARF info.
 CODEGENOPT(DebugColumnInfo, 1, 0) ///< Whether or not to use column information
                                   ///< in debug info.
 
 CODEGENOPT(DebugTypeExtRefs, 1, 0) ///< Whether or not debug info should contain
                                    ///< external references to a PCH or module.
 
 CODEGENOPT(DebugExplicitImport, 1, 0)  ///< Whether or not debug info should
                                        ///< contain explicit imports for

clang/include/clang/Driver/Options.td

 def gvms : Joined<["-"], "gvms">, Group<g_Group>, Flags<[Unsupported]>;
 def gtoggle : Flag<["-"], "gtoggle">, Group<g_flags_Group>, Flags<[Unsupported]>;
 def grecord_command_line : Flag<["-"], "grecord-command-line">,
   Group<g_flags_Group>;
 def gno_record_command_line : Flag<["-"], "gno-record-command-line">,
   Group<g_flags_Group>;
 def : Flag<["-"], "grecord-gcc-switches">, Alias<grecord_command_line>;
 def : Flag<["-"], "gno-record-gcc-switches">, Alias<gno_record_command_line>;
-def gstrict_dwarf : Flag<["-"], "gstrict-dwarf">, Group<g_flags_Group>;
-def gno_strict_dwarf : Flag<["-"], "gno-strict-dwarf">, Group<g_flags_Group>;
+defm strict_dwarf : BoolOption<"g", "strict-dwarf",
+  CodeGenOpts<"DebugStrictDwarf">, DefaultFalse,
+  PosFlag<SetTrue, [CC1Option]>, NegFlag<SetFalse>, BothFlags<[CoreOption]>>,
+  Group<g_flags_Group>;
 defm column_info : BoolOption<"g", "column-info",
   CodeGenOpts<"DebugColumnInfo">, DefaultTrue,
   NegFlag<SetFalse, [CC1Option]>, PosFlag<SetTrue>, BothFlags<[CoreOption]>>,
   Group<g_flags_Group>;
 def gsplit_dwarf : Flag<["-"], "gsplit-dwarf">, Group<g_flags_Group>;
 def gsplit_dwarf_EQ : Joined<["-"], "gsplit-dwarf=">, Group<g_flags_Group>,
   HelpText<"Set DWARF fission mode to either 'split' or 'single'">,
   Values<"split,single">;

clang/lib/Driver/ToolChains/Clang.cpp

EffectiveDWARFVersion =
         std::min(RequestedDWARFVersion, TC.getMaxDwarfVersion());
   }
 
   // -gline-directives-only supported only for the DWARF debug info.
   if (RequestedDWARFVersion == 0 &&
       DebugInfoKind == codegenoptions::DebugDirectivesOnly)
     DebugInfoKind = codegenoptions::NoDebugInfo;
 
-  // We ignore flag -gstrict-dwarf for now.
+  // strict DWARF is set to false by default. But for DBX, we need it to be set
+  // as true by default.
+  if (const Arg *A = Args.getLastArg(options::OPT_gstrict_dwarf))
+    (void)checkDebugInfoOption(A, Args, D, TC);
+  if (Args.hasFlag(options::OPT_gstrict_dwarf, options::OPT_gno_strict_dwarf,
+                   DebuggerTuning == llvm::DebuggerKind::DBX))
+    CmdArgs.push_back("-gstrict-dwarf");
+
   // And we handle flag -grecord-gcc-switches later with DWARFDebugFlags.
   Args.ClaimAllArgs(options::OPT_g_flags_Group);
 
   // Column info is included by default for everything except SCE and
   // CodeView. Clang doesn't track end columns, just starting columns, which,
   // in theory, is fine for CodeView (and PDB).  In practice, however, the
   // Microsoft debuggers don't handle missing end columns well, and the AIX
   // debugger DBX also doesn't handle the columns well, so it's better not to

clang/test/Driver/debug-options.c

 // 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
 
+// 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
+// RUN: %clang -### -c -g %s -target x86_64-linux-gnu 2>&1 \
+// RUN:             | FileCheck -check-prefix=NOSTRICT %s
+// RUN: %clang -### -c -g -ggdb %s -target powerpc-ibm-aix-xcoff 2>&1 \
+// RUN:             | FileCheck -check-prefix=NOSTRICT %s
+
 // On the AIX, -g defaults to -gno-column-info.
 // RUN: %clang -### -c -g %s -target powerpc-ibm-aix-xcoff 2>&1 \
 // RUN:             | FileCheck -check-prefix=NOCI %s
 // RUN: %clang -### -c -g %s -target powerpc64-ibm-aix-xcoff 2>&1 \
 // RUN:             | FileCheck -check-prefix=NOCI %s
 // RUN: %clang -### -c -g %s -target powerpc-ibm-aix-xcoff -gcolumn-info 2>&1 \
 // RUN:             | FileCheck -check-prefix=CI %s
 // RUN: %clang -### -c -g %s -target powerpc64-ibm-aix-xcoff -gcolumn-info \

 // G_DWARF2: "-dwarf-version=2"
 // G_DWARF4: "-dwarf-version=4"
 //
 // G_GDB:  "-debugger-tuning=gdb"
 // G_LLDB: "-debugger-tuning=lldb"
 // G_SCE:  "-debugger-tuning=sce"
 // G_DBX:  "-debugger-tuning=dbx"
 //
+// STRICT:  "-gstrict-dwarf"
+// NOSTRICT-NOT:  "-gstrict-dwarf"
+//
 // G_NOTUNING: "-cc1"
 // G_NOTUNING-NOT: "-debugger-tuning="
 //
 // This tests asserts that "-gline-tables-only" "-g0" disables debug info.
 // GLTO_NO: "-cc1"
 // GLTO_NO-NOT: -debug-info-kind=
 //
 // This tests asserts that "-gline-directives-only" "-g0" disables debug info.