[clang] Make "__GCC_HAVE_DWARF2_CFI_ASM" a proper predefined macro

Use a flag to determine whether this macro should be set when intializing the preprocessor.

This macro was added to the driver in 9d117e7 because it can be conditionally disabled, but before that, the flag to gate behavior was removed under the assumption it wasn't
conditional in b5b622a. This patch is to connect the macro with the preexisting flag

Author: cyndyishida

clang/include/clang/Basic/DebugOptions.def

@@ -46,6 +46,8 @@ ENUM_DEBUGOPT(EmitDwarfUnwind, EmitDwarfUnwindType, 2,
 DEBUGOPT(NoDwarfDirectoryAsm , 1, 0, Benign) ///< Set when -fno-dwarf-directory-asm
                                              ///< is enabled.
 
+DEBUGOPT(Dwarf2CFIAsm, 1, 0, NotCompatible) ///< Set when -fdwarf2-cfi-asm is enabled.
+
 DEBUGOPT(NoInlineLineTables, 1, 0, Benign) ///< Whether debug info should contain
                                            ///< inline line tables.
 

clang/include/clang/Driver/Options.td

@@ -2154,8 +2154,12 @@ defm dollars_in_identifiers : BoolFOption<"dollars-in-identifiers",
   PosFlag<SetTrue, [], [ClangOption], "Allow">,
   NegFlag<SetFalse, [], [ClangOption], "Disallow">,
   BothFlags<[], [ClangOption, CC1Option], " '$' in identifiers">>;
-def fdwarf2_cfi_asm : Flag<["-"], "fdwarf2-cfi-asm">, Group<clang_ignored_f_Group>;
-def fno_dwarf2_cfi_asm : Flag<["-"], "fno-dwarf2-cfi-asm">, Group<clang_ignored_f_Group>;
+
+defm dwarf2_cfi_asm
+    : BoolFOption<"dwarf2-cfi-asm", CodeGenOpts<"Dwarf2CFIAsm">, DefaultFalse,
+                  PosFlag<SetTrue, [], [ClangOption, CC1Option]>,
+                  NegFlag<SetFalse>>;
+
 defm dwarf_directory_asm : BoolFOption<"dwarf-directory-asm",
   CodeGenOpts<"NoDwarfDirectoryAsm">, DefaultFalse,
   NegFlag<SetTrue, [], [ClangOption, CC1Option]>,

clang/lib/Driver/ToolChains/Clang.cpp

@@ -7878,10 +7878,13 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
                        !TC.getTriple().isAndroid() && TC.useIntegratedAs()))
     CmdArgs.push_back("-faddrsig");
 
-  if ((Triple.isOSBinFormatELF() || Triple.isOSBinFormatMachO()) &&
+  const bool HasDefaultDwarf2CFIASM =
+      (Triple.isOSBinFormatELF() || Triple.isOSBinFormatMachO()) &&
       (EH || UnwindTables || AsyncUnwindTables ||
-       DebugInfoKind != llvm::codegenoptions::NoDebugInfo))
-    CmdArgs.push_back("-D__GCC_HAVE_DWARF2_CFI_ASM=1");
+       DebugInfoKind != llvm::codegenoptions::NoDebugInfo);
+  if (Args.hasFlag(options::OPT_fdwarf2_cfi_asm,
+                   options::OPT_fno_dwarf2_cfi_asm, HasDefaultDwarf2CFIASM))
+    CmdArgs.push_back("-fdwarf2-cfi-asm");
 
   if (Arg *A = Args.getLastArg(options::OPT_fsymbol_partition_EQ)) {
     std::string Str = A->getAsString(Args);

clang/lib/Frontend/InitPreprocessor.cpp

@@ -1516,6 +1516,9 @@ static void InitializePredefinedMacros(const TargetInfo &TI,
   if (LangOpts.PointerAuthIntrinsics)
     Builder.defineMacro("__PTRAUTH__");
 
+  if (CGOpts.Dwarf2CFIAsm)
+    Builder.defineMacro("__GCC_HAVE_DWARF2_CFI_ASM");
+
   // Get other target #defines.
   TI.getTargetDefines(LangOpts, Builder);
 }

clang/test/Preprocessor/unwind-tables.c

@@ -1,11 +1,13 @@
 // RUN: %clang %s -dM -E -target x86_64-windows | FileCheck %s --check-prefix=NO
 // RUN: %clang %s -dM -E -target x86_64 -fno-asynchronous-unwind-tables | FileCheck %s --check-prefix=NO
+// RUN: %clang %s -dM -E -target x86_64 -fno-dwarf2-cfi-asm | FileCheck %s --check-prefix=NO
 
 // RUN: %clang %s -dM -E -target x86_64 | FileCheck %s
 // RUN: %clang %s -dM -E -target x86_64 -funwind-tables -fno-asynchronous-unwind-tables -g | FileCheck %s
 // RUN: %clang %s -dM -E -target aarch64-apple-darwin | FileCheck %s
 // RUN: %clang %s -dM -E -target x86_64 -fno-asynchronous-unwind-tables -g | FileCheck %s
 // RUN: %clang %s -dM -E -target x86_64 -fno-asynchronous-unwind-tables -fexceptions | FileCheck %s
+// RUN: %clang %s -dM -E -target x86_64-windows -fdwarf2-cfi-asm | FileCheck %s
 
 // NO-NOT: #define __GCC_HAVE_DWARF2_CFI_ASM
 // CHECK: #define __GCC_HAVE_DWARF2_CFI_ASM 1