[Driver] Simplify hasFlag pattern with addOptInFlag/addOptOutFlag helpers

[dexonsmith]

Nice! LGTM.

clang/lib/Driver/ToolChains/Clang.cpp

static void RenderSCPOptions(const ToolChain &TC, const ArgList &Args,
 
   if (!EffectiveTriple.isOSFreeBSD() && !EffectiveTriple.isOSLinux())
     return;
 
   if (!EffectiveTriple.isX86() && !EffectiveTriple.isSystemZ() &&
       !EffectiveTriple.isPPC64())
     return;
 
-  if (Args.hasFlag(options::OPT_fstack_clash_protection,
-                   options::OPT_fno_stack_clash_protection, false))
-    CmdArgs.push_back("-fstack-clash-protection");
+  Args.addOptInFlag(CmdArgs, options::OPT_fstack_clash_protection,
+                    options::OPT_fno_stack_clash_protection);
 }
 
 static void RenderTrivialAutoVarInitOptions(const Driver &D,
                                             const ToolChain &TC,
                                             const ArgList &Args,
                                             ArgStringList &CmdArgs) {
   auto DefaultTrivialAutoVarInit = TC.GetDefaultTrivialAutoVarInit();
   StringRef TrivialAutoVarInit = "";
static void RenderModulesOptions(Compilation &C, const Driver &D,
 
   // -fmodule-maps enables implicit reading of module map files. By default,
   // this is enabled if we are using Clang's flavor of precompiled modules.
   if (Args.hasFlag(options::OPT_fimplicit_module_maps,
                    options::OPT_fno_implicit_module_maps, HaveClangModules))
     CmdArgs.push_back("-fimplicit-module-maps");
 
   // -fmodules-decluse checks that modules used are declared so (off by default)
-  if (Args.hasFlag(options::OPT_fmodules_decluse,
-                   options::OPT_fno_modules_decluse, false))
-    CmdArgs.push_back("-fmodules-decluse");
+  Args.addOptInFlag(CmdArgs, options::OPT_fmodules_decluse,
+                    options::OPT_fno_modules_decluse);
 
   // -fmodules-strict-decluse is like -fmodule-decluse, but also checks that
   // all #included headers are part of modules.
   if (Args.hasFlag(options::OPT_fmodules_strict_decluse,
                    options::OPT_fno_modules_strict_decluse, false))
     CmdArgs.push_back("-fmodules-strict-decluse");
 
   // -fno-implicit-modules turns off implicitly compiling modules on demand.
if (const Arg *A = Args.getLastArg(options::OPT__SLASH_diagnostics_classic,
     }
   }
 
   // -fcaret-diagnostics is default.
   if (!Args.hasFlag(options::OPT_fcaret_diagnostics,
                     options::OPT_fno_caret_diagnostics, CaretDefault))
     CmdArgs.push_back("-fno-caret-diagnostics");
 
-  // -fdiagnostics-fixit-info is default, only pass non-default.
-  if (!Args.hasFlag(options::OPT_fdiagnostics_fixit_info,
-                    options::OPT_fno_diagnostics_fixit_info, true))
-    CmdArgs.push_back("-fno-diagnostics-fixit-info");
-
-  // Enable -fdiagnostics-show-option by default.
-  if (!Args.hasFlag(options::OPT_fdiagnostics_show_option,
-                    options::OPT_fno_diagnostics_show_option, true))
-    CmdArgs.push_back("-fno-diagnostics-show-option");
+  Args.addOptOutFlag(CmdArgs, options::OPT_fdiagnostics_fixit_info,
+                     options::OPT_fno_diagnostics_fixit_info);
+  Args.addOptOutFlag(CmdArgs, options::OPT_fdiagnostics_show_option,
+                     options::OPT_fno_diagnostics_show_option);
 
   if (const Arg *A =
           Args.getLastArg(options::OPT_fdiagnostics_show_category_EQ)) {
     CmdArgs.push_back("-fdiagnostics-show-category");
     CmdArgs.push_back(A->getValue());
   }
 
-  if (Args.hasFlag(options::OPT_fdiagnostics_show_hotness,
-                   options::OPT_fno_diagnostics_show_hotness, false))
-    CmdArgs.push_back("-fdiagnostics-show-hotness");
+  Args.addOptInFlag(CmdArgs, options::OPT_fdiagnostics_show_hotness,
+                    options::OPT_fno_diagnostics_show_hotness);
 
   if (const Arg *A =
           Args.getLastArg(options::OPT_fdiagnostics_hotness_threshold_EQ)) {
     std::string Opt =
         std::string("-fdiagnostics-hotness-threshold=") + A->getValue();
     CmdArgs.push_back(Args.MakeArgString(Opt));
   }
 
if (Arg *A = Args.getLastArg(options::OPT_Wframe_larger_than_EQ)) {
     // about -fwarn-stack-size=.
     if (v.empty())
       D.Diag(diag::err_drv_missing_argument) << A->getSpelling() << 1;
     else
       CmdArgs.push_back(Args.MakeArgString("-fwarn-stack-size=" + v));
     A->claim();
   }
 
-  if (!Args.hasFlag(options::OPT_fjump_tables, options::OPT_fno_jump_tables,
-                    true))
-    CmdArgs.push_back("-fno-jump-tables");
-
-  if (Args.hasFlag(options::OPT_fprofile_sample_accurate,
-                   options::OPT_fno_profile_sample_accurate, false))
-    CmdArgs.push_back("-fprofile-sample-accurate");
-
-  if (!Args.hasFlag(options::OPT_fpreserve_as_comments,
-                    options::OPT_fno_preserve_as_comments, true))
-    CmdArgs.push_back("-fno-preserve-as-comments");
+  Args.addOptOutFlag(CmdArgs, options::OPT_fjump_tables,
+                     options::OPT_fno_jump_tables);
+  Args.addOptInFlag(CmdArgs, options::OPT_fprofile_sample_accurate,
+                    options::OPT_fno_profile_sample_accurate);
+  Args.addOptOutFlag(CmdArgs, options::OPT_fpreserve_as_comments,
+                     options::OPT_fno_preserve_as_comments);
 
   if (Arg *A = Args.getLastArg(options::OPT_mregparm_EQ)) {
     CmdArgs.push_back("-mregparm");
     CmdArgs.push_back(A->getValue());
   }
 
   if (Arg *A = Args.getLastArg(options::OPT_maix_struct_return,
                                options::OPT_msvr4_struct_return)) {
case CodeGenOptions::FramePointerKind::NonLeaf:
     break;
   case CodeGenOptions::FramePointerKind::All:
     FPKeepKindStr = "-mframe-pointer=all";
     break;
   }
   assert(FPKeepKindStr && "unknown FramePointerKind");
   CmdArgs.push_back(FPKeepKindStr);
 
-  if (!Args.hasFlag(options::OPT_fzero_initialized_in_bss,
-                    options::OPT_fno_zero_initialized_in_bss, true))
-    CmdArgs.push_back("-fno-zero-initialized-in-bss");
+  Args.addOptOutFlag(CmdArgs, options::OPT_fzero_initialized_in_bss,
+                     options::OPT_fno_zero_initialized_in_bss);
 
   bool OFastEnabled = isOptimizationLevelFast(Args);
   // If -Ofast is the optimization level, then -fstrict-aliasing should be
   // enabled.  This alias option is being used to simplify the hasFlag logic.
   OptSpecifier StrictAliasingAliasOption =
       OFastEnabled ? options::OPT_Ofast : options::OPT_fstrict_aliasing;
   // We turn strict aliasing off by default if we're in CL mode, since MSVC
   // doesn't do any TBAA.
   bool TBAAOnByDefault = !D.IsCLMode();
   if (!Args.hasFlag(options::OPT_fstrict_aliasing, StrictAliasingAliasOption,
                     options::OPT_fno_strict_aliasing, TBAAOnByDefault))
     CmdArgs.push_back("-relaxed-aliasing");
   if (!Args.hasFlag(options::OPT_fstruct_path_tbaa,
                     options::OPT_fno_struct_path_tbaa, true))
     CmdArgs.push_back("-no-struct-path-tbaa");
-  if (Args.hasFlag(options::OPT_fstrict_enums, options::OPT_fno_strict_enums,
-                   false))
-    CmdArgs.push_back("-fstrict-enums");
-  if (!Args.hasFlag(options::OPT_fstrict_return, options::OPT_fno_strict_return,
-                    true))
-    CmdArgs.push_back("-fno-strict-return");
-  if (Args.hasFlag(options::OPT_fallow_editor_placeholders,
-                   options::OPT_fno_allow_editor_placeholders, false))
-    CmdArgs.push_back("-fallow-editor-placeholders");
-  if (Args.hasFlag(options::OPT_fstrict_vtable_pointers,
-                   options::OPT_fno_strict_vtable_pointers,
-                   false))
-    CmdArgs.push_back("-fstrict-vtable-pointers");
-  if (Args.hasFlag(options::OPT_fforce_emit_vtables,
-                   options::OPT_fno_force_emit_vtables,
-                   false))
-    CmdArgs.push_back("-fforce-emit-vtables");
+  Args.addOptInFlag(CmdArgs, options::OPT_fstrict_enums,
+                    options::OPT_fno_strict_enums);
+  Args.addOptOutFlag(CmdArgs, options::OPT_fstrict_return,
+                     options::OPT_fno_strict_return);
+  Args.addOptInFlag(CmdArgs, options::OPT_fallow_editor_placeholders,
+                    options::OPT_fno_allow_editor_placeholders);
+  Args.addOptInFlag(CmdArgs, options::OPT_fstrict_vtable_pointers,
+                    options::OPT_fno_strict_vtable_pointers);
+  Args.addOptInFlag(CmdArgs, options::OPT_fforce_emit_vtables,
+                    options::OPT_fno_force_emit_vtables);
   if (!Args.hasFlag(options::OPT_foptimize_sibling_calls,
                     options::OPT_fno_optimize_sibling_calls, true))
     CmdArgs.push_back("-mdisable-tail-calls");
-  if (Args.hasFlag(options::OPT_fno_escaping_block_tail_calls,
-                   options::OPT_fescaping_block_tail_calls, false))
-    CmdArgs.push_back("-fno-escaping-block-tail-calls");
+  Args.addOptOutFlag(CmdArgs, options::OPT_fescaping_block_tail_calls,
+                     options::OPT_fno_escaping_block_tail_calls);
 
   Args.AddLastArg(CmdArgs, options::OPT_ffine_grained_bitfield_accesses,
                   options::OPT_fno_fine_grained_bitfield_accesses);
 
   Args.AddLastArg(CmdArgs, options::OPT_fexperimental_relative_cxx_abi_vtables,
                   options::OPT_fno_experimental_relative_cxx_abi_vtables);
 
   // Handle segmented stacks.

llvm/include/llvm/Option/ArgList.h

public:
 
   /// hasFlag - Given an option \p Pos, an alias \p PosAlias and its negative
   /// form \p Neg, return true if the option or its alias is present, false if
   /// the negation is present, and \p Default if none of the options are
   /// given. If multiple options are present, the last one wins.
   bool hasFlag(OptSpecifier Pos, OptSpecifier PosAlias, OptSpecifier Neg,
                bool Default) const;
 
+  /// Given an option Pos and its negative form Neg, render the option if Pos is
+  /// present.
+  void addOptInFlag(ArgStringList &Output, OptSpecifier Pos,
+                    OptSpecifier Neg) const;
+  /// Render the option if Neg is present.
+  void addOptOutFlag(ArgStringList &Output, OptSpecifier Pos,
+                     OptSpecifier Neg) const {
+    addOptInFlag(Output, Neg, Pos);
+  }
+
   /// Render only the last argument match \p Id0, if present.
   template<typename ...OptSpecifiers>
   void AddLastArg(ArgStringList &Output, OptSpecifiers ...Ids) const {
     if (Arg *A = getLastArg(Ids...)) // Calls claim() on all Ids's Args.
       A->render(*this, Output);
   }
 
   /// AddAllArgsExcept - Render all arguments matching any of the given ids

llvm/lib/Option/ArgList.cpp

 }
 
 std::vector<std::string> ArgList::getAllArgValues(OptSpecifier Id) const {
   SmallVector<const char *, 16> Values;
   AddAllArgValues(Values, Id);
   return std::vector<std::string>(Values.begin(), Values.end());
 }
 
+void ArgList::addOptInFlag(ArgStringList &Output, OptSpecifier Pos,
+                           OptSpecifier Neg) const {
+  if (Arg *A = getLastArg(Pos, Neg))
+    if (A->getOption().matches(Pos))
+      A->render(*this, Output);
+}
+
 void ArgList::AddAllArgsExcept(ArgStringList &Output,
                                ArrayRef<OptSpecifier> Ids,
                                ArrayRef<OptSpecifier> ExcludeIds) const {
   for (const Arg *Arg : *this) {
     bool Excluded = false;
     for (OptSpecifier Id : ExcludeIds) {
       if (Arg->getOption().matches(Id)) {
         Excluded = true;