[CIR] Add options to emit ClangIR and enable the ClangIR pipeline

[lanza]

Introduce just the option definitions and support for their existance at
a few different points in the frontend. This will be followed soon by
functionality that uses it.

[llvmbot]

@llvm/pr-subscribers-clangir
@llvm/pr-subscribers-clang

@llvm/pr-subscribers-clang-driver

Author: Nathan Lanza (lanza)

Changes

Introduce just the option definitions and support for their existance at
a few different points in the frontend. This will be followed soon by
functionality that uses it.

---

Full diff: https://github.com/llvm/llvm-project/pull/89030.diff

5 Files Affected:

• (modified) clang/include/clang/Driver/Options.td (+6)
• (modified) clang/include/clang/Frontend/FrontendOptions.h (+7-1)
• (modified) clang/lib/Driver/Driver.cpp (+3)
• (modified) clang/lib/Frontend/CompilerInvocation.cpp (+4)
• (modified) clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp (+2)

diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index e24626913add76..659650baf218f8 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -2882,6 +2882,12 @@ def flto_EQ : Joined<["-"], "flto=">,
   HelpText<"Set LTO mode">, Values<"thin,full">;
 def flto_EQ_jobserver : Flag<["-"], "flto=jobserver">, Visibility<[ClangOption, FlangOption]>, Group<f_Group>,
   Alias<flto_EQ>, AliasArgs<["full"]>, HelpText<"Enable LTO in 'full' mode">;
+/// ClangIR-specific options - BEGIN
+def fclangir_enable : Flag<["-"], "fclangir-enable">, Visibility<[ClangOption, CC1Option]>,
+  Group<f_Group>, HelpText<"Use ClangIR pipeline to compile">,
+  MarshallingInfoFlag<FrontendOpts<"UseClangIRPipeline">>;
+def emit_cir : Flag<["-"], "emit-cir">, Visibility<[ClangOption, CC1Option]>,
+  Group<Action_Group>, HelpText<"Build ASTs and then lower to ClangIR, emit the .cir file">;
 def flto_EQ_auto : Flag<["-"], "flto=auto">, Visibility<[ClangOption, FlangOption]>, Group<f_Group>,
   Alias<flto_EQ>, AliasArgs<["full"]>, HelpText<"Enable LTO in 'full' mode">;
 def flto : Flag<["-"], "flto">,
diff --git a/clang/include/clang/Frontend/FrontendOptions.h b/clang/include/clang/Frontend/FrontendOptions.h
index a738c1f3757682..236345b2143670 100644
--- a/clang/include/clang/Frontend/FrontendOptions.h
+++ b/clang/include/clang/Frontend/FrontendOptions.h
@@ -65,6 +65,9 @@ enum ActionKind {
   /// Translate input source into HTML.
   EmitHTML,
 
+  /// Emit a .cir file
+  EmitCIR,
+
   /// Emit a .ll file.
   EmitLLVM,
 
@@ -408,6 +411,9 @@ class FrontendOptions {
   LLVM_PREFERRED_TYPE(bool)
   unsigned GenReducedBMI : 1;
 
+  /// Use Clang IR pipeline to emit code
+  unsigned UseClangIRPipeline : 1;
+
   CodeCompleteOptions CodeCompleteOpts;
 
   /// Specifies the output format of the AST.
@@ -590,7 +596,7 @@ class FrontendOptions {
         EmitSymbolGraph(false), EmitExtensionSymbolGraphs(false),
         EmitSymbolGraphSymbolLabelsForTesting(false),
         EmitPrettySymbolGraphs(false), GenReducedBMI(false),
-        TimeTraceGranularity(500) {}
+        UseClangIRPipeline(), TimeTraceGranularity(500) {}
 
   /// getInputKindForExtension - Return the appropriate input kind for a file
   /// extension. For example, "c" would return Language::C.
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index 0da92001e08c27..d8ada220e6bd4a 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -361,6 +361,7 @@ phases::ID Driver::getFinalPhase(const DerivedArgList &DAL,
              (PhaseArg = DAL.getLastArg(options::OPT_rewrite_legacy_objc)) ||
              (PhaseArg = DAL.getLastArg(options::OPT__migrate)) ||
              (PhaseArg = DAL.getLastArg(options::OPT__analyze)) ||
+             (PhaseArg = DAL.getLastArg(options::OPT_emit_cir)) ||
              (PhaseArg = DAL.getLastArg(options::OPT_emit_ast))) {
     FinalPhase = phases::Compile;
 
@@ -4799,6 +4800,8 @@ Action *Driver::ConstructPhaseAction(
       return C.MakeAction<MigrateJobAction>(Input, types::TY_Remap);
     if (Args.hasArg(options::OPT_emit_ast))
       return C.MakeAction<CompileJobAction>(Input, types::TY_AST);
+    if (Args.hasArg(options::OPT_emit_cir))
+      return C.MakeAction<CompileJobAction>(Input, types::TY_CIR);
     if (Args.hasArg(options::OPT_module_file_info))
       return C.MakeAction<CompileJobAction>(Input, types::TY_ModuleFile);
     if (Args.hasArg(options::OPT_verify_pch))
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 1f1f5440ddd75f..27b75086029436 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -2544,6 +2544,7 @@ static const auto &getFrontendActionTable() {
       {frontend::DumpTokens, OPT_dump_tokens},
       {frontend::EmitAssembly, OPT_S},
       {frontend::EmitBC, OPT_emit_llvm_bc},
+      {frontend::EmitCIR, OPT_emit_cir},
       {frontend::EmitHTML, OPT_emit_html},
       {frontend::EmitLLVM, OPT_emit_llvm},
       {frontend::EmitLLVMOnly, OPT_emit_llvm_only},
@@ -2886,6 +2887,8 @@ static bool ParseFrontendArgs(FrontendOptions &Opts, ArgList &Args,
   if (Opts.ProgramAction != frontend::GenerateModule && Opts.IsSystemModule)
     Diags.Report(diag::err_drv_argument_only_allowed_with) << "-fsystem-module"
                                                            << "-emit-module";
+  if (Args.hasArg(OPT_fclangir_enable) || Args.hasArg(OPT_emit_cir))
+    Opts.UseClangIRPipeline = true;
 
   if (Args.hasArg(OPT_aux_target_cpu))
     Opts.AuxTargetCPU = std::string(Args.getLastArgValue(OPT_aux_target_cpu));
@@ -4327,6 +4330,7 @@ static bool isStrictlyPreprocessorAction(frontend::ActionKind Action) {
   case frontend::ASTView:
   case frontend::EmitAssembly:
   case frontend::EmitBC:
+  case frontend::EmitCIR:
   case frontend::EmitHTML:
   case frontend::EmitLLVM:
   case frontend::EmitLLVMOnly:
diff --git a/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp b/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp
index f85f0365616f9a..7476b1076d1038 100644
--- a/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp
+++ b/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp
@@ -53,6 +53,8 @@ CreateFrontendBaseAction(CompilerInstance &CI) {
   case DumpTokens:             return std::make_unique<DumpTokensAction>();
   case EmitAssembly:           return std::make_unique<EmitAssemblyAction>();
   case EmitBC:                 return std::make_unique<EmitBCAction>();
+  case EmitCIR:
+    llvm_unreachable("CIR suppport not built into clang");
   case EmitHTML:               return std::make_unique<HTMLPrintAction>();
   case EmitLLVM:               return std::make_unique<EmitLLVMAction>();
   case EmitLLVMOnly:           return std::make_unique<EmitLLVMOnlyAction>();