[CIR] Add back ability to process cir files in cc1 (#1628)

Reapplying
e66b670
which was reverted during rebase (after fixing some conflicts).
Un-xfails the test `cc1.cir` (#1497).

---------

Co-authored-by: Nathan Lanza <nathanlanza@gmail.com>

Author: fangyi-zhou

clang/include/clang/Basic/LangStandard.h

@@ -26,8 +26,8 @@ enum class Language : uint8_t {
   /// Assembly: we accept this only so that we can preprocess it.
   Asm,
 
-  /// LLVM IR: we accept this so that we can run the optimizer on it,
-  /// and compile it to assembly or object code.
+  /// LLVM IR & CIR: we accept these so that we can run the optimizer on them,
+  /// and compile them to assembly or object code (or LLVM for CIR).
   CIR,
   LLVM_IR,
 

clang/include/clang/Driver/Types.def

@@ -100,6 +100,7 @@ TYPE("lto-ir",                   LTO_IR,       INVALID,         "s",      phases
 TYPE("lto-bc",                   LTO_BC,       INVALID,         "o",      phases::Compile, phases::Backend, phases::Assemble, phases::Link)
 
 TYPE("mlir",                     MLIR,         INVALID,         "mlir",   phases::Compile, phases::Backend, phases::Assemble, phases::Link)
+TYPE("cir",                      CIR,          INVALID,         "cir",    phases::Compile, phases::Backend, phases::Assemble, phases::Link)
 
 // Misc.
 TYPE("ast",                      AST,          INVALID,         "ast",    phases::Compile, phases::Backend, phases::Assemble, phases::Link)

clang/lib/Frontend/CompilerInvocation.cpp

@@ -3239,6 +3239,7 @@ static bool ParseFrontendArgs(FrontendOptions &Opts, ArgList &Args,
                   .Cases("ast", "pcm", "precompiled-header",
                          InputKind(Language::Unknown, InputKind::Precompiled))
                   .Case("ir", Language::LLVM_IR)
+                  .Case("cir", Language::CIR)
                   .Default(Language::Unknown);
 
     if (DashX.isUnknown())
@@ -3708,7 +3709,8 @@ void CompilerInvocationBase::GenerateLangArgs(const LangOptions &Opts,
                                               const llvm::Triple &T,
                                               InputKind IK) {
   if (IK.getFormat() == InputKind::Precompiled ||
-      IK.getLanguage() == Language::LLVM_IR) {
+      IK.getLanguage() == Language::LLVM_IR ||
+      IK.getLanguage() == Language::CIR) {
     if (Opts.ObjCAutoRefCount)
       GenerateArg(Consumer, OPT_fobjc_arc);
     if (Opts.PICLevel != 0)
@@ -4011,7 +4013,8 @@ bool CompilerInvocation::ParseLangArgs(LangOptions &Opts, ArgList &Args,
   unsigned NumErrorsBefore = Diags.getNumErrors();
 
   if (IK.getFormat() == InputKind::Precompiled ||
-      IK.getLanguage() == Language::LLVM_IR) {
+      IK.getLanguage() == Language::LLVM_IR ||
+      IK.getLanguage() == Language::CIR) {
     // ObjCAAutoRefCount and Sanitize LangOpts are used to setup the
     // PassManager in BackendUtil.cpp. They need to be initialized no matter
     // what the input type is.

clang/lib/Frontend/FrontendOptions.cpp

@@ -34,5 +34,6 @@ InputKind FrontendOptions::getInputKindForExtension(StringRef Extension) {
       .Case("hip", Language::HIP)
       .Cases("ll", "bc", Language::LLVM_IR)
       .Case("hlsl", Language::HLSL)
+      .Case("cir", Language::CIR)
       .Default(Language::Unknown);
 }

clang/test/CIR/cc1.cir

@@ -1,6 +1,5 @@
 // RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-llvm %s -o %t.cir
 // RUN: FileCheck --input-file=%t.cir %s -check-prefix=LLVM
-// XFAIL: *
 
 module {
   cir.func @foo() {