[CIR] Upstream cir-canonicalize pass (#131891)

This change introduces the cir-canonicalize pass. This is a simple
cir-to-cir transformation that eliminates empty scopes and redundant
branches. It will be expanded in future changes to simplify other
redundant instruction sequences.

MLIR verification and mlir-specific command-line option handling is also
introduced here.

2 files changed, 29 insertions, 0 deletions

diff --git a/clang/lib/FrontendTool/CMakeLists.txt b/clang/lib/FrontendTool/CMakeLists.txt
index 7c83086..061e54c 100644
--- a/clang/lib/FrontendTool/CMakeLists.txt
+++ b/clang/lib/FrontendTool/CMakeLists.txt
@@ -20,8 +20,17 @@ if(CLANG_ENABLE_CIR)
   )
   list(APPEND link_libs
     clangCIRFrontendAction
+    MLIRCIRTransforms
     MLIRIR
+    MLIRPass
     )
+  list(APPEND deps
+    MLIRBuiltinLocationAttributesIncGen
+    MLIRBuiltinTypeInterfacesIncGen
+    )
+
+  include_directories(${LLVM_MAIN_SRC_DIR}/../mlir/include)
+  include_directories(${CMAKE_BINARY_DIR}/tools/mlir/include)
 endif()
 
 if(CLANG_ENABLE_STATIC_ANALYZER)
diff --git a/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp b/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp
index bb3bb0a..6fc587f 100644
--- a/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp
+++ b/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp
@@ -32,6 +32,10 @@
 #include "llvm/Support/ErrorHandling.h"
 
 #if CLANG_ENABLE_CIR
+#include "mlir/IR/AsmState.h"
+#include "mlir/IR/MLIRContext.h"
+#include "mlir/Pass/PassManager.h"
+#include "clang/CIR/Dialect/Passes.h"
 #include "clang/CIR/FrontendAction/CIRGenAction.h"
 #endif
 
@@ -270,6 +274,22 @@ bool ExecuteCompilerInvocation(CompilerInstance *Clang) {
   }
 #endif
 
+#if CLANG_ENABLE_CIR
+  if (!Clang->getFrontendOpts().MLIRArgs.empty()) {
+    mlir::registerCIRPasses();
+    mlir::registerMLIRContextCLOptions();
+    mlir::registerPassManagerCLOptions();
+    mlir::registerAsmPrinterCLOptions();
+    unsigned NumArgs = Clang->getFrontendOpts().MLIRArgs.size();
+    auto Args = std::make_unique<const char *[]>(NumArgs + 2);
+    Args[0] = "clang (MLIR option parsing)";
+    for (unsigned i = 0; i != NumArgs; ++i)
+      Args[i + 1] = Clang->getFrontendOpts().MLIRArgs[i].c_str();
+    Args[NumArgs + 1] = nullptr;
+    llvm::cl::ParseCommandLineOptions(NumArgs + 1, Args.get());
+  }
+#endif
+
   // If there were errors in processing arguments, don't do anything else.
   if (Clang->getDiagnostics().hasErrorOccurred())
     return false;