[CIR] Add reconcile unrealized casts pass

ghstack-source-id: 26c9399
Pull Request resolved: #147

Author: sitio-couto

clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp

@@ -1428,6 +1428,11 @@ lowerDirectlyFromCIRToLLVMIR(mlir::ModuleOp theModule,
   pm.addNestedPass<mlir::LLVM::LLVMFuncOp>(
       mlir::LLVM::createDIScopeForLLVMFuncOpPass());
 
+  // FIXME(cir): this shouldn't be necessary. It's meant to be a temporary
+  // workaround until we understand why some unrealized casts are being emmited
+  // and how to properly avoid them.
+  pm.addPass(mlir::createReconcileUnrealizedCastsPass());
+
   (void)mlir::applyPassManagerCLOptions(pm);
 
   auto result = !mlir::failed(pm.run(theModule));

clang/test/CIR/Lowering/tenary.cir

@@ -1,4 +1,4 @@
-// RUN: cir-tool %s -cir-to-llvm -o - | FileCheck %s -check-prefix=MLIR
+// RUN: cir-tool %s -cir-to-llvm -reconcile-unrealized-casts -o - | FileCheck %s -check-prefix=MLIR
 
 !s32i = !cir.int<s, 32>
 
@@ -23,8 +23,7 @@ cir.func @_Z1xi(%arg0: !s32i) -> !s32i {
   }
 }
 
-//      MLIR: module {
-//      MLIR: llvm.func @_Z1xi(%arg0: i32) -> i32 {
+//      MLIR:  llvm.func @_Z1xi(%arg0: i32) -> i32 {
 // MLIR-NEXT:    %0 = llvm.mlir.constant(1 : index) : i64
 // MLIR-NEXT:    %1 = llvm.alloca %0 x i32 {alignment = 4 : i64} : (i64) -> !llvm.ptr<i32>
 // MLIR-NEXT:    %2 = llvm.mlir.constant(1 : index) : i64
@@ -38,17 +37,14 @@ cir.func @_Z1xi(%arg0: !s32i) -> !s32i {
 // MLIR-NEXT:    llvm.cond_br %8, ^bb1, ^bb2
 // MLIR-NEXT:  ^bb1:  // pred: ^bb0
 // MLIR-NEXT:    %9 = llvm.mlir.constant(3 : i32) : i32
-// MLIR-NEXT:    %10 = builtin.unrealized_conversion_cast %9 : i32 to !s32i
 // MLIR-NEXT:    llvm.br ^bb3(%9 : i32)
 // MLIR-NEXT:  ^bb2:  // pred: ^bb0
-// MLIR-NEXT:    %11 = llvm.mlir.constant(5 : i32) : i32
-// MLIR-NEXT:    %12 = builtin.unrealized_conversion_cast %11 : i32 to !s32i
-// MLIR-NEXT:    llvm.br ^bb3(%11 : i32)
-// MLIR-NEXT:  ^bb3(%13: i32):  // 2 preds: ^bb1, ^bb2
+// MLIR-NEXT:    %10 = llvm.mlir.constant(5 : i32) : i32
+// MLIR-NEXT:    llvm.br ^bb3(%10 : i32)
+// MLIR-NEXT:  ^bb3(%11: i32):  // 2 preds: ^bb1, ^bb2
 // MLIR-NEXT:    llvm.br ^bb4
 // MLIR-NEXT:  ^bb4:  // pred: ^bb3
-// MLIR-NEXT:    llvm.store %13, %3 : !llvm.ptr<i32>
-// MLIR-NEXT:    %14 = llvm.load %3 : !llvm.ptr<i32>
-// MLIR-NEXT:    llvm.return %14 : i32
-// MLIR-NEXT:   }
-// MLIR-NEXT: }
+// MLIR-NEXT:    llvm.store %11, %3 : !llvm.ptr<i32>
+// MLIR-NEXT:    %12 = llvm.load %3 : !llvm.ptr<i32>
+// MLIR-NEXT:    llvm.return %12 : i32
+// MLIR-NEXT:  }

clang/tools/cir-tool/cir-tool.cpp

@@ -12,6 +12,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "mlir/Conversion/ReconcileUnrealizedCasts/ReconcileUnrealizedCasts.h"
 #include "mlir/Dialect/Arith/IR/Arith.h"
 #include "mlir/Dialect/DLTI/DLTI.h"
 #include "mlir/Dialect/Func/IR/FuncOps.h"
@@ -46,6 +47,10 @@ int main(int argc, char **argv) {
     return cir::direct::createConvertCIRToLLVMPass();
   });
 
+  ::mlir::registerPass([]() -> std::unique_ptr<::mlir::Pass> {
+    return mlir::createReconcileUnrealizedCastsPass();
+  });
+
   mlir::registerTransformsPasses();
 
   return failed(MlirOptMain(