[CIR][MLIR][Lowering] Op cir.select is lowered to arith.select. (#2033)

Author: terapines-osc-cir

clang/lib/CIR/Lowering/ThroughMLIR/LowerCIRToMLIR.cpp

@@ -1721,6 +1721,20 @@ class CIRPtrStrideOpLowering
   }
 };
 
+class CIRSelectOpLowering : public mlir::OpConversionPattern<cir::SelectOp> {
+public:
+  using OpConversionPattern<cir::SelectOp>::OpConversionPattern;
+
+  mlir::LogicalResult
+  matchAndRewrite(cir::SelectOp op, OpAdaptor adaptor,
+                  mlir::ConversionPatternRewriter &rewriter) const override {
+    rewriter.replaceOpWithNewOp<mlir::arith::SelectOp>(
+        op, adaptor.getCondition(), adaptor.getTrueValue(),
+        adaptor.getFalseValue());
+    return mlir::success();
+  }
+};
+
 class CIRUnreachableOpLowering
     : public mlir::OpConversionPattern<cir::UnreachableOp> {
 public:
@@ -1764,14 +1778,15 @@ void populateCIRToMLIRConversionPatterns(mlir::RewritePatternSet &patterns,
       CIRYieldOpLowering, CIRCosOpLowering, CIRGlobalOpLowering,
       CIRGetGlobalOpLowering, CIRComplexCreateOpLowering,
       CIRComplexRealOpLowering, CIRComplexImagOpLowering, CIRCastOpLowering,
-      CIRPtrStrideOpLowering, CIRGetElementOpLowering, CIRSqrtOpLowering,
-      CIRCeilOpLowering, CIRExp2OpLowering, CIRExpOpLowering, CIRFAbsOpLowering,
-      CIRAbsOpLowering, CIRFloorOpLowering, CIRLog10OpLowering,
-      CIRLog2OpLowering, CIRLogOpLowering, CIRRoundOpLowering, CIRSinOpLowering,
-      CIRTanOpLowering, CIRShiftOpLowering, CIRBitClzOpLowering,
-      CIRBitCtzOpLowering, CIRBitPopcountOpLowering, CIRBitClrsbOpLowering,
-      CIRBitFfsOpLowering, CIRBitParityOpLowering, CIRIfOpLowering,
-      CIRScopeOpLowering, CIRVectorCreateLowering, CIRVectorInsertLowering,
+      CIRPtrStrideOpLowering, CIRSelectOpLowering, CIRGetElementOpLowering,
+      CIRSqrtOpLowering, CIRCeilOpLowering, CIRExp2OpLowering, CIRExpOpLowering,
+      CIRFAbsOpLowering, CIRAbsOpLowering, CIRFloorOpLowering,
+      CIRLog10OpLowering, CIRLog2OpLowering, CIRLogOpLowering,
+      CIRRoundOpLowering, CIRSinOpLowering, CIRTanOpLowering,
+      CIRShiftOpLowering, CIRBitClzOpLowering, CIRBitCtzOpLowering,
+      CIRBitPopcountOpLowering, CIRBitClrsbOpLowering, CIRBitFfsOpLowering,
+      CIRBitParityOpLowering, CIRIfOpLowering, CIRScopeOpLowering,
+      CIRVectorCreateLowering, CIRVectorInsertLowering,
       CIRVectorExtractLowering, CIRVectorCmpOpLowering, CIRACosOpLowering,
       CIRASinOpLowering, CIRUnreachableOpLowering, CIRTrapOpLowering>(
       converter, patterns.getContext());

clang/test/CIR/Lowering/ThroughMLIR/select.cir

@@ -0,0 +1,30 @@
+// RUN: cir-opt %s -cir-to-mlir -o - | FileCheck %s -check-prefix=MLIR
+
+!u32i = !cir.int<u, 32>
+module {
+  cir.func @foo(%arg0: !u32i) -> !u32i {
+    %0 = cir.alloca !u32i, !cir.ptr<!u32i>, ["x", init] {alignment = 4 : i64}
+    cir.store %arg0, %0 : !u32i, !cir.ptr<!u32i>
+    %1 = cir.const #cir.int<100> : !u32i
+    %2 = cir.const #cir.int<10> : !u32i
+    %3 = cir.const #cir.int<20> : !u32i
+    %4 = cir.load %0 : !cir.ptr<!u32i>, !u32i
+    %5 = cir.cmp(gt, %4, %1) : !u32i, !cir.bool
+    %6 = cir.select if %5 then %1 else %2 : (!cir.bool, !u32i, !u32i) -> !u32i
+    cir.return %6 : !u32i
+  }
+}
+
+// MLIR: module {
+// MLIR-NEXT:  func.func @foo(%[[ARG0:.*]]: i32) -> i32 {
+// MLIR-NEXT:    %[[ALLOCA:.*]] = memref.alloca() {alignment = 4 : i64} : memref<i32>
+// MLIR-NEXT:    memref.store %[[ARG0]], %[[ALLOCA]][] : memref<i32>
+// MLIR-NEXT:    %[[C100_I32:.*]] = arith.constant 100 : i32
+// MLIR-NEXT:    %[[C10_I32:.*]] = arith.constant 10 : i32
+// MLIR-NEXT:    %[[C20_I32:.*]] = arith.constant 20 : i32
+// MLIR-NEXT:    %[[V:.*]] = memref.load %[[ALLOCA]][] : memref<i32>
+// MLIR-NEXT:    %[[C:.*]] = arith.cmpi ugt, %[[V]], %[[C100_I32]] : i32
+// MLIR-NEXT:    %[[OP:.*]] = arith.select %[[C]], %[[C100_I32]], %[[C10_I32]] : i32
+// MLIR-NEXT:    return %[[OP]] : i32
+// MLIR-NEXT:  }
+// MLIR-NEXT:}