[clang] [CIR] Upstream Cast kinds for ComplexType (PR #149717)

[Henrich Lauko via cfe-commits]

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@@ -24,11 +25,118 @@ struct LoweringPreparePass : public LoweringPrepareBase<LoweringPreparePass> {
   void runOnOperation() override;
 
   void runOnOp(mlir::Operation *op);
+  void lowerCastOp(cir::CastOp op);
   void lowerUnaryOp(cir::UnaryOp op);
 };
 
 } // namespace
 
+static mlir::Value lowerScalarToComplexCast(mlir::MLIRContext &ctx,
+                                            cir::CastOp op) {
+  CIRBaseBuilderTy builder(ctx);
+  builder.setInsertionPoint(op);
+
+  mlir::Value src = op.getSrc();
+  mlir::Value imag = builder.getNullValue(src.getType(), op.getLoc());
+  return builder.createComplexCreate(op.getLoc(), src, imag);
+}
+
+static mlir::Value lowerComplexToScalarCast(mlir::MLIRContext &ctx,
+                                            cir::CastOp op,
+                                            cir::CastKind elemToBoolKind) {
+  CIRBaseBuilderTy builder(ctx);
+  builder.setInsertionPoint(op);
+
+  mlir::Value src = op.getSrc();
+  if (!mlir::isa<cir::BoolType>(op.getType()))
+    return builder.createComplexReal(op.getLoc(), src);
+
+  // Complex cast to bool: (bool)(a+bi) => (bool)a || (bool)b
+  mlir::Value srcReal = builder.createComplexReal(op.getLoc(), src);
+  mlir::Value srcImag = builder.createComplexImag(op.getLoc(), src);
+
+  cir::BoolType boolTy = builder.getBoolTy();
+  mlir::Value srcRealToBool =
+      builder.createCast(op.getLoc(), elemToBoolKind, srcReal, boolTy);
+  mlir::Value srcImagToBool =
+      builder.createCast(op.getLoc(), elemToBoolKind, srcImag, boolTy);
+  return builder.createLogicalOr(op.getLoc(), srcRealToBool, srcImagToBool);
+}
+
+static mlir::Value lowerComplexToComplexCast(mlir::MLIRContext &ctx,
+                                             cir::CastOp op,
+                                             cir::CastKind scalarCastKind) {
+  CIRBaseBuilderTy builder(ctx);
+  builder.setInsertionPoint(op);
+
+  mlir::Value src = op.getSrc();
+  auto dstComplexElemTy =
+      mlir::cast<cir::ComplexType>(op.getType()).getElementType();
+
+  mlir::Value srcReal = builder.createComplexReal(op.getLoc(), src);
+  mlir::Value srcImag = builder.createComplexReal(op.getLoc(), src);
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xlauko wrote:

Shouldn't this be createComplexImag?

https://github.com/llvm/llvm-project/pull/149717