[mlir][spirv] Add pattern matching for arith.index_cast i1 to index for ArithToSPIRV

mlir/lib/Conversion/ArithToSPIRV/ArithToSPIRV.cpp

@@ -607,6 +607,41 @@ struct UIToFPI1Pattern final : public OpConversionPattern<arith::UIToFPOp> {
   }
 };
 
+//===----------------------------------------------------------------------===//
+// IndexCastOp
+//===----------------------------------------------------------------------===//
+
+/// Converts arith.index_cast to spirv.Select if the type of source is i1 or
+/// vector of i1.
+struct IndexCastI1Pattern final : public OpConversionPattern<arith::IndexCastOp> {
+  using OpConversionPattern::OpConversionPattern;
+
+  LogicalResult
+  matchAndRewrite(arith::IndexCastOp op, OpAdaptor adaptor,
+                  ConversionPatternRewriter &rewriter) const override {
+    Type srcType = adaptor.getOperands().front().getType();
+    if (!srcType.isInteger(1))
+      return failure();
+
+    Type dstType = getTypeConverter()->convertType(op.getType());
+    if (!dstType)
+      return getTypeConversionFailure(rewriter, op);
+    // if (!dstType.isIndex()) {
+    //   llvm::errs() << "why doesnt this work?\n";
+    //   return failure();
+    // }
+
+    auto *converter = this->template getTypeConverter<SPIRVTypeConverter>();
+    Location loc = op.getLoc();
+    Type spirvI32T = converter->getIndexType();
+    Value zero = spirv::ConstantOp::getZero(spirvI32T, loc, rewriter);
+    Value one = spirv::ConstantOp::getOne(spirvI32T, loc, rewriter);
+    auto newOp = rewriter.replaceOpWithNewOp<spirv::SelectOp>(
+        op, dstType, adaptor.getOperands().front(), one, zero);
+    return success();
+  }
+};
+
 //===----------------------------------------------------------------------===//
 // ExtSIOp
 //===----------------------------------------------------------------------===//
@@ -1328,7 +1363,7 @@ void mlir::arith::populateArithToSPIRVPatterns(
     TypeCastingOpPattern<arith::SIToFPOp, spirv::ConvertSToFOp>,
     TypeCastingOpPattern<arith::FPToUIOp, spirv::ConvertFToUOp>,
     TypeCastingOpPattern<arith::FPToSIOp, spirv::ConvertFToSOp>,
-    TypeCastingOpPattern<arith::IndexCastOp, spirv::SConvertOp>,
+    TypeCastingOpPattern<arith::IndexCastOp, spirv::SConvertOp>, IndexCastI1Pattern,
     TypeCastingOpPattern<arith::IndexCastUIOp, spirv::UConvertOp>,
     TypeCastingOpPattern<arith::BitcastOp, spirv::BitcastOp>,
     CmpIOpBooleanPattern, CmpIOpPattern,

mlir/test/Conversion/ArithToSPIRV/arith-to-spirv.mlir

@@ -734,6 +734,13 @@ func.func @index_castui4(%arg0: index) {
   return
 }
 
+// CHECK-LABEL: index_casti1_1
+func.func @index_casti1_1(%arg0 : i1) -> index {
+  // CHECK: spirv.Select %{{.+}}, %{{.+}}, %{{.+}} : i1, i32
+  %0 = arith.index_cast %arg0 : i1 to index
+  return %0 : index
+}
+
 // CHECK-LABEL: @bit_cast
 func.func @bit_cast(%arg0: vector<2xf32>, %arg1: i64) {
   // CHECK: spirv.Bitcast %{{.+}} : vector<2xf32> to vector<2xi32>