[MLIR][Arith] SelectOp fix invalid folding (#117555)

The pattern `select %x, true, false => %x` is only valid in case that
the return type is identical to the type of `%x` (i.e., i1). Hence, the
check `isInteger(1)` was replaced with `isSignlessInteger(1)`.

Fixes: #117554

Author: 7FM

mlir/lib/Dialect/Arith/IR/ArithOps.cpp

@@ -2322,7 +2322,8 @@ OpFoldResult arith::SelectOp::fold(FoldAdaptor adaptor) {
     return trueVal;
 
   // select %x, true, false => %x
-  if (getType().isInteger(1) && matchPattern(adaptor.getTrueValue(), m_One()) &&
+  if (getType().isSignlessInteger(1) &&
+      matchPattern(adaptor.getTrueValue(), m_One()) &&
       matchPattern(adaptor.getFalseValue(), m_Zero()))
     return condition;
 

mlir/test/Dialect/Arith/canonicalize.mlir

@@ -54,6 +54,18 @@ func.func @select_extui_i1(%arg0: i1) -> i1 {
   return %res : i1
 }
 
+// CHECK-LABEL: @select_no_fold_ui1
+//       CHECK:  %[[CONST_0:.+]] = "test.constant"() <{value = 0 : i32}> : () -> ui1
+//       CHECK:  %[[CONST_1:.+]] = "test.constant"() <{value = 1 : i32}> : () -> ui1
+//  CHECK-NEXT:  %[[RES:.+]] = arith.select %arg0, %[[CONST_1]], %[[CONST_0]] : ui1
+//  CHECK-NEXT:   return %[[RES]]
+func.func @select_no_fold_ui1(%arg0: i1) -> ui1 {
+  %c0_i1 = "test.constant"() {value = 0 : i32} : () -> ui1
+  %c1_i1 = "test.constant"() {value = 1 : i32} : () -> ui1
+  %res = arith.select %arg0, %c1_i1, %c0_i1 : ui1
+  return %res : ui1
+}
+
 // CHECK-LABEL: @select_cst_false_scalar
 //  CHECK-SAME:   (%[[ARG0:.+]]: i32, %[[ARG1:.+]]: i32)
 //  CHECK-NEXT:   return %[[ARG1]]