Do..while loop implementation and first test

compiler/testData/ir/irCfg/loop/digitCount.kt

@@ -0,0 +1,11 @@
+fun digitCountInNumber(n: Int, m: Int): Int {
+    var count = 0
+    var number = n
+    do {
+        if (m == number % 10) {
+            count++
+        }
+        number /= 10
+    } while (number > 0)
+    return count
+}

compiler/testData/ir/irCfg/loop/digitCount.txt

@@ -0,0 +1,52 @@
+// FILE: /digitCount.kt
+// FUN: digitCountInNumber
+BB 0
+CONTENT
+      1 FUN public fun digitCountInNumber(n: kotlin.Int, m: kotlin.Int): kotlin.Int
+      2 CONST Int type=kotlin.Int value='0'
+      3 VAR var count: kotlin.Int
+      4 GET_VAR 'value-parameter n: Int' type=kotlin.Int origin=null
+      5 VAR var number: kotlin.Int
+      6 DO_WHILE label=null origin=DO_WHILE_LOOP
+OUTGOING -> BB 1
+    Do..while entry: DO_WHILE label=null origin=DO_WHILE_LOOP
+BB 1
+INCOMING <- BB 0, 4
+    Do..while entry: DO_WHILE label=null origin=DO_WHILE_LOOP
+CONTENT
+      1 WHEN type=kotlin.Unit origin=null
+OUTGOING -> BB 2
+    CALL 'EQEQ(Any?, Any?): Boolean' type=kotlin.Boolean origin=EQEQ
+BB 2
+INCOMING <- BB 1
+    CALL 'EQEQ(Any?, Any?): Boolean' type=kotlin.Boolean origin=EQEQ
+CONTENT
+      1 TYPE_OP origin=IMPLICIT_COERCION_TO_UNIT typeOperand=kotlin.Unit
+OUTGOING -> BB 3
+    When exit: WHEN type=kotlin.Unit origin=null
+BB 3
+INCOMING <- BB 2
+    When exit: WHEN type=kotlin.Unit origin=null
+CONTENT
+      1 SET_VAR 'number: Int' type=kotlin.Unit origin=DIVEQ
+OUTGOING -> BB 4, 5
+    CALL 'GT0(Int): Boolean' type=kotlin.Boolean origin=GT
+BB 4
+INCOMING <- BB 3
+    CALL 'GT0(Int): Boolean' type=kotlin.Boolean origin=GT
+CONTENT
+OUTGOING -> BB 1
+    Do..while entry: DO_WHILE label=null origin=DO_WHILE_LOOP
+BB 5
+INCOMING <- BB 3
+    CALL 'GT0(Int): Boolean' type=kotlin.Boolean origin=GT
+CONTENT
+      1 GET_VAR 'count: Int' type=kotlin.Int origin=null
+      2 RETURN type=kotlin.Nothing from='digitCountInNumber(Int, Int): Int'
+OUTGOING -> NONE
+    Function exit: FUN public fun digitCountInNumber(n: kotlin.Int, m: kotlin.Int): kotlin.Int
+
+// END FUN: digitCountInNumber
+
+// END FILE: /digitCount.kt
+