While loop implementation && first loop test

compiler/ir/ir.ir2cfg/src/org/jetbrains/kotlin/ir2cfg/generators/FunctionGenerator.kt

@@ -126,6 +126,23 @@ class FunctionGenerator(val function: IrFunction) {
             return whenExit
         }
 
+        override fun visitWhileLoop(loop: IrWhileLoop, data: Boolean): IrElement? {
+            if (data) {
+                builder.add(loop)
+            }
+            val entry = MergeCfgElement(loop, "While entry")
+            builder.jump(entry)
+            val condition = loop.condition
+            condition.process(includeSelf = false)
+            builder.jump(condition)
+            val body = loop.body
+            if (!body?.process().isNothing()) {
+                builder.jump(entry)
+            }
+            builder.move(condition)
+            return condition
+        }
+
         override fun visitElement(element: IrElement, data: Boolean): IrElement? {
             TODO("not implemented")
         }

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

@@ -0,0 +1,7 @@
+fun factorial(i: Int): Int {
+    var result = 1
+    for (j in 2..i) {
+        result *= j
+    }
+    return result
+}

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

@@ -0,0 +1,40 @@
+// FILE: /factorial.kt
+// FUN: factorial
+BB 0
+CONTENT
+      1 FUN public fun factorial(i: kotlin.Int): kotlin.Int
+      2 CONST Int type=kotlin.Int value='1'
+      3 VAR var result: kotlin.Int
+      4 CALL 'iterator(): IntIterator' type=kotlin.collections.IntIterator origin=FOR_LOOP_ITERATOR
+      5 VAR IR_TEMPORARY_VARIABLE val tmp0_iterator: kotlin.collections.IntIterator
+      6 WHILE label=null origin=FOR_LOOP_INNER_WHILE
+OUTGOING -> BB 1
+    While entry: WHILE label=null origin=FOR_LOOP_INNER_WHILE
+BB 1
+INCOMING <- BB 0, 2
+    While entry: WHILE label=null origin=FOR_LOOP_INNER_WHILE
+CONTENT
+OUTGOING -> BB 2, 3
+    CALL 'hasNext(): Boolean' type=kotlin.Boolean origin=FOR_LOOP_HAS_NEXT
+BB 2
+INCOMING <- BB 1
+    CALL 'hasNext(): Boolean' type=kotlin.Boolean origin=FOR_LOOP_HAS_NEXT
+CONTENT
+      1 CALL 'next(): Int' type=kotlin.Int origin=FOR_LOOP_NEXT
+      2 VAR val j: kotlin.Int
+      3 SET_VAR 'result: Int' type=kotlin.Unit origin=MULTEQ
+OUTGOING -> BB 1
+    While entry: WHILE label=null origin=FOR_LOOP_INNER_WHILE
+BB 3
+INCOMING <- BB 1
+    CALL 'hasNext(): Boolean' type=kotlin.Boolean origin=FOR_LOOP_HAS_NEXT
+CONTENT
+      1 GET_VAR 'result: Int' type=kotlin.Int origin=null
+      2 RETURN type=kotlin.Nothing from='factorial(Int): Int'
+OUTGOING -> NONE
+    Function exit: FUN public fun factorial(i: kotlin.Int): kotlin.Int
+
+// END FUN: factorial
+
+// END FILE: /factorial.kt
+

compiler/tests/org/jetbrains/kotlin/ir/IrCfgTestCaseGenerated.java

@@ -71,6 +71,21 @@ public class IrCfgTestCaseGenerated extends AbstractIrCfgTestCase {
         doTest(fileName);
     }
 
+    @TestMetadata("compiler/testData/ir/irCfg/loop")
+    @TestDataPath("$PROJECT_ROOT")
+    @RunWith(JUnit3RunnerWithInners.class)
+    public static class Loop extends AbstractIrCfgTestCase {
+        public void testAllFilesPresentInLoop() throws Exception {
+            KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/ir/irCfg/loop"), Pattern.compile("^(.+)\\.kt$"), true);
+        }
+
+        @TestMetadata("factorial.kt")
+        public void testFactorial() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/ir/irCfg/loop/factorial.kt");
+            doTest(fileName);
+        }
+    }
+
     @TestMetadata("compiler/testData/ir/irCfg/when")
     @TestDataPath("$PROJECT_ROOT")
     @RunWith(JUnit3RunnerWithInners.class)