Intrinsics for 'reversed': generate in-const-bound ranges as countable

#KT-21323 In Progress

compiler/backend/src/org/jetbrains/kotlin/codegen/range/PrimitiveNumberRangeLiteralRangeValue.kt

@@ -29,6 +29,7 @@ import org.jetbrains.kotlin.resolve.constants.ByteValue
 import org.jetbrains.kotlin.resolve.constants.IntValue
 import org.jetbrains.kotlin.resolve.constants.IntegerValueConstant
 import org.jetbrains.kotlin.resolve.constants.ShortValue
+import org.jetbrains.kotlin.resolve.scopes.receivers.ExpressionReceiver
 import org.jetbrains.kotlin.utils.addToStdlib.safeAs
 
 class PrimitiveNumberRangeLiteralRangeValue(
@@ -40,21 +41,24 @@ class PrimitiveNumberRangeLiteralRangeValue(
             SimpleBoundedValue(codegen, rangeCall)
 
     override fun createForLoopGenerator(codegen: ExpressionCodegen, forExpression: KtForExpression): ForLoopGenerator =
-            getConstRangeForInRangeLiteralGenerator(codegen, forExpression) ?:
+            createConstBoundedForInRangeLiteralGenerator(codegen, forExpression) ?:
             ForInSimpleProgressionLoopGenerator.fromBoundedValueWithStep1(codegen, forExpression, getBoundedValue(codegen))
 
     override fun createForInReversedLoopGenerator(codegen: ExpressionCodegen, forExpression: KtForExpression): ForLoopGenerator =
-            // TODO const-bounded version
+            createConstBoundedRangeForInReversedRangeLiteralGenerator(codegen, forExpression) ?:
             ForInSimpleProgressionLoopGenerator.fromBoundedValueWithStepMinus1(codegen, forExpression, getBoundedValue(codegen))
 
-    private fun getConstRangeForInRangeLiteralGenerator(codegen: ExpressionCodegen, forExpression: KtForExpression): ForLoopGenerator? {
+    private fun createConstBoundedForInRangeLiteralGenerator(
+            codegen: ExpressionCodegen,
+            forExpression: KtForExpression
+    ): ForLoopGenerator? {
         val rhsExpression = rangeCall.valueArgumentsByIndex?.run { get(0).arguments[0].getArgumentExpression() } ?: return null
         val constValue = codegen.getCompileTimeConstant(rhsExpression).safeAs<IntegerValueConstant<*>>() ?: return null
         val untilValue = when (constValue) {
             is ByteValue -> constValue.value + 1
             is ShortValue -> constValue.value + 1
             is IntValue -> constValue.value + 1
-            else -> return null
+            else -> Int.MIN_VALUE
         }
 
         // Watch out for integer overflow
@@ -70,4 +74,32 @@ class PrimitiveNumberRangeLiteralRangeValue(
                     step = 1
             )
     }
+
+    private fun createConstBoundedRangeForInReversedRangeLiteralGenerator(
+            codegen: ExpressionCodegen,
+            forExpression: KtForExpression
+    ): ForLoopGenerator? {
+        val lhsExpression = rangeCall.extensionReceiver.safeAs<ExpressionReceiver>()?.expression ?: return null
+        val constValue = codegen.getCompileTimeConstant(lhsExpression).safeAs<IntegerValueConstant<*>>() ?: return null
+        val untilValue = when (constValue) {
+            is ByteValue -> constValue.value - 1
+            is ShortValue -> constValue.value - 1
+            is IntValue -> constValue.value - 1
+            else -> Int.MAX_VALUE
+        }
+
+        // Watch out for integer overflow
+        return if (untilValue == Int.MAX_VALUE)
+            null
+        else
+            ForInSimpleProgressionLoopGenerator(
+                    codegen, forExpression,
+                    startValue = codegen.generateCallSingleArgument(rangeCall),
+                    isStartInclusive = true,
+                    endValue = StackValue.integerConstant(untilValue, asmElementType),
+                    isEndInclusive = false,
+                    step = -1
+            )
+    }
+
 }

compiler/testData/codegen/box/ranges/forInReversed/forInReversedEmptyRangeLiteralWithNonConstBounds.kt

@@ -0,0 +1,25 @@
+// WITH_RUNTIME
+import kotlin.test.*
+
+fun intLow() = 4
+fun intHigh() = 1
+fun longLow() = 4L
+fun longHigh() = 1L
+fun charLow() = '4'
+fun charHigh() = '1'
+
+fun box(): String {
+    for (i in (intLow() .. intHigh()).reversed()) {
+        throw AssertionError("Loop should not be executed")
+    }
+
+    for (i in (longLow() .. longHigh()).reversed()) {
+        throw AssertionError("Loop should not be executed")
+    }
+
+    for (i in (charLow() .. charHigh()).reversed()) {
+        throw AssertionError("Loop should not be executed")
+    }
+
+    return "OK"
+}

compiler/testData/codegen/box/ranges/forInReversed/forInReversedRangeLiteralWithNonConstBounds.kt

@@ -0,0 +1,31 @@
+// WITH_RUNTIME
+import kotlin.test.*
+
+fun intLow() = 1
+fun intHigh() = 4
+fun longLow() = 1L
+fun longHigh() = 4L
+fun charLow() = '1'
+fun charHigh() = '4'
+
+fun box(): String {
+    var sum = 0
+    for (i in (intLow() .. intHigh()).reversed()) {
+        sum = sum * 10 + i
+    }
+    assertEquals(4321, sum)
+
+    var sumL = 0L
+    for (i in (longLow() .. longHigh()).reversed()) {
+        sumL = sumL * 10 + i
+    }
+    assertEquals(4321L, sumL)
+
+    var sumC = 0
+    for (i in (charLow() .. charHigh()).reversed()) {
+        sumC = sumC * 10 + i.toInt() - '0'.toInt()
+    }
+    assertEquals(4321, sumC)
+
+    return "OK"
+}

compiler/testData/codegen/bytecodeText/forLoop/forInReversed/forInReversedEmptyRangeLiteral.kt

@@ -14,6 +14,8 @@ fun box(): String {
 }
 
 // 0 reversed
+// 0 getStart
+// 0 getEnd
 // 0 getFirst
 // 0 getLast
 // 0 getStep

compiler/testData/codegen/bytecodeText/forLoop/forInReversed/forInReversedRangeLiteral.kt

@@ -24,6 +24,10 @@ fun box(): String {
 }
 
 // 0 reversed
+// 0 getStart
+// 0 getEnd
 // 0 getFirst
 // 0 getLast
-// 0 getStep
+// 0 getStep
+// 2 IF_ICMPEQ
+// ^ 1 for char progression, 1 for long progression

compiler/tests-ir-jvm/tests/org/jetbrains/kotlin/codegen/ir/IrBlackBoxCodegenTestGenerated.java

@@ -15247,11 +15247,23 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
                 doTest(fileName);
             }
 
+            @TestMetadata("forInReversedEmptyRangeLiteralWithNonConstBounds.kt")
+            public void testForInReversedEmptyRangeLiteralWithNonConstBounds() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/ranges/forInReversed/forInReversedEmptyRangeLiteralWithNonConstBounds.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("forInReversedRangeLiteral.kt")
             public void testForInReversedRangeLiteral() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/ranges/forInReversed/forInReversedRangeLiteral.kt");
                 doTest(fileName);
             }
+
+            @TestMetadata("forInReversedRangeLiteralWithNonConstBounds.kt")
+            public void testForInReversedRangeLiteralWithNonConstBounds() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/ranges/forInReversed/forInReversedRangeLiteralWithNonConstBounds.kt");
+                doTest(fileName);
+            }
         }
 
         @TestMetadata("compiler/testData/codegen/box/ranges/forInUntil")

compiler/tests/org/jetbrains/kotlin/codegen/BlackBoxCodegenTestGenerated.java

@@ -15247,11 +15247,23 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("forInReversedEmptyRangeLiteralWithNonConstBounds.kt")
+            public void testForInReversedEmptyRangeLiteralWithNonConstBounds() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/ranges/forInReversed/forInReversedEmptyRangeLiteralWithNonConstBounds.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("forInReversedRangeLiteral.kt")
             public void testForInReversedRangeLiteral() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/ranges/forInReversed/forInReversedRangeLiteral.kt");
                 doTest(fileName);
             }
+
+            @TestMetadata("forInReversedRangeLiteralWithNonConstBounds.kt")
+            public void testForInReversedRangeLiteralWithNonConstBounds() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/ranges/forInReversed/forInReversedRangeLiteralWithNonConstBounds.kt");
+                doTest(fileName);
+            }
         }
 
         @TestMetadata("compiler/testData/codegen/box/ranges/forInUntil")

compiler/tests/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java

@@ -15247,11 +15247,23 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
                 doTest(fileName);
             }
 
+            @TestMetadata("forInReversedEmptyRangeLiteralWithNonConstBounds.kt")
+            public void testForInReversedEmptyRangeLiteralWithNonConstBounds() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/ranges/forInReversed/forInReversedEmptyRangeLiteralWithNonConstBounds.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("forInReversedRangeLiteral.kt")
             public void testForInReversedRangeLiteral() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/ranges/forInReversed/forInReversedRangeLiteral.kt");
                 doTest(fileName);
             }
+
+            @TestMetadata("forInReversedRangeLiteralWithNonConstBounds.kt")
+            public void testForInReversedRangeLiteralWithNonConstBounds() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/ranges/forInReversed/forInReversedRangeLiteralWithNonConstBounds.kt");
+                doTest(fileName);
+            }
         }
 
         @TestMetadata("compiler/testData/codegen/box/ranges/forInUntil")

js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/JsCodegenBoxTestGenerated.java

@@ -16663,11 +16663,23 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("forInReversedEmptyRangeLiteralWithNonConstBounds.kt")
+            public void testForInReversedEmptyRangeLiteralWithNonConstBounds() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/ranges/forInReversed/forInReversedEmptyRangeLiteralWithNonConstBounds.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("forInReversedRangeLiteral.kt")
             public void testForInReversedRangeLiteral() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/ranges/forInReversed/forInReversedRangeLiteral.kt");
                 doTest(fileName);
             }
+
+            @TestMetadata("forInReversedRangeLiteralWithNonConstBounds.kt")
+            public void testForInReversedRangeLiteralWithNonConstBounds() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/ranges/forInReversed/forInReversedRangeLiteralWithNonConstBounds.kt");
+                doTest(fileName);
+            }
         }
 
         @TestMetadata("compiler/testData/codegen/box/ranges/forInUntil")