Allow to stop in suspend funciton on enter and before suspended return

This commit is needed to implement "step over" action over suspended
call. Debugger have to understand when function is going to be
suspended and be able to set a breakpoint on function re-enter.

 #KT-18453 In Progress

compiler/backend/src/org/jetbrains/kotlin/codegen/coroutines/CoroutineCodegen.kt

@@ -310,6 +310,7 @@ class CoroutineCodegenForLambda private constructor(
                         return CoroutineTransformerMethodVisitor(
                                 mv, access, name, desc, null, null,
                                 obtainClassBuilderForCoroutineState = { v },
+                                element = element,
                                 containingClassInternalName = v.thisName,
                                 isForNamedFunction = false
                         )

compiler/backend/src/org/jetbrains/kotlin/codegen/coroutines/CoroutineTransformerMethodVisitor.kt

@@ -17,6 +17,7 @@
 package org.jetbrains.kotlin.codegen.coroutines
 
 import com.intellij.util.containers.Stack
+import org.jetbrains.kotlin.backend.common.CodegenUtil
 import org.jetbrains.kotlin.codegen.AsmUtil
 import org.jetbrains.kotlin.codegen.ClassBuilder
 import org.jetbrains.kotlin.codegen.StackValue
@@ -28,6 +29,7 @@ import org.jetbrains.kotlin.codegen.optimization.common.*
 import org.jetbrains.kotlin.codegen.optimization.fixStack.FixStackMethodTransformer
 import org.jetbrains.kotlin.codegen.optimization.fixStack.top
 import org.jetbrains.kotlin.codegen.optimization.transformer.MethodTransformer
+import org.jetbrains.kotlin.psi.KtElement
 import org.jetbrains.kotlin.resolve.jvm.AsmTypes
 import org.jetbrains.kotlin.resolve.jvm.diagnostics.JvmDeclarationOrigin
 import org.jetbrains.kotlin.utils.sure
@@ -50,6 +52,7 @@ class CoroutineTransformerMethodVisitor(
         private val containingClassInternalName: String,
         obtainClassBuilderForCoroutineState: () -> ClassBuilder,
         private val isForNamedFunction: Boolean,
+        private val element: KtElement,
         // It's only matters for named functions, may differ from '!isStatic(access)' in case of DefaultImpls
         private val needDispatchReceiver: Boolean = false,
         // May differ from containingClassInternalName in case of DefaultImpls
@@ -59,8 +62,8 @@ class CoroutineTransformerMethodVisitor(
     private val classBuilderForCoroutineState: ClassBuilder by lazy(obtainClassBuilderForCoroutineState)
 
     private val continuationIndex = if (isForNamedFunction) getLastParameterIndex(desc, access) else 0
-    var dataIndex = if (isForNamedFunction) -1 else 1
-    var exceptionIndex = if (isForNamedFunction) -1 else 2
+    private var dataIndex = if (isForNamedFunction) -1 else 1
+    private var exceptionIndex = if (isForNamedFunction) -1 else 2
 
     override fun performTransformations(methodNode: MethodNode) {
         val suspensionPoints = collectSuspensionPoints(methodNode)
@@ -107,10 +110,16 @@ class CoroutineTransformerMethodVisitor(
             val startLabel = LabelNode()
             val defaultLabel = LabelNode()
             val firstToInsertBefore = actualCoroutineStart
+            val tableSwitchLabel = LabelNode()
+            val lineNumber = CodegenUtil.getLineNumberForElement(element, false) ?: 0
+
             // tableswitch(this.label)
             insertBefore(firstToInsertBefore,
                          insnListOf(
                                  *withInstructionAdapter { loadCoroutineSuspendedMarker() }.toArray(),
+                                 tableSwitchLabel,
+                                 // Allow debugger to stop on enter into suspend function
+                                 LineNumberNode(lineNumber, tableSwitchLabel),
                                  VarInsnNode(Opcodes.ASTORE, suspendMarkerVarIndex),
                                  VarInsnNode(Opcodes.ALOAD, continuationIndex),
                                  createInsnForReadingLabel(),
@@ -463,6 +472,8 @@ class CoroutineTransformerMethodVisitor(
     ): LabelNode {
         val continuationLabel = LabelNode()
         val continuationLabelAfterLoadedResult = LabelNode()
+        val suspendElementLineNumber = CodegenUtil.getLineNumberForElement(element, false) ?: 0
+        val nextLineNumberNode = suspension.suspensionCallEnd.findNextOrNull { it is LineNumberNode } as? LineNumberNode
         with(methodNode.instructions) {
             // Save state
             insertBefore(suspension.suspensionCallBegin,
@@ -479,6 +490,10 @@ class CoroutineTransformerMethodVisitor(
                 ifacmpne(continuationLabelAfterLoadedResult.label)
 
                 // Exit
+                val returnLabel = LabelNode()
+                visitLabel(returnLabel.label)
+                // Special line number to stop in debugger before suspend return
+                visitLineNumber(suspendElementLineNumber, returnLabel.label)
                 load(suspendMarkerVarIndex, AsmTypes.OBJECT_TYPE)
                 areturn(AsmTypes.OBJECT_TYPE)
                 // Mark place for continuation
@@ -503,6 +518,11 @@ class CoroutineTransformerMethodVisitor(
                 load(dataIndex, AsmTypes.OBJECT_TYPE)
 
                 visitLabel(continuationLabelAfterLoadedResult.label)
+
+                // Extend next instruction linenumber. Can't use line number of suspension point here because both non-suspended execution
+                // and re-entering after suspension passes this label.
+                val afterSuspensionPointLineNumber = nextLineNumberNode?.line ?: suspendElementLineNumber
+                visitLineNumber(afterSuspensionPointLineNumber, continuationLabelAfterLoadedResult.label)
             })
         }
 
@@ -720,4 +740,4 @@ private fun AbstractInsnNode?.isInvisibleInDebugVarInsn(methodNode: MethodNode):
 }
 
 private val SAFE_OPCODES =
-        ((Opcodes.DUP..Opcodes.DUP2_X2) + Opcodes.POP + Opcodes.POP2 + (Opcodes.IFEQ..Opcodes.GOTO)).toSet()
+        ((Opcodes.DUP..Opcodes.DUP2_X2) + Opcodes.POP + Opcodes.POP2 + (Opcodes.IFEQ..Opcodes.GOTO)).toSet()

compiler/backend/src/org/jetbrains/kotlin/codegen/coroutines/SuspendFunctionGenerationStrategy.kt

@@ -57,6 +57,7 @@ class SuspendFunctionGenerationStrategy(
         return CoroutineTransformerMethodVisitor(
                 mv, access, name, desc, null, null, containingClassInternalName, this::classBuilderForCoroutineState,
                 isForNamedFunction = true,
+                element = declaration,
                 needDispatchReceiver = originalSuspendDescriptor.dispatchReceiverParameter != null,
                 internalNameForDispatchReceiver = containingClassInternalNameOrNull()
         ).also {