Don't coerce intrisic value, it's already coerced

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/ExpressionCodegen.kt

@@ -329,7 +329,7 @@ class ExpressionCodegen(
 
     override fun visitFunctionAccess(expression: IrFunctionAccessExpression, data: BlockInfo): PromisedValue {
         classCodegen.context.irIntrinsics.getIntrinsic(expression.symbol)
-            ?.invoke(expression, this, data)?.let { return it.coerce(expression.type) }
+            ?.invoke(expression, this, data)?.let { return it }
 
         val callable = methodSignatureMapper.mapToCallableMethod(expression)
         val callee = expression.symbol.owner
@@ -409,7 +409,8 @@ class ExpressionCodegen(
             }
             expression is IrConstructorCall ->
                 MaterialValue(this, asmType, expression.type)
-            expression is IrDelegatingConstructorCall ->
+            expression.type.isUnit() && callable.asmMethod.returnType == Type.VOID_TYPE ->
+                //don't generate redundant UNIT/pop instructions
                 immaterialUnitValue
             expression.type.isUnit() ->
                 // NewInference allows casting `() -> T` to `() -> Unit`. A CHECKCAST here will fail.

compiler/testData/codegen/bytecodeText/disabledOptimizations/noUnitInstanceInDefaultParameterInitialization.kt

@@ -0,0 +1,7 @@
+// KOTLIN_CONFIGURATION_FLAGS: +JVM.DISABLE_OPTIMIZATION
+
+fun foo(s: String = "123") {}
+
+// 1 IF
+// 0 Unit\.INSTANCE
+// 0 POP

compiler/testData/codegen/bytecodeText/disabledOptimizations/noUnitInstanceOnVoidFunctionCall.kt

@@ -0,0 +1,10 @@
+// KOTLIN_CONFIGURATION_FLAGS: +JVM.DISABLE_OPTIMIZATION
+
+fun bar() {}
+
+fun foo() {
+    bar()
+}
+
+// 0 Unit\.INSTANCE
+// 0 POP

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

@@ -1635,6 +1635,16 @@ public class BytecodeTextTestGenerated extends AbstractBytecodeTextTest {
         public void testNoJumpInSingleBranch() throws Exception {
             runTest("compiler/testData/codegen/bytecodeText/disabledOptimizations/noJumpInSingleBranch.kt");
         }
+
+        @TestMetadata("noUnitInstanceInDefaultParameterInitialization.kt")
+        public void testNoUnitInstanceInDefaultParameterInitialization() throws Exception {
+            runTest("compiler/testData/codegen/bytecodeText/disabledOptimizations/noUnitInstanceInDefaultParameterInitialization.kt");
+        }
+
+        @TestMetadata("noUnitInstanceOnVoidFunctionCall.kt")
+        public void testNoUnitInstanceOnVoidFunctionCall() throws Exception {
+            runTest("compiler/testData/codegen/bytecodeText/disabledOptimizations/noUnitInstanceOnVoidFunctionCall.kt");
+        }
     }
 
     @TestMetadata("compiler/testData/codegen/bytecodeText/enum")

compiler/tests/org/jetbrains/kotlin/codegen/ir/IrBytecodeTextTestGenerated.java

@@ -1590,6 +1590,16 @@ public class IrBytecodeTextTestGenerated extends AbstractIrBytecodeTextTest {
         public void testNoJumpInSingleBranch() throws Exception {
             runTest("compiler/testData/codegen/bytecodeText/disabledOptimizations/noJumpInSingleBranch.kt");
         }
+
+        @TestMetadata("noUnitInstanceInDefaultParameterInitialization.kt")
+        public void testNoUnitInstanceInDefaultParameterInitialization() throws Exception {
+            runTest("compiler/testData/codegen/bytecodeText/disabledOptimizations/noUnitInstanceInDefaultParameterInitialization.kt");
+        }
+
+        @TestMetadata("noUnitInstanceOnVoidFunctionCall.kt")
+        public void testNoUnitInstanceOnVoidFunctionCall() throws Exception {
+            runTest("compiler/testData/codegen/bytecodeText/disabledOptimizations/noUnitInstanceOnVoidFunctionCall.kt");
+        }
     }
 
     @TestMetadata("compiler/testData/codegen/bytecodeText/enum")