From 69dcb4dbdadf5536f4a49ada9f7e5091c0496761 Mon Sep 17 00:00:00 2001
From: Irmen de Jong <irmen@razorvine.net>
Date: Sat, 27 Nov 2021 21:22:34 +0100
Subject: [PATCH] fix reporting of (not) unused code after GoSub jump

---
 .../src/prog8/optimizer/UnusedCodeRemover.kt          | 11 ++++++-----
 examples/test.p8                                      | 11 +++++++++++
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/codeOptimizers/src/prog8/optimizer/UnusedCodeRemover.kt b/codeOptimizers/src/prog8/optimizer/UnusedCodeRemover.kt
index c118aea0a..a906a6a98 100644
--- a/codeOptimizers/src/prog8/optimizer/UnusedCodeRemover.kt
+++ b/codeOptimizers/src/prog8/optimizer/UnusedCodeRemover.kt
@@ -28,27 +28,28 @@ class UnusedCodeRemover(private val program: Program,
     }
 
     override fun before(breakStmt: Break, parent: Node): Iterable<IAstModification> {
-        reportUnreachable(breakStmt, parent as IStatementContainer)
+        reportUnreachable(breakStmt)
         return emptyList()
     }
 
     override fun before(jump: Jump, parent: Node): Iterable<IAstModification> {
-        reportUnreachable(jump, parent as IStatementContainer)
+        if(!jump.isGosub)
+            reportUnreachable(jump)
         return emptyList()
     }
 
     override fun before(returnStmt: Return, parent: Node): Iterable<IAstModification> {
-        reportUnreachable(returnStmt, parent as IStatementContainer)
+        reportUnreachable(returnStmt)
         return emptyList()
     }
 
     override fun before(functionCallStatement: FunctionCallStatement, parent: Node): Iterable<IAstModification> {
         if(functionCallStatement.target.nameInSource.last() == "exit")
-            reportUnreachable(functionCallStatement, parent as IStatementContainer)
+            reportUnreachable(functionCallStatement)
         return emptyList()
     }
 
-    private fun reportUnreachable(stmt: Statement, parent: IStatementContainer) {
+    private fun reportUnreachable(stmt: Statement) {
         when(val next = stmt.nextSibling()) {
             null, is Label, is Directive, is VarDecl, is InlineAssembly, is Subroutine -> {}
             else -> errors.warn("unreachable code", next.position)
diff --git a/examples/test.p8 b/examples/test.p8
index e2fb4cf2d..a4c55d542 100644
--- a/examples/test.p8
+++ b/examples/test.p8
@@ -21,6 +21,13 @@ main {
 ;        void sys.pop()
 
         routine2(uw, 11,22, true, 33)
+        routine2(uw, 11,22, true, 33)
+        routine2(uw, 11,22, true, 33)
+        routine2(uw, 11,22, true, 33)
+        blerp(22)
+        blerp(22)
+        blerp(22)
+        blerp(22)
 
         test_stack.test()
 
@@ -29,6 +36,10 @@ main {
 
     }
 
+    sub blerp(uword z) {
+        z++
+    }
+
     asmsub routine2(uword num @AY, ubyte a1 @R1, ubyte a2 @R2, ubyte switch @Pc, ubyte a3 @X) {
         %asm {{
             adc #20