From 656dbef1845fc85ca766d45e162b5137aaf8fe03 Mon Sep 17 00:00:00 2001
From: Karol Stasiak <karol.m.stasiak@gmail.com>
Date: Mon, 5 Mar 2018 11:32:31 +0100
Subject: [PATCH] Optimize pulling a known constant from the stack in more
 cases

---
 .../assembly/opt/AlwaysGoodOptimizations.scala | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/src/main/scala/millfork/assembly/opt/AlwaysGoodOptimizations.scala b/src/main/scala/millfork/assembly/opt/AlwaysGoodOptimizations.scala
index 199f7ae6..8500efbe 100644
--- a/src/main/scala/millfork/assembly/opt/AlwaysGoodOptimizations.scala
+++ b/src/main/scala/millfork/assembly/opt/AlwaysGoodOptimizations.scala
@@ -260,6 +260,24 @@ object AlwaysGoodOptimizations {
 
   val PointlessStackStashing = new RuleBasedAssemblyOptimization("Pointless stack stashing",
     needsFlowInfo = FlowInfoRequirement.NoRequirement,
+    (Elidable & HasOpcode(LDA) & HasAddrMode(Immediate)) ~
+      (Elidable & HasOpcode(PHA)) ~
+      (Linear & Not(ConcernsStack) | HasOpcodeIn(Set(JSR, BSR))).* ~
+      (Elidable & HasOpcode(PLA)) ~~> { code =>
+      code.head :: (code.drop(2).init :+ code.head)
+    },
+    (Elidable & HasOpcode(LDX) & HasAddrMode(Immediate)) ~
+      (Elidable & HasOpcode(PHX)) ~
+      (Linear & Not(ConcernsStack) | HasOpcodeIn(Set(JSR, BSR))).* ~
+      (Elidable & HasOpcode(PLX)) ~~> { code =>
+      code.head :: (code.drop(2).init :+ code.head)
+    },
+    (Elidable & HasOpcode(LDY) & HasAddrMode(Immediate)) ~
+      (Elidable & HasOpcode(PHY)) ~
+      (Linear & Not(ConcernsStack) | HasOpcodeIn(Set(JSR, BSR))).* ~
+      (Elidable & HasOpcode(PLY)) ~~> { code =>
+      code.head :: (code.drop(2).init :+ code.head)
+    },
     (Elidable & HasOpcode(LDA) & MatchAddrMode(0) & MatchParameter(1)) ~
       (Elidable & HasOpcode(PHA)) ~
       (Linear & Not(ConcernsStack) & DoesntChangeIndexingInAddrMode(0) & DoesntChangeMemoryAt(0, 1)).* ~