From b6e61f16ecaac3234ac9f70de4bbad01ca2033ea Mon Sep 17 00:00:00 2001
From: Karol Stasiak <karol.m.stasiak@gmail.com>
Date: Fri, 1 Jun 2018 09:51:59 +0200
Subject: [PATCH] Optimizations of adding one

---
 .../opt/AlwaysGoodOptimizations.scala         | 37 +++++++++++++++++++
 .../test/AssemblyOptimizationSuite.scala      | 34 +++++++++++++++++
 2 files changed, 71 insertions(+)

diff --git a/src/main/scala/millfork/assembly/opt/AlwaysGoodOptimizations.scala b/src/main/scala/millfork/assembly/opt/AlwaysGoodOptimizations.scala
index 05331e23..c3f4ca63 100644
--- a/src/main/scala/millfork/assembly/opt/AlwaysGoodOptimizations.scala
+++ b/src/main/scala/millfork/assembly/opt/AlwaysGoodOptimizations.scala
@@ -1388,8 +1388,32 @@ object AlwaysGoodOptimizations {
       (Elidable & HasOpcode(ADC) & MatchAddrMode(0) & MatchParameter(1) & HasClear(State.D) & DoesntMatterWhatItDoesWith(State.V)) ~~> { code =>
       List(code.head, AssemblyLine.implied(ROL))
     },
+    (Elidable & HasOpcode(ADC) & HasImmediate(0) & HasClear(State.C) & DoesntMatterWhatItDoesWith(State.V, State.C, State.N, State.Z)) ~~> (_ => Nil),
     (Elidable & HasOpcode(ROL) & HasClear(State.C)) ~~> (code => code.map(_.copy(opcode = ASL))),
     (Elidable & HasOpcode(ROR) & HasClear(State.C)) ~~> (code => code.map(_.copy(opcode = LSR))),
+    (HasOpcode(AND) & HasImmediate(1)) ~
+      (Linear & Not(ChangesNAndZ) & Not(HasOpcode(CLC)) & Not(ChangesA)).* ~
+      (Elidable & HasOpcode(CLC) & HasClear(State.D)) ~
+      (Elidable & HasOpcode(ADC) & MatchAddrMode(0) & MatchParameter(1) & HasAddrModeIn(Set(ZeroPage, ZeroPageX, Absolute, AbsoluteX))) ~
+      (Elidable & HasOpcode(STA) & MatchAddrMode(0) & MatchParameter(1) & DoesntMatterWhatItDoesWith(State.C, State.V, State.Z, State.N, State.A)) ~~> { code =>
+      val label = getNextLabel("in")
+      code.take(code.length - 3) ++ List(
+        AssemblyLine.relative(BEQ, label),
+        code.last.copy(opcode = INC),
+        AssemblyLine.label(label)
+      )
+    },
+    (HasOpcode(ANC) & HasImmediate(1)) ~
+      (Linear & Not(ChangesNAndZ) & Not(ChangesA) & (Not(ChangesC) | HasOpcode(CLC))).* ~
+      (Elidable & HasOpcode(ADC) & MatchAddrMode(0) & MatchParameter(1) & HasClear(State.D) & HasAddrModeIn(Set(ZeroPage, ZeroPageX, Absolute, AbsoluteX))) ~
+      (Elidable & HasOpcode(STA) & MatchAddrMode(0) & MatchParameter(1) & DoesntMatterWhatItDoesWith(State.C, State.V, State.Z, State.N, State.A)) ~~> { code =>
+      val label = getNextLabel("in")
+      code.head.copy(opcode = AND) :: code.take(code.length - 2).tail ++ List(
+        AssemblyLine.relative(BEQ, label),
+        code.last.copy(opcode = INC),
+        AssemblyLine.label(label)
+      )
+    },
   )
 
   val IndexSequenceOptimization = new RuleBasedAssemblyOptimization("Index sequence optimization",
@@ -1542,6 +1566,19 @@ object AlwaysGoodOptimizations {
       (Elidable & HasOpcode(ROR) & DoesntMatterWhatItDoesWith(State.N, State.Z, State.C) & MatchAddrMode(0) & MatchParameter(1)) ~~> { code =>
       code.init.last :: code.last :: code.drop(2).init.init
     },
+    (Elidable & HasOpcode(ASL) & MatchAddrMode(0) & MatchParameter(1)) ~
+      (Elidable & HasOpcode(INC) & MatchAddrMode(0) & MatchParameter(1)) ~~> { code =>
+      List(AssemblyLine.implied(SEC), code.head.copy(opcode = ROL))
+    },
+    (Elidable & HasOpcode(ASL) & HasAddrMode(AddrMode.Implied)) ~
+      (Elidable & HasOpcode(CLC)) ~
+      (Elidable & HasOpcode(ADC) & HasImmediate(1) & DoesntMatterWhatItDoesWith(State.C, State.V)) ~~> { code =>
+      List(AssemblyLine.implied(SEC), code.head.copy(opcode = ROL))
+    },
+    (Elidable & HasOpcode(ASL) & HasAddrMode(AddrMode.Implied)) ~
+      (Elidable & HasOpcodeIn(Set(ORA, EOR)) & HasImmediate(1)) ~~> { code =>
+      List(AssemblyLine.implied(SEC), code.head.copy(opcode = ROL))
+    },
   )
 
   private def blockIsIdempotentWhenItComesToIndexRegisters(i: Int) = Where(ctx => {
diff --git a/src/test/scala/millfork/test/AssemblyOptimizationSuite.scala b/src/test/scala/millfork/test/AssemblyOptimizationSuite.scala
index 9aac53fb..1df9c4c6 100644
--- a/src/test/scala/millfork/test/AssemblyOptimizationSuite.scala
+++ b/src/test/scala/millfork/test/AssemblyOptimizationSuite.scala
@@ -506,4 +506,38 @@ class AssemblyOptimizationSuite extends FunSuite with Matchers {
         m.readByte(0xc000) should equal(0x46)
       }
     }
+
+  test("Shift and increase") {
+      EmuBenchmarkRun(
+        """
+          | byte output @$c000
+          | void main() {
+          |   output = twicePlusOne(5)
+          | }
+          | noinline byte twicePlusOne (byte x) {
+          |   return x * 2 + 1
+          | }
+        """.stripMargin
+      ){m =>
+        m.readByte(0xc000) should equal(11)
+      }
+    }
+
+  test("Add one bit") {
+      EmuBenchmarkRun(
+        """
+          | byte output @$c000
+          | void main() {
+          |   output = 0
+          |   increaseByBit(5)
+          | }
+          | noinline void increaseByBit (byte y) {
+          |   output += y & 1
+          | }
+        """.stripMargin
+      ){m =>
+        m.readByte(0xc000) should equal(1)
+      }
+    }
+
 }