Fixed problem with nested do loops being mixed up during empty block culling. Improved flipper implementation.

src/dk/camelot64/kickc/TODO.txt

@@ -3,9 +3,11 @@ Features
 - Implement Register Allocation (that utilize real registers - and non-zeropage memory)
 - Add Fixed Point number types
 - Create a proper main function for the compiler
-- Add for loop
+- Add a for loop for(init;condition;increment) {stmt} -> { init; do { stmt; increment } while (condition) }
 - Add imports
 - Add structs
+- Add ++/-- incrementing/decrementing operators.
+- Let { stmt } introduce a new anonymous scope.
 - Add preprocessing / find a way to allow some functions to run at compile time
 - Implement inline compilation of functions (and a mechanism for choosing which methods / calls to inline)
 - Add ability to call ASM code from KC.
@@ -13,7 +15,7 @@ Features
 - Add inline ASM (maybe?)
 
 Process/Code Structure Improvement
-- Make each phase return a separate object graph (allowing for keeping the history in memory & performing rollbacks)
+- Make each phase return a separate object graph (allowing for keeeping the history in memory & performing rollbacks)
 - Implemenent Assertions for the output of different phases (ensuring that the result of the phase is consistent)
 - Refactor Expression Operator Implementation & Evaluation into one class per operator
 
@@ -25,6 +27,7 @@ Testing
 - Add assert statements to the language. Create KC programs that test the compiler by compiling, running and testing assertions.
 
 Optimizations
+- Optimize phi transitions by ensuring that identical phi-transitions with regards to register allocation are collected into a single transition.
 - Optimize register allocation by combining with knowledge of ASM program cost (bytes/cycles) and different ASM fragments with different clobbering.
 - Optimize by finding optimal sequence for multiple phi assignments in entry-segments.
 - Optimize by allowing resequencing of statements and phi assignemtns in a final phase. Perhaps by converting phi statements to "normal" statements and using some optimization step.

src/dk/camelot64/kickc/asm/fragment/aby=_star_cowo1.asm

@@ -0,0 +1 @@
+lda {cowo1}

src/dk/camelot64/kickc/asm/fragment/aby_neq_coby1_then_la1.asm

@@ -0,0 +1,2 @@
+cmp #{coby1}
+bne {la1}

src/dk/camelot64/kickc/asm/fragment/zpby1=zpby1_minus_1.asm

@@ -0,0 +1 @@
+dec {zpby1}

src/dk/camelot64/kickc/icl/Pass1GenerateStatementSequence.java

@@ -61,7 +61,9 @@ public class Pass1GenerateStatementSequence extends KickCBaseVisitor<Object> {
 
    @Override
    public Void visitStmtBlock(KickCParser.StmtBlockContext ctx) {
+      if(ctx.stmtSeq()!=null) {
          this.visit(ctx.stmtSeq());
+      }
       return null;
    }
 
@@ -127,7 +129,9 @@ public class Pass1GenerateStatementSequence extends KickCBaseVisitor<Object> {
       Label beginJumpLabel = getCurrentSymbols().addLabelIntermediate();
       StatementLabel beginJumpTarget = new StatementLabel(beginJumpLabel);
       sequence.addStatement(beginJumpTarget);
+      if(ctx.stmt()!=null) {
          this.visit(ctx.stmt());
+      }
       RValue rValue = (RValue) this.visit(ctx.expr());
       Statement doJmpStmt = new StatementConditionalJump(rValue, beginJumpLabel);
       sequence.addStatement(doJmpStmt);

src/dk/camelot64/kickc/icl/Pass2CullEmptyBlocks.java

@@ -11,17 +11,20 @@ public class Pass2CullEmptyBlocks extends Pass2SsaOptimization {
 
    @Override
    public boolean optimize() {
-      List<ControlFlowBlock> remove = new ArrayList<>();
+      final List<ControlFlowBlock> remove = new ArrayList<>();
-      Map<Label, Label> replace = new HashMap<>();
       for (ControlFlowBlock block : getGraph().getAllBlocks()) {
          if (block.getStatements().isEmpty() && block.getLabel().isIntermediate()) {
             remove.add(block);
          }
       }
-      for (ControlFlowBlock removeBlock : remove) {
+
+      for (final ControlFlowBlock removeBlock : remove) {
          ControlFlowBlock successor = getGraph().getDefaultSuccessor(removeBlock);
-         for (ControlFlowBlock predecessor : getGraph().getPredecessors(removeBlock)) {
+         // Replace all jumps (default/conditional/call) to @removeBlock with a jump to the default successor
-            replace.put(removeBlock.getLabel(), predecessor.getLabel());
+         final List<ControlFlowBlock> predecessors = getGraph().getPredecessors(removeBlock);
+         for (ControlFlowBlock predecessor : predecessors) {
+            Map<Label, Label> replace = new HashMap<>();
+            replace.put(removeBlock.getLabel(), successor.getLabel());
             if (removeBlock.getLabel().equals(predecessor.getDefaultSuccessor())) {
                predecessor.setDefaultSuccessor(successor.getLabel());
             }
@@ -31,12 +34,35 @@ public class Pass2CullEmptyBlocks extends Pass2SsaOptimization {
             if (removeBlock.getLabel().equals(predecessor.getCallSuccessor())) {
                predecessor.setCallSuccessor(successor.getLabel());
             }
+            replaceLabels(predecessor, replace);
          }
+         // In all phi functions of a successor blocks make a copy of the phi assignment for each predecessor
+         ControlFlowGraphBaseVisitor<Void> phiFixVisitor = new ControlFlowGraphBaseVisitor<Void>() {
+            @Override
+            public Void visitPhi(StatementPhi phi) {
+               for (StatementPhi.PreviousSymbol previousSymbol : phi.getPreviousVersions()) {
+                  if(previousSymbol.getBlock().equals(removeBlock.getLabel())) {
+                     // Found a phi function referencing the remove block - add copies for each predecessor
+                     RValue previousRValue = previousSymbol.getRValue();
+                     for (ControlFlowBlock predecessor : predecessors) {
+                        if(previousSymbol!=null) {
+                           previousSymbol.setBlock(predecessor.getLabel());
+                           previousSymbol = null;
+                        } else {
+                           phi.addPreviousVersion(predecessor.getLabel(), previousRValue);
+                        }
+                     }
+                     break;
+                  }
+               }
+               return null;
+            }
+         };
+         phiFixVisitor.visitBlock(successor);
          getGraph().getAllBlocks().remove(removeBlock);
          getSymbols().remove(removeBlock.getLabel());
          System.out.println("Culled Empty Block " + removeBlock.getLabel());
       }
-      replaceLabels(replace);
       return remove.size()>0;
    }
 

src/dk/camelot64/kickc/icl/Pass2SsaOptimization.java

@@ -171,7 +171,23 @@ public abstract class Pass2SsaOptimization {
     * @param replacements Variables that have alias values.
     */
    public void replaceLabels(final Map<Label, Label> replacements) {
-      ControlFlowGraphBaseVisitor<Void> visitor = new ControlFlowGraphBaseVisitor<Void>() {
+      ControlFlowGraphBaseVisitor<Void> visitor = getLabelReplaceVisitor(replacements);
+      visitor.visitGraph(graph);
+   }
+
+   /**
+    * Replace all usages of a label in statements with another label.
+    *
+    * @param replacements Variables that have alias values.
+    */
+   public void replaceLabels(ControlFlowBlock block, final Map<Label, Label> replacements) {
+      ControlFlowGraphBaseVisitor<Void> visitor = getLabelReplaceVisitor(replacements);
+      visitor.visitBlock(block);
+   }
+
+   /** Creates a visitor that can replace labels. */
+   private ControlFlowGraphBaseVisitor<Void> getLabelReplaceVisitor(final Map<Label, Label> replacements) {
+      return new ControlFlowGraphBaseVisitor<Void>() {
 
             @Override
             public Void visitConditionalJump(StatementConditionalJump conditionalJump) {
@@ -200,7 +216,6 @@ public abstract class Pass2SsaOptimization {
                return null;
             }
          };
-      visitor.visitGraph(graph);
    }
 
    /**
@@ -244,13 +259,13 @@ public abstract class Pass2SsaOptimization {
    }
 
    /**
-    * Remove variables from the symbol table
+    * Remove symbols from the symbol table
     *
-    * @param variables The variables to remove
+    * @param symbols The symbols to remove
     */
-   public void deleteSymbols(Collection<? extends LValue> variables) {
+   public void deleteSymbols(Collection<? extends Symbol> symbols) {
-      for (LValue variable : variables) {
+      for (Symbol symbol : symbols) {
-         scope.remove((Symbol) variable);
+         symbol.getScope().remove(symbol);
       }
    }
 

src/dk/camelot64/kickc/icl/Pass3RegisterAllocation.java

@@ -119,6 +119,13 @@ public class Pass3RegisterAllocation {
       allocation.allocate(symbols.getVariable("flip::i#2"), RegisterAllocation.getRegisterX());
       allocation.allocate(symbols.getVariable("flip::$0"), RegisterAllocation.getRegisterA());
       allocation.allocate(symbols.getVariable("flip::$8"), RegisterAllocation.getRegisterA());
+      allocation.allocate(symbols.getVariable("$1"), RegisterAllocation.getRegisterA());
+      allocation.allocate(symbols.getVariable("$3"), RegisterAllocation.getRegisterA());
+      allocation.allocate(symbols.getVariable("c#0"), RegisterAllocation.getRegisterX());
+      allocation.allocate(symbols.getVariable("c#1"), RegisterAllocation.getRegisterX());
+      allocation.allocate(symbols.getVariable("c#2"), RegisterAllocation.getRegisterX());
+      allocation.allocate(symbols.getVariable("c#3"), RegisterAllocation.getRegisterX());
+      allocation.allocate(symbols.getVariable("c#4"), RegisterAllocation.getRegisterX());
 
       symbols.setAllocation(allocation);
 
@@ -137,6 +144,8 @@ public class Pass3RegisterAllocation {
                currentZp = currentZp + 2;
             } else if (symbol.getType().equals(SymbolTypeBasic.BOOLEAN)) {
                allocation.allocate(var, new RegisterAllocation.RegisterZpBool(currentZp++));
+            } else if (symbol.getType().equals(SymbolTypeBasic.VOID)) {
+               // No need to allocate register for VOID value
             } else if (symbol.getType() instanceof SymbolTypePointer) {
                allocation.allocate(var, new RegisterAllocation.RegisterZpPointerByte(currentZp));
                currentZp = currentZp + 2;

src/dk/camelot64/kickc/test/flipper-rex2.kc

@@ -2,10 +2,18 @@ byte[1000] SCREEN = $0400;
 byte[16*16] buffer = $1000;
 byte[16*16] buffer2 = $1100;
 
+byte *RASTER = $d012;
+
 prepare();
 do {
-   plot();
+   byte c = 25;
+   do{
+     do { } while(*RASTER!=254)
+     do { } while(*RASTER!=255)
+     c=c-1;
+   } while(c!=0)
    flip();
+   plot();
 } while(true)
 
 // Prepare buffer
@@ -21,18 +29,18 @@ void prepare() {
 void flip() {
    byte srcIdx = 0;
    byte dstIdx = 15;
-   byte r=0;
+   byte r=16;
    do {
-      byte c = 0;
+      byte c = 16;
       do {
          buffer2[dstIdx] = buffer[srcIdx];
          srcIdx = srcIdx+1;
          dstIdx = dstIdx+16;
-         c=c+1;
+         c=c-1;
-      } while(c<16)
+      } while(c!=0)
-      r=r+1;
       dstIdx = dstIdx-1;
-    } while(r<16)
+      r=r-1;
+     } while(r!=0)
    byte i=0;
    do {
       buffer[i] = buffer2[i];
@@ -43,7 +51,7 @@ void flip() {
 // Plot buffer on screen
 void plot() {
    byte* line = SCREEN+5*40+12;
-   byte y=0;
+   byte y=16;
    byte i=0;
    do {
       byte x=0;
@@ -53,6 +61,6 @@ void plot() {
          i=i+1;
       } while(x<16)
       line = line+40;
-      y=y+1;
+      y=y-1;
-   } while(y<16)
+   } while(y!=0)
 }