* net/loveruby/cflat/compiler/CodeGenerator.java: apply jump elimination.

* net/loveruby/cflat/asm/PeepholeOptimizer.java: new optimization method: jump elimination.
* net/loveruby/cflat/asm/Assembler.java: refactoring: #string -> #toSource.
* net/loveruby/cflat/asm/Assembler.java: refactoring: list -> assemblies.
* net/loveruby/cflat/asm/Assembly.java: new method #isDirective and #isComment.
* net/loveruby/cflat/asm/Directive.java: implement it.
* net/loveruby/cflat/asm/AsmComment.java: implement it.
* net/loveruby/cflat/asm/Label.java: implement it.
* net/loveruby/cflat/asm/Label.java: new method #equals, #hashCode.
* net/loveruby/cflat/asm/Instruction.java: add jump related methods to analyze jump instruction.
* net/loveruby/cflat/asm/LabelRef.java: new method #label to allow extracting a Label.
* net/loveruby/cflat/asm/Register.java: new method #equals, #hashCode.
* net/loveruby/cflat/asm/AsmStatistics.java: use Object for map keys.
* net/loveruby/cflat/asm/AsmStatistics.java: new method #doesRegisterUsed.
* net/loveruby/cflat/utils/ClonableIterator.java: new utility.


git-svn-id: file:///Users/aamine/c/gitwork/public/cbc/trunk@4050 1b9489fe-b721-0410-924e-b54b9192deb8

ChangeLog

@@ -1,3 +1,46 @@
+Tue Sep 23 22:50:52 2008  Minero Aoki  <aamine@loveruby.net>
+
+	* net/loveruby/cflat/compiler/CodeGenerator.java: apply jump
+	  elimination.
+
+	* net/loveruby/cflat/asm/PeepholeOptimizer.java: new optimization
+	  method: jump elimination.
+
+	* net/loveruby/cflat/asm/Assembler.java: refactoring: #string ->
+	  #toSource.
+
+	* net/loveruby/cflat/asm/Assembler.java: refactoring: list ->
+	  assemblies.
+
+	* net/loveruby/cflat/asm/Assembly.java: new method #isDirective
+	  and #isComment.
+
+	* net/loveruby/cflat/asm/Directive.java: implement it.
+
+	* net/loveruby/cflat/asm/AsmComment.java: implement it.
+
+	* net/loveruby/cflat/asm/Label.java: implement it.
+
+	* net/loveruby/cflat/asm/Label.java: new method #equals,
+	  #hashCode.
+
+	* net/loveruby/cflat/asm/Instruction.java: add jump related
+	  methods to analyze jump instruction.
+
+	* net/loveruby/cflat/asm/LabelRef.java: new method #label to allow
+	  extracting a Label.
+
+	* net/loveruby/cflat/asm/Register.java: new method #equals,
+	  #hashCode.
+
+	* net/loveruby/cflat/asm/AsmStatistics.java: use Object for map
+	  keys.
+
+	* net/loveruby/cflat/asm/AsmStatistics.java: new method
+	  #doesRegisterUsed.
+
+	* net/loveruby/cflat/utils/ClonableIterator.java: new utility.
+
 Tue Sep 23 22:45:00 2008  Minero Aoki  <aamine@loveruby.net>
 
 	* lib/Makefile: parameterize.

net/loveruby/cflat/asm/AsmComment.java

@@ -13,6 +13,10 @@ public class AsmComment extends Assembly {
         this.indentLevel = indentLevel;
     }
 
+    public boolean isComment() {
+        return true;
+    }
+
     public String toSource() {
         return "\t" + indent() + "# " + string;
     }

net/loveruby/cflat/asm/AsmStatistics.java

@@ -20,12 +20,16 @@ public class AsmStatistics {
         insnUsage = new HashMap();
     }
 
-    public int numRegisterUsage(String name) {
+    public boolean doesRegisterUsed(Register reg) {
-        return fetchCount(registerUsage, name);
+        return numRegisterUsage(reg) > 0;
     }
 
-    public void registerUsed(String name) {
+    public int numRegisterUsage(Register reg) {
-        incrementCount(registerUsage, name);
+        return fetchCount(registerUsage, reg);
+    }
+
+    public void registerUsed(Register reg) {
+        incrementCount(registerUsage, reg);
     }
 
     public int numInstructionUsage(String insn) {
@@ -36,8 +40,8 @@ public class AsmStatistics {
         incrementCount(insnUsage, insn);
     }
 
-    protected int fetchCount(Map m, String name) {
+    protected int fetchCount(Map m, Object key) {
-        Integer n = (Integer)m.get(name);
+        Integer n = (Integer)m.get(key);
         if (n == null) {
             return 0;
         }
@@ -46,7 +50,7 @@ public class AsmStatistics {
         }
     }
 
-    protected void incrementCount(Map m, String name) {
+    protected void incrementCount(Map m, Object key) {
-        m.put(name, new Integer(fetchCount(m, name) + 1));
+        m.put(key, new Integer(fetchCount(m, key) + 1));
     }
 }

net/loveruby/cflat/asm/Assembler.java

@@ -4,7 +4,7 @@ import net.loveruby.cflat.utils.*;
 import java.util.*;
 
 public class Assembler {
-    protected List list;        // List<Assembly>
+    protected List assemblies;        // List<Assembly>
     protected Type naturalType;
     protected int commentIndentLevel;
 
@@ -13,24 +13,24 @@ public class Assembler {
     }
 
     public Assembler(Type naturalType) {
-        this.list = new ArrayList();
+        this.assemblies = new ArrayList();
         this.naturalType = naturalType;
         this.commentIndentLevel = 0;
     }
 
     public List assemblies() {
-        return this.list;
+        return this.assemblies;
     }
 
     public void addAll(List assemblies) {
-        this.list.addAll(assemblies);
+        this.assemblies.addAll(assemblies);
     }
 
-    public String string() {
+    public String toSource() {
         StringBuffer buf = new StringBuffer();
-        Iterator i = list.iterator();
+        Iterator asms = assemblies.iterator();
-        while (i.hasNext()) {
+        while (asms.hasNext()) {
-            Assembly asm = (Assembly)i.next();
+            Assembly asm = (Assembly)asms.next();
             buf.append(asm.toSource());
             buf.append("\n");
         }
@@ -38,7 +38,7 @@ public class Assembler {
     }
 
     public void comment(String str) {
-        list.add(new AsmComment(str, commentIndentLevel));
+        assemblies.add(new AsmComment(str, commentIndentLevel));
     }
 
     public void indentComment() {
@@ -50,39 +50,39 @@ public class Assembler {
     }
 
     public void label(String sym) {
-        list.add(new Label(sym));
+        assemblies.add(new Label(sym));
     }
 
     public void label(Label label) {
-        list.add(label);
+        assemblies.add(label);
     }
 
     protected void directive(String direc) {
-        list.add(new Directive(direc));
+        assemblies.add(new Directive(direc));
     }
 
     protected void insn(String op) {
-        list.add(new Instruction(op));
+        assemblies.add(new Instruction(op));
     }
 
     protected void insn(String op, AsmOperand a) {
-        list.add(new Instruction(op, "", a));
+        assemblies.add(new Instruction(op, "", a));
     }
 
     protected void insn(String op, String suffix, AsmOperand a) {
-        list.add(new Instruction(op, suffix, a));
+        assemblies.add(new Instruction(op, suffix, a));
     }
 
     protected void insn(Type t, String op, AsmOperand a) {
-        list.add(new Instruction(op, typeSuffix(t), a));
+        assemblies.add(new Instruction(op, typeSuffix(t), a));
     }
 
     protected void insn(String op, String suffix, AsmOperand a, AsmOperand b) {
-        list.add(new Instruction(op, suffix, a, b));
+        assemblies.add(new Instruction(op, suffix, a, b));
     }
 
     protected void insn(Type t, String op, AsmOperand a, AsmOperand b) {
-        list.add(new Instruction(op, typeSuffix(t), a, b));
+        assemblies.add(new Instruction(op, typeSuffix(t), a, b));
     }
 
     protected String typeSuffix(Type t1, Type t2) {

net/loveruby/cflat/asm/Assembly.java

@@ -11,6 +11,14 @@ abstract public class Assembly {
         return false;
     }
 
+    public boolean isDirective() {
+        return false;
+    }
+
+    public boolean isComment() {
+        return false;
+    }
+
     public void collectStatistics(AsmStatistics stats) {
         // does nothing by default.
     }

net/loveruby/cflat/asm/Directive.java

@@ -7,6 +7,10 @@ public class Directive extends Assembly {
         this.content = content;
     }
 
+    public boolean isDirective() {
+        return true;
+    }
+
     public String toSource() {
         return this.content;
     }

net/loveruby/cflat/asm/Instruction.java

@@ -41,6 +41,17 @@ public class Instruction extends Assembly {
         return this.mnemonic;
     }
 
+    public boolean isJumpInstruction() {
+        return mnemonic.equals("jmp")
+                || mnemonic.equals("jz")
+                || mnemonic.equals("jne")
+                || mnemonic.equals("je")
+                || mnemonic.equals("jne");
+    }
+
+    /**
+     * Returns the number of operands.
+     */
     public int numOperands() {
         return this.operands.length;
     }
@@ -53,6 +64,14 @@ public class Instruction extends Assembly {
         return this.operands[1];
     }
 
+    /**
+     * Extract jump destination label from operands.
+     */
+    public Label jmpDestination() {
+        DirectMemoryReference ref = (DirectMemoryReference)(operands[0]);
+        return ((LabelRef)ref.value()).label();
+    }
+
     public void collectStatistics(AsmStatistics stats) {
         stats.instructionUsed(mnemonic);
         for (int i = 0; i < operands.length; i++) {

net/loveruby/cflat/asm/Label.java

@@ -14,6 +14,10 @@ public class Label extends Assembly {
         name = n;
     }
 
+    public boolean isLabel() {
+        return true;
+    }
+
     public long seq() {
         return seq;
     }
@@ -22,6 +26,23 @@ public class Label extends Assembly {
         return name;
     }
 
+    public boolean equals(Object other) {
+        if (other instanceof Label) {
+            return equals((Label)other);
+        }
+        else {
+            return false;
+        }
+    }
+
+    public int hashCode() {
+        return name.hashCode();
+    }
+
+    public boolean equals(Label label) {
+        return name.equals(label.name());
+    }
+
     public String toSource() {
         return name + ":";
     }

net/loveruby/cflat/asm/LabelRef.java

@@ -7,6 +7,10 @@ public class LabelRef extends Literal {
         this.label = label;
     }
 
+    public Label label() {
+        return label;
+    }
+
     public String symbol() {
         return label.name();
     }

net/loveruby/cflat/asm/PeepholeOptimizer.java

@@ -1,4 +1,5 @@
 package net.loveruby.cflat.asm;
+import net.loveruby.cflat.utils.ClonableIterator;
 import java.util.*;
 
 public class PeepholeOptimizer implements AsmOptimizer {
@@ -8,6 +9,10 @@ public class PeepholeOptimizer implements AsmOptimizer {
         this.filters = defaultFilterSet();
     }
 
+    public List optimize(List assemblies) {
+        return jumpElimination(insnOptimization(assemblies));
+    }
+
     // List<Filter>
     protected List defaultFilterSet() {
         List set = new ArrayList();
@@ -123,7 +128,7 @@ public class PeepholeOptimizer implements AsmOptimizer {
         return new AnyRegisterPattern();
     }
 
-    public List optimize(List assemblies) {
+    public List insnOptimization(List assemblies) {
         List result = new ArrayList();
         Iterator asms = assemblies.iterator();
         while (asms.hasNext()) {
@@ -205,4 +210,64 @@ public class PeepholeOptimizer implements AsmOptimizer {
     interface InsnTemplate {
         abstract public Instruction apply(Instruction insn);
     }
+
+    //
+    // jumpElimination
+    //
+
+    public List jumpElimination(List assemblies) {
+        List result = new ArrayList();
+        ClonableIterator asms = new ClonableIterator(assemblies);
+        while (asms.hasNext()) {
+            Assembly asm = (Assembly)asms.next();
+            if (isUselessJump(asm, asms)) {
+                ;  // remove useless jump
+            }
+            else {
+                result.add(asm);
+            }
+        }
+        return result;
+    }
+
+    protected boolean isUselessJump(Assembly asm, ClonableIterator asms) {
+        if (! asm.isInstruction()) return false;
+        Instruction insn = (Instruction)asm;
+        if (! insn.isJumpInstruction()) return false;
+        return doesLabelFollows(asms.dup(), insn.jmpDestination());
+    }
+
+    /**
+     * Returns true if jmpDest is found in asms before any instruction
+     * or directives.  For example, this method returns true if contents
+     * of asms are:
+     *
+     *    if_end3:
+     *          # comment
+     *    jmpDest:
+     *          mov
+     *          mov
+     *          add
+     */
+    protected boolean doesLabelFollows(ClonableIterator asms, Label jmpDest) {
+        while (asms.hasNext()) {
+            Assembly asm = (Assembly)asms.next();
+            if (asm.isLabel()) {
+                Label label = (Label)asm;
+                if (label.equals(jmpDest)) {
+                    return true;
+                }
+                else {
+                    continue;
+                }
+            }
+            else if (asm.isComment()) {
+                continue;
+            }
+            else {
+                return false;
+            }
+        }
+        return false;
+    }
 }

net/loveruby/cflat/asm/Register.java

@@ -32,6 +32,22 @@ public class Register extends AsmOperand {
         return true;
     }
 
+    public boolean equals(Object other) {
+        if (!(other instanceof Register)) return false;
+        return equals((Register)other);
+    }
+
+    public int hashCode() {
+        return name.hashCode();
+    }
+
+    /**
+     * size difference does NOT matter.
+     */
+    public boolean equals(Register reg) {
+        return name.equals(reg.baseName());
+    }
+
     public String baseName() {
         return name;
     }
@@ -62,7 +78,7 @@ public class Register extends AsmOperand {
     }
 
     public void collectStatistics(AsmStatistics stats) {
-        stats.registerUsed(name);
+        stats.registerUsed(this);
     }
 
     public String toSource() {

net/loveruby/cflat/compiler/CodeGenerator.java

@@ -9,7 +9,7 @@ public class CodeGenerator extends Visitor implements ASTLHSVisitor {
     protected AsmOptimizer optimizer;
     protected ErrorHandler errorHandler;
     protected boolean verboseAsm;
-    protected Assembler assembler;
+    protected LinkedList asStack;
     protected Assembler as;
     protected TypeTable typeTable;
     protected DefinedFunction currentFunction;
@@ -20,6 +20,7 @@ public class CodeGenerator extends Visitor implements ASTLHSVisitor {
         this.optimizer = optimizer;
         this.errorHandler = errorHandler;
         this.verboseAsm = verboseAsm;
+        this.asStack = new LinkedList();
     }
     // #@@}
 
@@ -27,12 +28,26 @@ public class CodeGenerator extends Visitor implements ASTLHSVisitor {
     // #@@range/generate
     public String generate(AST ast) {
         this.typeTable = ast.typeTable();
-        this.assembler = newAssembler();
+        pushAssembler();
-        this.as = this.assembler;
         allocateGlobalVariables(ast.globalVariables());
         allocateCommonSymbols(ast.commonSymbols());
         compileAST(ast);
-        return as.string();
+        return popAssembler().toSource();
+    }
+
+    protected void pushAssembler() {
+        asStack.add(newAssembler());
+        this.as = (Assembler)asStack.getLast();
+    }
+
+    protected Assembler popAssembler() {
+        Assembler poped = (Assembler)asStack.removeLast();
+        this.as = asStack.isEmpty() ? null : (Assembler)asStack.getLast();
+        return poped;
+    }
+
+    protected Assembler newAssembler() {
+        return new Assembler(typeTable.unsignedLong());
     }
 
     public void compileAST(AST ast) {
@@ -54,10 +69,6 @@ public class CodeGenerator extends Visitor implements ASTLHSVisitor {
     }
     // #@@}
 
-    protected Assembler newAssembler() {
-        return new Assembler(typeTable.unsignedLong());
-    }
-
     /**
      * Sets memory reference for...
      *   * public global variables
@@ -189,37 +200,38 @@ public class CodeGenerator extends Visitor implements ASTLHSVisitor {
     /** Compiles a function. */
     // #@@range/compileFunction{
     protected void compileFunction(DefinedFunction func) {
-        long numSavedRegs = 0;  // 1 for PIC
         allocateParameters(func);
         allocateLocalVariablesTemp(func.body().scope());
 
-        List bodyAsms = compileFunctionBody(func);
-        AsmStatistics stats = AsmStatistics.collect(bodyAsms);
-        List usedCalleeSavedRegs = usedCalleeSavedRegs(stats);
-        long lvarBytes = allocateLocalVariables(func.body().scope(),
-                                                usedCalleeSavedRegs.size());
-
         String symbol = csymbol(func.name());
         if (! func.isPrivate()) {
             _globl(symbol);
         }
         _type(symbol, "@function");
         label(symbol);
-        prologue(func, usedCalleeSavedRegs, lvarBytes);
+        compileFunctionBody(func);
-        as.addAll(bodyAsms);
-        epilogue(func, usedCalleeSavedRegs, lvarBytes);
         _size(symbol, ".-" + symbol);
     }
     // #@@}
 
-    protected List compileFunctionBody(DefinedFunction func) {
+    protected void compileFunctionBody(DefinedFunction func) {
+        List bodyAsms = compileStmts(func);
+        AsmStatistics stats = AsmStatistics.collect(bodyAsms);
+        List saveRegs = usedCalleeSavedRegisters(stats);
+        long lvarBytes = allocateLocalVariables(func.body().scope(),
+                                                saveRegs.size());
+        prologue(func, saveRegs, lvarBytes);
+        as.addAll(bodyAsms);
+        epilogue(func, saveRegs, lvarBytes);
+    }
+
+    protected List compileStmts(DefinedFunction func) {
+        pushAssembler();
         currentFunction = func;
-        this.as = newAssembler();
         compile(func.body());
-        List assemblies = this.as.assemblies();
+        label(epilogueLabel(func));
-        this.as = this.assembler;
         currentFunction = null;
-        return optimizer.optimize(assemblies);
+        return optimizer.optimize(popAssembler().assemblies());
     }
 
     // #@@range/compile{
@@ -250,12 +262,12 @@ public class CodeGenerator extends Visitor implements ASTLHSVisitor {
     }
     // #@@}
 
-    protected List usedCalleeSavedRegs(AsmStatistics stats) {
+    protected List usedCalleeSavedRegisters(AsmStatistics stats) {
         List result = new ArrayList();
         Iterator regs = calleeSavedRegisters().iterator();
         while (regs.hasNext()) {
             Register reg = (Register)regs.next();
-            if (stats.numRegisterUsage(reg.baseName()) > 0) {
+            if (stats.doesRegisterUsed(reg)) {
                 result.add(reg);
             }
         }
@@ -318,16 +330,8 @@ public class CodeGenerator extends Visitor implements ASTLHSVisitor {
                             List saveRegs, long lvarBytes) {
         push(bp());
         mov(sp(), bp());
-        Iterator regs = saveRegs.iterator();
+        saveRegisters(saveRegs);
-        while (regs.hasNext()) {
-            Register reg = (Register)regs.next();
-            // bp is already saved
-            if (! reg.baseName().equals("bp")) {
-                push(reg);
-            }
-        }
         extendStack(lvarBytes);
-
         if (verboseAsm) {
             Iterator vars = func.localVariables();
             while (vars.hasNext()) {
@@ -341,21 +345,34 @@ public class CodeGenerator extends Visitor implements ASTLHSVisitor {
     // #@@range/epilogue{
     protected void epilogue(DefinedFunction func,
                             List savedRegs, long lvarBytes) {
-        label(epilogueLabel(func));
         shrinkStack(lvarBytes);
-        Iterator regs = savedRegs.iterator();
+        restoreRegisters(savedRegs);
-        while (regs.hasNext()) {
-            Register reg = (Register)regs.next();
-            if (! reg.baseName().equals("bp")) {
-                pop(reg);
-            }
-        }
         mov(bp(), sp());
         pop(bp());
         ret();
     }
     // #@@}
 
+    protected void saveRegisters(List saveRegs) {
+        Iterator regs = saveRegs.iterator();
+        while (regs.hasNext()) {
+            Register reg = (Register)regs.next();
+            if (! reg.equals(bp())) {   // bp is already saved.
+                push(reg);
+            }
+        }
+    }
+
+    protected void restoreRegisters(List savedRegs) {
+        Iterator regs = savedRegs.iterator();
+        while (regs.hasNext()) {
+            Register reg = (Register)regs.next();
+            if (! reg.equals(bp())) {   // bp is going to be restored.
+                pop(reg);
+            }
+        }
+    }
+
     // #@@range/jmpEpilogue{
     protected void jmpEpilogue() {
         jmp(new Label(epilogueLabel(currentFunction)));

net/loveruby/cflat/utils/ClonableIterator.java

@@ -0,0 +1,40 @@
+package net.loveruby.cflat.utils;
+import java.util.*;
+
+public class ClonableIterator implements Iterator {
+    protected List list;
+    protected int index;
+
+    public ClonableIterator(List list) {
+        this(list, 0);
+    }
+
+    protected ClonableIterator(List list, int index) {
+        this.list = list;
+        this.index = index;
+    }
+
+    public Object clone() {
+        return new ClonableIterator(list, index);
+    }
+
+    public ClonableIterator dup() {
+        return new ClonableIterator(list, index);
+    }
+
+    public boolean hasNext() {
+        return index < list.size();
+    }
+
+    public Object next() {
+        return list.get(index++);
+    }
+
+    public void remove() {
+        list.remove(index);
+    }
+
+    public String toString() {
+        return "#<ClonableIterator list=" + list + " index=" + index + ">";
+    }
+}