mjc2wsl - new option to toggle locals as array or separate

this introduces the code to generate local variables in procedures
to be separate and separatly be put on the stack (though not
exactly in the same way as in the original VM), instead of
using one array to store all of the local varaiables which simulated
the "stack frame".

diff --git a/src/com/quemaster/transformations/mjc2wsl/mjc2wsl.java b/src/com/quemaster/transformations/mjc2wsl/mjc2wsl.java
index ce82101..233d5ae 100644 (file)
--- a/src/com/quemaster/transformations/mjc2wsl/mjc2wsl.java
+++ b/src/com/quemaster/transformations/mjc2wsl/mjc2wsl.java
@@ -56,6 +56,9 @@ public class mjc2wsl{
        
        private boolean genLocalVars = true;
 
+       // make an array for all local variables OTHERWISE make them separate
+       private boolean genLocalsAsArray = true;
+
        /** Constant used for marking a regular comment from the original file */
        public static final char C_REG = ' ';
        /**
@@ -185,7 +188,10 @@ public class mjc2wsl{
                        ret.append("\n\ttempa := 0, tempb :=0, tempres := 0,");
                } else
                        ret.append("\n\tmjvm_flag_jump := 0,");
-               ret.append("mjvm_locals := ARRAY(1,0),");
+
+               if (genLocalsAsArray)
+                       ret.append("mjvm_locals := ARRAY(1,0),");
+
                ret.append("\n\tmjvm_statics := ARRAY("+numWords+",0),");
                ret.append("\n\tmjvm_arrays := < >,");
                ret.append("\n\tmjvm_objects := < >,");
@@ -246,7 +252,10 @@ public class mjc2wsl{
        
        private String createLocal(int i) {
                // arrays start at 1 in WSL, so we need an offset
-               return "mjvm_locals[" + (i + 1) + "]";
+               if (genLocalsAsArray)
+                       return "mjvm_locals[" + (i + 1) + "]";
+               else
+                       return "mjvm_locals_" + i;
        }
 
        private String createStatic(int i) {
@@ -354,6 +363,10 @@ public class mjc2wsl{
                
                prl(createStandardStart(mjInput.getNumberOfWords(this)));
                prl("SKIP;\n ACTIONS a" + (14 + mjInput.getMainAdr(this)) + " :");
+
+               // the number of Locals for procedures; need to remember it for exits
+               int numberOfLocals = 0;
+
                int op = mjInput.get();
                while (op >= 0) {
                        prl(" a" + mjInput.getCounter() + " ==");
@@ -635,15 +648,29 @@ public class mjc2wsl{
                        case enter: {
                                int parameters = mjInput.get();
 
-                               int locals = mjInput.get();
-                               prl(createToMStack("mjvm_locals"));
-                               prl("mjvm_locals := ARRAY(" + locals + ",0);");
+                               numberOfLocals = mjInput.get();
+                               if (genLocalsAsArray) {
+                                       prl(createToMStack("mjvm_locals"));
+                                       prl("mjvm_locals := ARRAY(" + numberOfLocals + ",0);");
+                               } else {
+                                       // TODO maybe we should generate VAR block for these somewhere
+                                       for (int i = 0; i < numberOfLocals; i++) {
+                                               prl(createToMStack(createLocal(i)));
+                                       }
+                               }
+
                                for (int i = parameters - 1; i >= 0; i--)
                                        prl(createFromEStack(createLocal(i)));
                                break;
                        }
                        case exit: {
-                               prl(createFromMStack("mjvm_locals"));
+                               if (genLocalsAsArray) {
+                                       prl(createFromMStack("mjvm_locals"));
+                               } else {
+                                       // there are as many locals as defined in the last enter
+                                       for (int i = numberOfLocals -1; i >= 0; i--)
+                                               prl(createFromMStack(createLocal(i)));
+                               }
                                break;
                        }
 
@@ -777,6 +804,11 @@ public class mjc2wsl{
                System.out.println(" --genLocalVars generate local VAR block for temp variables");
                System.out.print(!genLocalVars?'*':' ');
                System.out.println(" --genGlobalVars do NOT generate local VAR block for temp variables");
+               System.out.println();
+               System.out.print(genLocalsAsArray?'*':' ');
+               System.out.println(" --genLocalsAsArray generate local variables as an array");
+               System.out.print(!genLocalsAsArray?'*':' ');
+               System.out.println(" --genLocalsSeparate generate local variables as separate entities");
        }
 
        public void printHelpHelp() {
@@ -859,6 +891,10 @@ public class mjc2wsl{
                                        genLocalVars = true;
                                } else if (args[i].compareToIgnoreCase("--genGlobalVars") == 0) {
                                        genLocalVars = false;
+                               } else if (args[i].compareToIgnoreCase("--genLocalsAsArray") == 0) {
+                                       genLocalsAsArray = true;
+                               } else if (args[i].compareToIgnoreCase("--genLocalsSeparate") == 0) {
+                                       genLocalsAsArray = false;
                                } else {
                                        System.err.println("unknown option: "+args[i]);
                                }