Improve bytecode generation.

src/jse/org/luaj/vm2/luajc/BasicBlock.java

@@ -3,7 +3,6 @@
  */
 package org.luaj.vm2.luajc;
 
-import java.util.Hashtable;
 import java.util.Vector;
 
 import org.luaj.vm2.Lua;
@@ -13,6 +12,7 @@ public class BasicBlock {
 	int pc0,pc1;        // range of program counter values for the block
 	BasicBlock[] prev;  // previous basic blocks (0-n of these)
 	BasicBlock[] next;  // next basic blocks (0, 1, or 2 of these)
+	boolean islive;     // true if this block is used
 	
 	public BasicBlock(Prototype p, int pc0) {
 		this.pc0 = this.pc1 = pc0;
@@ -151,35 +151,30 @@ public class BasicBlock {
 		}
 	}
 	
-	public static BasicBlock[] sortDepthFirst(BasicBlock[] blocks) {
-		Vector list = new Vector();
-		Hashtable seen = new Hashtable();
+	public static BasicBlock[] findLiveBlocks(BasicBlock[] blocks) {
+		// add reachable blocks
 		Vector next = new Vector ();
-		BasicBlock b0,b1,b[];
-
 		next.addElement( blocks[0] );
-		seen.put( blocks[0], Boolean.TRUE );
-		while ( (b = toBasicBlockArray(next)) != null ) {
-			next.clear();
-			for ( int i=0; i<b.length; i++ ) {
-				list.addElement( b0 = b[i] );
-				for ( int k=0, n=b0.next!=null? b0.next.length: 0; k<n; k++ ) {
-					if ( seen.get( b1 = b0.next[k] ) == null ) {
-						seen.put( b1, Boolean.TRUE );
-						next.addElement( b1 );
+		while ( ! next.isEmpty() ) {
+			BasicBlock b = (BasicBlock) next.elementAt(0);
+			next.removeElementAt(0);
+			if ( ! b.islive ) {
+				b.islive = true;
+				for ( int i=0, n=b.next!=null? b.next.length: 0; i<n; i++ )
+					if ( ! b.next[i].islive )
+						next.addElement( b.next[i] );
 			}
 		}
-			}
-		}
-		return toBasicBlockArray(list);
-	}
 		
-	private static BasicBlock[] toBasicBlockArray(Vector list) {
-		if ( list.size() <= 0 )
-			return null;
+		// create list in natural order
+		Vector list = new Vector();
+		for ( int i=0; i<blocks.length; i=blocks[i].pc1+1 )
+			if ( blocks[i].islive )
+				list.addElement(blocks[i]);
+		
+		// convert to array
 		BasicBlock[] array = new BasicBlock[list.size()];
 		list.copyInto(array);
 		return array;
 	}
-
 }

src/jse/org/luaj/vm2/luajc/JavaGen.java

@@ -66,15 +66,19 @@ public class JavaGen {
 		Prototype p = pi.prototype;
 		int vresultbase = -1;
 		
-		for ( int pc=0, n=p.code.length; pc<n; pc++ ) {
+		for ( int bi=0; bi<pi.blocklist.length; bi++ ) {
+			BasicBlock b0 = pi.blocklist[bi];
 
-			// skip dead blocks
-			BasicBlock b0 = pi.blocks[pc];
-			if ( b0.pc0>0 && b0.prev == null ) {
-				pc = b0.pc1;
-				continue;
+			// convert upvalues that are phi-variables
+			for ( int slot=0; slot<p.maxstacksize; slot++ ) {
+				int pc = b0.pc0;
+				boolean c = pi.isUpvalueCreate(pc, slot);
+				if ( c && pi.vars[slot][pc].isPhiVar() )
+					builder.convertToUpvalue(pc, slot);
 			}
 			
+			for ( int pc=b0.pc0; pc<=b0.pc1; pc++ ) {
+				
 				int pc0 = pc; // closure changes pc
 				int ins = p.code[pc];
 				final int o = Lua.GET_OPCODE(ins);
@@ -391,28 +395,6 @@ public class JavaGen {
 					
 				case Lua.OP_CLOSURE: /*	A Bx	R(A):= closure(KPROTO[Bx], R(A), ... ,R(A+n))	*/
 				{
-				/*
-				String protoname = closureName(classname, bx);
-				int nups = p.p[bx].nups;
-				for ( int k=1; k<=nups; ++k ) {
-					builder.dup();
-					int i = p.code[pc+k];
-					b = Lua.GETARG_B(i);
-					if ( (i&4) == 0 ) {
-						builder.closureInitUpvalueFromUpvalue( protoname, k-1, b );
-					} else {
-						builder.closureInitUpvalueFromLocal( protoname, k-1, pc, b );
-					}
-				}
-				v[a][pc] = new VarInfo(a,pc);
-				for ( int k=1; k<=nups; ++k ) {
-					for ( int j=0; j<m; j++ )
-						v[j][pc+k] = v[j][pc];
-				}
-				pc += nups;
-/*/
-				
-				
 					Prototype newp = p.p[bx];
 					String protoname = closureName(classname, bx);
 					int nup = newp.nups;
@@ -434,7 +416,6 @@ public class JavaGen {
 						}
 						pc += nup;
 					}
-				//*/
 					break;
 				}				
 				case Lua.OP_VARARG: /*	A B	R(A), R(A+1), ..., R(A+B-1) = vararg		*/
@@ -455,6 +436,7 @@ public class JavaGen {
 				builder.onEndOfLuaInstruction( pc0 );
 			}
 		}
+	}
 
 	private void loadVarargResults(JavaBuilder builder, int pc, int a, int vresultbase) {
 		if ( vresultbase <= a ) {

src/jse/org/luaj/vm2/luajc/ProtoInfo.java

@@ -22,7 +22,6 @@ public class ProtoInfo {
 	public final UpvalInfo[] upvals;      // from outer scope
 	public final UpvalInfo[][] openups;   // per slot, upvalues allocated by this prototype
 	
-	
 	public ProtoInfo(Prototype p, String name) {
 		this(p,name,null);
 	}
@@ -35,8 +34,7 @@ public class ProtoInfo {
 		
 		// find basic blocks
 		this.blocks = BasicBlock.findBasicBlocks(p);
-		this.blocklist = BasicBlock.sortDepthFirst(blocks);
-
+		this.blocklist = BasicBlock.findLiveBlocks(blocks);
 		
 		// params are inputs to first block
 		this.params = new VarInfo[p.maxstacksize];
@@ -65,8 +63,9 @@ public class ProtoInfo {
 			sb.append( " up["+i+"]: "+upvals[i]+"\n" );
 		
 		// basic blocks
-		for ( int pc0=blocks[0].pc0; pc0<prototype.code.length; pc0=blocks[pc0].pc1+1 ) {
-			BasicBlock b = blocks[pc0];
+		for ( int i=0; i<blocklist.length; i++ ) {
+			BasicBlock b = blocklist[i];
+			int pc0 = b.pc0;
 			sb.append( "  block "+b.toString() );
 			appendOpenUps( sb, -1 );
 			
@@ -143,19 +142,18 @@ public class ProtoInfo {
 						if ( v[slot][bp.pc1] == VarInfo.INVALID )
 							var = VarInfo.INVALID;
 					}
+				}
 				if ( var == null )
 					var = VarInfo.PHI(this, slot, b0.pc0);
-				}
 				v[slot][b0.pc0] = var;
 			}
 
 			// process instructions for this basic block
 			for ( int pc=b0.pc0; pc<=b0.pc1; pc++ ) {
 			
-				// propogate previous for all but block boundaries
+				// propogate previous values except at block boundaries
 				if (  pc > b0.pc0 )
-					for ( int j=0; j<m; j++ )
-						v[j][pc] = v[j][pc-1];
+					propogateVars( v, pc-1, pc );
 				
 				int a,b,c,nups;
 				int ins = prototype.code[pc];
@@ -322,10 +320,8 @@ public class ProtoInfo {
 						}
 					}
 					v[a][pc] = new VarInfo(a,pc);
-					for ( int k=1; k<=nups; ++k ) {
-						for ( int j=0; j<m; j++ )
-							v[j][pc+k] = v[j][pc];
-					}
+					for ( int k=1; k<=nups; k++ )
+						propogateVars( v, pc, pc+k );
 					pc += nups;
 					break;
 				case Lua.OP_CLOSE: /*	A 	close all variables in the stack up to (>=) R(A)*/
@@ -369,11 +365,16 @@ public class ProtoInfo {
 		return v;
 	}
 
+	private static void propogateVars(VarInfo[][] v, int pcfrom, int pcto) {
+		for ( int j=0, m=v.length; j<m; j++ )
+			v[j][pcto] = v[j][pcfrom];
+	}
+
 	private void replaceTrivialPhiVariables() {		
 		for ( int i=0; i<blocklist.length; i++ ) {
 			BasicBlock b0 = blocklist[i];
 			for ( int slot=0; slot<prototype.maxstacksize; slot++ ) {
-				VarInfo vold = vars[slot][b0.pc1];
+				VarInfo vold = vars[slot][b0.pc0];
 				VarInfo vnew = vold.resolvePhiVariableValues();
 				if ( vnew != null )
 					substituteVariable( slot, vold, vnew );
@@ -443,7 +444,7 @@ public class ProtoInfo {
 
 	public boolean isUpvalueRefer(int pc, int slot) {
 		// special case when both refer and assign in same instruction
-		if ( pc >= 0 && vars[slot][pc] != null && vars[slot][pc].pc == pc )
+		if ( pc > 0 && vars[slot][pc] != null && vars[slot][pc].pc == pc && vars[slot][pc-1] != null  )
 			pc -= 1;
 		VarInfo v = pc<0? params[slot]: vars[slot][pc];
 		return v != null && v.upvalue != null && v.upvalue.rw;

src/jse/org/luaj/vm2/luajc/VarInfo.java

@@ -63,6 +63,10 @@ public class VarInfo {
 		vars.add(this);
 	}
 
+	public boolean isPhiVar() {
+		return false;
+	}
+
 	private static final class PhiVarInfo extends VarInfo {
 		private final ProtoInfo pi;
 		VarInfo[] values;
@@ -72,6 +76,10 @@ public class VarInfo {
 			this.pi = pi;
 		}
 
+		public boolean isPhiVar() {
+			return true;
+		}
+
 		public String toString() {
 			StringBuffer sb = new StringBuffer();
 			sb.append( super.toString() );
@@ -108,6 +116,8 @@ public class VarInfo {
 
 		protected void collectUniqueValues(Set visitedBlocks, Set vars) {
 			BasicBlock b = pi.blocks[pc];
+			if ( pc == 0 )
+				vars.add(pi.params[slot]);
 			for (int i = 0, n = b.prev != null ? b.prev.length : 0; i < n; i++) {
 				BasicBlock bp = b.prev[i];
 				if (!visitedBlocks.contains(bp)) {

test/junit/org/luaj/vm2/FragmentsTest.java

@@ -501,5 +501,53 @@ public class FragmentsTest extends TestSuite {
 			        "    return c,b,a\n" +
 			        "end\n" );
 		}
+		
+		public void testPhiUpvalue() {
+			runFragment( LuaValue.valueOf(6), 
+					"local a = foo or 0\n"+
+					"local function b(c)\n"+
+					"	if c > a then a = c end\n" +
+					"	return a\n"+
+					"end\n" +
+					"b(6)\n" +
+					"return a\n" );
+		}
+		
+		public void testAssignReferUpvalues() {
+			runFragment( LuaValue.valueOf(123), 
+					"local entity = 234\n" +
+				    "local function c()\n" +
+					"    return entity\n" +
+					"end\n" +
+				    "entity = (a == b) and 123\n" +
+				    "if entity then\n" +
+				    "    return entity\n" +
+				    "end\n" );			
+		}
+		
+		public void testSimpleRepeatUntil() {
+			runFragment( LuaValue.valueOf(5), 
+					"local a\n"+
+					"local w\n"+
+					"repeat\n"+
+					"	a = w\n"+
+					"until not a\n" +
+					"return 5\n" );
+		}
+		
+		public void testTwoLoops() {
+			runFragment( LuaValue.valueOf("b"), 
+					"local env = {}\n" +
+					"for a,b in pairs(_G) do\n" +
+					"	c = function()\n" +
+					"		return b\n" +
+					"	end\n" +
+					"end\n" +
+					"local e = env\n" +
+					"local f = {a='b'}\n" +
+					"for k,v in pairs(f) do\n" +
+					"	return env[k] or v\n" +
+					"end\n");
+		}
 	}
 }