Merge pull request #297 from fglock/fix/range-operator-asm-crash

Fix ASM frame crash when range operator RHS is a constant sub

Author: fglock

src/main/java/org/perlonjava/backend/jvm/EmitOperator.java

@@ -541,9 +541,31 @@ static void handleGlobBuiltin(EmitterVisitor emitterVisitor, OperatorNode node)
 
     // Handles the 'range' operator, which creates a range of values.
     static void handleRangeOperator(EmitterVisitor emitterVisitor, BinaryOperatorNode node) {
-        // Accept both left and right operands in SCALAR context.
-        node.left.accept(emitterVisitor.with(RuntimeContextType.SCALAR));
-        node.right.accept(emitterVisitor.with(RuntimeContextType.SCALAR));
+        // Spill the left operand before evaluating the right side so non-local control flow
+        // propagation can't jump to returnLabel with an extra value on the JVM operand stack.
+        if (ENABLE_SPILL_BINARY_LHS) {
+            MethodVisitor mv = emitterVisitor.ctx.mv;
+            node.left.accept(emitterVisitor.with(RuntimeContextType.SCALAR));
+
+            int leftSlot = emitterVisitor.ctx.javaClassInfo.acquireSpillSlot();
+            boolean pooled = leftSlot >= 0;
+            if (!pooled) {
+                leftSlot = emitterVisitor.ctx.symbolTable.allocateLocalVariable();
+            }
+            mv.visitVarInsn(Opcodes.ASTORE, leftSlot);
+
+            node.right.accept(emitterVisitor.with(RuntimeContextType.SCALAR));
+
+            mv.visitVarInsn(Opcodes.ALOAD, leftSlot);
+            mv.visitInsn(Opcodes.SWAP);
+
+            if (pooled) {
+                emitterVisitor.ctx.javaClassInfo.releaseSpillSlot();
+            }
+        } else {
+            node.left.accept(emitterVisitor.with(RuntimeContextType.SCALAR));
+            node.right.accept(emitterVisitor.with(RuntimeContextType.SCALAR));
+        }
         emitOperator(node, emitterVisitor);
     }