Fix use condition

Author: nielsdos

Zend/Optimizer/dfa_pass.c

@@ -1125,7 +1125,7 @@ void zend_dfa_optimize_op_array(zend_op_array *op_array, zend_optimizer_ctx *ctx
 		}
 
 		// TODO: move me to other function?
-		for (v = 0; v < ssa->vars_count; v++) {
+		for (v = 0; v < ssa->vars_count&&op_array->function_name/*TODO*/; v++) {
 			int var = ssa->vars[v].var;
 			if (var >= op_array->last_var) {
 				continue;
@@ -1155,14 +1155,15 @@ void zend_dfa_optimize_op_array(zend_op_array *op_array, zend_optimizer_ctx *ctx
 					fprintf(stderr, "OP1: %d (var=%d)\n", ssa->vars[ssa->ops[next_use].op1_def].var, var);
 				}
 #endif
-				/* Either there is no next use which is okay, or the next use is an assignment
-				 * which overrides the previous value, which is also okay. */
-				if (next_use < 0
-					|| (op_array->opcodes[next_use].opcode == ZEND_ASSIGN
-						&& ssa->ops[next_use].op1_use == v
-						&& ssa->vars[v].var == var
-						&& zend_ssa_next_use(ssa->ops, v, next_use) < 0)) {
-							//fprintf(stderr, "HELLO\n");
+				/* The next use must be an assignment, and there should be no uses after that.
+				 * If there is no next use or the next use is not an assignment, then we cannot safely 
+				 * perform the operation without a copy because the nullified value would be observable indirectly
+				 * through compact(), func_get_args(), ... */
+				if (next_use >= 0
+					&& op_array->opcodes[next_use].opcode == ZEND_ASSIGN
+					&& ssa->ops[next_use].op1_use == v
+					&& ssa->vars[v].var == var
+					&& zend_ssa_next_use(ssa->ops, v, next_use) < 0) {
 					ZEND_ASSERT(op_array->opcodes[use].extended_value == 0);
 					op_array->opcodes[use].extended_value = 1;
 				}

Zend/zend_vm_def.h

@@ -9900,7 +9900,7 @@ ZEND_VM_HOT_TYPE_SPEC_HANDLER(ZEND_SEND_VAR, op->op2_type == IS_UNUSED && op->ex
 	arg = ZEND_CALL_VAR(EX(call), opline->result.var);
 
 	ZVAL_COPY_VALUE(arg, varptr);
-	ZVAL_NULL(varptr);
+	ZVAL_NULL(varptr);//TODO: what if this is uninit?
 	//fprintf(stderr, "Hello world, %d\n", Z_REFCOUNTED_P(arg));
 
 	ZEND_VM_NEXT_OPCODE();