Only clear it if it needs to be cleared

Author: nielsdos

Zend/Optimizer/dfa_pass.c

@@ -466,12 +466,14 @@ int zend_dfa_optimize_calls(zend_op_array *op_array, zend_ssa *ssa)
 							int var_num = ssa_op->op1_use;
 							zend_ssa_var *var = ssa->vars + var_num;
 
-							/* TODO: move to somewhere common */
-							int op1_new = ssa_op->op1_use;
-							/* zend_ssa_rename_var_uses() clear use_chain & phi_use_chain for us */
-							zend_ssa_rename_var_uses(ssa, ssa_op->op1_def, op1_new, true);
-							ssa->vars[ssa_op->op1_def].definition = -1;
-							ssa_op->op1_def = -1;
+							if (ssa_op->op1_def >= 0) {
+								/* TODO: move to somewhere common */
+								int op1_new = ssa_op->op1_use;
+								/* zend_ssa_rename_var_uses() clear use_chain & phi_use_chain for us */
+								zend_ssa_rename_var_uses(ssa, ssa_op->op1_def, op1_new, true);
+								ssa->vars[ssa_op->op1_def].definition = -1;
+								ssa_op->op1_def = -1;
+							}
 							//ZEND_ASSERT(ssa_op->op1_def < 0);
 							zend_ssa_unlink_use_chain(ssa, op_num, ssa_op->op1_use);
 							ssa_op->op1_use = -1;