Implement optimization to cast values instead of verifying the type

Zend/Optimizer/dfa_pass.c

@@ -316,6 +316,54 @@ static inline bool can_elide_return_type_check(
 	return false;
 }
 
+static inline bool can_return_value_safely_be_coerced(
+	const zend_op_array *op_array, const zend_ssa *ssa, const zend_ssa_op *ssa_op, zend_op *opline
+) {
+	const uint32_t return_type_mask = ZEND_TYPE_FULL_MASK(op_array->arg_info[-1].type);
+	const zend_ssa_var_info *use_info = &ssa->var_info[ssa_op->op1_use];
+
+	/* Type preference order: int -> float -> string -> bool */
+	/* Can always safely cast booleans to inter */
+	if (return_type_mask & MAY_BE_LONG) {
+		if (use_info->type & MAY_BE_BOOL) {
+			opline->opcode = ZEND_CAST_VALUE_FOR_RETURN_TYPE;
+			opline->extended_value = IS_LONG;
+			return true;
+		}
+		return false;
+	}
+	if (return_type_mask & MAY_BE_DOUBLE) {
+		/* Can always safely cast booleans, and integers to float */
+		if (use_info->type & (MAY_BE_LONG|MAY_BE_BOOL)) {
+			opline->opcode = ZEND_CAST_VALUE_FOR_RETURN_TYPE;
+			opline->extended_value = IS_DOUBLE;
+			return true;
+		}
+		return false;
+	}
+	/* Can always safely cast booleans, and integers to string,
+	 * float value must not be NAN */
+	if (return_type_mask & MAY_BE_STRING) {
+		if (use_info->type & (MAY_BE_LONG|MAY_BE_BOOL)) {
+			opline->opcode = ZEND_CAST_VALUE_FOR_RETURN_TYPE;
+			opline->extended_value = IS_STRING;
+			return true;
+		}
+		return false;
+	}
+	return false;
+	if ((return_type_mask & MAY_BE_BOOL) == MAY_BE_BOOL) {
+		/* Can always safely cast integers and strings to bool,
+		 * float value must not be NAN */
+		if (use_info->type & (MAY_BE_LONG|MAY_BE_STRING)) {
+			opline->opcode = ZEND_CAST_VALUE_FOR_RETURN_TYPE;
+			opline->extended_value = IS_FALSE;
+			return true;
+		}
+		return false;
+	}
+}
+
 static bool opline_supports_assign_contraction(
 		zend_op_array *op_array, zend_ssa *ssa, zend_op *opline, int src_var, uint32_t cv_var) {
 	if (opline->opcode == ZEND_NEW) {
@@ -1287,6 +1335,8 @@ void zend_dfa_optimize_op_array(zend_op_array *op_array, zend_optimizer_ctx *ctx
 
 						MAKE_NOP(opline);
 						remove_nops = 1;
+					} else if (can_return_value_safely_be_coerced(op_array, ssa, &ssa->ops[op_1], opline)) {
+						continue;
 					}
 				}
 			}

Zend/zend_vm_def.h

@@ -22,6 +22,8 @@
  * php zend_vm_gen.php
  */
 
+#include "zend_variables.h"
+
 ZEND_VM_HELPER(zend_add_helper, ANY, ANY, zval *op_1, zval *op_2)
 {
 	USE_OPLINE
@@ -4532,6 +4534,40 @@ ZEND_VM_COLD_CONST_HANDLER(124, ZEND_VERIFY_RETURN_TYPE, CONST|TMP|VAR|UNUSED|CV
 	}
 }
 
+ZEND_VM_COLD_CONST_HANDLER(45, ZEND_CAST_VALUE_FOR_RETURN_TYPE, TMP|VAR|CV, UNUSED)
+{
+	USE_OPLINE
+	zval *retval_ptr = GET_OP1_ZVAL_PTR_UNDEF(BP_VAR_R);
+	ZEND_ASSERT(!Z_ISREF_P(retval_ptr));
+
+	switch (opline->extended_value) {
+		case IS_LONG: {
+			zend_long lval = zval_get_long(retval_ptr);
+			zval_ptr_dtor(retval_ptr);
+			ZVAL_LONG(retval_ptr, lval);
+			break;
+		}
+		case IS_DOUBLE: {
+			double dval = zval_get_double(retval_ptr);
+			zval_ptr_dtor(retval_ptr);
+			ZVAL_DOUBLE(retval_ptr, dval);
+			break;
+		}
+		case IS_STRING:
+			/* retval_ptr cannot be a refcounted value */
+			ZVAL_STR(retval_ptr, zval_get_string(retval_ptr));
+			break;
+		case IS_FALSE: { /* Used for booleans */
+			bool bval = i_zend_is_true(retval_ptr);
+			zval_ptr_dtor(retval_ptr);
+			ZVAL_BOOL(retval_ptr, bval);
+			break;
+		}
+		/* Default case assert? */
+	}
+	ZEND_VM_NEXT_OPCODE();
+}
+
 ZEND_VM_COLD_HANDLER(201, ZEND_VERIFY_NEVER_TYPE, UNUSED, UNUSED)
 {
 	SAVE_OPLINE();