Add JIT support for generic constructor arg inference

Infers generic type arguments from constructor parameters in JIT-compiled
code paths. Adds zend_jit_infer_generic_ctor_args helper and hooks it
into both the IR backend and VM leave-func helpers to run before $this
is released.

Co-Authored-By: Llama <noreply@meta.com>

Author: php-generics

ext/opcache/jit/zend_jit_helpers.c

@@ -2058,6 +2058,16 @@ static void ZEND_FASTCALL zend_jit_verify_generic_return(
 	zend_verify_return_error((zend_function*)op_array, arg);
 }
 
+static void ZEND_FASTCALL zend_jit_infer_generic_ctor_args(zend_execute_data *execute_data)
+{
+	if (UNEXPECTED(EX(func)->common.fn_flags & ZEND_ACC_CTOR)) {
+		zend_object *obj = Z_OBJ(execute_data->This);
+		if (obj->ce->generic_params_info && !obj->generic_args) {
+			zend_infer_generic_args_from_constructor(obj, execute_data);
+		}
+	}
+}
+
 static void ZEND_FASTCALL zend_jit_fetch_obj_r_slow(zend_object *zobj)
 {
 	zval *retval;

ext/opcache/jit/zend_jit_ir.c

@@ -3137,6 +3137,7 @@ static void zend_jit_setup_disasm(void)
 	REGISTER_HELPER(zend_jit_verify_arg_slow);
 	REGISTER_HELPER(zend_jit_verify_generic_arg);
 	REGISTER_HELPER(zend_jit_verify_generic_return);
+	REGISTER_HELPER(zend_jit_infer_generic_ctor_args);
 	REGISTER_HELPER(zend_missing_arg_error);
 	REGISTER_HELPER(zend_jit_only_vars_by_reference);
 	REGISTER_HELPER(zend_jit_leave_func_helper);
@@ -11286,6 +11287,8 @@ static int zend_jit_leave_func(zend_jit_ctx         *jit,
 			fast_path = ir_END();
 			ir_IF_TRUE(if_release);
 		}
+		// JIT: Infer generic args from constructor before releasing $this
+		ir_CALL_1(IR_VOID, ir_CONST_FC_FUNC(zend_jit_infer_generic_ctor_args), jit_FP(jit));
 		// JIT: OBJ_RELEASE(execute_data->This))
 		jit_OBJ_RELEASE(jit, ir_LOAD_A(jit_EX(This.value.obj)));
 		if (fast_path) {

ext/opcache/jit/zend_jit_vm_helpers.c

@@ -23,6 +23,7 @@
 #include "Zend/zend_closures.h"
 #include "Zend/zend_constants.h"
 #include "Zend/zend_API.h"
+#include "Zend/zend_generics.h"
 
 #include <ZendAccelerator.h>
 #include "Optimizer/zend_func_info.h"
@@ -59,6 +60,13 @@ ZEND_OPCODE_HANDLER_RET ZEND_OPCODE_HANDLER_CCONV zend_jit_leave_func_helper_tai
 
 		zend_vm_stack_free_extra_args_ex(call_info, execute_data);
 		if (UNEXPECTED(call_info & ZEND_CALL_RELEASE_THIS)) {
+			/* Infer generic args from constructor before releasing $this */
+			if (UNEXPECTED(EX(func)->common.fn_flags & ZEND_ACC_CTOR)) {
+				zend_object *obj = Z_OBJ(execute_data->This);
+				if (obj->ce->generic_params_info && !obj->generic_args) {
+					zend_infer_generic_args_from_constructor(obj, execute_data);
+				}
+			}
 			OBJ_RELEASE(Z_OBJ(execute_data->This));
 		} else if (UNEXPECTED(call_info & ZEND_CALL_CLOSURE)) {
 			OBJ_RELEASE(ZEND_CLOSURE_OBJECT(EX(func)));
@@ -110,6 +118,13 @@ ZEND_OPCODE_HANDLER_RET ZEND_FASTCALL zend_jit_leave_nested_func_helper(ZEND_OPC
 
 	zend_vm_stack_free_extra_args_ex(call_info, execute_data);
 	if (UNEXPECTED(call_info & ZEND_CALL_RELEASE_THIS)) {
+		/* Infer generic args from constructor before releasing $this */
+		if (UNEXPECTED(EX(func)->common.fn_flags & ZEND_ACC_CTOR)) {
+			zend_object *obj = Z_OBJ(execute_data->This);
+			if (obj->ce->generic_params_info && !obj->generic_args) {
+				zend_infer_generic_args_from_constructor(obj, execute_data);
+			}
+		}
 		OBJ_RELEASE(Z_OBJ(execute_data->This));
 	} else if (UNEXPECTED(call_info & ZEND_CALL_CLOSURE)) {
 		OBJ_RELEASE(ZEND_CLOSURE_OBJECT(EX(func)));