Implement INIT_FCALL offset optimization

Closes GH-13634

Author: iluuu1994

Zend/zend_compile.c

@@ -4807,7 +4807,8 @@ static void zend_compile_call(znode *result, zend_ast *ast, uint32_t type) /* {{
 		zend_op *opline;
 
 		lcname = zend_string_tolower(Z_STR_P(name));
-		fbc = zend_hash_find_ptr(CG(function_table), lcname);
+		zval *fbc_zv = zend_hash_find(CG(function_table), lcname);
+		fbc = fbc_zv ? Z_PTR_P(fbc_zv) : NULL;
 
 		/* Special assert() handling should apply independently of compiler flags. */
 		if (fbc && zend_string_equals_literal(lcname, "assert") && !is_callable_convert) {
@@ -4842,6 +4843,12 @@ static void zend_compile_call(znode *result, zend_ast *ast, uint32_t type) /* {{
 		opline = zend_emit_op(NULL, ZEND_INIT_FCALL, NULL, &name_node);
 		opline->result.num = zend_alloc_cache_slot();
 
+		/* Store offset to function from symbol table in op2.extra. */
+		if (fbc->type == ZEND_INTERNAL_FUNCTION) {
+			Bucket *fbc_bucket = (Bucket*)((uintptr_t)fbc_zv - XtOffsetOf(Bucket, val));
+			Z_EXTRA_P(CT_CONSTANT(opline->op2)) = fbc_bucket - CG(function_table)->arData;
+		}
+
 		zend_compile_call_common(result, args_ast, fbc, ast->lineno);
 	}
 }

Zend/zend_vm_def.h

@@ -3959,6 +3959,24 @@ ZEND_VM_HOT_HANDLER(61, ZEND_INIT_FCALL, NUM, CONST, NUM|CACHE_SLOT)
 	ZEND_VM_NEXT_OPCODE();
 }
 
+ZEND_VM_HOT_TYPE_SPEC_HANDLER(ZEND_INIT_FCALL, Z_EXTRA_P(RT_CONSTANT(op, op->op2)) != 0, ZEND_INIT_FCALL_OFFSET, NUM, CONST, NUM|CACHE_SLOT)
+{
+	USE_OPLINE
+	zend_function *fbc;
+	zend_execute_data *call;
+	fbc = CACHED_PTR(opline->result.num);
+	if (UNEXPECTED(fbc == NULL)) {
+		fbc = Z_PTR(EG(function_table)->arData[Z_EXTRA_P(RT_CONSTANT(opline, opline->op2))].val);
+		CACHE_PTR(opline->result.num, fbc);
+	}
+	call = _zend_vm_stack_push_call_frame_ex(
+		opline->op1.num, ZEND_CALL_NESTED_FUNCTION,
+		fbc, opline->extended_value, NULL);
+	call->prev_execute_data = EX(call);
+	EX(call) = call;
+	ZEND_VM_NEXT_OPCODE();
+}
+
 ZEND_VM_HOT_HANDLER(129, ZEND_DO_ICALL, ANY, ANY, SPEC(RETVAL,OBSERVER))
 {
 	USE_OPLINE