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13f1d53b68
Sometimes, one wants to accept several types for a given parameter. zpp has special functionality for detecting the NULL type, since the NULL type is frequently used to skip parameters. However, supporting several types is otherwise very tedious. There are many cases where this situation arises -- for instance one may want to accept an arbitrary number of integer and expect them in an array, but allow a bare integer too; one may want to accept something that will be used as an array key (which can be either and int or a string); one may want to accept integer and double numbers. A search for IS_LONG reveals many situations where this need arises. The usual solution is to fetch the argument with 'z'/'Z', check its type, and then convert the argument, e.g. with convert_to_long_ex(). As explain in the last commit, this has different behavior and generates inconsistency. Another -- even more flawed strategy --, is to try zpp with a specific format, forcing it quiet, and if it fails retrying with another form. But because zpp changes the arguments directly in the stack (for instance, using "l" converts the zval in the stack to IS_LONG), the arguments may look different after the first zpp, leaving subtle bugs. This commit also allows more complex scenarios, for instance where the expected type of one parameter depends on other parameters.
ZEND_VM
=======
ZEND_VM architecture allows specializing opcode handlers according to op_type
fields and using different execution methods (call threading, switch threading
and direct threading). As a result ZE2 got more than 20% speedup on raw PHP
code execution (with specialized executor and direct threading execution
method). As in most PHP applications raw execution speed isn't the limiting
factor but system calls and database callls are, your mileage with this patch
will vary.
Most parts of the old zend_execute.c go into zend_vm_def.h. Here you can
find opcode handlers and helpers. The typical opcode handler template looks
like this:
ZEND_VM_HANDLER(<OPCODE-NUMBER>, <OPCODE>, <OP1_TYPES>, <OP2_TYPES>)
{
<HANDLER'S CODE>
}
<OPCODE-NUMBER> is a opcode number (0, 1, ...)
<OPCODE> is an opcode name (ZEN_NOP, ZEND_ADD, :)
<OP1_TYPES> & <OP2_TYPES> are masks for allowed operand op_types. Specializer
will generate code only for defined combination of types. You can use any
combination of the following op_types UNUSED, CONST, VAR, TMP and CV also
you can use ANY mask to disable specialization according operand's op_type.
<HANDLER'S CODE> is a handler's code itself. For most handlers it stills the
same as in old zend_execute.c, but now it uses macros to access opcode operands
and some internal executor data.
You can see the conformity of new macros to old code in the following list:
EXECUTE_DATA
execute_data
ZEND_VM_DISPATCH_TO_HANDLER(<OP>)
return <OP>_helper(ZEND_OPCODE_HANDLER_ARGS_PASSTHRU)
ZEND_VM_DISPATCH_TO_HELPER(<NAME>)
return <NAME>(ZEND_OPCODE_HANDLER_ARGS_PASSTHRU)
ZEND_VM_DISPATCH_TO_HELPER_EX(<NAME>,<PARAM>,<VAL>)
return <NAME>(<VAL>, ZEND_OPCODE_HANDLER_ARGS_PASSTHRU)
ZEND_VM_CONTINUE()
return 0
ZEND_VM_NEXT_OPCODE()
NEXT_OPCODE()
ZEND_VM_SET_OPCODE(<TARGET>
SET_OPCODE(<TARGET>
ZEND_VM_INC_OPCODE()
INC_OPCOD()
ZEND_VM_RETURN_FROM_EXECUTE_LOOP()
RETURN_FROM_EXECUTE_LOOP()
ZEND_VM_C_LABEL(<LABEL>):
<LABEL>:
ZEND_VM_C_GOTO(<LABEL>)
goto <LABEL>
OP<X>_TYPE
opline->op<X>.op_type
GET_OP<X>_ZVAL_PTR(<TYPE>)
get_zval_ptr(&opline->op<X>, EX(Ts), &free_op<X>, <TYPE>)
GET_OP<X>_ZVAL_PTR_PTR(<TYPE>)
get_zval_ptr_ptr(&opline->op<X>, EX(Ts), &free_op<X>, <TYPE>)
GET_OP<X>_OBJ_ZVAL_PTR(<TYPE>)
get_obj_zval_ptr(&opline->op<X>, EX(Ts), &free_op<X>, <TYPE>)
GET_OP<X>_OBJ_ZVAL_PTR_PTR(<TYPE>)
get_obj_zval_ptr_ptr(&opline->op<X>, EX(Ts), &free_op<X>, <TYPE>)
IS_OP<X>_TMP_FREE()
IS_TMP_FREE(free_op<X>)
FREE_OP<X>()
FREE_OP(free_op<X>)
FREE_OP<X>_IF_VAR()
FREE_VAR(free_op<X>)
FREE_OP<X>_VAR_PTR()
FREE_VAR_PTR(free_op<X>)
Executor's helpers can be defined without parameters or with one parameter.
This is done with the following constructs:
ZEND_VM_HELPER(<HELPER-NAME>, <OP1_TYPES>, <OP2_TYPES>)
{
<HELPER'S CODE>
}
ZEND_VM_HELPER_EX(<HELPER-NAME>, <OP1_TYPES>, <OP2_TYPES>, <PARAM_SPEC>)
{
<HELPER'S CODE>
}
Executor's code is generated by PHP script zend_vm_gen.php it uses zend_vm_def.h
and zend_vm_execute.skl as input and produces zend_vm_opcodes.h and
zend_vm_execute.h. The first file is a list of opcode definitions. It is
included from zend_compile.h. The second one is an executor code itself. It is
included from zend_execute.c.
zend_vm_gen.php can produce different kind of executors. You can select
different opcode threading model using --with-vm-kind=CALL|SWITCH|GOTO. You can
disable opcode specialization using --without-specializer. You can include or
exclude old executor together with specialized one using --without-old-executor.
At last you can debug executor using original zend_vm_def.h or generated file
zend_vm_execute.h. Debugging with original file requires --with-lines
option. By default ZE2 uses the following command to generate executor:
$ php zend_vm_gen.php --with-vm-kind=CALL
Zend Engine II currently includes two executors during the build process, one
is the specialized version and the other is the old one non-specialized with
function handlers. By default Zend Engine II uses the specialized one but you
can switch to the old executor at runtime by calling zend_vm_use_old_executor().