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109 lines
4.0 KiB
Plaintext
109 lines
4.0 KiB
Plaintext
ZEND_VM
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=======
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ZEND_VM architecture allows specializing opcode handlers according to op_type
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fields and using different execution methods (call threading, switch threading
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and direct threading). As a result ZE2 got more than 20% speedup on raw PHP
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code execution (with specialized executor and direct threading execution
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method). As in most PHP applications raw execution speed isn't the limiting
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factor but system calls and database callls are, your mileage with this patch
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will vary.
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Most parts of the old zend_execute.c go into zend_vm_def.h. Here you can
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find opcode handlers and helpers. The typical opcode handler template looks
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like this:
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ZEND_VM_HANDLER(<OPCODE-NUMBER>, <OPCODE>, <OP1_TYPES>, <OP2_TYPES>)
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{
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<HANDLER'S CODE>
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}
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<OPCODE-NUMBER> is a opcode number (0, 1, ...)
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<OPCODE> is an opcode name (ZEN_NOP, ZEND_ADD, :)
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<OP1_TYPES> & <OP2_TYPES> are masks for allowed operand op_types. Specializer
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will generate code only for defined combination of types. You can use any
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combination of the following op_types UNUSED, CONST, VAR, TMP and CV also
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you can use ANY mask to disable specialization according operand's op_type.
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<HANDLER'S CODE> is a handler's code itself. For most handlers it stills the
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same as in old zend_execute.c, but now it uses macros to access opcode operands
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and some internal executor data.
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You can see the conformity of new macros to old code in the following list:
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EXECUTE_DATA
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execute_data
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ZEND_VM_DISPATCH_TO_HANDLER(<OP>)
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return <OP>_helper(ZEND_OPCODE_HANDLER_ARGS_PASSTHRU)
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ZEND_VM_DISPATCH_TO_HELPER(<NAME>)
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return <NAME>(ZEND_OPCODE_HANDLER_ARGS_PASSTHRU)
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ZEND_VM_DISPATCH_TO_HELPER_EX(<NAME>,<PARAM>,<VAL>)
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return <NAME>(<VAL>, ZEND_OPCODE_HANDLER_ARGS_PASSTHRU)
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ZEND_VM_CONTINUE()
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return 0
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ZEND_VM_NEXT_OPCODE()
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NEXT_OPCODE()
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ZEND_VM_SET_OPCODE(<TARGET>
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SET_OPCODE(<TARGET>
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ZEND_VM_INC_OPCODE()
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INC_OPCOD()
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ZEND_VM_RETURN_FROM_EXECUTE_LOOP()
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RETURN_FROM_EXECUTE_LOOP()
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ZEND_VM_C_LABEL(<LABEL>):
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<LABEL>:
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ZEND_VM_C_GOTO(<LABEL>)
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goto <LABEL>
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OP<X>_TYPE
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opline->op<X>.op_type
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GET_OP<X>_ZVAL_PTR(<TYPE>)
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get_zval_ptr(&opline->op<X>, EX(Ts), &free_op<X>, <TYPE>)
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GET_OP<X>_ZVAL_PTR_PTR(<TYPE>)
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get_zval_ptr_ptr(&opline->op<X>, EX(Ts), &free_op<X>, <TYPE>)
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GET_OP<X>_OBJ_ZVAL_PTR(<TYPE>)
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get_obj_zval_ptr(&opline->op<X>, EX(Ts), &free_op<X>, <TYPE>)
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GET_OP<X>_OBJ_ZVAL_PTR_PTR(<TYPE>)
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get_obj_zval_ptr_ptr(&opline->op<X>, EX(Ts), &free_op<X>, <TYPE>)
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IS_OP<X>_TMP_FREE()
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IS_TMP_FREE(free_op<X>)
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FREE_OP<X>()
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FREE_OP(free_op<X>)
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FREE_OP<X>_IF_VAR()
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FREE_VAR(free_op<X>)
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FREE_OP<X>_VAR_PTR()
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FREE_VAR_PTR(free_op<X>)
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Executor's helpers can be defined without parameters or with one parameter.
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This is done with the following constructs:
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ZEND_VM_HELPER(<HELPER-NAME>, <OP1_TYPES>, <OP2_TYPES>)
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{
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<HELPER'S CODE>
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}
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ZEND_VM_HELPER_EX(<HELPER-NAME>, <OP1_TYPES>, <OP2_TYPES>, <PARAM_SPEC>)
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{
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<HELPER'S CODE>
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}
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Executor's code is generated by PHP script zend_vm_gen.php it uses zend_vm_def.h
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and zend_vm_execute.skl as input and produces zend_vm_opcodes.h and
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zend_vm_execute.h. The first file is a list of opcode definitions. It is
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included from zend_compile.h. The second one is an executor code itself. It is
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included from zend_execute.c.
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zend_vm_gen.php can produce different kind of executors. You can select
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different opcode threading model using --with-vm-kind=CALL|SWITCH|GOTO. You can
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disable opcode specialization using --without-specializer. You can include or
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exclude old executor together with specialized one using --without-old-executor.
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At last you can debug executor using original zend_vm_def.h or generated file
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zend_vm_execute.h. Debugging with original file requires --with-lines
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option. By default ZE2 uses the following command to generate executor:
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$ php zend_vm_gen.php --with-vm-kind=CALL
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Zend Engine II currently includes two executors during the build process, one
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is the specialized version and the other is the old one non-specialized with
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function handlers. By default Zend Engine II uses the specialized one but you
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can switch to the old executor at runtime by calling zend_vm_use_old_executor().
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