已经找到标准答案，在Delphi帮助中：标题:Parameter passingParameters are transferred to procedures and functions via CPU registers or the stack, depending on the routine抯 calling convention. For information about calling conventions, see Calling conventions. Variable (var) parameters are always passed by reference, as 32-bit pointers that point to the actual storage location. Value and constant (const) parameters are passed by value or by reference, depending on the type and size of the parameter:An ordinal parameter is passed as an 8-bit, 16-bit, 32-bit, or 64-bit value, using the same format as a variable of the corresponding type. A real parameter is always passed on the stack. A Single parameter occupies 4 bytes, and a Double, Comp, or Currency parameter occupies 8 bytes. A Real48 occupies 8 bytes, with the Real48 value stored in the lower 6 bytes. An Extended occupies 12 bytes, with the Extended value stored in the lower 10 bytes.A short-string parameter is passed as a 32-bit pointer to a short string. A long-string or dynamic-array parameter is passed as a 32-bit pointer to the dynamic memory block allocated for the long string. The value nil is passed for an empty long string. A pointer, class, class-reference, or procedure-pointer parameter is passed as a 32-bit pointer. A method pointer is passed on the stack as two 32-bit pointers. The instance pointer is pushed before the method pointer so that the method pointer occupies the lowest address.Under the register and pascal conventions, a variant parameter is passed as a 32-bit pointer to a Variant value. Sets, records, and static arrays of 1, 2, or 4 bytes are passed as 8-bit, 16-bit, and 32-bit values. Larger sets, records, and static arrays are passed as 32-bit pointers to the value. An exception to this rule is that records are always passed directly on the stack under the cdecl, stdcall, and safecall conventions; the size of a record passed this way is rounded upward to the nearest double-word boundary.An open-array parameter is passed as two 32-bit values. The first value is a pointer to the array data, and the second value is one less than the number of elements in the array.When two parameters are passed on the stack, each parameter occupies a multiple of 4 bytes (a whole number of double words). For an 8-bit or 16-bit parameter, even though the parameter occupies only a byte or a word, it is passed as a double word. The contents of the unused parts of the double word are undefined. Under the pascal, cdecl, stdcall and safecall conventions, all parameters are passed on the stack. Under the pascal convention, parameters are pushed in the order of their declaration (left-to-right), so that the first parameter ends up at the highest address and the last parameter ends up at the lowest address. Under the cdecl, stdcall, and safecall conventions, parameters are pushed in reverse order of declaration (right-to-left), so that the first parameter ends up at the lowest address and the last parameter ends up at the highest address.Under the register convention, up to three parameters are passed in CPU registers, and the rest (if any) are passed on the stack. The parameters are passed in order of declaration (as with the pascal convention), and the first three parameters that qualify are passed in the EAX, EDX, and ECX registers, in that order. Real, method-pointer, variant, Int64, and structured types do not qualify as register parameters, but all other parameters do. If more than three parameters qualify as register parameters, the first three are passed in EAX, EDX, and ECX, and the remaining parameters are pushed onto the stack in order of declaration. For example, given the declarationprocedure Test(A: Integer; var B: Char; C: Double; const D: string; E: Pointer);a call to Test passes A in EAX as a 32-bit integer, B in EDX as a pointer to a Char, and D in ECX as a pointer to a long-string memory block; C and E are pushed onto the stack as two double-words and a 32-bit pointer, in that order.Register saving conventionsProcedures and functions must preserve the EBX, ESI, EDI, and EBP registers, but can modify the EAX, EDX, and ECX registers. When implementing a constructor or destructor in assembler, be sure to preserve the DL register. Procedures and functions are invoked with the assumption that the CPU抯 direction flag is cleared (corresponding to a CLD instruction) and must return with the direction flag cleared.
已经找到标准答案，在Delphi帮助中：标题:Parameter passingParameters are transferred to procedures and functions via CPU registers or the stack, depending on the routine抯 calling convention. For information about calling conventions, see Calling conventions.
Variable (var) parameters are always passed by reference, as 32-bit pointers that point to the actual storage location.
Value and constant (const) parameters are passed by value or by reference, depending on the type and size of the parameter:An ordinal parameter is passed as an 8-bit, 16-bit, 32-bit, or 64-bit value, using the same format as a variable of the corresponding type.
A real parameter is always passed on the stack. A Single parameter occupies 4 bytes, and a Double, Comp, or Currency parameter occupies 8 bytes. A Real48 occupies 8 bytes, with the Real48 value stored in the lower 6 bytes. An Extended occupies 12 bytes, with the Extended value stored in the lower 10 bytes.A short-string parameter is passed as a 32-bit pointer to a short string.
A long-string or dynamic-array parameter is passed as a 32-bit pointer to the dynamic memory block allocated for the long string. The value nil is passed for an empty long string.
A pointer, class, class-reference, or procedure-pointer parameter is passed as a 32-bit pointer.
A method pointer is passed on the stack as two 32-bit pointers. The instance pointer is pushed before the method pointer so that the method pointer occupies the lowest address.Under the register and pascal conventions, a variant parameter is passed as a 32-bit pointer to a Variant value.
Sets, records, and static arrays of 1, 2, or 4 bytes are passed as 8-bit, 16-bit, and 32-bit values. Larger sets, records, and static arrays are passed as 32-bit pointers to the value. An exception to this rule is that records are always passed directly on the stack under the cdecl, stdcall, and safecall conventions; the size of a record passed this way is rounded upward to the nearest double-word boundary.An open-array parameter is passed as two 32-bit values. The first value is a pointer to the array data, and the second value is one less than the number of elements in the array.When two parameters are passed on the stack, each parameter occupies a multiple of 4 bytes (a whole number of double words). For an 8-bit or 16-bit parameter, even though the parameter occupies only a byte or a word, it is passed as a double word. The contents of the unused parts of the double word are undefined.
Under the pascal, cdecl, stdcall and safecall conventions, all parameters are passed on the stack. Under the pascal convention, parameters are pushed in the order of their declaration (left-to-right), so that the first parameter ends up at the highest address and the last parameter ends up at the lowest address. Under the cdecl, stdcall, and safecall conventions, parameters are pushed in reverse order of declaration (right-to-left), so that the first parameter ends up at the lowest address and the last parameter ends up at the highest address.Under the register convention, up to three parameters are passed in CPU registers, and the rest (if any) are passed on the stack. The parameters are passed in order of declaration (as with the pascal convention), and the first three parameters that qualify are passed in the EAX, EDX, and ECX registers, in that order. Real, method-pointer, variant, Int64, and structured types do not qualify as register parameters, but all other parameters do. If more than three parameters qualify as register parameters, the first three are passed in EAX, EDX, and ECX, and the remaining parameters are pushed onto the stack in order of declaration. For example, given the declarationprocedure Test(A: Integer; var B: Char; C: Double; const D: string; E: Pointer);a call to Test passes A in EAX as a 32-bit integer, B in EDX as a pointer to a Char, and D in ECX as a pointer to a long-string memory block; C and E are pushed onto the stack as two double-words and a 32-bit pointer, in that order.Register saving conventionsProcedures and functions must preserve the EBX, ESI, EDI, and EBP registers, but can modify the EAX, EDX, and ECX registers. When implementing a constructor or destructor in assembler, be sure to preserve the DL register. Procedures and functions are invoked with the assumption that the CPU抯 direction flag is cleared (corresponding to a CLD instruction) and must return with the direction flag cleared.