21.11 Implicit Calls to Library Routines

Here is an explanation of implicit calls to library routines.

MULSI3_LIBCALL

A C string constant giving the name of the function to call for multiplication of one signed full-word by another. If you do not define this macro, the default name is used, which is __mulsi3, a function defined in `libgcc.a'.

DIVSI3_LIBCALL

A C string constant giving the name of the function to call for division of one signed full-word by another. If you do not define this macro, the default name is used, which is __divsi3, a function defined in `libgcc.a'.

UDIVSI3_LIBCALL

A C string constant giving the name of the function to call for division of one unsigned full-word by another. If you do not define this macro, the default name is used, which is __udivsi3, a function defined in `libgcc.a'.

MODSI3_LIBCALL

A C string constant giving the name of the function to call for the remainder in division of one signed full-word by another. If you do not define this macro, the default name is used, which is __modsi3, a function defined in `libgcc.a'.

UMODSI3_LIBCALL

A C string constant giving the name of the function to call for the remainder in division of one unsigned full-word by another. If you do not define this macro, the default name is used, which is __umodsi3, a function defined in `libgcc.a'.

MULDI3_LIBCALL

A C string constant giving the name of the function to call for multiplication of one signed double-word by another. If you do not define this macro, the default name is used, which is __muldi3, a function defined in `libgcc.a'.

DIVDI3_LIBCALL

A C string constant giving the name of the function to call for division of one signed double-word by another. If you do not define this macro, the default name is used, which is __divdi3, a function defined in `libgcc.a'.

UDIVDI3_LIBCALL

A C string constant giving the name of the function to call for division of one unsigned full-word by another. If you do not define this macro, the default name is used, which is __udivdi3, a function defined in `libgcc.a'.

MODDI3_LIBCALL

A C string constant giving the name of the function to call for the remainder in division of one signed double-word by another. If you do not define this macro, the default name is used, which is __moddi3, a function defined in `libgcc.a'.

UMODDI3_LIBCALL

A C string constant giving the name of the function to call for the remainder in division of one unsigned full-word by another. If you do not define this macro, the default name is used, which is __umoddi3, a function defined in `libgcc.a'.

INIT_TARGET_OPTABS

Define this macro as a C statement that declares additional library routines renames existing ones. init_optabs calls this macro after initializing all the normal library routines.

FLOAT_LIB_COMPARE_RETURNS_BOOL

Define this macro as a C statement that returns nonzero if a call to the floating point comparison library function will return a boolean value that indicates the result of the comparison. It should return zero if one of gcc's own libgcc functions is called.

Most ports don't need to define this macro.

TARGET_EDOM

The value of EDOM on the target machine, as a C integer constant expression. If you don't define this macro, GCC does not attempt to deposit the value of EDOM into errno directly. Look in `/usr/include/errno.h' to find the value of EDOM on your system.

If you do not define TARGET_EDOM, then compiled code reports domain errors by calling the library function and letting it report the error. If mathematical functions on your system use matherr when there is an error, then you should leave TARGET_EDOM undefined so that matherr is used normally.

GEN_ERRNO_RTX

Define this macro as a C expression to create an rtl expression that refers to the global "variable" errno. (On certain systems, errno may not actually be a variable.) If you don't define this macro, a reasonable default is used.

TARGET_MEM_FUNCTIONS

Define this macro if GCC should generate calls to the ISO C (and System V) library functions memcpy, memmove and memset rather than the BSD functions bcopy and bzero.

LIBGCC_NEEDS_DOUBLE

Define this macro if only float arguments cannot be passed to library routines (so they must be converted to double). This macro affects both how library calls are generated and how the library routines in `libgcc1.c' accept their arguments. It is useful on machines where floating and fixed point arguments are passed differently, such as the i860.

FLOAT_ARG_TYPE

Define this macro to override the type used by the library routines to pick up arguments of type float. (By default, they use a union of float and int.)

The obvious choice would be float---but that won't work with traditional C compilers that expect all arguments declared as float to arrive as double. To avoid this conversion, the library routines ask for the value as some other type and then treat it as a float.

On some systems, no other type will work for this. For these systems, you must use LIBGCC_NEEDS_DOUBLE instead, to force conversion of the values double before they are passed.

FLOATIFY (passed-value)

Define this macro to override the way library routines redesignate a float argument as a float instead of the type it was passed as. The default is an expression which takes the float field of the union.

FLOAT_VALUE_TYPE

Define this macro to override the type used by the library routines to return values that ought to have type float. (By default, they use int.)

The obvious choice would be float---but that won't work with traditional C compilers gratuitously convert values declared as float into double.

INTIFY (float-value)

Define this macro to override the way the value of a float-returning library routine should be packaged in order to return it. These functions are actually declared to return type FLOAT_VALUE_TYPE (normally int).

These values can't be returned as type float because traditional C compilers would gratuitously convert the value to a double.

A local variable named intify is always available when the macro INTIFY is used. It is a union of a float field named f and a field named i whose type is FLOAT_VALUE_TYPE or int.

If you don't define this macro, the default definition works by copying the value through that union.

nongcc_SI_type

Define this macro as the name of the data type corresponding to SImode in the system's own C compiler.

You need not define this macro if that type is long int, as it usually is.

nongcc_word_type

Define this macro as the name of the data type corresponding to the word_mode in the system's own C compiler.

You need not define this macro if that type is long int, as it usually is.

perform_...

Define these macros to supply explicit C statements to carry out various arithmetic operations on types float and double in the library routines in `libgcc1.c'. See that file for a full list of these macros and their arguments.

On most machines, you don't need to define any of these macros, because the C compiler that comes with the system takes care of doing them.

NEXT_OBJC_RUNTIME

Define this macro to generate code for Objective C message sending using the calling convention of the NeXT system. This calling convention involves passing the object, the selector and the method arguments all at once to the method-lookup library function.

The default calling convention passes just the object and the selector to the lookup function, which returns a pointer to the method.